Engine starting control method, device and computer readable storage medium

Abstract

The application provides an engine starting control method, device and computer readable storage medium. The method comprises the following steps: in the process of starting the range extender system, when the engine speed is zero, the decompression rocker arm small piston of the engine valve train is controlled to extend; the start and launch integrated motor is powered to adopt the start and launch integrated motor to drag the engine in reverse, so as to increase the engine speed, and when the engine speed is greater than the first preset engine speed, the decompression rocker arm small piston is controlled to retract; when the engine speed is greater than the second preset engine speed, the engine is controlled to inject fuel and ignite, and when the ignition is successful, the torque of the start and launch integrated motor is adjusted according to the preset torque unloading strategy, and when the torque of the start and launch integrated motor is adjusted to the preset torque, the engine starting is completed. The problem that the engine shaking in the process of starting the range extender system affects the comfort of the whole vehicle passengers is solved.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of engine starting control, in particular to an engine starting control method and device, a computer readable storage medium and an electronic device. BACKGROUND

[0002] In order to ensure the battery endurance during the vehicle running process, the range extender needs to timely involve the engine to generate electricity; thus, the engine is frequently started to provide power input for the generator. Due to the frequent starting of the engine, the vehicle shaking problem occurs frequently, which leads to poor comfort of the driver and passenger.

[0003] During the engine starting process in the range extender, in the stage of the engine being dragged by the integrated motor, the residual gas in the cylinder of the engine is compressed to generate a high cylinder pressure peak value in the compression stroke, which causes the engine to shake and leads to poor comfort of the driver and passenger of the vehicle; in addition, the high cylinder pressure makes the crankshaft-piston and other moving parts bear a large load, the engine friction torque is large, the starting time is long, and the electric energy consumption is large. SUMMARY

[0004] The main purpose of the present application is to provide an engine starting control method and device, a computer readable storage medium and an electronic device, so as to at least solve the problem that the engine shaking in the stage of the engine being dragged by the integrated motor during the starting process of the existing range extender affects the comfort of the driver and passenger of the vehicle.

[0005] In order to achieve the above-mentioned purpose, according to one aspect of the present application, an engine starting control method is provided, which comprises: in the process of starting the range extender system and under the condition that the engine speed is determined to be zero, the decompression rocker arm small piston of the engine valve train is controlled to extend out, the range extender system comprising an engine, an integrated motor and the engine valve train, under the condition that the decompression rocker arm small piston extends out, the decompression rocker arm small piston contacts the valve of the engine valve train to reduce the pressure of the engine compression cylinder; under the condition that the decompression rocker arm small piston is determined to extend out, the integrated motor is powered to drag the engine by using the integrated motor, so as to increase the engine speed, and under the condition that the engine speed is detected to be greater than a first preset engine speed, the decompression rocker arm small piston is controlled to retract; under the condition that the engine speed is detected to be greater than a second preset engine speed, the engine is controlled to inject fuel and ignite, and under the condition that the engine ignition is successful, the torque of the integrated motor is adjusted according to a preset torque unloading strategy, and under the condition that the torque of the integrated motor is adjusted to a preset torque, the engine starting is completed, wherein the second preset engine speed is greater than the first preset engine speed.

[0006] Optionally, the torque of the integrated motor-starter is adjusted according to a preset torque unloading strategy, and the engine starting is completed when the torque of the integrated motor-starter is adjusted to the preset torque, including: adjusting the torque of the integrated motor-starter to a first torque according to a step torque unloading strategy, wherein the step torque unloading strategy is a control strategy in which the torque decreases step by step over time; in a case where it is determined that the torque of the integrated motor-starter reaches the first torque, adjusting the torque of the integrated motor-starter to the preset torque using a linear torque unloading strategy, wherein the linear torque unloading strategy is a control strategy in which the torque gradually decreases linearly over time; and in a case where it is determined that the torque of the integrated motor-starter reaches the preset torque, determining that the engine starting operation is completed.

[0007] Optionally, in a case where it is determined that the torque of the integrated motor-starter reaches the first torque, adjusting the torque of the integrated motor-starter to the preset torque using a linear torque unloading strategy includes: in a case where it is determined that the torque of the integrated motor-starter reaches the first torque, determining a running time at which the torque of the integrated motor-starter reaches the first torque; in a case where it is determined that the running time reaches a first preset time period, determining whether the torque fluctuation of the integrated motor-starter is less than a fluctuation setting value; and in a case where the torque fluctuation of the integrated motor-starter is less than the fluctuation setting value, adjusting the torque of the integrated motor-starter to the preset torque using the linear torque unloading strategy.

[0008] Optionally, before adjusting the torque of the integrated motor-starter to the preset torque using the linear torque unloading strategy, the method further includes:

[0009] using a formula: ,

[0010] evaluating the speed fluctuation stability of the engine, wherein λ is the speed fluctuation stability, ω max is a maximum speed fluctuation value, ω min is a minimum speed fluctuation value, and ω m is a preset speed fluctuation difference value; and determining whether to adjust the torque of the integrated motor-starter using the linear torque unloading strategy according to the speed fluctuation stability.

