Method, system and product for evaluating knocking risk in engine starting process

Abstract

The invention provides an engine starting process knocking risk assessment method, system and product, and relates to the technical field of automobiles, the method comprises the steps that a torsional dynamics model of a power system is constructed based on a target component of the power system, and the target component is a component related to the flow direction of a power flow in the engine starting process; constructing a control strategy model, wherein the control strategy model is used for controlling the output torque of an engine and a starting motor in the torsional dynamics model; performing coupling simulation on the control strategy model and the torsion dynamics model according to a selected engine starting working condition point to obtain a corresponding simulation result; and according to the simulation result, whether the knocking risk exists in the engine starting process or not is determined. The invention aims to reduce the related cost of noise optimization in the engine starting process of the hybrid power system.

Description

Technical Field

[0001] The present application relates to the field of automobile technology, and in particular to a method, system and product for evaluating knocking risk during an engine starting process. Background Art

[0002] With the booming development of the new energy vehicle market, in order to satisfy users' pure electric driving experience while increasing the mileage and solving users' mileage anxiety, various OEMs have successively launched new energy vehicles equipped with hybrid systems, which greatly increased the comprehensive mileage of the vehicles. When the battery power is lower than a certain value, the engine is started, and the mechanical energy generated by the engine is converted into electrical energy through the generator to supply the drive motor to drive the vehicle, and the excess electrical energy is charged to the battery; when the vehicle speed is higher than a certain value, the engine reaches the economic efficiency range, and the engine is started to provide power for the entire vehicle. However, during the start-up process of the above engine, due to the unreasonable design and matching of the parameters of the various components of the hybrid system, noise is easily generated, affecting the user's driving experience.

[0003] Currently, calibration tests are mainly carried out after prototypes are produced. The noise problem during engine starting is optimized by calibrating relevant parameters of the engine or starter motor. This process requires a lot of manpower, material resources and related equipment support, which will not only increase the project development cycle, but also increase the development cost. Summary of the invention

[0004] In view of this, the present application provides a method, system and product for assessing knock risk during engine startup, aiming to solve or partially solve the problems existing in the background technology.

[0005] In a first aspect, the present application provides a method for assessing knock risk during an engine starting process, the method comprising: Building a torsional dynamics model of the power system based on a target component of the power system, wherein the target component is a component related to the power flow direction during the engine starting process; Constructing a control strategy model, wherein the control strategy model is used to control the output torque of the engine and the starter motor in the torsional dynamics model; According to the selected engine starting operating point, coupling simulation is performed on the control strategy model and the torsional dynamics model to obtain corresponding simulation results; According to the simulation results, it is determined whether there is a knock risk during the engine starting process.

[0006] Optionally, when the target components include an engine, a torque limiter, a gear pair and a starter motor, the step of constructing a torsional dynamics model of the power system based on the target components of the power system includes: Build engine model, torque limiter model, gear pair model and starter motor model based on target components of the powertrain; The active end of the torque limiter model is connected to the engine crankshaft of the engine model, the passive end of the torque limiter model is connected to the active gear system of the gear pair model, and the driven gear system of the gear pair model is connected to the motor rotor system of the starter motor model, so as to construct a torsional dynamics model of the power system.

[0007] Optionally, according to the selected engine starting operating point, coupling simulation is performed on the control strategy model and the torsional dynamics model to obtain corresponding simulation results, including: According to the selected engine starting operating point, the starting motor control strategy model outputs a switch signal to control the starting motor model to output torque, so as to drive the components of the power source to reach the target speed; When the engine model reaches the target speed, the load factor is output by the engine control strategy model to control the torque output of the engine model, so as to realize the torque interaction between the engine model and the starter motor model and obtain the corresponding simulation result.

[0008] Optionally, before performing coupling simulation on the control strategy model and the torsional dynamics model according to the selected engine starting operating point to obtain corresponding simulation results, the method further includes: Inputting the step-changed torque signal to the torque port of the starter motor control strategy model to calibrate the parameters of the starter motor torque control module in the starter motor control strategy model to obtain a first calibration result; When the first calibration result shows that the output torque meets the response characteristic requirement, the speed signal with step change is input into the speed port of the starter motor control strategy model to calibrate the speed control parameter to obtain a second calibration result; When the second calibration result shows that the characteristic of the output torque is consistent with the measured characteristic of the output torque of the starter motor, a starter motor control strategy model capable of performing coupling simulation is obtained; Controlling the engine control strategy model to output a constant load factor under steady-state conditions to control the output torque of the engine model, and calibrating the engine control strategy model using torque test data actually measured by the engine to obtain a third calibration result; When the third calibration result shows that the characteristic of the output torque is consistent with the measured characteristic of the engine output torque, an engine control strategy model capable of performing coupled simulation is obtained.

[0009] Optionally, determining whether there is a knock risk during the engine startup process according to the simulation result includes: When the simulation result satisfies the first preset condition and / or the second preset condition, determining that there is a knock risk during the engine starting process; The first preset condition is that during the coupled simulation engine startup process, the number of positive and negative changes in the torsion angle difference between the active end and the passive end of the torque limiter model in the torsion dynamics model is greater than or equal to a preset number; The second preset condition is that during the coupled simulation engine startup process, tooth knocking occurs during the meshing process of the gear pair model and the tooth knocking force is greater than a set threshold.

[0010] Optionally, the method further includes: Optimizing control parameters in the control strategy model in the presence of knock risk during engine starting; Based on the optimized control parameters, the control strategy model and the torsional dynamics model are re-coupled and simulated until a target simulation result is obtained, wherein the target simulation result is a result indicating that there is no knock risk during the engine starting process.

[0011] Optionally, build an engine model, including: According to the number of engine cylinders, the engine is discretized into an equivalent crank cylinder pressure model; The crank cylinder pressure model is connected through stiffness and damping elements, and the ignition sequence is set to construct an engine model.

[0012] Optionally, build a torque limiter model, including: The torque limiter is divided into an active end and a passive end using the damping spring inside the torque limiter as a boundary; Determine the active end and the passive end as inertia elements respectively; The inertia element at the active end and the inertia element at the passive end are connected via stiffness and damping elements to construct a torque limiter model.

