Engine shutdown control method and device of power split hybrid power system

Abstract

The invention discloses an engine shutdown control method and device for a power split hybrid power system, and the method comprises the steps: determining a shutdown drag curve enabling the longitudinal impact degree of a vehicle to be minimum in the shutdown process of an engine according to a target crankshaft angle, the longitudinal impact degree of the vehicle in the shutdown process of the engine and the rotating speed of the engine; according to the difference value between the rotating speed of the engine in the kth second in the shutdown process and the target rotating speed of the engine in the kth second on the shutdown dragging curve, the output torque of the generator is determined, and the rotating speed of the engine in the kth second is controlled to reach the target rotating speed of the engine in the kth second on the shutdown dragging curve according to the output torque of the generator, the engine crank angle is adjusted to reach the target crank angle according to the generator output torque determined according to the shutdown drag curve, the adverse effect on vehicle driving smoothness caused by crank angle adjustment in the engine shutdown process is effectively reduced, the impact feeling in the engine shutdown process is reduced, and the vehicle driving smoothness is improved.

Description

Technical Field

[0001] The present application relates to the technical field of power-split hybrid electric vehicles, and in particular to an engine shutdown control method and device for a power-split hybrid electric vehicle system. Background Art

[0002] The power-split hybrid system engine is directly connected to the planetary carrier. The torque fluctuation caused by the engine start and stop acts on the wheel end through the transmission system. The impact caused by the engine start and stop process will be directly transmitted to the wheel end, seriously affecting the vehicle's driving smoothness.

[0003] At present, relevant technologies reduce the impact during engine start-stop by controlling the drive motor torque to load in advance, and adjust the engine crankshaft angle during shutdown to reduce the impact during engine startup.

[0004] However, adjusting the engine crank angle during the shutdown process may adversely affect the vehicle's driving smoothness during the shutdown process. Summary of the invention

[0005] In view of this, the purpose of this application is to provide an engine shutdown control method and device for a power split hybrid system, which reduces the adverse effect of adjusting the crankshaft angle during the engine shutdown process on the vehicle driving smoothness, reduces the impact of the engine shutdown process, and improves the vehicle driving smoothness. The specific scheme is as follows:

[0006] In a first aspect, the present application provides an engine shutdown control method for a power-split hybrid system, the method comprising:

[0007] Determine a shutdown drag curve that minimizes the longitudinal impact of the vehicle during the engine shutdown process according to a target crankshaft angle, a longitudinal impact of the vehicle during the engine shutdown process, and an engine speed, wherein the engine speed is the speed during the engine shutdown process, the longitudinal impact of the vehicle is determined by the rate of change of the vehicle acceleration per unit time, the target crankshaft angle is the angle that minimizes the longitudinal impact of the vehicle during the engine startup process, the shutdown drag curve is a curve of a target speed varying with time within N seconds when the crankshaft angle of the engine is adjusted to reach the target crankshaft angle, the target speed is the speed that minimizes the longitudinal impact of the vehicle during the engine shutdown process, the size of N is determined by the engine speed, and N seconds is the time period from when the engine speed starts to decrease to when it decreases to 0 during the shutdown process;

[0008] Determine the output torque of the generator according to the difference between the engine speed at the kth second during the shutdown process and the target speed at the kth second on the shutdown drag curve, where the kth second is any second within the N seconds;

[0009] According to the generator output torque, the engine speed at the kth second is controlled to reach the target speed at the kth second on the shutdown drag curve.

[0010] Optionally, the method further comprises:

[0011] Obtaining the longitudinal impact degree of the vehicle when the engine is started for the (i+1)th time;

[0012] determining an i-th crankshaft angle compensation value of the engine according to the longitudinal impact degree of the vehicle when the engine is started for the i+1th time, wherein the i-th crankshaft angle compensation value is used to update the target crankshaft angle when the engine is stopped for the i-th time to generate the target crankshaft angle when the engine is stopped for the i+1th time;

[0013] The i+1th shutdown drag curve that minimizes the vehicle longitudinal impact during the i+1th shutdown is determined based on the target crankshaft angle during the i+1th shutdown, the vehicle longitudinal impact during the i+1th shutdown, and the engine speed during the i+1th shutdown.

[0014] Optionally, determining a shutdown drag curve that minimizes the longitudinal impact of the vehicle during the engine shutdown process according to a target crankshaft angle, the longitudinal impact of the vehicle during the engine shutdown process, and the engine speed includes:

[0015] Determining a cost function according to the engine speed during the engine shutdown process, the vehicle longitudinal impact degree during the engine shutdown process, and the target crankshaft angle, wherein the cost function takes minimizing the vehicle longitudinal impact degree as a target;

[0016] Determining, based on the cost function, the target rotational speed corresponding to the kth second within the N seconds of adjusting the crankshaft angle to reach the target crankshaft angle;

[0017] The shutdown drag curve is determined according to the target speed corresponding to the kth second.