[0011] Optionally, the first preset engine speed is determined according to an ambient temperature, an altitude, a coolant temperature, an oil temperature, a motor rotor moment of inertia, a motor efficiency curve, and a vehicle battery power, and the second preset engine speed is determined according to the ambient temperature, the altitude, the coolant temperature, the oil temperature, an engine intake air amount, and a fuel injection amount.

[0012] Optionally, the control of the retraction of the decompression rocker arm small piston under the condition that the engine speed is greater than the first preset engine speed comprises: detecting the engine speed after a second preset time period; and controlling the retraction of the decompression rocker arm small piston under the condition that the engine speed is greater than the first preset engine speed.

[0013] Optionally, the second preset time period is determined according to an ambient temperature, an altitude, a coolant temperature and an oil temperature.

[0014] According to another aspect of the present application, there is provided a control device for engine starting, comprising: a first control unit configured to control a decompression rocker arm small piston of an engine valve train to extend during a starting process of a range extender system, and to extend the decompression rocker arm small piston under the condition that an engine speed is determined to be zero, the range extender system comprising an engine, a motor-generator and the engine valve train, the decompression rocker arm small piston being in contact with a valve of the engine valve train under the condition that the decompression rocker arm small piston is extended, and being configured to decompress a compression cylinder of the engine; a second control unit configured to supply power to the motor-generator under the condition that the decompression rocker arm small piston is determined to be extended, to use the motor-generator to reverse-drive the engine to increase the engine speed, and to control the decompression rocker arm small piston to retract under the condition that the engine speed is detected to be greater than a first preset engine speed; and a third control unit configured to control the engine to inject fuel and ignite under the condition that the engine speed is detected to be greater than a second preset engine speed, to adjust a torque of the motor-generator according to a preset torque unloading strategy under the condition that the engine is successfully ignited, and to complete the starting of the engine under the condition that the torque of the motor-generator is adjusted to a preset torque, wherein the second preset engine speed is greater than the first preset engine speed.

[0015] According to still another aspect of the present application, there is provided a computer readable storage medium, comprising a stored program, wherein the computer readable storage medium is caused to perform any of the control methods for engine starting when the program is executed.

[0016] According to yet another aspect of the present application, there is provided an electronic device, comprising: one or more processors, a memory, and one or more programs, wherein the one or more programs are stored in the memory and configured to be executed by the one or more processors, and the one or more programs comprise instructions for performing any of the control methods for engine starting.

[0017] The application discloses an engine starting control method and an engine starting control device. BRIEF DESCRIPTION OF DRAWINGS BRIEF DESCRIPTION OF DRAWINGS

[0018] The drawings constituting a part of the specification of the application are used to provide further understanding of the application, the illustrative embodiments of the application and the description thereof are used to explain the application, and do not constitute improper limitation on the application. In the drawings:

[0019] Figure 1 A flowchart of an engine starting control method provided by an embodiment of the application is shown;

[0020] Figure 2 A structural diagram of an engine valve train provided by an embodiment of the application is shown;

[0021] Figure 3 A pressure release principle diagram provided by an embodiment of the application is shown;

[0022] Figure 4 A valve lift curve diagram of an exhaust valve provided by an embodiment of the application is shown;

[0023] Figure 5 A movement diagram of a pressure release rocker arm small piston provided by an embodiment of the application is shown;

[0024] Figure 6 A control logic diagram of a specific engine starting control method provided by an embodiment of the application is shown;

[0025] Figure 7 An engine cylinder pressure curve comparison diagram provided by an embodiment of the application is shown;

[0026] Figure 8 An engine start time comparison diagram provided by an embodiment of the application is shown;

[0027] Figure 9 A schematic diagram of a set time 1 dynamic adjustment correction algorithm provided by an embodiment of the application is shown;

[0028] Figure 10 A dynamic adjustment correction schematic diagram of an engine speed set value 2 provided by an embodiment of the application is shown;

[0029] Figure 11 A dynamic adjustment correction schematic diagram of an engine speed set value 3 provided by an embodiment of the application is shown;

[0030] Figure 12 A start and launch integrated motor torque unloading schematic diagram provided by an embodiment of the application is shown;

[0031] Figure 13 A structural block diagram of a control device of an engine start provided by an embodiment of the application is shown.

[0032] Among the above figures, the following reference signs are included:

[0033] 1, cam; 2, rocker arm structure; 2-1, brake rocker arm; 2-2, exhaust rocker arm; 2-3, pressure reduction rocker arm small piston; 3, valve bridge; 4, valve spring; 5, valve; 6, cylinder head; 7, valve gap compensation structure. DETAILED DESCRIPTION

[0034] It should be noted that the embodiments in the present application and the features in the embodiments can be combined with each other without conflict. The technical solutions in the embodiments of the present application will be described in detail below with reference to the accompanying drawings and in combination with the embodiments.