[0013] Optionally, build a gear pair model, including: Determining a driving gear system of the gear pair as an inertia element, and determining a driven gear system of the gear pair as an inertia element; The inertia element of the driving gear system and the inertia element of the driven gear system are connected through a gear pair functional unit to construct a gear pair model.

[0014] Optionally, build a starter motor model, including: The motor rotor system of the starter motor is determined as the inertia element; A starter motor model is constructed based on the inertia elements of the motor rotor system and the core components of the starter motor system.

[0015] A second aspect of the present application provides a system for assessing knock risk during an engine startup process, the system comprising: A first model building module is used to build a torsional dynamics model of the power system based on a target component of the power system, wherein the target component is a component related to the power flow direction during the engine starting process; A second model building module, used to build a control strategy model, wherein the control strategy model is used to control the output torque of the engine and the starter motor in the torsional dynamics model; A simulation module, used for performing coupling simulation on the control strategy model and the torsional dynamics model according to the selected engine starting operating point to obtain corresponding simulation results; The knock risk determination module is used to determine whether there is a knock risk during the engine starting process according to the simulation results.

[0016] The third aspect of the present application provides an electronic device, comprising: a processor, a memory, and a computer program stored in the memory and running on the processor, wherein when the computer program is executed by the processor, the steps in the method for assessing the knocking risk during the engine starting process as described in the first aspect of the present application are implemented.

[0017] A fourth aspect of the present application provides a computer-readable storage medium having a computer program stored thereon. When the computer program is executed by a processor, the steps in a method for assessing knocking risk during an engine starting process as described in the first aspect of the present application are implemented.

[0018] The method for assessing knock risk during engine starting provided by the present application has the following advantages: The embodiment of the present application provides a method for evaluating the knocking risk during the engine starting process. First, based on the target components of the power system, a torsional dynamics model of the power system is constructed, and the target components are components related to the power flow direction during the engine starting process; a control strategy model is constructed, and the control strategy model is used to control the output torque of the engine and the starter motor in the torsional dynamics model; according to the selected engine starting operating point, the control strategy model and the torsional dynamics model are coupled to simulate to obtain the corresponding simulation results; according to the simulation results, it is determined whether there is a knocking risk during the engine starting process. Therefore, before the prototype sample is produced, the present application simulates whether there is a knocking risk during the engine starting process in the hybrid system in the form of simulation, and indirectly determines whether there is noise that will affect the driving experience during the engine starting process based on the knocking risk results obtained by simulation. This method can effectively shorten the project development cycle, and at the same time, there is no need to invest a lot of manpower, material resources and related equipment for support, so the development cost is significantly reduced. At the same time, when constructing the torsional dynamics model of the power system required for simulation, the present application only considers the components related to the power flow direction during the engine starting process, which can effectively improve the simulation efficiency. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] In order to more clearly illustrate the technical solutions of the embodiments of the present application, the drawings required for use in the description of the embodiments of the present application will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present application. For ordinary technicians in this field, other drawings can be obtained based on these drawings without creative labor.

[0020] Figure 1 A flowchart of a method for assessing knock risk during an engine starting process is shown as an embodiment of the present application; Figure 2 A structural diagram of a hybrid power system in a method for assessing knock risk during engine starting process shown in one embodiment of the present application; Figure 3 A flowchart of coupled simulation in a method for assessing knock risk during engine starting process shown in one embodiment of the present application; Figure 4 A schematic diagram of the torsion characteristics of a torque limiter in a method for assessing knock risk during an engine starting process, shown in one embodiment of the present application; Figure 5 Another schematic diagram of the torsion characteristics of a torque limiter in a method for assessing knocking risk during an engine starting process according to an embodiment of the present application; Figure 6 A schematic diagram of the torsion angle difference of a torque limiter in a method for assessing knocking risk during an engine starting process, shown in one embodiment of the present application; Figure 7 A schematic diagram of a system for assessing knock risk during engine starting is shown as an embodiment of the present application. DETAILED DESCRIPTION

[0021] The following will be combined with the drawings in the embodiments of the present application to clearly and completely describe the technical solutions in the embodiments of the present application. Obviously, the described embodiments are part of the embodiments of the present application, not all of the embodiments. Based on the embodiments in the present application, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of this application.

[0022] refer to Figure 1 , Figure 1 The following is a flow chart showing a method for evaluating knock risk during engine startup according to an embodiment of the present application. Figure 1 As shown, the method includes: Step S1: constructing a torsional dynamics model of the power system based on a target component of the power system, wherein the target component is a component related to the power flow direction during the engine starting process.

[0023] In this embodiment, the present application is applied to a hybrid vehicle equipped with a hybrid power system. The present application will construct a torsional dynamics model of the hybrid vehicle power system and convert the mechanical system into a dynamics simulation model. The method for assessing the knocking risk during the engine start-up process provided in the present application is mainly used to analyze the knocking risk during the engine start-up process in a hybrid power system. Therefore, when constructing the torsional dynamics model of the power system, the present application only considers the components related to the power flow direction during the engine start-up process (that is, the target components of the power system), and ignores the components that are not related to the power flow direction, so as to improve the simulation efficiency. Among them, the target components include the engine, torque limiter, gear pair (including gear shaft) and starter motor.

[0024] Specifically, based on the principle of one-dimensional torsional motion dynamics, the target components of the power system are discretized into multiple inertial node units through the concentrated mass method, and a torsional dynamics model consisting of multiple inertial elements, stiffness and damping elements is established. Among them, the expression of the one-dimensional torsional motion dynamics principle is: , where J is the inertia matrix, C is the damping matrix, K is the stiffness matrix, θ is the torsion angle, and M is the input torque matrix. The simulation software for constructing the torsion dynamics model is preferably Simcenter Amesim. It should be understood that the simulation software can also be other simulation software, which is not specifically limited here.

[0025] Step S2: constructing a control strategy model, wherein the control strategy model is used to control the output torque of the engine and the starter motor in the torsional dynamics model.

[0026] In this embodiment, a control strategy model is constructed by simulation software, and the control strategy model will be used to control the output torque of the engine and the starter motor in the torsional dynamics model. Among them, the simulation software for constructing the control strategy model is preferably Simulink. It should be understood that the simulation software can also be other simulation software, which is not specifically limited here.