[0018] Optionally, the method further comprises:

[0019] When the engine speed reaches below 150 r / min, obtaining the crankshaft angle at the nth second, where the nth second is any second within a time period when the engine speed is between 150 r / min and 0;

[0020] Based on the difference between the crankshaft angle at the nth second and the target crankshaft angle, the compensation torque of the drive motor is determined, and the compensation torque is used to reduce the influence of the longitudinal impact of the vehicle on adjusting the crankshaft angle to reach the target crankshaft angle during the time period when the engine speed is between 150r / min and 0.

[0021] In a second aspect, an embodiment of the present application provides an engine shutdown control device for a power split hybrid system, the device comprising:

[0022] a first determining unit, for determining a shutdown drag curve that minimizes the longitudinal impact of the vehicle during the engine shutdown process according to a target crankshaft angle, a longitudinal impact of the vehicle during the engine shutdown process, and an engine speed, wherein the engine speed is the speed during the engine shutdown process, the longitudinal impact of the vehicle is determined by a rate of change of vehicle acceleration per unit time, the target crankshaft angle is an angle that minimizes the longitudinal impact of the vehicle during the engine startup process, the shutdown drag curve is a curve of a target speed varying with time within N seconds when the crankshaft angle of the engine is adjusted to reach the target crankshaft angle, the target speed is a speed that minimizes the longitudinal impact of the vehicle during the engine shutdown process, the size of N is determined by the engine speed, and N seconds is a time period during which the engine speed decreases from the beginning to 0 during the shutdown process;

[0023] A second determining unit is used to determine the output torque of the generator according to the difference between the speed of the engine at the kth second during the shutdown process and the target speed at the kth second on the shutdown drag curve, wherein the kth second is any second within the N seconds;

[0024] A control unit is used to control the speed of the engine at the kth second to reach the target speed at the kth second on the shutdown drag curve according to the output torque of the generator.

[0025] Optionally, the device further comprises:

[0026] A first acquisition unit, used for acquiring the longitudinal impact degree of the vehicle when the engine is started for the (i+1)th time;

[0027] a third determining unit, for determining an i-th crankshaft angle compensation value of the engine according to the longitudinal impact degree of the vehicle when the engine is started for an i+1th time, wherein the i-th crankshaft angle compensation value is used to update the target crankshaft angle when the engine is stopped for an i-th time to generate the target crankshaft angle when the engine is stopped for an i+1th time;

[0028] The fourth determination unit is used to determine the i+1th shutdown drag curve that minimizes the longitudinal impact of the vehicle during the i+1th shutdown process based on the target crankshaft angle at the i+1th shutdown, the longitudinal impact of the vehicle during the i+1th shutdown process, and the engine speed during the i+1th shutdown process.

[0029] In a third aspect, the present application provides an electronic device, the electronic device comprising:

[0030] Memory for storing computer programs or computer instructions;

[0031] A processor is used to execute the computer program or computer instructions stored in the memory, so that the electronic device executes the method described in the first aspect of the present application or any possible implementation method of the first aspect according to the computer instructions.

[0032] In a fourth aspect, the present application provides a computer program product comprising instructions, which, when executed on a computer, enables the computer to execute the method described in the first aspect of the present application or any possible implementation of the first aspect.

[0033] In a fifth aspect, the present application provides a computer-readable storage medium, comprising computer instructions, wherein the computer instructions instruct a computer to execute the method described in the first aspect of the present application or any possible implementation of the first aspect.

[0034] Based on the implementations provided in the above aspects, this application can also be further combined to provide more implementations.

[0035] It can be seen from the above technical solutions that the present application has the following beneficial effects:

[0036] The present application determines a shutdown drag curve that minimizes the longitudinal impact of the vehicle during engine shutdown according to the engine speed during engine shutdown, the longitudinal impact of the vehicle during shutdown and the target crankshaft angle, controls the generator output torque, and reduces the engine speed along the shutdown drag curve, and reduces the engine speed according to the shutdown drag curve while ensuring that the impact of the shutdown process is minimized. Since the engine output torque is adjusting the engine crankshaft angle while controlling the reduction in engine speed, adjusting the crankshaft angle to the target crankshaft angle according to the engine output torque determined by the shutdown drag curve can minimize the impact of the impact caused by adjusting the engine crankshaft angle during shutdown. Therefore, the technical solution of the present application effectively reduces the adverse effects of adjusting the crankshaft angle during engine shutdown on the vehicle driving smoothness, reduces the impact of the engine shutdown process, and improves the vehicle driving smoothness. BRIEF DESCRIPTION OF THE DRAWINGS

[0037] In order to more clearly illustrate the technical solutions in the embodiments of the present application, the drawings required for use in the description of the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments recorded in the present application. For ordinary technicians in this field, other drawings can also be obtained based on these drawings.

