Method for starting engine and vehicle

Abstract

The invention provides a method for starting an engine and a vehicle, the method is applied to the technical field of hybrid power control, and the method comprises the steps that under the condition that the vehicle needs to start the engine, the target rotating speed of a motor is determined based on the state of a lock-up clutch in a hydraulic torque converter; controlling a motor based on the target rotating speed, and controlling a clutch to increase torque in a sliding friction state, so that the motor drives an engine to rotate; and under the condition that the actual rotating speed of the engine reaches the ignition rotating speed threshold value, the engine is controlled to be ignited to start the engine. According to the method, pause and vibration of the vehicle when the engine is started can be reduced, the stability of the vehicle is improved, and the vehicle using experience of a user is improved.

Description

Technical Field

[0001] This application relates to the field of hybrid power control technology, and more specifically, to a method and vehicle for starting an engine in the field of hybrid power control technology. Background Technology

[0002] Some hybrid vehicles have a single electric motor at the front. When switching from pure electric to hybrid drive, this motor transmits torque through a clutch between the motor and the engine to start the engine. Throughout the start-up process, the motor must be responsible for pure electric drive or energy recovery, while also smoothly outputting additional torque to assist the clutch in driving the engine.

[0003] The existing control logic requests clutch pressurization while simultaneously requesting a matching starting torque from the motor. However, due to inconsistencies in the clutch's hydraulic control, non-linear output torque, varying oil temperatures, different self-learning deviations, and signal transmission delays, the actual clutch pressurization effect is affected, making it difficult to match the motor's torque increase with the clutch's hydraulic pressurization. If the motor torque increases more than the clutch pressurization, the extra torque is transmitted to the transmission output, causing vehicle jerking. If the motor torque increases less than the clutch pressurization, the insufficient torque is transmitted to the transmission output, causing vehicle deceleration jerking, affecting vehicle stability and the user's driving experience. Summary of the Invention

[0004] This application provides a method for starting an engine and a vehicle that can reduce vehicle fuel consumption, avoid energy waste, improve vehicle braking flexibility and comfort, and enhance the user's driving experience.

[0005] In a first aspect, a method for starting an engine is provided, applicable to a hybrid vehicle, the vehicle including an engine, a clutch, an electric motor, a torque converter, and a transmission, wherein the engine is connected to the electric motor via the clutch, and the electric motor is connected to the transmission via the torque converter; the method includes: when the vehicle needs to start the engine, determining a target speed of the electric motor based on the state of the lock-up clutch in the torque converter; controlling the electric motor based on the target speed, and controlling the clutch to increase torque in a slipping state so that the electric motor drives the engine to rotate; and when the actual speed of the engine reaches an ignition speed threshold, controlling the engine to ignite to start the engine.

[0006] In the above technical solution, when the vehicle needs to start the engine, considering that the state of the lock-up clutch in the torque converter affects power transmission and thus the starting of the engine by the motor, the target speed of the motor is determined based on the state of the lock-up clutch in the torque converter. This ensures that the determined target speed matches the current state of the lock-up clutch, guaranteeing that the engine can be started by the motor regardless of the lock-up clutch's state. Controlling the motor based on the target speed allows it to follow a stable target speed, eliminating signal transmission delays and avoiding the problem of vehicle deceleration jerking caused by non-linear clutch pressure during engine start-up. This improves the smoothness of engine start-up and enhances the user's driving experience.

[0007] In conjunction with the first aspect, in some possible implementations, the target speed of the motor is determined based on the state of the lock-up clutch in the hydraulic torque converter, including: controlling the motor to enter a speed control mode when the lock-up clutch is in the open state; determining the drive torque transmitted by the motor to the hydraulic torque converter when the motor enters the speed control mode; and determining the target speed based on the requested torque and drive torque of the motor.

[0008] In the above technical solution, with the lock-up clutch in the open state, it can be determined that the pump impeller and turbine of the hydraulic torque converter are connected by a hydraulic soft connection. At this time, a slip value is allowed between the pump impeller and turbine, and the motor is controllable. The motor then enters speed control mode, and the target speed is determined to control the motor. This speed control mode allows the motor to drive the engine. The motor following a stable target speed eliminates signal transmission delays and the effects of non-linear clutch pressure. This avoids the lag of torque control mode and the large short-term fluctuations in motor torque and clutch torque in torque control mode, which can cause vehicle jerking due to non-linear clutch pressure, thus improving vehicle stability.

[0009] Combining the first aspect and the above implementation methods, in some possible implementation methods, determining the drive torque transmitted from the motor to the hydraulic torque converter includes: obtaining the actual speed of the motor; determining a target coefficient based on the oil temperature of the hydraulic torque converter, the speed ratio of the turbine to the pump impeller, and the torque ratio of the turbine to the pump impeller; and determining the drive torque based on the target coefficient and the actual speed.

[0010] In the above technical solution, considering that the oil temperature of the hydraulic torque converter affects the speed ratio of the turbine and the pump wheel, as well as the torque ratio of the turbine and the pump wheel, the target coefficient is determined by combining the oil temperature of the hydraulic torque converter. This allows for the determination of a target coefficient that is consistent with the current oil temperature, thereby improving the accuracy of determining the drive torque and thus improving the accuracy of the target speed.

[0011] Combining the first aspect and the above implementation methods, in some possible implementation methods, determining the target speed based on the motor's requested torque and drive torque includes: subtracting the drive torque from the requested torque to obtain the target torque; calculating the motor's angular acceleration based on the target torque; obtaining the motor's speed change rate in each cycle based on the angular acceleration and the preset cycle duration; and determining the motor's target speed in each cycle based on the motor's actual speed and speed change rate.

[0012] In the above technical solution, the target torque for increasing the motor speed is obtained by subtracting the drive torque from the requested torque. The angular acceleration of the motor is calculated based on the target torque, and the rate of change of the motor speed in each cycle is determined. The target speed of the drive motor in each cycle can be determined in real time, which improves the accuracy of motor speed control, ensures smooth and efficient engine starting, and improves the stability and safety of the vehicle.

[0013] In combination with the first aspect and the above implementation methods, in some possible implementation methods, the method further includes: obtaining the actual speed of the motor in the previous cycle of the first cycle after calculating the target speed of the motor in the first cycle after entering the speed control mode; determining the speed increment of each cycle based on the speed change rate, and multiplying the speed increment by the cycle delay number to obtain the target speed increment; and determining the target speed of the motor in the first cycle based on the actual speed and the target speed increment.

[0014] Combining the first aspect and the above implementation methods, in some possible implementation methods, the target speed of the motor is determined based on the state of the lock-up clutch in the hydraulic torque converter, including: determining the target slip value that the hydraulic torque converter needs to establish when the lock-up clutch is in the closed state or in the process of closing, and determining the target speed of the motor based on the target slip value.

[0015] In the above technical solution, when it is determined that the lock-up clutch is in the closed state or in the process of closing, the target slip is determined, and the target speed of the motor is determined based on the target slip. This effectively ensures that the lock-up clutch establishes the target slip, which can effectively reduce the impact of the motor on the vehicle's stability when starting the engine. Furthermore, the lock-up clutch is not directly disengaged, ensuring the continuous transmission of motor power and avoiding the problem of power interruption caused by opening the lock-up clutch when starting the engine.

[0016] Combining the first aspect and the above implementation methods, in some possible implementation methods, controlling the motor based on the target speed includes: controlling the lock-up clutch to reduce torque and controlling the motor to adjust the actual speed to the target speed so that the hydraulic torque converter establishes a target slip value; when the speed difference between the actual speed and the target speed of the motor is less than a first preset speed difference, controlling the motor to enter the speed control mode and controlling the motor to maintain the target speed.

[0017] In the above technical solution, by controlling the lock-up clutch to reduce torque, the torque used by the motor for driving is reduced, so that the motor can adjust its own speed to the target speed based on the remaining torque, thereby establishing the target slip of the hydraulic torque converter, ensuring that the engine can be started smoothly based on the motor.

[0018] In combination with the first aspect and the above implementation methods, in some possible implementation methods, after controlling the engine to ignite and start the engine when the actual engine speed reaches the ignition speed threshold, the method further includes: controlling the engine based on the current speed of the motor; when the speed difference between the current engine speed and the current motor speed is less than a second preset speed difference, controlling the clutch to be in a closed state and controlling the motor to exit the speed control mode; after the motor exits the speed control mode, it enters the torque control mode.