[0027] In this embodiment, an optional implementation method for constructing a control strategy model is: constructing an engine control strategy model and a starter motor control strategy model through simulation software, and the constructed engine control strategy model and the starter motor control strategy model together constitute a control strategy model. The engine control strategy model in the control strategy model is used to control the output torque of the engine model in the torsional dynamics model, and the starter motor control strategy model in the control strategy model is used to control the output torque of the starter motor model in the torsional dynamics model.

[0028] Step S3: According to the selected engine starting operating point, coupling simulation is performed on the control strategy model and the torsional dynamics model to obtain corresponding simulation results.

[0029] In this embodiment, the engine starting operating point is selected to determine the target speed of the engine starting and the torque curve of the engine starting process. If the engine already has its own test data of the torque curve of the starting process, the test data of the torque curve is directly used. If the engine does not have its own test data of the torque curve of the starting process, the test data of the torque curve of the starting process of the same type as the engine or the benchmark model of the engine is selected for use. Based on the target speed of the engine starting and the torque curve of the engine starting process corresponding to the selected engine starting operating point, the constructed control strategy model and the constructed torsional dynamics model are coupled simulated to obtain the corresponding simulation results.

[0030] Step S4: Determine whether there is a knock risk during the engine starting process based on the simulation results.

[0031] In this embodiment, based on the simulation results obtained by the coupled simulation in step S3, it is determined whether there is a knocking risk during the engine starting process. If there is a knocking risk, it is determined that noise that affects the user's driving experience will be generated during the engine starting process. If there is no knocking risk, it is determined that no noise that affects the user's driving experience will be generated during the engine starting process.

[0032] The embodiment of the present application provides a method for evaluating the knocking risk during the engine starting process. First, based on the target components of the power system, a torsional dynamics model of the power system is constructed, and the target components are components related to the power flow direction during the engine starting process; a control strategy model is constructed, and the control strategy model is used to control the output torque of the engine and the starter motor in the torsional dynamics model; according to the selected engine starting operating point, the control strategy model and the torsional dynamics model are coupled to simulate to obtain the corresponding simulation results; according to the simulation results, it is determined whether there is a knocking risk during the engine starting process. Therefore, before the prototype sample is produced, the present application simulates whether there is a knocking risk during the engine starting process in the hybrid system in the form of simulation, and indirectly determines whether there is noise that will affect the driving experience during the engine starting process based on the knocking risk results obtained by simulation. This method can effectively shorten the project development cycle, and at the same time, there is no need to invest a lot of manpower, material resources and related equipment for support, so the development cost is significantly reduced. At the same time, when constructing the torsional dynamics model of the power system required for simulation, the present application only considers the components related to the power flow direction during the engine starting process, which can effectively improve the simulation efficiency.

[0033] In combination with the above embodiments, in one implementation, the present application also provides a method for assessing the knock risk during the engine startup process. In the method for assessing the knock risk during the engine startup process, when the target components include an engine, a torque limiter, a gear pair, and a starter motor, step S1 may include steps S11 to S12: Step S11: constructing an engine model, a torque limiter model, a gear pair model and a starter motor model based on target components of the power system.

[0034] In this embodiment, when the target components related to the power flow direction of the engine starting process include the engine, torque limiter, gear pair (including gear shaft) and starter motor, the engine model, torque limiter model, gear pair model and starter motor model corresponding to these target components are respectively constructed through simulation software.

[0035] Step S12: Connecting the active end of the torque limiter model to the engine crankshaft of the engine model, connecting the passive end of the torque limiter model to the active gear system of the gear pair model, and connecting the driven gear system of the gear pair model to the motor rotor system of the starter motor model, so as to construct a torsional dynamics model of the power system.

[0036] In this embodiment, if Figure 2As shown, after the engine model, torque limiter model, gear pair model and starter motor model are constructed through step S11, the active end of the torque limiter model is connected to the engine crankshaft of the engine model, and the passive end of the torque limiter model is connected to the active gear system of the gear pair model, and the driven gear system of the gear pair model is connected to the motor rotor system of the starter motor model, and finally the torsional dynamics model of the power system is constructed. Among them, the active gear system of the gear pair model includes the active gear and the active gear shaft of the gear pair; the driven gear system of the gear pair model includes the driven gear and the driven gear shaft of the gear pair; the motor rotor system of the starter motor model includes the motor rotor and the rotor shaft of the starter motor.

[0037] In combination with the above embodiments, in one implementation, the embodiment of the present application also provides a method for evaluating the knocking risk during the engine starting process. In the method for evaluating the knocking risk during the engine starting process, step S3 may include: according to the selected engine starting operating point, the starting motor control strategy model outputs a switch signal to control the output torque of the starting motor model to drive the components of the power source to reach the target speed; when the engine model reaches the target speed, the engine control strategy model outputs a load factor to control the torque output of the engine model to achieve torque interaction between the engine model and the starting motor model, and obtain corresponding simulation results.

[0038] In this embodiment, the starter motor control strategy model in the control strategy model controls the output torque of the starter motor model in the torsional dynamics model by outputting the switch signal required to control the three-phase six-bridge arm of the inverter, converting the DC bus voltage into a three-phase AC voltage to start the engine, thereby meeting the torque control or speed control requirements of the starter motor. During the engine starting process, the starter motor can be controlled by torque control or speed control, or a combination of torque control and speed control. In this embodiment, taking speed control as an example, the starter motor control strategy model includes modules such as a speed control loop, a torque control loop, and a voltage modulation algorithm (such as SVPWM). The starter motor control strategy model converts the speed signal into a switch signal to drive the starter motor model to output torque to start the engine. The output torque of the driven starter motor model will drive the components of the power source to reach the target speed at the engine starting operating point. When the engine model reaches the target speed, the engine control strategy model will output a control signal, which will control the output torque of the engine model in the torsional dynamics model to achieve control of the engine starting process. For the engine control strategy model, the state machine is used in this embodiment to control the output torque of the engine model in the torsional dynamics model by outputting the load factor to simulate the output torque of the engine during the starting process. The output load factor comes from the real test data of the engine starting condition, and the load factor is calculated by dividing the engine output torque by the external characteristic torque. It should be understood that this is only an optional engine torque calculation method, and a more complex engine torque calculation model can also be used to more accurately control the engine output torque, which is not specifically limited here.