[0038] Figure 1 This is a flow chart of an engine shutdown control method of a power split hybrid system in an embodiment of the present application;

[0039] Figure 2 This is a schematic diagram of a hybrid power transmission structure in an embodiment of the present application;

[0040] Figure 3 This is a flow chart of an engine shutdown control method of a power split hybrid system in an embodiment of the present application;

[0041] Figure 4 A schematic diagram of a shutdown drag curve in an embodiment of the present application;

[0042] Figure 5 Schematic diagram of the structure of an engine shutdown control device of a power-split hybrid system in an embodiment of the present application. DETAILED DESCRIPTION

[0043] The embodiments of the present application will be described in more detail below with reference to the accompanying drawings. Although certain embodiments of the present application are shown in the accompanying drawings, it should be understood that the present application can be implemented in various forms and should not be construed as being limited to the embodiments described herein. Instead, these embodiments are provided to provide a more thorough and complete understanding of the present application. It should be understood that the drawings and embodiments of the present application are only for exemplary purposes and are not intended to limit the scope of protection of the present application.

[0044] The term "including" and its variations used herein are open inclusions, i.e., "including but not limited to". The term "based on" means "based at least in part on". The term "one embodiment" means "at least one embodiment"; the term "another embodiment" means "at least one additional embodiment"; the term "some embodiments" means "at least some embodiments". The relevant definitions of other terms will be given in the following description.

[0045] As described in the background technology, adjusting the engine crankshaft angle during the shutdown process will have an adverse effect on the vehicle driving smoothness during the shutdown process. Based on this, the embodiment of the present application provides an engine shutdown control method for a power-split hybrid system, which determines a shutdown drag curve that minimizes the vehicle longitudinal impact during the engine shutdown process according to the engine speed during the engine shutdown process, the vehicle longitudinal impact during the shutdown process, and the target crankshaft angle, controls the generator output torque, and reduces the engine speed along the shutdown drag curve. Under the premise of ensuring that the impact of the shutdown process is minimized, the engine speed is reduced according to the shutdown drag curve, which effectively reduces the impact of adjusting the engine crankshaft angle during the shutdown process on the impact of the shutdown process, reduces the impact of the engine shutdown process, and improves the vehicle driving smoothness.

[0046] Figure 2 The present application is a structural schematic diagram of a dedicated hybrid transmission, which is a hybrid system that uses a dual-motor hybrid technology and couples the motor and the engine together using a planetary gear mechanism. Figure 2 1 is an internal combustion engine (ICE). In the field of vehicles, it refers to a traditional engine that relies on burning gasoline, diesel or other fossil fuels to generate power. It is referred to as an engine below. Engine 1 is connected to the planet carrier 4 of the P1 planetary gear. The planetary gear refers to a planetary gear transmission, which consists of a sun gear, planetary gears, a planet carrier, a ring gear, etc. Figure 2 2 is an integrated intelligent starter generator (ISG), hereinafter referred to as generator. The ISG motor can start the engine in the power split hybrid system, and can adjust the speed and regenerate power during normal driving. Generator 2 is connected to the sun gear 5 of the P1 planetary gear, and the ring gear 3 of the P1 planetary gear outputs power and is connected to the transient motor 6 (TM) and the gearbox input shaft 7. The gearbox output shaft 9 is connected to the wheel end. The transient motor is used as a drive motor in the power split hybrid system, mainly responsible for driving the vehicle, and is hereinafter referred to as the drive motor.

[0047] In order to make the technical solution of the present application clearer and easier to understand, the method provided by the present application is introduced below in conjunction with specific embodiments.

[0048] Figure 1 This is a flow chart of an engine shutdown control method for a power split hybrid system provided by an embodiment of the present application. The engine shutdown control method for a power split hybrid system provided by this embodiment includes the following steps:

[0049] S101: Determine a stop drag curve that minimizes the longitudinal impact of the vehicle during the engine shutdown process according to a target crankshaft angle, the longitudinal impact of the vehicle during the engine shutdown process, and the engine speed.