[0019] In the above technical solution, by controlling the speed difference between the current engine speed and the current motor speed to be less than a second preset speed difference, the speeds at both ends of the clutch are synchronized, ensuring the smoothness and safety of clutch engagement. Even if the motor exits the speed control mode and enters the torque control mode, the motor can respond to the vehicle's torque request, ensuring the normal operation of the vehicle.

[0020] Combining the first aspect and the above implementation methods, in some possible implementation methods, controlling the motor to exit the speed control mode includes: obtaining the actual torque of the motor in the last cycle of the speed control mode; determining the torque difference between the actual torque and the motor's current requested torque; determining the target torque gradient based on the torque difference, and controlling the motor to adjust from the actual torque to the current requested torque based on the target torque gradient.

[0021] In the above technical solution, when exiting the torque control mode, the target torque gradient is determined based on the torque difference between the actual torque of the motor in the speed control mode and the currently requested torque. Based on the target torque gradient, the torque of the motor can be controlled to gradually transition to the currently requested torque, ensuring a smooth torque transition and further improving the stability of the vehicle.

[0022] Secondly, an engine starting device is provided for a hybrid vehicle, the vehicle including an engine, a clutch, an electric motor, a torque converter, and a transmission, wherein the engine is connected to the electric motor via the clutch, and the electric motor is connected to the transmission via the torque converter; the device includes: a determining module for determining a target speed of the electric motor based on the state of the lock-up clutch in the torque converter when the vehicle needs to start the engine; a first control module for controlling the electric motor based on the target speed and controlling the clutch to increase torque in a slipping state so that the electric motor drives the engine to rotate; and a second control module for controlling the engine to ignite to start the engine when the actual engine speed reaches the ignition speed threshold.

[0023] In conjunction with the second aspect, in some possible implementations, the determining module is specifically used to: control the motor to enter the speed control mode when the lock-up clutch is in the open state; determine the drive torque transmitted by the motor to the hydraulic torque converter when the motor enters the speed control mode; and determine the target speed based on the motor's requested torque and drive torque.

[0024] In combination with the second aspect and the above implementation methods, in some possible implementation methods, the determining module is specifically used to: determine the driving torque transmitted from the motor to the hydraulic torque converter, including: obtaining the actual speed of the motor; determining the target coefficient based on the oil temperature of the hydraulic torque converter, the speed ratio of the turbine to the pump wheel, and the torque ratio of the turbine to the pump wheel; and determining the driving torque based on the target coefficient and the actual speed.

[0025] Combining the second aspect and the above implementation methods, in some possible implementation methods, the determining module is specifically used to: subtract the driving torque from the requested torque to obtain the target torque; calculate the angular acceleration of the motor based on the target torque; obtain the motor speed change rate in each cycle based on the angular acceleration and the preset cycle duration; and determine the target speed of the motor in each cycle based on the actual speed of the motor and the speed change rate.

[0026] Combining the second aspect and the above implementation methods, in some possible implementation methods, the determining module is specifically used to: obtain the actual speed of the motor in the previous cycle of the first cycle when calculating the target speed of the motor in the first cycle after entering the speed control mode; determine the speed increment of each cycle based on the speed change rate, and multiply the speed increment by the cycle delay number to obtain the target speed increment; determine the target speed of the motor in the first cycle based on the actual speed and the target speed increment.

[0027] Combining the second aspect and the above implementation methods, in some possible implementation methods, the determining module is specifically used to: determine the target slip value that the hydraulic torque converter needs to establish when the lock-up clutch is in the closed state or in the process of closing, and determine the target speed of the motor based on the target slip value.

[0028] In combination with the second aspect and the above implementation methods, in some possible implementation methods, the first control module is specifically used to: control the lock-up clutch to reduce torque and control the motor to adjust the actual speed to the target speed so that the hydraulic torque converter establishes the target slip value; when the speed difference between the actual speed and the target speed of the motor is less than the first preset speed difference, control the motor to enter the speed control mode and control the motor to maintain the target speed.

[0029] In combination with the second aspect and the above implementation, in some possible implementations, the device further includes: a third control module, used to control the engine based on the current speed of the motor; when the speed difference between the current speed of the engine and the current speed of the motor is less than a second preset speed difference, the clutch is controlled to be in a closed state, and the motor is controlled to exit the speed control mode; after the motor exits the speed control mode, it enters the torque control mode.

[0030] Combining the second aspect and the above implementation methods, in some possible implementation methods, the third control module is specifically used to: obtain the actual torque of the motor in the last cycle of the speed control mode; determine the torque difference between the actual torque and the current requested torque of the motor; determine the target torque gradient based on the torque difference, and control the motor to adjust from the actual torque to the current requested torque based on the target torque gradient.

[0031] Thirdly, an electronic device is provided, including a memory and a processor. The memory is used to store executable program code, and the processor is used to call and run the executable program code from the memory, causing the electronic device to perform the methods of the first aspect or any possible implementation thereof.

[0032] Fourthly, this application provides a vehicle including an electronic device for performing the methods described in the first aspect or any of the embodiments described above.

[0033] Fifthly, a computer program product is provided, comprising: computer program code, which, when run on a computer, causes the computer to perform the methods described in the first aspect or any possible implementation thereof.

[0034] In a sixth aspect, a non-volatile storage medium is provided, which stores computer program code that, when executed on a computer, causes the computer to perform the method described in the first aspect or any possible implementation thereof. Attached Figure Description

[0035] Figure 1 This is a schematic diagram of the architecture of a hybrid vehicle provided in an embodiment of this application.

[0036] Figure 2 This is a schematic flowchart of a method for starting an engine provided in an embodiment of this application.

[0037] Figure 3 This is a flowchart illustrating another method for starting an engine provided in an embodiment of this application.

[0038] Figure 4This is a schematic diagram of a device for starting an engine provided in an embodiment of this application.

[0039] Figure 5 This is a schematic diagram of the structure of a vehicle provided in an embodiment of this application. Detailed Implementation

[0040] The technical solutions in this application will be clearly and thoroughly described below with reference to the accompanying drawings. In the description of the embodiments of this application, unless otherwise stated, " / " means "or," for example, A / B can mean A or B. "And / or" in the text is merely a description of the relationship between related objects, indicating that three relationships can exist. For example, A and / or B can represent: A existing alone, A and B existing simultaneously, and B existing alone. Furthermore, in the description of the embodiments of this application, "multiple" refers to two or more than two.

[0041] Hereinafter, the terms "first" and "second" are used for descriptive purposes only and should not be construed as implying or suggesting relative importance or implicitly indicating the number of technical features indicated. Thus, a feature defined as "first" or "second" may explicitly or implicitly include one or more of that feature.

[0042] Some hybrid vehicles have a single electric motor at the front. When switching from pure electric to hybrid drive, this motor transmits torque through a clutch between the motor and the engine to start the engine. Throughout the start-up process, the motor must be responsible for pure electric drive or energy recovery, while also smoothly outputting additional torque to assist the clutch in driving the engine.

[0043] The existing control logic requests clutch pressurization while simultaneously requesting a matching starting torque from the motor. However, due to inconsistencies in the clutch's hydraulic control, non-linear output torque, varying oil temperatures, different self-learning deviations, and signal transmission delays, the actual clutch pressurization effect is affected, making it difficult to match the motor's torque increase with the clutch's hydraulic pressurization. If the motor torque increases more than the clutch pressurization, the extra torque is transmitted to the transmission output, causing vehicle jerking. If the motor torque increases less than the clutch pressurization, the insufficient torque is transmitted to the transmission output, causing vehicle deceleration jerking and affecting vehicle stability.

[0044] Based on this, this application proposes a method for starting an engine that can reduce vehicle jerking and jerkiness during engine start-up, improve vehicle stability, and enhance the user's driving experience.

[0045] Figure 1 This is a schematic diagram of the architecture of a hybrid vehicle provided in an embodiment of this application.

[0046] For example, such as Figure 1 As shown, the hybrid vehicle includes: an engine 101, a clutch 102, an electric motor 103, a torque converter 104, and a transmission 105.

[0047] Engine 101 is one of the power sources of the vehicle, generating power by burning fuel (such as gasoline or diesel). The power generated by engine 101 is transmitted to gearbox 105 via clutch 102, ultimately driving the wheels of the vehicle.