[0039] In this embodiment, the torque interaction between the engine and the starter motor can be realized through the control process of the starter motor control strategy model and the engine control strategy model in the above control strategy model, so as to simulate the engine starting process and obtain the final simulation result.

[0040] In combination with the above embodiments, in one implementation, the embodiment of the present application further provides a method for assessing the knock risk during the engine starting process. In the method for assessing the knocking risk during the engine starting process, before performing the coupling simulation in step S3, the method further includes: inputting a step-changing torque signal into the torque port of the starting motor control strategy model to calibrate the parameters of the starting motor torque control module in the starting motor control strategy model to obtain a first calibration result; when the first calibration result is that the output torque meets the response characteristic requirements, inputting a step-changing speed signal into the speed port of the starting motor control strategy model to calibrate the speed control parameters to obtain a second calibration result; when the second calibration result is that the characteristics of the output torque are consistent with the measured characteristics of the output torque of the starting motor, a starting motor control strategy model that can be coupled with simulation is obtained; controlling the engine control strategy model to output a constant load factor under steady-state conditions to control the output torque of the engine model, and calibrating the engine control strategy model through the torque test data actually measured by the engine to obtain a third calibration result; when the third calibration result is that the characteristics of the output torque are consistent with the measured characteristics of the engine output torque, an engine control strategy model that can be coupled with simulation is obtained.

[0041] In this embodiment, before the coupling simulation is performed, the application calibrates the constructed starter motor control strategy model. The specific calibration process is as follows: first, a step-changing torque signal is input to the torque port of the starter motor control strategy model, and the parameters of the starter motor torque control module in the starter motor control strategy model are calibrated to obtain the corresponding first calibration result. When the first calibration result is that the output torque obtained after calibration meets the response characteristic requirements, the calibration process of the first step is completed. At this time, the second step of calibration will be performed. At this time, a step-changing speed signal is input to the speed port of the starter motor control strategy model, and the speed control parameters are further calibrated to obtain the corresponding second calibration result. When the second calibration result is that the characteristics of the output torque of the starter motor model obtained after calibration are consistent with the measured characteristics of the output torque of the starter motor, it is determined that the second step of calibration is completed, and the starter motor control strategy model obtained at this time is a qualified starter motor control strategy model that can be used for coupling simulation. Among them, the characteristics of the output torque at least include the average value, the fluctuation amount and the frequency component. Among them, the measured characteristics of the starter motor output torque can be obtained through the existing measured torque test data of the starter motor. If the starter motor has no measured torque test data, it can be obtained through the measured torque test data of the starter motor of the same type or benchmark model as the starter motor.

[0042] In this embodiment, the present application calibrates the constructed engine control strategy model before performing coupling simulation. The specific calibration process is: control the engine control strategy model to output a constant load factor under a certain steady-state condition to drive the output torque of the engine model, and at the same time calibrate the engine control strategy model with the experimentally measured torque test data of the engine to obtain the corresponding third calibration result. When the third calibration result is that the characteristics of the engine output torque obtained after calibration are consistent with the measured characteristics of the engine output torque, it is determined that the engine control strategy model obtained at this time is a qualified engine control strategy model that can be used for coupling simulation. Among them, the characteristics of the output torque at least include the average value, the fluctuation amount and the frequency component. Among them, the measured characteristics of the engine output torque can be obtained through the measured torque test data of the engine. If the engine does not have the measured torque test data, it is obtained through the measured torque test data of the same type or benchmark engine as the engine.

[0043] In combination with the above embodiments, in one implementation, the embodiment of the present application further provides a method for assessing the knock risk during the engine startup process. In the method for assessing the knock risk during the engine startup process, an engine model is constructed, including: discretizing the engine into an equivalent crank cylinder pressure model according to the number of engine cylinders; connecting the crank cylinder pressure model through stiffness and damping elements, and setting the ignition order to construct the engine model.

[0044] In this embodiment, according to the number of engine cylinders, the engine is discretized into multiple equivalent crank cylinder pressure models with the same number as the number of engine cylinders, wherein the crank cylinder pressure model should include geometric parameters of components such as crankshaft, connecting rod, piston, etc. and equivalent rotational inertia of related components. Then, each crank cylinder pressure model is connected through stiffness and damping elements, and the ignition sequence is set to construct an engine model to realize the function of converting gas pressure into engine output torque.

[0045] In combination with the above embodiments, in one implementation, the embodiment of the present application also provides a method for assessing the knock risk during the engine startup process. In the method for assessing the knock risk during the engine startup process, a torque limiter model is constructed, including: using the damping spring inside the torque limiter as a boundary, dividing the torque limiter into an active end and a passive end; determining the active end and the passive end as inertia elements respectively; connecting the inertia element of the active end and the inertia element of the passive end through stiffness and damping elements to construct a torque limiter model.

[0046] In this embodiment, the present application takes the damping spring inside the torque limiter as the boundary, divides the torque limiter into an active end and a passive end, simplifies and determines the active end of the torque limiter as an inertia element by the lumped mass method, and at the same time simplifies and determines the passive end of the torque limiter as an inertia element by the lumped mass method. Then, the inertia element of the active end and the inertia element of the passive end are connected through stiffness and damping elements to construct a torque limiter model. Among them, the stiffness and damping values of the elements in the torque limiter model will be calibrated according to the torque / rotation angle characteristic curve provided by the torque limiter supplier to make the damping characteristics of the torque limiter model close to those of the physical object.

[0047] Combined with the above embodiments, in one implementation, the embodiment of the present application also provides a method for evaluating the knocking risk during the engine starting process. In this method for evaluating the knocking risk during the engine starting process, a gear pair model is constructed, including: determining the driving gear system of the gear pair as an inertia element, and determining the driven gear system of the gear pair as an inertia element; connecting the inertia element of the driving gear system and the inertia element of the driven gear system through a gear pair functional unit to construct a gear pair model.