[0050] There is low-speed pulsation resistance in the engine start-up phase. Different crankshaft angles correspond to different engine resistance torques. The smaller the total resistance torque, the better the smoothness of the engine start-up and the faster the responsiveness. The influence of different engine initial crankshaft positions on the longitudinal impact of the whole vehicle during the engine start-up process can be obtained through simulation analysis. By establishing a transmission system model of the power system and testing the longitudinal impact of the vehicle during the engine start-up process according to different initial crankshaft angles, the crankshaft angle corresponding to the minimum longitudinal impact of the vehicle can be found. The angle that minimizes the longitudinal impact of the vehicle during the engine start-up process is defined as the target crankshaft angle. The longitudinal impact of the vehicle is a measure of the impact of the vehicle. It can be understood that the greater the impact, the greater the vehicle vibration and the worse the driving smoothness of the vehicle. The longitudinal impact of the vehicle is determined by the rate of change of the longitudinal acceleration of the vehicle. Selecting it as an evaluation index to evaluate the longitudinal smoothness caused by the control of the vehicle power system can not only synchronize with human senses, but also exclude the acceleration caused by road conditions and bumps. The engine speed is the engine speed during the shutdown process. The shutdown drag curve is a curve of the target speed changing with time within N seconds when the crankshaft angle of the engine is adjusted to reach the target crankshaft angle. The target speed is the speed that minimizes the longitudinal impact of the vehicle during the engine shutdown process determined according to the shutdown drag curve. The size of N is determined by the engine speed, and N seconds is the time period from the beginning of the engine speed decreasing to 0 during the engine shutdown process.

[0051] In one possible implementation, the target crankshaft angle during the shutdown process of the same vehicle will change with factors such as the vehicle's usage time, usage, and engine status. The target crankshaft angle needs to be corrected during each engine start and stop process to ensure that the engine crankshaft angle can be stopped to a crankshaft angle that minimizes the longitudinal impact of the vehicle when the engine is started next time.

[0052] The embodiment of the present application provides a method for correcting a target crankshaft angle, and the method specifically comprises the following steps:

[0053] S201: Obtaining the longitudinal impact degree of the vehicle when the engine is started for the (i+1)th time.

[0054] S202: Determine the i-th crank angle compensation value of the engine according to the longitudinal impact degree of the vehicle when the engine is started for the i+1th time.

[0055] S203: Determine the i+1th stop drag curve that minimizes the vehicle longitudinal impact during the i+1th stop according to the target crankshaft angle during the i+1th stop, the vehicle longitudinal impact during the i+1th stop, and the engine speed during the i+1th stop.

[0056] When the engine is started for the i+1th time, the longitudinal impact degree of the vehicle is detected, and the i-th crankshaft angle compensation value for updating the target crankshaft angle when the engine is stopped for the i-th time is determined according to the longitudinal impact degree of the vehicle when the engine is started for the i+1th time; the target crankshaft angle at the i-th stop is corrected according to the i-th crankshaft angle compensation value to obtain the target crankshaft angle at the i+1th stop; during the i+1th stop, the i+1th stop drag curve that minimizes the longitudinal impact degree of the vehicle during the i+1th stop is determined according to the i+1th target crankshaft angle, the longitudinal impact degree of the vehicle during the i+1th stop, and the engine speed during the i+1th stop; a stop drag curve library corresponding to different target crankshaft angles is constructed according to the target crankshaft angle at each stop; during the i+1th stop, the stop drag curve corresponding to the i+1th target crankshaft angle in the stop drag curve library can be called according to the corrected i+1th target crankshaft angle to perform shutdown.

[0057] When the engine is started, the generator speed is adjusted to reverse the engine to start, and the drive motor performs torque compensation to reduce the impact. When the engine is started, the current crankshaft angle position and the longitudinal impact of the vehicle are detected, and the target crankshaft angle at the last shutdown is corrected according to the change in the longitudinal impact of the vehicle. The corrected target crankshaft angle is used as the target crankshaft angle for this shutdown, which can effectively reduce the change in the target crankshaft angle caused by different vehicle conditions during each start and stop of the vehicle, thereby avoiding the situation where the engine crankshaft angle cannot be stopped at the crankshaft angle that minimizes the longitudinal impact of the vehicle at the next start during the shutdown process. This can effectively reduce the impact of the engine starting process and improve the driving smoothness of the vehicle.

[0058] In one possible implementation, Figure 4 The stall drag curve shown as the engine speed decreases to zero over time can be determined by a dynamic programming algorithm.

[0059] The present application provides a method for calculating a shutdown drag curve, which specifically includes the following steps:

[0060] S301: Determine a cost function according to the engine speed during the engine shutdown process, the vehicle longitudinal impact degree during the engine shutdown process, and the target crankshaft angle.

[0061] S302: Determine, based on the cost function, the target rotational speed corresponding to the kth second within N seconds of adjusting the crankshaft angle to reach the target crankshaft angle.

[0062] S303: Determine a shutdown drag curve according to the target speed corresponding to the kth second.

[0063] The cost function is an objective function used to find the optimal solution. The cost function with the minimum longitudinal impact of the vehicle as the goal is determined according to the engine speed during engine shutdown, the longitudinal impact of the vehicle during engine shutdown, and the target crankshaft angle. The state quantities select the engine speed and the crankshaft angle. The dynamic programming algorithm is used within N seconds to control the engine speed from the beginning to 0 and adjust the engine crankshaft angle to the target crankshaft angle. The kth second is any second within N seconds. The shutdown drag curve with the minimum longitudinal impact of the vehicle during shutdown is determined according to the target speed corresponding to the kth second, and the shutdown drag curve solved is used for shutdown control.