[0048] The clutch 102 is used to connect or disconnect the engine 101 and the motor 103. When the clutch 102 is in the open state, the engine 101 is disconnected from the motor 103. When the clutch 102 is in the closed state, the engine 101 is connected to the motor 103.

[0049] Motor 103, also called drive motor or P2 motor, can drive the vehicle using electrical energy provided by the power battery via gearbox 105. In some embodiments, motor 103 can also function as a generator to produce electrical energy.

[0050] The hydraulic torque converter 104 transmits power through the kinetic energy of a liquid (usually transmission oil), which can amplify the torque of the engine and motor during start-up or low-speed operation, improve the vehicle's starting performance and low-speed power, and make it easier for the vehicle to overcome resistance (such as climbing hills or starting under heavy load).

[0051] The hydraulic torque converter 104 includes a pump wheel and a turbine. The pump wheel is the power input side, the turbine is the power output side, the motor 103 is connected to the pump wheel, and the turbine is connected to the input shaft of the gearbox 105.

[0052] The gearbox 105 includes multiple gears, each corresponding to a different transmission ratio, which is used to adjust the vehicle's power output (such as speed and torque) so that the vehicle can adapt to different driving conditions.

[0053] Understandable, Figure 1 The architecture shown is an example, and this application does not specifically limit the architecture of hybrid vehicles.

[0054] Figure 2 This is a flowchart illustrating a method for starting an engine according to an embodiment of this application. The method is applied to an electronic device, which may specifically be... Figure 1 The vehicle shown is a hybrid vehicle. The vehicle includes an engine, a clutch, an electric motor, a torque converter, and a transmission, wherein the engine is connected to the electric motor via the clutch, and the electric motor is connected to the transmission via the torque converter. For example, such as Figure 2 As shown, the method 200 includes: Step 201: When the vehicle needs to start the engine, determine the target speed of the motor based on the state of the lock-up clutch in the torque converter. Step 202: Control the motor based on the target speed and control the clutch to increase torque in the slipping state so that the motor drives the engine to rotate; Step 203: When the actual engine speed reaches the ignition speed threshold, control the engine to ignite and start the engine.

[0055] exist Figure 2 In the illustrated embodiment, when the vehicle needs to start the engine, considering that the state of the lock-up clutch in the torque converter affects power transmission and thus the engine starting via the motor, the target speed of the motor is determined based on the state of the lock-up clutch. This ensures that the determined target speed matches the current state of the lock-up clutch, guaranteeing that the engine can be started via the motor regardless of the lock-up clutch's state. By controlling the motor based on the target speed, the motor can follow the stable target speed, eliminating signal transmission delays and avoiding the problem of vehicle deceleration jerking caused by non-linear clutch pressure during engine starting. This improves the smoothness of engine starting and enhances the user's driving experience.

[0056] In step 201, the vehicle can currently be in pure electric mode, driven by the motor, and the engine is not currently running. It can be determined whether the vehicle needs to start the engine by judging whether there is an engine start request.

[0057] As one implementation method, when the battery charge is too low, for example below 15%, the vehicle needs to start the engine to prevent the battery from continuing to discharge and becoming depleted. Specifically, the vehicle's battery management system monitors the battery charge in real time and sends the battery charge information to the vehicle control unit (VCU). Based on the received charge information, if the VCU determines that the battery charge is too low and the engine is not currently running, the VCU will generate an engine start request, at which point it is determined that the vehicle needs to start the engine.

[0058] Among them, the power battery, also known as the high-voltage battery, is used to provide electrical energy to the motor so that the motor can output torque to drive the vehicle.

[0059] In some embodiments, the user can directly send a command to the vehicle to start the engine. Upon receiving the command, the vehicle determines that an engine start request exists and therefore needs to start the engine.

[0060] Users can send commands to start the engine to the vehicle through mechanical buttons near the driver's seat, virtual buttons on the vehicle's large screen or authorized electronic devices (such as mobile phones, tablets, etc.) connected to the vehicle, or voice commands (such as speaking a voice containing keywords such as "start engine").

[0061] The hydraulic torque converter 104 includes a lock-up clutch, which has an open and a closed state. When the lock-up clutch is closed, the pump impeller and turbine in the hydraulic torque converter are rigidly connected, achieving a transmission efficiency close to 100% and reducing fuel consumption. When the lock-up clutch is open, the pump impeller drives the turbine via fluid, amplifying the torque.

[0062] Typically, when the current vehicle speed is determined to be less than the preset vehicle speed, the lock-up clutch in the torque converter is kept open, allowing the torque output from the engine to be flexibly transmitted to the transmission to drive the vehicle, thus improving the smoothness of torque transmission during vehicle operation.

[0063] The preset speed is the minimum speed at which the lock-up clutch is engaged, for example, 20 kph. When the vehicle's current speed is less than the preset speed, it indicates that the vehicle may be in a starting or climbing situation, requiring a larger output torque. In this case, the lock-up clutch needs to be engaged to amplify the torque.

[0064] When the current vehicle speed is greater than or equal to the preset vehicle speed, the lock-up clutch in the torque converter is closed, making the torque converter rigidly connected. At this time, the engine power can be transmitted to the transmission without buffering to drive the vehicle.

[0065] Understandably, when the vehicle's current speed is greater than or equal to the preset speed, it indicates that the vehicle requires significant power. To improve vehicle efficiency, the lock-up clutch needs to engage to ensure the torque converter is in a rigidly connected state. This rigidly connected torque converter allows for 100% uninterrupted power transmission from the engine to the transmission, guaranteeing vehicle efficiency.

[0066] Controlling the lock-up clutch to be in the closed state includes: adjusting the speed of the pump wheel and the turbine to be close, and controlling the lock-up clutch to be in the closed state when the speed difference between the pump wheel and the turbine is less than a first preset speed difference. The first preset speed difference can be, for example, 5 rpm (revolutions per minute).

[0067] The target speed is the target speed that the motor needs to reach when starting the engine. The target speed of the motor is related to the state of the motor's gripper and the lock-up clutch. Therefore, when it is determined that the engine needs to be started, the current state of the lock-up clutch can be determined, and the target speed that the motor needs to reach can be determined based on the state of the lock-up clutch.

[0068] In one possible implementation, the target speed of the motor is determined based on the state of the lock-up clutch in the hydraulic torque converter, including: controlling the motor to enter a speed control mode when the lock-up clutch is in the open state; determining the drive torque transmitted by the motor to the hydraulic torque converter when the motor enters the speed control mode; and determining the target speed based on the requested torque and drive torque of the motor.

[0069] In speed control mode, the motor torque is controlled based on the target motor speed. Specifically, in speed control mode, the output torque of the motor is adjusted in real time based on the difference between the target speed and the actual motor speed, so that the actual motor speed accurately follows the target speed.

[0070] With the lock-up clutch in the open state, the pump wheel and turbine are connected by a hydraulic soft connection. At this time, a slip value is allowed between the pump wheel and turbine. The load on the motor output shaft is hydraulically isolated, controllable and without rigid constraints. Therefore, when it is determined that the lock-up clutch is in the open state, the motor can be directly controlled to enter the speed control mode.

[0071] Once it is determined that the motor has entered speed control mode, the target speed of the motor can be determined, and the motor can then be controlled based on the target speed. Specifically, when the motor has entered speed control mode, the drive torque transmitted from the motor to the hydraulic torque converter can be determined, and the target speed can be determined based on the motor's requested torque and drive torque.

[0072] Specifically, the drive torque transmitted from the motor to the torque converter refers to the torque transmitted from the motor to the turbine end of the torque converter. The requested torque refers to the target torque requested from the motor output.

[0073] Specifically, the current accelerator pedal opening or brake pedal opening of the vehicle can be obtained, and the requested torque of the motor can be determined based on the accelerator pedal opening or brake pedal opening.

[0074] Understandably, when the lock-up clutch is open, a portion of the torque output by the motor is used to drive the vehicle; this torque used to drive the vehicle is denoted as the drive torque. The remaining portion of the motor's output torque, besides the drive torque, is used to increase its own speed. Therefore, the target speed can be determined based on the motor's requested torque and the drive torque.

[0075] In the above method, when the lock-up clutch is confirmed to be in the open state, it can be determined that the pump impeller and turbine of the hydraulic torque converter are connected by a hydraulic soft connection. At this time, a slip value is allowed between the pump impeller and turbine, and the motor is controllable. The motor is then controlled to enter speed control mode. By determining the target speed and controlling the motor, the motor can drive the engine. The motor following a stable target speed eliminates signal transmission delays and the effects of non-linear clutch pressure. This avoids the lag of torque control mode and the large short-term fluctuations in motor torque and clutch torque in torque control mode, which can cause vehicle jerking due to non-linear clutch pressure, thus improving vehicle stability.