[0048] In this embodiment, the present application simplifies and determines the driving gear system of the gear pair as an inertia element by the lumped mass method, and at the same time simplifies and determines the driven gear system of the gear pair as an inertia element by the lumped mass method. Then, the inertia element of the driving gear system and the inertia element of the driven gear system are connected through a gear pair functional unit, and the macroscopic parameters of the gear of the gear pair functional unit are set. The macroscopic parameters of the gear include speed ratio, meshing stiffness, backlash, etc., to construct a gear pair model. Among them, the driving gear system includes a driving gear and a driving gear shaft, and the driven gear system includes a driven gear and a driven gear shaft.

[0049] Combined with the above embodiments, in one implementation, the embodiment of the present application also provides a method for evaluating the knocking risk during the engine starting process. In this method for evaluating the knocking risk during the engine starting process, a starting motor model is constructed, including: determining the motor rotor system of the starting motor as an inertia element; constructing a starting motor model based on the inertia element of the motor rotor system and the core components of the starting motor system.

[0050] In this embodiment, as Figure 3As shown, the present application simplifies the motor rotor system of the starter motor into an inertia element through the mass concentration method. At the same time, in order to realize the control of the output torque of the starter motor by the control strategy model, when constructing the starter motor model, the starter motor model will be constructed based on the core components of the starter motor system, so that the switch signal output by the control strategy model converts the DC voltage into a three-phase AC voltage, drives the starter motor to operate, and feeds back the current state of the starter motor to the control strategy model. That is, the starter motor model is obtained based on the inertia element of the motor rotor system and the core components of the starter motor system. Among them, the motor rotor system includes a motor rotor and a rotor shaft; the core components of the starter motor system include at least a DC voltage source, an inverter bridge arm switch module, a speed sensor, a current sensor, and a position sensor.

[0051] In combination with the above embodiments, in one implementation, the embodiment of the present application further provides a method for assessing the risk of knocking during the engine starting process. In the method for assessing the risk of knocking during the engine starting process, the passive end of the torque limiter model is connected to the active gear system of the gear pair model, including: connecting the inertia element of the passive end of the torque limiter model to the inertia element of the active gear system of the gear pair model through a spring and a damping unit.

[0052] In this embodiment, an optional implementation method of connecting the passive end of the torque limiter model with the active gear system of the gear pair model is: connecting the inertia element of the passive end of the torque limiter model with the inertia element of the active gear system of the gear pair model through a spring and a damping unit.

[0053] In combination with the above embodiments, in one implementation, the embodiment of the present application further provides a method for assessing the knock risk during the engine starting process. In the method for assessing the knock risk during the engine starting process, the driven gear system of the gear pair model is connected to the motor rotor system of the starter motor model, including: connecting the inertia element of the driven gear system of the gear pair model to the inertia element of the motor rotor system of the starter motor model through a spring and a damping unit.

[0054] In this embodiment, an optional implementation method of connecting the driven gear system of the gear pair model with the motor rotor system of the starter motor model is: connecting the inertia element of the driven gear system of the gear pair model with the inertia element of the motor rotor system of the starter motor model through a spring and a damping unit.

[0055] In this embodiment, the inertia parameters and stiffness parameters of the inertia elements, spring and damping units, stiffness and damping elements involved in the process of constructing the torsion dynamics model can be calculated using professional engineering software such as CAD and CAE, and the damping coefficient can be obtained by the formula Calculated, where ζ is the damping ratio, J is the inertia, and K is the stiffness.

[0056] In combination with the above embodiments, in one implementation, the embodiment of the present application also provides a method for assessing the risk of knocking during the engine starting process. In the method for assessing the risk of knocking during the engine starting process, step S4 may include: determining that there is a risk of knocking during the engine starting process when the simulation result satisfies the first preset condition and / or the second preset condition; the first preset condition is that during the coupled simulation engine starting process, the number of positive and negative changes in the torsion angle difference between the active end and the passive end of the torque limiter model in the torsional dynamics model is greater than or equal to the preset number; the second preset condition is that during the coupled simulation engine starting process, tooth knocking occurs during the meshing process of the gear pair model and the tooth knocking force is greater than the set threshold.

[0057] In this embodiment, since this application determines whether the engine start process in the hybrid system will generate noise that affects the user's driving experience through simulation before the prototype is produced, but this form cannot test the produced prototype and intuitively monitor the noise (such as monitoring the decibel size of the sound generated during the actual engine start process to determine whether the engine start process will generate noise that affects the user's driving experience), the present application provides a method for evaluating the knocking risk of the engine start process by determining whether there is a knocking risk in the engine start process of the simulated hybrid system, so as to indirectly determine whether the engine start process will generate noise that affects the user's driving experience. Specifically, it is determined whether the simulation result obtained by the simulation satisfies the first preset condition and / or the second preset condition. If the simulation result satisfies any one of the two preset conditions or satisfies the two preset conditions at the same time, it is determined that there is a knocking risk in the engine start process that may generate noise that affects the user's driving experience. At this time, the control parameters for controlling the engine start process will be further optimized, and then the engine start process will be re-simulated with the optimized control parameters to obtain the optimal engine start parameters. Satisfying the first preset condition means that during the coupled simulation engine start-up process, the number of positive and negative changes in the torsion angle difference formed between the inertia element at the active end and the inertia element at the passive end of the torque limiter model in the torsion dynamics model is greater than or equal to the preset number of times, then it is determined that the first preset condition is satisfied; wherein, the preset number is preferably 2 times, and the positive and negative changes in the torsion angle difference refer to the torque between the active end and the passive end having a reversal. Satisfying the second preset condition means that during the coupled simulation engine start-up process, the gear pair model has a knocking phenomenon during the meshing process, and the knocking force is greater than the set threshold, and the set threshold can be obtained by the simulation model reverse labeling method based on the engine and starter motor torque curve test data obtained during the start-up process of the previous project. Since the knocking phenomenon of the gear pair during the engine start-up process is a relatively common phenomenon and cannot be absolutely avoided, when determining whether there is a knocking risk during the engine start-up process, the present application not only needs to show that the knocking phenomenon occurs during the meshing process of the gear pair model, but also the knocking force needs to be greater than the set threshold, only then it is determined that there is a knocking risk during the engine start-up process, which may produce noise that affects the user's driving experience.