[0064] The cost function is determined by the engine speed, the target crankshaft angle, and the longitudinal impact of the vehicle. The cost function aims to minimize the longitudinal impact of the vehicle during the shutdown process. A dynamic programming algorithm is used in the process of controlling the engine speed to drop to 0 and adjusting the engine crankshaft angle to reach the target crankshaft angle to solve the shutdown drag curve with the minimum longitudinal impact of the vehicle during the shutdown process. The solved shutdown drag curve is used for shutdown control, which can effectively reduce the adverse effects of adjusting the crankshaft angle on the vehicle impact during the shutdown process.

[0065] S102: Determine the generator output torque according to the difference between the engine speed at the kth second during the shutdown process and the target speed at the kth second on the shutdown drag curve.

[0066] The kth second is any second within N seconds during which the engine speed drops to 0 during shutdown. The output torque of the generator used to drag the engine from the speed of the kth second to the target speed of the kth second on the shutdown drag curve is calculated based on the difference between the engine speed of the kth second and the target speed of the kth second on the shutdown drag curve. That is, the engine can be dragged from the speed of the kth second to the target speed of the kth second on the shutdown drag curve by the calculated output torque of the generator.

[0067] S103: According to the generator output torque, the engine speed at the kth second is controlled to reach the target speed at the kth second on the shutdown drag curve.

[0068] The generator output torque drags the engine speed to decrease along the shutdown drag curve, that is, the engine speed at the kth second is controlled to reach the target speed at the kth second on the shutdown drag curve.

[0069] A shutdown drag curve that minimizes the longitudinal impact of the vehicle during engine shutdown is determined based on the engine speed during engine shutdown, the longitudinal impact of the vehicle during shutdown, and the target crankshaft angle, and the generator output torque is controlled to reduce the engine speed along the shutdown drag curve. The engine speed is reduced according to the shutdown drag curve while ensuring that the impact during the shutdown process is minimized. Since the engine output torque is adjusting the engine crankshaft angle while controlling the reduction in engine speed, the crankshaft angle is adjusted according to the engine output torque determined by the shutdown drag curve to reach the target crankshaft angle, which can minimize the influence of adjusting the engine crankshaft angle on the longitudinal impact of the vehicle during shutdown. Therefore, the technical solution of the present application effectively reduces the adverse effect of adjusting the crankshaft angle during engine shutdown on the driving smoothness of the vehicle, reduces the impact during the engine shutdown process, and improves the driving smoothness of the vehicle.

[0070] In one possible implementation, when the engine speed is low (below 150r / min), the torque fluctuation generated by the engine is the largest, which may affect the position adjustment of the crankshaft angle, causing a certain deviation between the crankshaft angle adjusted according to the shutdown drag curve and the target crankshaft angle.

[0071] The present application provides a method for reducing the longitudinal impact of a vehicle when the engine speed is low during shutdown, and the method specifically comprises the following steps:

[0072] S401: When the engine speed reaches below 150 r / min, the crankshaft angle at the nth second is obtained.

[0073] S402: Determine a compensation torque of a driving motor according to a difference between the crankshaft angle at the nth second and the target crankshaft angle.

[0074] During the engine shutdown process, the torque fluctuations caused by the engine's pumping resistance, inertia resistance and friction resistance may cause the whole vehicle to shake. Especially when the engine speed is low (below 150r / min), the impact of these torque fluctuations may be more obvious. The nth second is any second in the time period between 150r / min and 0 when the engine speed is between 0. The compensation torque of the drive motor determined according to the difference between the crankshaft angle of the engine at the nth second and the target crankshaft angle is used to reduce the influence of the longitudinal impact of the vehicle on the crankshaft angle adjustment, to prevent the longitudinal impact of the vehicle from being too large when the engine speed is low, affecting the generator output torque to adjust the engine crankshaft angle, resulting in the crankshaft angle position not being able to adjust to the target crankshaft angle, and the torque compensation is performed by the drive motor, which reduces the longitudinal impact of the vehicle during the shutdown process, and also improves the accuracy of the generator output torque to adjust the crankshaft angle.