[0076] In one possible implementation, determining the drive torque transmitted from the motor to the hydraulic torque converter includes: obtaining the actual speed of the motor; determining a target coefficient based on the oil temperature of the hydraulic torque converter, the speed ratio of the turbine to the pump impeller, and the torque ratio of the turbine to the pump impeller; and determining the drive torque based on the target coefficient and the actual speed.

[0077] A speed sensor can be installed in the motor to collect the motor speed in real time. The actual speed of the motor can be obtained by acquiring the current speed of the motor collected by the speed sensor.

[0078] The turbine-to-pump impeller speed ratio refers to the ratio between the pump impeller speed n1 and the turbine speed n2. It is usually obtained by dividing the turbine speed n2 by the pump impeller speed n1, denoted as: I1 = n2 / n1. The turbine-to-pump impeller torque ratio refers to the ratio between the pump impeller torque Tb and the turbine torque Tw. It is usually obtained by dividing the turbine torque Tw by the pump impeller torque Tb, denoted as: I2 = Tw / Tb.

[0079] For example, if the pump impeller speed n1 = 2000 rpm and the pump impeller speed n2 = 2500 rpm, then the speed ratio of the turbine to the pump impeller is I1 = n2 / n1 = 2500 / 2000 = 1.25. Assuming the pump impeller torque Tb = 150 Nm and the turbine torque Tw = 120 Nm, then the torque ratio of the turbine to the pump impeller is I2 = Tw / Tb = 120 / 150 = 0.8.

[0080] The oil temperature mentioned above refers to the temperature of the automatic transmission fluid circulating inside the torque converter, which can be obtained through an oil temperature sensor.

[0081] The turbine-to-pump wheel speed ratio I1 and the turbine-to-pump wheel torque ratio I2 can be calibrated values ​​and stored in the vehicle in advance. The turbine-to-pump wheel speed ratio I1 and the turbine-to-pump wheel torque ratio I2 stored in the vehicle can be directly obtained.

[0082] In some embodiments, since the oil temperature of the hydraulic actuator affects the turbine-pump wheel speed ratio I1 and the turbine-pump wheel torque ratio I2, after obtaining the turbine-pump wheel speed ratio I1 and the turbine-pump wheel torque ratio I2, the calibration values ​​I1 and I2 can be corrected based on the oil temperature to obtain the corrected turbine-pump wheel speed ratio I1 and the corrected turbine-pump wheel torque ratio I2.

[0083] Understandably, since hydraulic torque converters rely on oil to transmit power, and the viscosity of the oil changes with temperature, which affects its flow characteristics and power transmission capacity, it is necessary to correct the turbine-pump speed ratio I1 and the turbine-pump torque ratio I2 based on the oil temperature.

[0084] Specifically, the lower the oil temperature, the higher the oil viscosity, resulting in greater flow resistance and poorer fluidity between the pump impeller blades. This leads to a decrease in the efficiency of momentum transfer from the pump impeller to the turbine, reducing the torque and speed obtained by the turbine. Consequently, the turbine-pump impeller speed ratio I1 and the turbine-pump impeller torque ratio I2 increase. Therefore, the rule for correcting the turbine-pump impeller speed ratio I1 and the turbine-pump impeller torque ratio I2 based on oil temperature is: the lower the oil temperature, the larger the corrected turbine-pump impeller speed ratio I1 and the turbine-pump impeller torque ratio I2.

[0085] The vehicle can pre-store the initial correspondence between the turbine-to-pump wheel speed ratio I1 and the turbine-to-pump wheel torque ratio I2 and the conversion coefficient K. Based on the corrected turbine-to-pump wheel speed ratio I1 and the corrected turbine-to-pump wheel torque ratio I2, the previously stored initial correspondence can be looked up to obtain the coefficient K. Then, the coefficient K is substituted into the formula C = 1 / K. 2 The target coefficient C is obtained.

[0086] In some embodiments, after obtaining the turbine-to-pump wheel speed ratio I1 and the turbine-to-pump wheel torque ratio I2, a basic coefficient K can be obtained by first finding a first correspondence based on I1 and I2. Then, the basic coefficient K is corrected based on oil temperature to obtain the final coefficient K. The final conversion coefficient K is then substituted into the formula C = 1 / K. 2 Thus, the target coefficient C is obtained.

[0087] The steps for determining the drive torque of the hydraulic torque converter based on the target coefficient and the actual rotational speed may include: calculating the square of the actual rotational speed, multiplying the square of the actual rotational speed by the target coefficient to obtain the drive torque, then the drive torque T1 = C*N. 2 C = 1 / K 2 Substituting the values, we get T1 = 1 / K 2 *N 2 .

[0088] For example, if the final coefficient K is 200, then the target coefficient C = 1 / 200. 2 =1 / 40000. Assuming the actual motor speed N = 2000 rpm, then T1 = 1 / K 2 *N 2 =1 / 40000*2000 2 =100Nm.

[0089] In the above method, considering that the oil temperature of the hydraulic torque converter affects the speed ratio of the turbine and pump wheel and the torque ratio of the turbine and pump wheel, the target coefficient is determined by combining the oil temperature of the hydraulic torque converter. This allows for the determination of a target coefficient that is consistent with the current oil temperature, thereby improving the accuracy of determining the drive torque and thus improving the accuracy of the target speed.

[0090] In one possible implementation, determining the target speed based on the motor's requested torque and drive torque includes: subtracting the drive torque from the requested torque to obtain the target torque; calculating the motor's angular acceleration based on the target torque; obtaining the motor's speed change rate in each cycle based on the angular acceleration and a preset cycle duration; and determining the motor's target speed in each cycle based on the motor's actual speed and speed change rate.

[0091] The requested torque is the target torque that the motor will output, meaning the actual torque output by the motor will reach this requested torque. The target torque is obtained by subtracting the drive torque from the requested torque. This target torque is the remaining torque in the motor's output torque, excluding the drive torque. This remaining torque will be used to increase the motor's speed. In some embodiments, the target torque may also be referred to as the incremental torque for increasing the motor's speed.

[0092] For example, if the requested torque of the motor is T2 = 160 Nm and the calculated driving torque T1 = 100 Nm in the above embodiment, then the target torque T = T2 - T1 = 160 Nm - 100 Nm = 60 Nm.

[0093] After obtaining the target torque, the moment of inertia I can be acquired. Based on the moment of inertia I and the target torque T, the angular acceleration A that the target torque can provide to the motor can be calculated. Specifically, based on the formula T=IA, the angular acceleration A=T / I can be derived. Then, the target torque T can be divided by the moment of inertia I to obtain the angular acceleration A.

[0094] Wherein, the moment of inertia I is the moment of inertia of the entire front-end system of the hydraulic converter, specifically the "sum of rotational inertia" of all rotating components before the pump wheel of the hydraulic torque converter. The moment of inertia is an inherent property of the system (i.e., the calibration value) and can be directly obtained.

[0095] It is understandable that the moment of inertia determines how easy it is to adjust the speed of a motor. The smaller the moment of inertia, the easier it is for the motor to accelerate and the less incremental torque is required. The larger the moment of inertia, the more "difficult" it is for the motor to accelerate and the more incremental torque is required. Therefore, based on the moment of inertia and the target torque, the angular acceleration that the target torque can provide for the motor can be calculated.

[0096] In some embodiments, the moment of inertia I is affected by the degree of clutch engagement. After obtaining the stored moment of inertia, the degree of clutch engagement can also be obtained. The moment of inertia I is then corrected based on the degree of clutch engagement to obtain the corrected moment of inertia. The target torque T is divided by the corrected moment of inertia I to obtain the angular acceleration A.

[0097] The clutch engagement degree refers to the degree of engagement between the two gears of the clutch, which can be expressed as 0% to 100%. 0% indicates that the clutch is in the open state, and 100% indicates that the clutch is fully engaged, at which point the clutch is in the closed state.

[0098] In some embodiments, the greater the degree of clutch engagement, the greater the corrected moment of inertia; the smaller the degree of clutch engagement, the smaller the corrected moment of inertia.