[0058] In this embodiment, if Figure 4 , Figure 5 and Figure 6As shown, the torque limiter torsion characteristics based on the number of positive and negative changes in the torsion angle difference proposed in this application to determine whether there is a knocking risk during the engine starting process are described. For the sake of convenience, the damping effect is ignored, and the active end component and the passive end component on both sides of the torque limiter spring are equivalent to inertia J1 and J2, and their torsion angles are θ1 and θ2 respectively. The torque limiter spring stiffness is k, the active end component is subjected to the driving torque T1 from the engine, and the passive end component is subjected to the driving torque T2 from the starter motor. According to Figure 4 and Figure 5 The schematic diagram shown in the figure can be used to obtain the kinetic equation: and In knowing Figure 4 and Figure 5 Under the condition of parameter input boundary of the model shown, the torque difference θ1-θ2 between the active end component and the passive end component can be calculated by numerical analysis method, such as time step of 0.01s. During the engine starting process, the torque difference may change from positive to negative or from negative to positive. Therefore, the present application found that the reversal of the transmission surface is the main reason for the torque limiter knocking, that is, Figure 4 and Figure 5 The state switching between state a and state b is shown as Figure 6 As shown, during the engine startup process, the torque difference repeatedly changes positively and negatively (such as Figure 6 If the torque angle difference changes positively or negatively 7 times), it is determined that there is a risk of torque limiter knocking during engine starting.

[0059] In combination with the above embodiments, in one implementation, the embodiment of the present application also provides a method for evaluating the knocking risk during the engine starting process. In the method for evaluating the knocking risk during the engine starting process, the method also includes: optimizing the control parameters in the control strategy model when there is a knocking risk during the engine starting process; based on the optimized control parameters, re-coupling the control strategy model and the torsional dynamics model until the target simulation result is obtained, and the target simulation result is a result that characterizes that there is no knocking risk during the engine starting process.

[0060] In this embodiment, when the simulation results obtained by simulation indicate that there is a knocking risk during the engine starting process, it indicates that noise that affects the user's driving experience may be generated at this time. At this time, the present application will optimize the control parameters for controlling the engine starting process in the control strategy model, which control parameters include but are not limited to the speed slope limit threshold and the Kp control parameter in the PI control algorithm. Then, based on the optimized control parameters, the control strategy model and the torsional dynamics model are coupled and simulated again to obtain the corresponding simulation results. If the simulation results still indicate that there is a knocking risk during the engine starting process, the control parameters for controlling the engine starting process in the control strategy model are optimized to perform a new round of coupling simulation until the simulation results obtained indicate that there is no knocking risk during the engine starting process, and it is determined that the target simulation results are obtained. In this case, no noise that affects the user's driving experience will be generated. At this time, the simulation is terminated, and the control parameters corresponding to the target simulation results are used to control the engine starting process in the hybrid power system.

[0061] The present application provides a method for assessing knocking risk during the engine start process, which can identify the knocking risk during the engine start process in a hybrid system in advance in the early stage of project development. It can be used for knocking risk identification and analysis during the engine start process of a hybrid system, or to cooperate with the project team to rectify problems, and can also be used for component selection analysis in the conceptual design stage to provide guidance and reference. Therefore, it can effectively reduce part of the calibration workload of calibration engineers in the engine start control process, and at the same time reduce the large amount of manpower and equipment invested by NVH test engineers in rectifying noise problems, shorten the project development cycle, and save project development costs.

[0062] Based on the same inventive concept, an embodiment of the present application provides a system for assessing knock risk during engine starting, such as Figure 7 As shown, the system 700 includes: A first model building module 701 is used to build a torsional dynamics model of the power system based on a target component of the power system, wherein the target component is a component related to the power flow direction during the engine starting process; A second model building module 702, for building a control strategy model, wherein the control strategy model is used to control the output torque of the engine and the starter motor in the torsional dynamics model; A simulation module 703 is used to perform coupling simulation on the control strategy model and the torsional dynamics model according to the selected engine starting operating point to obtain corresponding simulation results; The knock risk determination module 704 is used to determine whether there is a knock risk during the engine startup process according to the simulation results.

[0063] Optionally, the first model building module 701 is used to build an engine model, a torque limiter model, a gear pair model and a starter motor model based on the target components of the power system; and is used to connect the active end of the torque limiter model to the engine crankshaft of the engine model, and connect the passive end of the torque limiter model to the active gear system of the gear pair model, and connect the driven gear system of the gear pair model to the motor rotor system of the starter motor model, so as to construct a torsional dynamics model of the power system.

[0064] Optionally, the simulation module 703 includes: A first simulation module is used to control the output torque of the starting motor model by outputting a switch signal through the starting motor control strategy model according to the selected engine starting operating point, so as to drive the components of the power source to reach the target speed; The second simulation module is used to control the torque output of the engine model by outputting a load coefficient through the engine control strategy model when the engine model reaches the target speed, so as to realize the torque interaction between the engine model and the starter motor model and obtain the corresponding simulation result.

[0065] Optionally, the system 700 further includes: A first calibration module, used for inputting the step-changing torque signal into the torque port of the starter motor control strategy model to calibrate the parameters of the starter motor torque control module in the starter motor control strategy model to obtain a first calibration result; A second calibration module is used to input the speed signal with a step change into the speed port of the starter motor control strategy model to calibrate the speed control parameter and obtain a second calibration result when the first calibration result is that the output torque meets the response characteristic requirement; and to obtain a starter motor control strategy model that can perform coupling simulation when the second calibration result is that the characteristic of the output torque is consistent with the measured characteristic of the output torque of the starter motor; The third calibration module is used to control the engine control strategy model to output a constant load factor under steady-state conditions to control the output torque of the engine model, and to calibrate the engine control strategy model through the torque test data actually measured by the engine to obtain a third calibration result; and to obtain an engine control strategy model that can be used for coupled simulation when the characteristics of the output torque of the third calibration result are consistent with the measured characteristics of the engine output torque.

[0066] Optionally, a knocking risk determination module 704 is used to determine whether there is a knocking risk during the engine starting process when the simulation result satisfies a first preset condition and / or a second preset condition; the first preset condition is that during the coupled simulation engine starting process, the number of positive and negative changes in the torsion angle difference between the active end and the passive end of the torque limiter model in the torsional dynamics model is greater than or equal to a preset number; the second preset condition is that during the coupled simulation engine starting process, tooth knocking occurs during the meshing process of the gear pair model and the tooth knocking force is greater than a set threshold.