[0075] Figure 3This is a flow chart of an engine shutdown control method for a power split hybrid system in an embodiment of the present application. When the engine receives a shutdown command, the engine has not yet been shut down and stopped. The engine is stopped by dragging the generator to follow the shutdown drag curve. The shutdown drag curve is a curve of the engine speed changing with time that can minimize the longitudinal impact of the vehicle during the shutdown process, obtained by fitting the longitudinal impact of the vehicle and the crankshaft angle position. When the engine speed reaches the idle speed, the oil is cut off and the flame is turned off. When the engine is running, if the accelerator pedal is completely relaxed, the engine is in an idle state. The speed of the engine at idle speed is called the idle speed. When the engine speed is low (below 150r / min), the drive motor performs torque compensation to prevent the adverse effect of the crankshaft angle adjustment due to excessive longitudinal impact of the vehicle when the engine speed is low. After the engine is shut down and the flame is turned off, the generator continues to drag the engine to stop. After the engine speed is controlled to drop to 0 and the engine crankshaft angle reaches the target crankshaft angle, the shutdown is completed. When the engine receives the start command, the generator adjusts the speed to reverse the engine start, detects the longitudinal impact of the vehicle during the start process, and determines the crankshaft angle compensation value used to update the target crankshaft angle at the last shutdown based on the longitudinal impact of the vehicle during the start process. The updated target crankshaft angle at this shutdown is more suitable for the current vehicle condition, which can more effectively reduce the longitudinal impact of the vehicle at the next start and reduce the engine start time. During the entire process of engine start, the drive motor performs torque compensation to reduce the longitudinal impact of the vehicle during the start process, and the start is completed.

[0076] In a possible implementation, the initial value of the target crankshaft angle may be obtained by simulating a power-split hybrid powertrain model.

[0077] When the vehicle is shut down for the first time, the target crankshaft angle during the shutdown process is obtained through power split hybrid system simulation. The simulated target crankshaft angle is the angle that has the least impact on the longitudinal impact of the vehicle at the next start, which can improve the driving smoothness of the vehicle at the start.

[0078] Figure 5 This is a schematic diagram of the structure of an engine shutdown control device of a power split hybrid system in an embodiment of the present application, the device comprising:

[0079] A first determining unit 501 is used to determine a shutdown drag curve that minimizes the longitudinal impact of the vehicle during the engine shutdown process according to a target crankshaft angle, a longitudinal impact of the vehicle during the engine shutdown process, and an engine speed, wherein the engine speed is the speed during the engine shutdown process, the longitudinal impact of the vehicle is determined by a rate of change of vehicle acceleration per unit time, the target crankshaft angle is an angle that minimizes the longitudinal impact of the vehicle during the engine startup process, the shutdown drag curve is a curve of a target speed varying with time within N seconds when the crankshaft angle of the engine is adjusted to reach the target crankshaft angle, the target speed is a speed that minimizes the longitudinal impact of the vehicle during the engine shutdown process, the size of N is determined by the engine speed, and N seconds is a time period during which the engine speed decreases from the beginning to 0 during the shutdown process;

[0080] A second determining unit 502 is used to determine the output torque of the generator according to the difference between the speed of the engine at the kth second during the shutdown process and the target speed at the kth second on the shutdown drag curve, wherein the kth second is any second within the N seconds;

[0081] The control unit 503 is used to control the speed of the engine at the kth second to reach the target speed at the kth second on the shutdown drag curve according to the output torque of the generator.

[0082] As can be seen from the above, the embodiment of the present application also provides a shutdown control device for a power-split hybrid system, wherein the first determination unit 501 determines a shutdown drag curve that minimizes the longitudinal impact of the vehicle during the engine shutdown process according to the target crankshaft angle, the longitudinal impact of the vehicle during the engine shutdown process, and the engine speed, and the second determination unit 502 determines the generator output torque according to the difference between the engine speed at the kth second during the shutdown process and the target speed at the kth second on the shutdown drag curve, and the control unit 503 is used to control the engine speed at the kth second to reach the target speed at the kth second on the shutdown drag curve according to the generator output torque, and reduce the engine speed according to the shutdown drag curve while ensuring that the impact of the shutdown process is minimized. Since the engine output torque is also adjusting the engine crankshaft angle while controlling the engine speed to be reduced, the engine output torque determined according to the shutdown drag curve adjusts the crankshaft angle to reach the target crankshaft angle, so that the influence of adjusting the engine crankshaft angle on the longitudinal impact of the vehicle during the shutdown process can be minimized, the impact of the engine shutdown process can be reduced, and the vehicle driving smoothness can be improved.

[0083] In a possible implementation manner, the apparatus further includes a first acquiring unit, a third determining unit, and a fourth determining unit, configured to:

[0084] A first acquisition unit, used for acquiring the longitudinal impact degree of the vehicle when the engine is started for the (i+1)th time;

[0085] a third determining unit, for determining an i-th crankshaft angle compensation value of the engine according to the longitudinal impact degree of the vehicle when the engine is started for an i+1th time, wherein the i-th crankshaft angle compensation value is used to update the target crankshaft angle when the engine is stopped for an i-th time to generate the target crankshaft angle when the engine is stopped for an i+1th time;

[0086] The fourth determination unit is used to determine the i+1th shutdown drag curve that minimizes the longitudinal impact of the vehicle during the i+1th shutdown process based on the target crankshaft angle at the i+1th shutdown, the longitudinal impact of the vehicle during the i+1th shutdown process, and the engine speed during the i+1th shutdown process.