[0099] Understandable, Figure 1 The greater the engagement of the clutch 102, the more the engine 101 is engaged, and therefore the greater the moment of inertia of the entire hydraulic transformer front-end system. Conversely, the less the clutch 102 is engaged, the less the engine 101 is engaged, and therefore the smaller the moment of inertia of the entire hydraulic transformer front-end system.

[0100] For example, the corrected moment of inertia is I = 0.233 kgm. 2 (kg / m²), target torque T = T2 - T1 = 160 Nm - 100 Nm = 60 Nm, then angular acceleration A = T / I = 60 / 0.233 ≈ 257.51 rad / s² 2 (radians per square second).

[0101] The preset period duration can be the sampling period duration for the VCU to collect motor speed. For example, the preset period duration t can be 0.01s (seconds).

[0102] Based on angular acceleration and a preset cycle length, the rate of change of motor speed in each cycle can be obtained. Specifically, the angular acceleration A can be multiplied by the preset cycle length t to obtain the rate of change of motor speed ω in each cycle, which can be expressed as: ω = A * t.

[0103] For example, the angular acceleration A ≈ 257.51 rad / s² 2Given a preset cycle length of t = 0.01 s, the rate of change of motor speed in each cycle is ω = A * t = 257.51 rad / s. 2 *0.01s=2.5751rad / s.

[0104] The steps for determining the target speed of the motor in each cycle based on the actual speed and the rate of change of the speed include: converting the rate of change of angular velocity into a speed increment Δn to obtain the speed increment Δn of the motor in each cycle; for each cycle, obtaining the actual speed of the motor in the previous cycle, adding the speed increment Δn to the actual speed to obtain the target speed of the motor in the current cycle, and thus obtaining the target speed of the motor in each cycle.

[0105] Specifically, the conversion relationship between angular velocity ω (rad / s) and rotational speed n (r / min) is ω = 2πn / 60, which can be transformed into n = ω30 / π. Based on this, the formula for converting the rate of change of angular velocity into the speed increment Δn is: Δn = ω * 30 / π. For each cycle, if the actual speed of the motor in the previous cycle is obtained as n0, then the target speed in the current cycle is n = n0 + Δn.

[0106] For example, substituting ω = 2.5751 rad / s into the formula for the speed increment Δn = ω * 30 / π, we can calculate that the speed increment Δn = ω * 30 / π ≈ 2.5751 rad / s * 30 / 3.14 = 24.6 rpm. Assuming that the actual motor speed n0 in the previous cycle was 50 rpm, then the target motor speed for the current cycle is n = n0 + Δn = 50 rpm + 24.6 rpm = 74.6 rpm.

[0107] Based on the above method, the VCU can calculate a new target speed in each cycle. After the VCU requests the motor to enter speed control mode, it sends the corresponding target speed to the motor in each cycle. The motor responds to the target speed in that cycle and performs stable speed control.

[0108] In one possible implementation, the method further includes: calculating the target speed of the motor in the first cycle after the motor enters the speed control mode, obtaining the actual speed of the motor in the previous cycle of the first cycle; determining the speed increment for each cycle based on the speed change rate, and multiplying the speed increment by the cycle delay to obtain the target speed increment; and determining the target speed of the motor in the first cycle based on the actual speed and the target speed increment.

[0109] The first cycle mentioned above is the first cycle after the motor enters the speed control mode. The target speed calculated in the first cycle can be called the first target speed.

[0110] The previous cycle of the first cycle is the last cycle in which the motor has not entered the speed control mode. During this cycle, the motor is in working condition and has a certain speed. The actual speed of the motor during this cycle can be obtained to get the actual speed of the motor in the previous cycle of the first cycle.

[0111] The process of determining the speed increment Δn for each cycle based on the speed change rate can be as described in the above embodiment, and will not be repeated here.

[0112] The cycle delay is the number of cycles corresponding to the duration of the CAN (Controller Area Network) communication delay. For example, CAN (Controller Area Network) communication may have a delay of 20ms-30ms, resulting in a delay of 2-3 cycles between the target speed and the actual speed of the motor. In this case, the cycle delay is 2 or 3.

[0113] The cycle delay can be multiplied by the speed increment to obtain the sum of the speed increments corresponding to the cycle delay, which is the target speed increment mentioned above. Then, the actual speed of the motor in the previous cycle of the first cycle is compared with the target speed increment to obtain the target speed of the first cycle. In some embodiments, when calculating the first target speed, the VCU also needs to calculate the target speed for the current cycle based on the actual speed and speed increment of the motor in the previous cycle. However, since CAN (Controller Area Network) communication has a delay of 20ms-30ms, there is a delay of 2-3 cycles between the target speed and the actual speed of the motor. Therefore, the actual speed can be added to the actual speed by 2-3 speed increments to obtain the first target speed. Assuming a delay of 3 cycles, the first target speed = the actual speed of the previous cycle + 3 * speed increment. Then, the first target speed is sent to the motor, causing the motor to rotate based on the first target speed, thus eliminating the delay of the CAN communication system.

[0114] In the above method, the target torque for increasing the motor speed is obtained by subtracting the drive torque from the requested torque. The angular acceleration of the motor is calculated based on the target torque, and the rate of change of the motor speed in each cycle is determined. This allows for the real-time determination of the target speed of the drive motor in each cycle, improving the accuracy of motor speed control, ensuring smooth and efficient engine starting, and enhancing the stability and safety of the vehicle.

[0115] In one possible implementation, the target speed of the motor is determined based on the state of the lock-up clutch in the hydraulic torque converter, including: determining the target slip value that the hydraulic torque converter needs to establish when the lock-up clutch is in the closed state or in the process of closing, and determining the target speed of the motor based on the target slip value.

[0116] Slip value refers to the speed difference between the pump impeller and the turbine of the hydraulic torque converter. The target slip value is the slip value that the pump impeller and turbine of the hydraulic torque converter need to maintain when starting the engine. When the hydraulic torque converter establishes the target slip value, the engine can be started based on the electric motor.

[0117] Understandably, when the lock-up clutch is engaged, the pump impeller and turbine of the torque converter are rigidly connected, and the motor load is rigidly coupled to the transmission and wheel ends. If the engine needs to be started at this time, changes in the motor's torque or speed can easily affect vehicle operation, leading to uneven driving. Therefore, with the lock-up clutch engaged, the engine cannot be started using the motor; it is necessary to control the torque converter to establish a target slip value.

[0118] When the lock-up clutch is confirmed to be engaged, the pump impeller and turbine of the torque converter are in a semi-rigid slip-friction connection. At this point, a slip value exists between the pump impeller and turbine. However, this slip value may be too large or too small. If the slip value is too small, changes in the torque or speed of the electric motor when starting the engine will affect vehicle operation, resulting in an uneven driving experience. Therefore, when the lock-up clutch is engaged or in the process of engaging, it is necessary to first control the torque converter to establish a target slip value before starting the engine based on the electric motor.

[0119] In some embodiments, the requested torque of the motor and its incremental value can be obtained. Based on the requested torque and its incremental value, a second correspondence is looked up to determine the target slip value that the lock-up clutch needs to establish. The second correspondence is the relationship between the requested torque and its incremental value stored in the vehicle beforehand and the target slip value. In the second correspondence: the larger the requested torque, the larger the target slip value; the larger the incremental value of the requested torque, the larger the target slip value.

[0120] The vehicle may currently be in driving mode or regenerative braking mode. When the vehicle is in driving mode, the requested torque of the motor is positive; when the vehicle is in regenerative braking mode, the requested torque of the motor is negative. If the requested torque of the motor is negative, a negative slip value needs to be established; if the requested torque of the motor is positive, a positive slip value needs to be established.

[0121] Negative slip refers to the difference between the pump impeller speed and the turbine speed being less than zero, while positive slip refers to the difference between the pump impeller speed and the turbine speed being greater than zero.

[0122] In some embodiments, the target slip value can be appropriately adjusted based on the changing trend of the incremental value of the requested torque. For example, if the requested torque is negative, and it is determined that the incremental value is getting smaller (i.e., the absolute value is getting larger), appropriately increasing the negative slip value can improve deceleration performance, which is suitable for deceleration conditions. If the requested torque is positive, and it is determined that the incremental value is getting larger, appropriately increasing the positive slip value can improve power performance, which is suitable for acceleration conditions. Specifically, the slip value can be increased by multiplying it by a coefficient greater than 1.