[0067] Optionally, the system 700 further includes: An optimization module for optimizing control parameters in the control strategy model when there is a risk of knocking during engine starting; The simulation module 703 is used to re-simulate the coupling of the control strategy model and the torsional dynamics model based on the optimized control parameters until a target simulation result is obtained, wherein the target simulation result is a result indicating that there is no knock risk during the engine starting process.

[0068] Optionally, the first model building module 701 includes an engine model building module, which is used to discretize the engine into an equivalent crank cylinder pressure model according to the number of engine cylinders; and to connect the crank cylinder pressure model through stiffness and damping elements, and set the ignition sequence to construct the engine model.

[0069] Optionally, the first model construction module 701 includes a torque limiter model construction module, wherein the torque limiter model construction module is used to divide the torque limiter into an active end and a passive end using a damping spring inside the torque limiter as a boundary; and to determine the active end and the passive end as inertia elements, respectively; and to connect the inertia element of the active end and the inertia element of the passive end through stiffness and damping elements to construct a torque limiter model.

[0070] Optionally, the first model building module 701 includes a gear pair model building module, which is used to determine the driving gear system of the gear pair as an inertia element, and to determine the driven gear system of the gear pair as an inertia element; and to connect the inertia element of the driving gear system and the inertia element of the driven gear system through a gear pair functional unit to construct a gear pair model.

[0071] Optionally, the first model building module 701 includes a starter motor model building module, which is used to determine the motor rotor system of the starter motor as an inertia element; and to build a starter motor model based on the inertia element of the motor rotor system and the core components of the starter motor system.

[0072] Based on the same inventive concept, an embodiment of the present application provides an electronic device, including: a processor, a memory, and a computer program stored in the memory and running on the processor. When the computer program is executed by the processor, it implements the steps in a method for assessing knocking risks during an engine starting process as described in the first aspect of the present application.

[0073] Based on the same inventive concept, an embodiment of the present application provides a computer-readable storage medium, on which a computer program is stored. When the computer program is executed by a processor, the steps in a method for assessing knocking risk during an engine starting process as described in the first aspect of the present application are implemented.

[0074] As for the system embodiment, since it is basically similar to the method embodiment, the description is relatively simple, and the relevant parts can be referred to the partial description of the method embodiment.

[0075] It should be noted that, for the method embodiments, for the sake of simplicity, they are all described as a series of action combinations, but those skilled in the art should be aware that the embodiments of the present application are not limited by the described order of actions, because according to the embodiments of the present application, certain steps can be performed in other orders or simultaneously. Secondly, those skilled in the art should also be aware that the embodiments described in the specification are all preferred embodiments, and the actions involved are not necessarily required by the embodiments of the present application.

[0076] The various embodiments in this specification are described in a progressive manner, and each embodiment focuses on the differences from other embodiments. The same or similar parts between the various embodiments can be referenced to each other.

[0077] Those skilled in the art will appreciate that the embodiments of the present application may be provided as methods, systems, or computer program products. Therefore, the embodiments of the present application may adopt the form of complete hardware embodiments, complete software embodiments, or embodiments in combination with software and hardware. Moreover, the embodiments of the present application may adopt the form of a computer program product implemented in one or more computer-usable storage media (including but not limited to disk storage, CD-ROM, optical storage, etc.) that contain computer-usable program code.

[0078] The embodiments of the present application are described with reference to the flowcharts and / or block diagrams of the methods, terminal devices (systems), and computer program products according to the embodiments of the present application. It should be understood that each process and / or box in the flowchart and / or block diagram, as well as the combination of the processes and / or boxes in the flowchart and / or block diagram, can be implemented by computer program instructions. These computer program instructions can be provided to a processor of a general-purpose computer, a special-purpose computer, an embedded processor, or other programmable data processing terminal device to generate a machine, so that the instructions executed by the processor of the computer or other programmable data processing terminal device generate instructions for implementing the processes in the flowchart and / or block diagram. Figure 1 A process or multiple processes and / or boxes Figure 1 A device that provides the functions specified in a block or multiple blocks.

[0079] These computer program instructions may also be stored in a computer-readable memory capable of directing a computer or other programmable data processing terminal device to operate in a specific manner, so that the instructions stored in the computer-readable memory produce a manufactured product including an instruction device, which implements the process Figure 1 A process or multiple processes and / or boxes Figure 1 A function specified in one or more boxes.

[0080] These computer program instructions can also be loaded onto a computer or other programmable data processing terminal device so that a series of operating steps are executed on the computer or other programmable terminal device to produce a computer-implemented process, thereby providing instructions for executing on the computer or other programmable terminal device to implement the process. Figure 1 A process or multiple processes and / or boxes Figure 1 The steps for the functions specified in one or more boxes.

[0081] Although the preferred embodiments of the present application have been described, those skilled in the art may make additional changes and modifications to these embodiments once they have learned the basic creative concept. Therefore, the appended claims are intended to be interpreted as including the preferred embodiments and all changes and modifications that fall within the scope of the embodiments of the present application.

[0082] Finally, it should be noted that, in this article, relational terms such as first and second, etc. are only used to distinguish one entity or operation from another entity or operation, and do not necessarily require or imply any such actual relationship or order between these entities or operations. Moreover, the terms "include", "comprise" or any other variants thereof are intended to cover non-exclusive inclusion, so that a process, method, article or terminal device including a series of elements includes not only those elements, but also other elements not explicitly listed, or also includes elements inherent to such process, method, article or terminal device. In the absence of further restrictions, the elements defined by the sentence "comprise a ..." do not exclude the existence of other identical elements in the process, method, article or terminal device including the elements.

[0083] The above is a detailed introduction to the method, system and product for assessing the knocking risk during the engine starting process provided by the present application. Specific examples are used in this article to illustrate the principles and implementation methods of the present application. The description of the above embodiments is only used to help understand the method of the present application and its core idea; at the same time, for general technical personnel in this field, according to the idea of ​​the present application, there will be changes in the specific implementation method and application scope. In summary, the content of this specification should not be understood as a limitation on the present application.