[0087] In a possible implementation manner, the first determining unit 501 is specifically configured to:

[0088] Determining a cost function according to the engine speed during the engine shutdown process, the vehicle longitudinal impact degree during the engine shutdown process, and the target crankshaft angle, wherein the cost function takes minimizing the vehicle longitudinal impact degree as a target;

[0089] Determining, based on the cost function, the target rotational speed corresponding to the kth second within the N seconds of adjusting the crankshaft angle to reach the target crankshaft angle;

[0090] The shutdown drag curve is determined according to the target speed corresponding to the kth second.

[0091] In a possible implementation manner, the apparatus further includes a second acquiring unit and a fifth determining unit, configured to:

[0092] A second acquisition unit is used to acquire the crankshaft angle at the nth second when the engine speed reaches below 150 r / min, where the nth second is any second in a time period when the engine speed is between 150 r / min and 0;

[0093] The fifth determination unit is used to determine the compensation torque of the drive motor according to the difference between the crankshaft angle at the nth second and the target crankshaft angle, and the compensation torque is used to reduce the influence of the longitudinal impact degree of the vehicle on adjusting the crankshaft angle to reach the target crankshaft angle during the time period when the engine speed is between 150r / min and 0.

[0094] In a possible implementation, the initial value of the target crankshaft angle is obtained through model simulation of the power-split hybrid power system.

[0095] The present application provides an electronic device, the electronic device comprising:

[0096] Memory for storing computer programs or computer instructions;

[0097] The processor is used to execute the computer program or computer instruction stored in the memory, so that the electronic device executes the method provided by the above embodiment.

[0098] An embodiment of the present application provides a computer program product including instructions, which, when executed on a computing device, enables the computing device to execute the method provided in the above embodiment.

[0099] An embodiment of the present application provides a computer-readable storage medium, which is used to store a computer program so that the computer program executes the method provided by the above embodiment.

[0100] Through the description of the above implementation methods, it can be known that those skilled in the art can clearly understand that all or part of the steps in the above-mentioned embodiment method can be implemented by means of software plus a general hardware platform. Based on such an understanding, the technical solution of the present application can be embodied in the form of a software product, which can be stored in a storage medium, such as a read-only memory (ROM) / RAM, a magnetic disk, an optical disk, etc., including a number of instructions for a computer device (which can be a personal computer, a server, or a network communication device such as a router) to execute the methods described in each embodiment of the present application or some parts of the embodiments.

[0101] Each embodiment in this specification is described in a progressive manner, and the same or similar parts between the embodiments can refer to each other, and each embodiment focuses on the differences from other embodiments. In particular, for the device embodiment, since it is basically similar to the method embodiment, the description is relatively simple, and the relevant parts can refer to the partial description of the method embodiment. The device embodiment described above is only schematic, in which the modules described as separate components may or may not be physically separated, and the components displayed as modules may or may not be physical modules, that is, they may be located in one place, or they may be distributed on multiple network units. Some or all of the modules can be selected according to actual needs to achieve the purpose of the scheme of this embodiment. Ordinary technicians in this field can understand and implement it without paying creative work.

[0102] The above description is merely an exemplary embodiment of the present application and is not intended to limit the protection scope of the present application.

Claims

1. An engine shutdown control method for a power-split hybrid system, characterized in that: The method comprises: Determine a shutdown drag curve that minimizes the longitudinal impact of the vehicle during the engine shutdown process according to a target crankshaft angle, a longitudinal impact of the vehicle during the engine shutdown process, and an engine speed, wherein the engine speed is the speed during the engine shutdown process, the longitudinal impact of the vehicle is determined by the rate of change of the longitudinal acceleration of the vehicle, the target crankshaft angle is the angle that minimizes the longitudinal impact of the vehicle during the engine startup process, the shutdown drag curve is a curve of target speed change over time within N seconds when the crankshaft angle of the engine is adjusted to reach the target crankshaft angle, the target speed is the speed that minimizes the longitudinal impact of the vehicle during the engine shutdown process, the size of N is determined by the engine speed, and N seconds is the time period from the beginning of the engine speed decreasing to the time of decreasing to 0 during the shutdown process; Determine the output torque of the generator according to the difference between the engine speed at the kth second during the shutdown process and the target speed at the kth second on the shutdown drag curve, where the kth second is any second within the N seconds; According to the generator output torque, the engine speed at the kth second is controlled to reach the target speed at the kth second on the shutdown drag curve.