[0123] After obtaining the target slip value, the target pump impeller speed can be determined based on the turbine speed and the target slip value. Since the motor and pump impeller are mechanically connected, the target pump impeller speed can be used as the target motor speed. Specifically, the target speed can be obtained by adding the target slip value to the turbine speed. The turbine speed can be acquired using a speed sensor.

[0124] For example, the target slip value is 500 rpm, which means that the difference between the pump wheel speed and the turbine speed needs to reach 500 rpm. The current turbine speed is 200 rpm, so the pump wheel speed (i.e. the target speed) can be calculated as 200 rpm + 500 rpm = 700 rpm.

[0125] In the above method, when it is determined that the lock-up clutch is in the closed state or in the process of closing, the target slip is determined, and the target speed of the motor is determined based on the target slip. This effectively ensures that the lock-up clutch establishes the target slip, which can effectively reduce the impact of the motor on the vehicle's stability when starting the engine. Furthermore, it does not directly disengage the lock-up clutch, ensuring the continuous transmission of motor power and avoiding the problem of power interruption caused by opening the lock-up clutch when starting the engine.

[0126] In one possible implementation, the motor is controlled based on the target speed, including: controlling the lock-up clutch to reduce torque and controlling the motor to adjust the actual speed to the target speed so that the hydraulic torque converter establishes a target slip value; when the speed difference between the actual speed and the target speed of the motor is less than a first preset speed difference, controlling the motor to enter the speed control mode and controlling the motor to maintain the target speed.

[0127] Specifically, the lock-up clutch increases the maximum torque it can transmit by applying pressure, while controlling the lock-up clutch to reduce torque refers to controlling the lock-up clutch to reduce the pressure, thereby reducing the maximum torque that the lock-up clutch can transmit.

[0128] When the torque of the lock-up clutch decreases, the torque transmitted by the lock-up clutch also decreases. At this time, the torque used to drive the vehicle in the motor output torque decreases, and the remaining torque obtained by subtracting the torque used to drive the vehicle from the current output torque of the motor increases. At this time, the motor can adjust its own speed based on the remaining torque, thereby creating a certain slip between the turbine and pump impeller of the hydraulic torque converter.

[0129] Specifically, based on the above embodiments, the target motor speed determined by the target slip value to be established by the torque converter can be used to determine the torque value that the lock-up clutch needs to reduce, and the torque of the lock-up clutch can be controlled to reduce to this torque value. When the lock-up clutch reduces to this torque value, part of the torque output by the motor drives the vehicle, and the remaining torque will control the motor speed to adjust to the target speed. When the actual motor speed reaches the target speed, the torque converter establishes the target slip value.

[0130] When the difference between the actual speed of the motor and the target speed is less than the first preset speed difference, it is determined that the actual speed of the motor has reached the target speed. At this time, the motor is controlled to enter the speed control mode, and the motor is controlled based on the target speed in the speed control mode so that the motor can maintain the target speed.

[0131] The first preset speed difference is a small speed difference value set in advance, used to determine that the actual speed of the motor is close to the target speed. The first preset speed difference can be, for example, 5 rpm.

[0132] Before controlling the lock-up clutch to reduce torque, the VCU first determines the specific state of the lock-up clutch. If the lock-up clutch is already in a slipping state, the VCU requests the lock-up clutch to remain in a slipping state; if the lock-up clutch is already in a closed state, the VCU requests the lock-up clutch to switch to a slipping state; then the torque reduction control of the lock-up clutch is performed.

[0133] In the above method, by controlling the lock-up clutch to reduce torque, the torque used by the motor for driving is reduced, so that the motor can adjust its own speed to the target speed based on the remaining torque, thereby establishing the target slip of the hydraulic torque converter, ensuring that the engine can be started smoothly based on the motor.

[0134] In step 202, the specific steps of controlling the motor based on the target speed in the speed control mode include: determining the difference between the actual speed of the motor and the target speed; determining the torque adjustment amount based on the difference; and controlling the torque of the motor based on the torque adjustment amount so that the actual speed of the motor reaches the target speed.

[0135] It is understandable that the actual speed of the motor changes in real time as the torque is adjusted. Therefore, it is necessary to determine the amount of torque adjustment based on the difference between the actual speed and the target speed in real time, and adjust the motor torque to ensure that the actual speed of the motor can reach and maintain the target speed.

[0136] While controlling the motor based on the target speed, it is also necessary to control the clutch (i.e. Figure 1 The clutch 102 is in a slipping state. When the clutch is in a slipping state, the clutch pressure is increased to increase the torque transmitted by the clutch. After the clutch torque is increased, the motor can drive the engine to rotate through the clutch.

[0137] In step 203, while the motor drives the engine to rotate, the actual speed of the engine is detected. When the actual speed of the engine reaches the ignition speed threshold, the engine is controlled to ignite and start.

[0138] The ignition speed threshold is the minimum engine speed at which the engine can ignite. For example, the ignition speed threshold can be 1000 rpm. When the actual engine speed is determined to be greater than or equal to the ignition speed threshold, it is determined that the engine can ignite, and the engine is then controlled to ignite and start.

[0139] In one possible implementation, after controlling the engine to ignite and start the engine when the actual engine speed reaches the ignition speed threshold, the method further includes: controlling the engine based on the current speed of the motor; when the speed difference between the current engine speed and the current motor speed is less than a second preset speed difference, controlling the clutch to be in a closed state and controlling the motor to exit the speed control mode; after the motor exits the speed control mode, it enters the torque control mode.

[0140] After controlling the engine to ignite, the current speed of the motor can be obtained, and the engine speed can be controlled in a closed loop based on the current speed of the motor so that the current speed of the engine is close to the current speed of the motor.

[0141] It is understandable that the motor is currently in speed control mode. At this time, the motor is controlled based on the target speed so that the actual speed of the motor is maintained at the target speed. Therefore, the current speed of the motor is equal to the target speed of the motor.

[0142] Specifically, the current speed of the motor can be used as the target speed of the engine, and the target torque of the engine can be determined based on the difference between the current speed and the target speed. The output torque of the engine can be requested to be the target torque, so as to control the current speed of the engine to be close to the current speed of the motor.

[0143] It is understandable that the engine's current speed changes in real time, so the target torque requested from the engine is also adjusted in real time according to the difference between the engine's current speed and the target motor's current speed.

[0144] During the process of controlling the engine based on the current speed of the motor, the speed difference between the current speed of the engine and the current speed of the motor is detected in real time. If the speed difference between the current speed of the engine and the current speed of the motor is less than the second preset speed difference, it is determined that the speeds at both ends of the clutch are synchronized, and the clutch is controlled to be in the closed state.

[0145] like Figure 1 As shown, the two ends of the clutch 102 are the engine 101 and the motor 103, respectively. The motor 103 and the engine 101 are mechanically connected through the clutch. Therefore, by controlling the speed of the engine and the speed of the motor to be synchronized, the speed of the two ends of the clutch can be synchronized.

[0146] The second preset difference is the maximum speed difference between the two ends of the clutch when the clutch can be closed, set in advance. For example, the second preset difference can be 10 rpm. If the speed difference between the current engine speed and the current motor speed is less than the second preset speed difference, it can be determined that the speeds at both ends of the clutch are synchronized, and the clutch can be controlled to close.

[0147] The motor also includes a torque control mode. In torque control mode, the target torque for the motor output needs to be determined, and the motor output torque needs to be controlled to reach that target torque. During the clutch engagement process, the motor can be controlled to exit the speed control mode, at which point the motor enters the torque control mode, and the VCU no longer controls the motor based on the target speed.

[0148] In some embodiments, to avoid clutch impact and wear caused by excessive speed difference between the engine and the motor, the clutch is briefly disengaged from a slipping state after engine ignition, allowing the engine to accelerate rapidly with the clutch disengaged, at which point the clutch torque is reduced to zero. During closed-loop speed control of the engine, if the clutch torque is determined to be less than a preset torque (e.g., 5 Nm), the motor is controlled to exit speed control mode.

[0149] In the above method, by controlling the speed difference between the current engine speed and the current motor speed to be less than a second preset speed difference, the speeds at both ends of the clutch are synchronized, ensuring smooth and safe clutch engagement. Even if the motor exits the speed control mode and enters the torque control mode, the motor can respond to the vehicle's torque request, ensuring normal vehicle operation.