Claims

1. A method for assessing knock risk during engine starting, characterized in that: The method comprises: Building a torsional dynamics model of the power system based on a target component of the power system, wherein the target component is a component related to the power flow direction during the engine starting process; Constructing a control strategy model, wherein the control strategy model is used to control the output torque of the engine and the starter motor in the torsional dynamics model; According to the selected engine starting operating point, coupling simulation is performed on the control strategy model and the torsional dynamics model to obtain corresponding simulation results; According to the simulation results, it is determined whether there is a knock risk during the engine starting process.

2. The method for assessing knock risk during engine starting according to claim 1, characterized in that: In the case where the target components include an engine, a torque limiter, a gear pair, and a starter motor, the torsional dynamics model of the power system is constructed based on the target components of the power system, including: Build engine model, torque limiter model, gear pair model and starter motor model based on target components of the powertrain; The active end of the torque limiter model is connected to the engine crankshaft of the engine model, the passive end of the torque limiter model is connected to the active gear system of the gear pair model, and the driven gear system of the gear pair model is connected to the motor rotor system of the starter motor model, so as to construct a torsional dynamics model of the power system.

3. The method for assessing knock risk during engine starting according to claim 2, characterized in that: According to the selected engine starting operating point, the control strategy model and the torsional dynamics model are coupled simulated to obtain corresponding simulation results, including: According to the selected engine starting operating point, the starting motor control strategy model outputs a switch signal to control the starting motor model to output torque, so as to drive the components of the power source to reach the target speed; When the engine model reaches the target speed, the load factor is output by the engine control strategy model to control the torque output of the engine model, so as to realize the torque interaction between the engine model and the starter motor model and obtain the corresponding simulation result.

4. The method for assessing knock risk during engine starting according to claim 2, characterized in that: Before performing coupling simulation on the control strategy model and the torsional dynamics model according to the selected engine starting operating point to obtain corresponding simulation results, the method further includes: Inputting the step-changed torque signal to the torque port of the starter motor control strategy model to calibrate the parameters of the starter motor torque control module in the starter motor control strategy model to obtain a first calibration result; When the first calibration result shows that the output torque meets the response characteristic requirement, the speed signal with step change is input into the speed port of the starter motor control strategy model to calibrate the speed control parameter to obtain a second calibration result; When the second calibration result shows that the characteristic of the output torque is consistent with the measured characteristic of the output torque of the starter motor, a starter motor control strategy model capable of performing coupling simulation is obtained; Controlling the engine control strategy model to output a constant load factor under steady-state conditions to control the output torque of the engine model, and calibrating the engine control strategy model using torque test data actually measured by the engine to obtain a third calibration result; When the third calibration result shows that the characteristic of the output torque is consistent with the measured characteristic of the engine output torque, an engine control strategy model capable of performing coupled simulation is obtained.

5. The method for assessing knock risk during engine starting process according to claim 1, characterized in that: Based on the simulation results, determine whether there is a knock risk during the engine starting process, including: When the simulation result satisfies the first preset condition and / or the second preset condition, determining that there is a knock risk during the engine starting process; The first preset condition is that during the coupled simulation engine startup process, the number of positive and negative changes in the torsion angle difference between the active end and the passive end of the torque limiter model in the torsion dynamics model is greater than or equal to a preset number; The second preset condition is that during the coupled simulation engine startup process, tooth knocking occurs during the meshing process of the gear pair model and the tooth knocking force is greater than a set threshold.

6. The method for assessing knock risk during engine starting process according to claim 1, characterized in that: The method further comprises: Optimizing control parameters in the control strategy model in the presence of knock risk during engine starting; Based on the optimized control parameters, the control strategy model and the torsional dynamics model are re-coupled and simulated until a target simulation result is obtained, wherein the target simulation result is a result indicating that there is no knock risk during the engine starting process.

7. The method for assessing knock risk during engine starting process according to claim 2, characterized in that: Build an engine model, including: According to the number of engine cylinders, the engine is discretized into an equivalent crank cylinder pressure model; The crank cylinder pressure model is connected through stiffness and damping elements, and the ignition sequence is set to construct an engine model.

8. The method for assessing knock risk during engine starting process according to claim 2, characterized in that: Construct a torque limiter model, including: The torque limiter is divided into an active end and a passive end using the damping spring inside the torque limiter as a boundary; Determine the active end and the passive end as inertia elements respectively; The inertia element at the active end and the inertia element at the passive end are connected via stiffness and damping elements to construct a torque limiter model.

9. The method for assessing knock risk during engine starting process according to claim 6, characterized in that: Build a gear pair model, including: determining a driving gear system of the gear pair as an inertia element, and determining a driven gear system of the gear pair as an inertia element; The inertia element of the driving gear system and the inertia element of the driven gear system are connected through a gear pair functional unit to construct a gear pair model.

10. The method for assessing knock risk during engine starting process according to claim 9, characterized in that: Build a starter motor model, including: The motor rotor system of the starter motor is determined as the inertia element; A starter motor model is constructed based on the inertia elements of the motor rotor system and the core components of the starter motor system.

11. A system for assessing knock risk during engine starting, characterized in that: The system comprises: A first model building module is used to build a torsional dynamics model of the power system based on a target component of the power system, wherein the target component is a component related to the power flow direction during the engine starting process; A second model building module, used to build a control strategy model, wherein the control strategy model is used to control the output torque of the engine and the starter motor in the torsional dynamics model; A simulation module, used for performing coupling simulation on the control strategy model and the torsional dynamics model according to the selected engine starting operating point to obtain corresponding simulation results; The knock risk determination module is used to determine whether there is a knock risk during the engine starting process according to the simulation results.

12. An electronic device, characterized in that: include: A processor, a memory, and a computer program stored in the memory and running on the processor, wherein when the computer program is executed by the processor, the steps in the method for assessing knocking risk during an engine starting process as described in claims 1 to 10 are implemented.

13. A computer-readable storage medium, characterized in that: The computer-readable storage medium stores a computer program, and when the computer program is executed by a processor, the steps in the method for assessing knock risk during an engine starting process as claimed in claims 1 to 10 are implemented.

Images