2. The method according to claim 1, characterized in that The method further comprises: Obtaining the longitudinal impact degree of the vehicle when the engine is started for the (i+1)th time; determining an i-th crankshaft angle compensation value of the engine according to the longitudinal impact degree of the vehicle when the engine is started for the i+1th time, wherein the i-th crankshaft angle compensation value is used to update the target crankshaft angle when the engine is stopped for the i-th time to generate the target crankshaft angle when the engine is stopped for the i+1th time; The i+1th shutdown drag curve that minimizes the vehicle longitudinal impact during the i+1th shutdown is determined based on the target crankshaft angle during the i+1th shutdown, the vehicle longitudinal impact during the i+1th shutdown, and the engine speed during the i+1th shutdown.

3. The method according to claim 1, characterized in that The step of determining the shutdown drag curve that minimizes the longitudinal impact of the vehicle during the engine shutdown process according to the target crankshaft angle, the longitudinal impact of the vehicle during the engine shutdown process, and the engine speed includes: Determining a cost function according to the engine speed during the engine shutdown process, the vehicle longitudinal impact degree during the engine shutdown process, and the target crankshaft angle, wherein the cost function takes minimizing the vehicle longitudinal impact degree as a target; Determining, based on the cost function, the target rotational speed corresponding to the kth second within the N seconds of adjusting the crankshaft angle to reach the target crankshaft angle; The shutdown drag curve is determined according to the target speed corresponding to the kth second.

4. The method according to claim 1, characterized in that: The method further comprises: When the engine speed reaches below 150 r / min, obtaining the crankshaft angle at the nth second, where the nth second is any second within a time period when the engine speed is between 150 r / min and 0; Based on the difference between the crankshaft angle at the nth second and the target crankshaft angle, the compensation torque of the drive motor is determined, and the compensation torque is used to reduce the influence of the vehicle longitudinal impact on adjusting the crankshaft angle to reach the target crankshaft angle during the time period when the engine speed is between 150r / min and 0.

5. The method according to claim 1, characterized in that The initial value of the target crankshaft angle is obtained through model simulation of the power split hybrid power system.

6. An engine shutdown control device for a power-split hybrid system, characterized in that: The device comprises: a first determining unit, for determining a shutdown drag curve that minimizes the longitudinal impact of the vehicle during the engine shutdown process according to a target crankshaft angle, a longitudinal impact of the vehicle during the engine shutdown process, and an engine speed, wherein the engine speed is the speed during the engine shutdown process, the longitudinal impact of the vehicle is determined by a rate of change of vehicle acceleration per unit time, the target crankshaft angle is an angle that minimizes the longitudinal impact of the vehicle during the engine startup process, the shutdown drag curve is a curve of a target speed varying with time within N seconds when the crankshaft angle of the engine is adjusted to reach the target crankshaft angle, the target speed is a speed that minimizes the longitudinal impact of the vehicle during the engine shutdown process, the size of N is determined by the engine speed, and N seconds is a time period during which the engine speed decreases from the beginning to 0 during the shutdown process; A second determining unit is used to determine the output torque of the generator according to the difference between the speed of the engine at the kth second during the shutdown process and the target speed at the kth second on the shutdown drag curve, wherein the kth second is any second within the N seconds; A control unit is used to control the speed of the engine at the kth second to reach the target speed at the kth second on the shutdown drag curve according to the output torque of the generator.

7. The device according to claim 6, characterized in that The device also includes: A first acquisition unit, used for acquiring the longitudinal impact degree of the vehicle when the engine is started for the (i+1)th time; a third determining unit, for determining an i-th crankshaft angle compensation value of the engine according to the longitudinal impact degree of the vehicle when the engine is started for an i+1th time, wherein the i-th crankshaft angle compensation value is used to update the target crankshaft angle when the engine is stopped for an i-th time to generate the target crankshaft angle when the engine is stopped for an i+1th time; The fourth determination unit is used to determine the i+1th shutdown drag curve that minimizes the longitudinal impact of the vehicle during the i+1th shutdown process based on the target crankshaft angle at the i+1th shutdown, the longitudinal impact of the vehicle during the i+1th shutdown process, and the engine speed during the i+1th shutdown process.

8. An electronic device, characterized in that: The electronic device comprises: Memory for storing computer programs or computer instructions; A processor, configured to execute a computer program or computer instruction stored in the memory, so that the electronic device executes the method as claimed in any one of claims 1 to 5.

9. A computer program product, characterized in that When the computer program product is run on a computer, the computer is caused to execute the method according to any one of claims 1 to 5.

10. A computer-readable storage medium, characterized in that: The method comprises computer instructions, wherein the computer instructions instruct a computer to execute the method according to any one of claims 1 to 5.

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