[0150] In one possible implementation, controlling the motor to exit the speed control mode includes: obtaining the actual torque of the motor in the last cycle of the speed control mode; determining the torque difference between the actual torque and the motor's current requested torque; determining a target torque gradient based on the torque difference; and controlling the motor to adjust from the actual torque to the current requested torque based on the target torque gradient.

[0151] The aforementioned last cycle refers to the last cycle obtained by dividing the time the motor is in speed control mode into the preset cycle length in the above embodiment. When the motor exits the speed control mode, the actual torque of the motor in the last cycle of speed control mode can be obtained. Specifically, the motor is equipped with a torque sensor, and the actual torque of the motor can be obtained based on this torque sensor.

[0152] When the motor exits the speed control mode, the requested torque of the motor at the current moment can be determined based on the vehicle's current throttle opening, thus obtaining the current requested torque. The absolute value of the actual torque of the motor in the last cycle of the speed control mode is subtracted from the current requested torque to determine the torque difference.

[0153] For example, if the actual torque of the motor in the last cycle of the speed control mode is 200 Nm, and the current requested torque of the motor is determined to be 300 Nm based on the current throttle opening, then the torque difference can be determined as |current requested torque - actual torque| = |300 Nm - 200 Nm| = 100 Nm.

[0154] The vehicle can pre-store a third correspondence between torque differences and torque gradients. After obtaining the torque difference, the third correspondence can be looked up to determine the target torque gradient corresponding to the torque difference. Then, the motor is controlled to adjust from the actual torque to the currently requested torque based on the target torque gradient. In the third correspondence, the larger the torque difference, the larger the corresponding torque gradient.

[0155] The difference between the requested torque and the actual torque can be positive or negative. When the difference is positive, the requested torque is greater than the actual torque, and the vehicle needs to accelerate. In this case, the actual torque can be gradually increased by adding the target torque gradient to the actual torque. When the difference is negative, the requested torque is less than the actual torque, and the vehicle needs to decelerate. In this case, the actual torque can be gradually decreased by subtracting the target torque gradient from the actual torque.

[0156] For operating conditions with a large torque difference, it can be determined that the vehicle is currently in a situation requiring rapid acceleration or braking. In such cases, the torque difference should be reduced as quickly as possible so that the actual torque of the motor can quickly follow the torque requested by the VCU. For operating conditions with a small torque difference, more emphasis should be placed on ensuring driving smoothness, and the motor can follow the torque requested by the VCU more slowly. Therefore, in the third correspondence, the larger the torque difference, the greater the corresponding torque gradient.

[0157] For example, the torque difference = |current requested torque - actual torque| = |300Nm - 200Nm| = 100Nm. Based on this torque difference, the target torque gradient is determined to be 20Nm / s. Then, the motor torque is controlled to increase by 20Nm per second from the actual torque of 100Nm until the actual torque of the motor equals the current requested torque of 300Nm.

[0158] Figure 3 This is a flowchart illustrating another method for starting an engine provided in an embodiment of this application.

[0159] For example, such as Figure 3 As shown, the method 300 includes: Step 301: If the vehicle triggers a request to start the engine, determine the state of the lock-up clutch; Step 302: When the lock-up clutch is in the open state, calculate the target speed of the motor based on the characteristics of the lock-up clutch; when the lock-up clutch is in the closed state or in the process of closing, perform slip control on the clutch according to the requested torque of the motor to determine the speed of the motor. The characteristics of a lock-up clutch can be based on the following formula: T2 (requested torque of the motor) - CN 2 (Drive torque) is expressed as IA (the incremental torque that increases the motor speed), and drive torque T1 = CN. 2 The target torque is T=IA.

[0160] Where C = 1 / K 2 K is the torque converter's speed ratio and torque ratio, calculated from tables at different oil temperatures based on the current hardware characteristics of the hydraulic torque converter at various oil temperatures; T2 is the requested torque of the motor; I is the moment of inertia of the entire hydraulic converter front-end system, which needs to be corrected based on the clutch engagement degree; N is the actual speed of the motor; and A is the angular acceleration. The angular acceleration A can be calculated based on the characteristics of the lock-up clutch.

[0161] Multiplying the angular acceleration A by the preset cycle length t yields the rate of change of motor speed ω in each cycle, which can be expressed as: ω = A * t. Based on the conversion relationship between angular velocity ω (rad / s) and speed n (r / min) as ω = 2πn / 60, we can transform it to obtain n = ω³⁰ / π. Therefore, the formula for converting the rate of change of angular velocity into the speed increment Δn is: Δn = ω * 30 / π. For each cycle, if the actual motor speed of the previous cycle is obtained as n₀, then the target speed of the current cycle is n = n₀ + Δn.

[0162] When the lock-up clutch is in the closed state or during the closing process, as in the above embodiment, the target slip value that the hydraulic torque converter needs to establish can be determined based on the requested torque of the motor and the incremental value of the requested torque; the target speed of the motor is determined based on the target slip value, and the clutch is subjected to torque reduction control so that the actual speed of the motor reaches the target speed, so that the hydraulic torque converter establishes the target slip value.

[0163] Step 303: After the slip of the lock-up clutch stabilizes, the control electric motor enters the speed control mode and controls the motor to maintain the target speed. Step 304: While the motor enters the speed control mode and follows the target speed, the clutch is pressurized to drive the engine to rotate. Step 305: After the engine is ignited, the motor exits the speed control mode and enters the torque control mode. Based on the difference between the actual torque of the motor in speed control and the current requested torque of the motor, the torque of the motor is gradient transitioned.

[0164] In the above method, when exiting the torque control mode, the target torque gradient is determined based on the torque difference between the actual torque of the motor in the speed control mode and the currently requested torque. Based on the target torque gradient, the motor torque can be controlled to gradually transition to the currently requested torque, ensuring a smooth torque transition and further improving the vehicle's stability.

[0165] Figure 4 This is a schematic diagram of a device for starting an engine, provided in an embodiment of this application. Applied to hybrid vehicles, the vehicle includes an engine, a clutch, an electric motor, a torque converter, and a transmission. The engine is connected to the electric motor via the clutch, and the electric motor is connected to the transmission via the torque converter.

[0166] For example, such as Figure 4 As shown, the device 400 includes: The determination module 401 is used to determine the target speed of the motor based on the state of the lock-up clutch in the torque converter when the vehicle needs to start the engine. The first control module 402 is used to control the motor based on the target speed and control the clutch to increase torque in the slipping state so that the motor drives the engine to rotate. The second control module 403 is used to control the engine to ignite and start the engine when the actual engine speed reaches the ignition speed threshold.

[0167] In one possible implementation, the determining module 401 is specifically used to: control the motor to enter the speed control mode when the lock-up clutch is in the open state; determine the drive torque transmitted by the motor to the hydraulic torque converter when the motor enters the speed control mode; and determine the target speed based on the motor's requested torque and drive torque.

[0168] In one possible implementation, the determining module 401 is specifically used to: determine the drive torque transmitted from the motor to the hydraulic torque converter, including: obtaining the actual speed of the motor; determining a target coefficient based on the oil temperature of the hydraulic torque converter, the speed ratio of the turbine to the pump impeller, and the torque ratio of the turbine to the pump impeller; and determining the drive torque based on the target coefficient and the actual speed.

[0169] In one possible implementation, the determining module 401 is specifically used to: subtract the driving torque from the requested torque to obtain the target torque; calculate the angular acceleration of the motor based on the target torque; obtain the motor speed change rate in each cycle based on the angular acceleration and the preset cycle duration; and determine the target speed of the motor in each cycle based on the actual speed of the motor and the speed change rate.

[0170] In one possible implementation, the determining module 401 is specifically used to: determine the target slip value that the hydraulic torque converter needs to establish when the lock-up clutch is in a closed state or in the process of closing, and determine the target speed of the motor based on the target slip value.

[0171] In one possible implementation, the determining module 401 is specifically used to: obtain the actual speed of the motor in the previous cycle of the first cycle after calculating the target speed of the motor in the first cycle after entering the speed control mode; determine the speed increment of each cycle based on the speed change rate, and multiply the speed increment by the cycle delay number to obtain the target speed increment; and determine the target speed of the motor in the first cycle based on the actual speed and the target speed increment.

[0172] In one possible implementation, the first control module 402 is specifically used to: control the lock-up clutch to reduce torque and control the motor to adjust the actual speed to the target speed so that the hydraulic torque converter establishes the target slip value; when the speed difference between the actual speed and the target speed of the motor is less than the first preset speed difference, control the motor to enter the speed control mode and control the motor to maintain the target speed.

[0173] In one possible implementation, the device 400 further includes: a third control module for controlling the engine based on the current speed of the motor; when the speed difference between the current speed of the engine and the current speed of the motor is less than a second preset speed difference, controlling the clutch to be in a closed state and controlling the motor to exit the speed control mode; after the motor exits the speed control mode, it enters the torque control mode.

[0174] In one possible implementation, the third control module is specifically used to: obtain the actual torque of the motor in the last cycle of the speed control mode; determine the torque difference between the actual torque and the motor's current requested torque; determine the target torque gradient based on the torque difference, and control the motor to adjust from the actual torque to the current requested torque based on the target torque gradient.

[0175] Figure 5 This is a schematic diagram of the structure of a vehicle provided in an embodiment of this application.

[0176] For example, such as Figure 5 As shown, the vehicle 500 includes a memory 501 and a processor 502. The memory 501 stores executable program code 5011, and the processor 502 is used to call and execute the executable program code 5011 to perform a method for starting an engine.

[0177] Furthermore, embodiments of this application also protect an apparatus that may include a memory and a processor, wherein the memory stores executable program code, and the processor is used to call and execute the executable program code to perform a method for starting an engine provided in embodiments of this application.

[0178] This embodiment can divide the device into functional modules according to the above method example. For example, each module can correspond to a separate function, or two or more functions can be integrated into one processing module. The integrated module can be implemented in hardware. It should be noted that the module division in this embodiment is illustrative and only represents one logical functional division. In actual implementation, there may be other division methods.

[0179] When each functional module is divided according to its corresponding function, the device may also include a judgment module, a first control module, and a second control module. It should be noted that all relevant content regarding the steps involved in the above method embodiments can be referenced from the functional descriptions of the corresponding functional modules, and will not be repeated here.

[0180] It should be understood that the apparatus provided in this embodiment is used to perform the above-described method for starting an engine, and therefore can achieve the same effect as the above-described implementation method.

[0181] When using an integrated unit, the device may include a processing module and a storage module. When the device is applied to a vehicle, the processing module can be used to control and manage the vehicle's movements. The storage module can be used to support the vehicle in executing relevant program code.

[0182] The processing module may be a processor or a controller, which can implement or execute various exemplary logic blocks, modules, and circuits shown in conjunction with the disclosure of this application. The processor may also be a combination of functions that implement computing capabilities, such as a combination of one or more microprocessors, a combination of digital signal processing (DSP) and a microprocessor, etc., and the storage module may be a memory.

[0183] In addition, the device provided in the embodiments of this application may specifically be a chip, component or module. The chip may include a connected processor and a memory. The memory is used to store instructions. When the processor calls and executes the instructions, the chip can execute a method for starting an engine provided in the above embodiments.

[0184] This embodiment also provides a non-volatile storage medium storing computer program code. When the computer program code is run on a computer, the computer executes the above-described related method steps to implement the method for starting an engine provided in the above embodiment.

[0185] This embodiment also provides a computer program product that, when run on a computer, causes the computer to perform the aforementioned steps to implement a method for starting an engine provided in the above embodiment.

[0186] In this embodiment, the device, non-volatile storage medium, computer program product or chip are all used to execute the corresponding method provided above. Therefore, the beneficial effects that can be achieved can be referred to the beneficial effects of the corresponding method provided above, and will not be repeated here.

[0187] Through the above description of the embodiments, those skilled in the art will understand that, for the sake of convenience and brevity, only the division of the above functional modules is used as an example. In actual applications, the above functions can be assigned to different functional modules as needed, that is, the internal structure of the device can be divided into different functional modules to complete all or part of the functions described above.

[0188] In the embodiments provided in this application, it should be understood that the disclosed apparatus and methods can be implemented in other ways. For example, the apparatus embodiments described above are merely illustrative; for instance, the division of modules or units is only a logical functional division, and in actual implementation, there may be other division methods. For example, multiple units or components may be combined or integrated into another device, or some features may be ignored or not executed. Furthermore, the coupling or direct coupling or communication connection shown or discussed may be through some interfaces; the indirect coupling or communication connection between devices or units may be electrical, mechanical, or other forms.

[0189] The above description is merely a specific embodiment of this application, but the scope of protection of this application is not limited thereto. Any variations or substitutions that can be easily conceived by those skilled in the art within the scope of the technology disclosed in this application should be included within the scope of protection of this application. Therefore, the scope of protection of this application should be determined by the scope of the claims.

Claims

1. A method for starting an engine, characterized in that, A hybrid vehicle includes an engine, a clutch, an electric motor, a torque converter, and a transmission, wherein the engine is connected to the electric motor via the clutch, and the electric motor is connected to the transmission via the torque converter. The method includes: When the vehicle needs to start the engine, the target speed of the motor is determined based on the state of the lock-up clutch in the torque converter. The motor is controlled based on the target rotational speed, and the clutch is controlled to increase torque in a slipping state so that the motor drives the engine to rotate; When the actual engine speed reaches the ignition speed threshold, the engine is controlled to ignite and start.

2. The method according to claim 1, characterized in that, Determining the target speed of the motor based on the state of the lock-up clutch in the hydraulic torque converter includes: With the lock-up clutch in the open state, the motor is controlled to enter the speed control mode; When the motor enters the speed control mode, the drive torque transmitted by the motor to the hydraulic torque converter is determined; The target speed is determined based on the requested torque of the motor and the driving torque.

3. The method according to claim 2, characterized in that, Determining the drive torque transmitted from the motor to the hydraulic torque converter includes: Obtain the actual speed of the motor; The target coefficient is determined based on the oil temperature of the hydraulic torque converter, the speed ratio of the turbine to the pump impeller, and the torque ratio of the turbine to the pump impeller. The driving torque is determined based on the target coefficient and the actual rotational speed.

4. The method according to claim 2, characterized in that, Determining the target speed based on the requested torque of the motor and the drive torque includes: Subtract the driving torque from the requested torque to obtain the target torque; The angular acceleration of the motor is calculated based on the target torque; Based on the angular acceleration and the preset period duration, the rate of change of the motor speed in each period is obtained; Based on the actual speed of the motor and the rate of change of speed, the target speed of the motor in each cycle is determined.

5. The method according to claim 4, characterized in that, The method further includes: After calculating the target speed of the motor in the first cycle after it enters the speed control mode, the actual speed of the motor in the previous cycle of the first cycle is obtained; The speed increment for each cycle is determined based on the speed change rate, and the speed increment is multiplied by the cycle delay to obtain the target speed increment. The target speed of the motor in the first cycle is determined based on the actual speed and the target speed increment.

6. The method according to claim 1, characterized in that, Determining the target speed of the motor based on the state of the lock-up clutch in the hydraulic torque converter includes: When the lock-up clutch is in the closed state or in the process of closing, determine the target slip value that the hydraulic torque converter needs to establish, and determine the target speed of the motor based on the target slip value.

7. The method according to claim 6, characterized in that, The control of the motor based on the target speed includes: The lock-up clutch is controlled to reduce torque, and the motor is controlled to adjust its actual speed to the target speed, so that the hydraulic torque converter can establish the target slip value; When the speed difference between the actual speed of the motor and the target speed is less than a first preset speed difference, the motor is controlled to enter the speed control mode and the motor is controlled to maintain the target speed.

8. The method according to claim 2 or 7, characterized in that, After controlling the engine to ignite and start the engine when the actual engine speed reaches the ignition speed threshold, the method further includes: The engine is controlled based on the current speed of the motor; If the speed difference between the current engine speed and the current motor speed is less than a second preset speed difference, the clutch is controlled to be in a closed state, and the motor is controlled to exit the speed control mode; after exiting the speed control mode, the motor enters the torque control mode.

9. The method according to claim 8, characterized in that, The control of the motor to exit the speed control mode includes: Obtain the actual torque of the motor in the last cycle of the speed control mode; Determine the torque difference between the actual torque and the motor's current requested torque; The target torque gradient is determined based on the torque difference, and the motor is controlled to adjust from the actual torque to the currently requested torque based on the target torque gradient.

10. A vehicle, characterized in that, The vehicles include: Memory, used to store executable program code; A processor for calling and running the executable program code from the memory, causing the vehicle to perform the method as described in any one of claims 1 to 9.

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