[0035] In order for those skilled in the art to better understand the present application, the technical solutions in the embodiments of the present application will be described in detail below with reference to the accompanying drawings. Obviously, the described embodiments are only a part of the embodiments of the present application, not all. Based on the embodiments in the present application, all other embodiments obtained by those skilled in the art without creative labor should be within the scope of protection of the present application.

[0036] It should be noted that the terms "first", "second", etc. in the specification and claims of the present application and the above-mentioned drawings are used to distinguish similar objects, and do not necessarily describe a specific order or sequence. It should be understood that the data used in this way can be interchanged under appropriate circumstances, so that the embodiments of the present application described herein. In addition, the terms "include" and "have" and any variations thereof are intended to cover non-exclusive inclusion, for example, a process, method, system, product or device including a series of steps or units does not necessarily limit to those steps or units clearly listed, but can include other steps or units not clearly listed or inherent to these processes, methods, products or devices.

[0037] For the convenience of description, the following describes some nouns or terms related to the embodiments of the present application:

[0038] Range extender: composed of an engine and a start-integrated motor, the engine is connected to the start-integrated motor through mechanical connection, the engine shaft drives the motor shaft to work, and the start-integrated motor generates electricity. The start-integrated motor can generate electricity or act as a motor. In the range extender, the engine starts by relying on the start-integrated motor to drag the start. In the range extender, the engine is not mechanically connected to the vehicle transmission system, and is separated from the road slope load excitation. After the engine starts, it always runs in the high efficiency area.

[0039] Starting mode: the start-integrated motor reversely drags the engine speed to a certain speed, the start-integrated motor gradually exits, the engine starts to inject fuel, and finally realizes the start of the engine. The starting process refers to the continuous process from the start of the engine crankshaft to the start of fuel injection.

[0040] As introduced in the background, in the existing range extender starting process, the engine shaking during the start-integrated motor reverse dragging engine stage affects the comfort of the vehicle passengers. To solve the problem of engine shaking during the start-integrated motor reverse dragging engine stage in the existing range extender starting process, which affects the comfort of the vehicle passengers, the embodiments of the present application provide a control method, device, computer readable storage medium and electronic equipment for engine starting.

[0041] The technical solutions in the embodiments of the present application will be described clearly and completely in combination with the drawings in the embodiments of the present application.

[0042] In the embodiments, a control method for engine starting running on a mobile terminal, a computer terminal or a similar computing device is provided. It should be noted that the steps shown in the flowchart of the drawings can be executed in a computer system such as a group of computer executable instructions, and although the logical order is shown in the flowchart, in some cases, the steps shown or described can be executed in an order different from that here.

[0043] Figure 1 is a flow chart of a control method of engine starting according to an embodiment of the present application. As shown in Figure 1 , the method comprises the following steps:

[0044] Step S201, in the process of starting the range extender system, and in the case of determining that the engine speed is zero, control the decompression rocker arm small piston of the engine valve train to extend, the range extender system comprises an engine, an integrated starter-generator and the engine valve train, in the case of the decompression rocker arm small piston extending, the decompression rocker arm small piston contacts the valve of the engine valve train, for decompression of the engine compression cylinder;

[0045] The range extender starting process can be divided into two processes, the first process is that the integrated starter-generator quickly drags the engine to a certain speed, the motoring engine stage, the residual gas in the cylinder of the engine is compressed to produce a high cylinder pressure peak value in the compression stroke, causing engine vibration, resulting in poor comfort of the vehicle passengers. The second stage is the engine ignition stage, the integrated starter-generator gradually withdraws, and the engine attempts to self-ignite until the range extender shaft speed stabilizes.

[0046] The structure diagram of the engine valve train is shown in Figure 2 , which comprises a cam 1, a rocker arm structure 2, a valve structure, an engine control structure and a valve clearance compensation structure 7, the valve clearance compensation structure 7 is arranged between the rocker arm structure 2 and the valve structure, the rocker arm structure 2 comprises an exhaust rocker arm 2-2, a decompression rocker arm small piston 2-3 and a brake rocker arm 2-1, the cam 1 contacts one end of the brake rocker arm 2-1, the other end of the brake rocker arm 2-1 is integrated with the exhaust rocker arm 2-2, and the other end of the exhaust rocker arm 2-2 is connected to the valve structure through the valve clearance compensation structure 7. The valve structure comprises a valve bridge 3, a valve spring 4, a valve 5 and a cylinder head 6.

[0047] The extension and retraction of the decompression rocker arm small piston are guaranteed by using a small motor to control the driving mechanism.

[0048] Step S202, in the case of determining that the decompression rocker arm small piston extends, power is supplied to the integrated starter-generator to adopt the integrated starter-generator to motoring the engine to increase the engine speed, and in the case of detecting that the engine speed is greater than a first preset engine speed, control the decompression rocker arm small piston to retract;

[0049] Specifically, during the engine starting process, when in the stage of the launch integrated motor dragging the engine backward, the decompression rocker arm small piston is extended, an exhaust valve is opened during the compression stroke and the expansion stroke, the compression pressure in the cylinder is released, the cylinder pressure is greatly reduced, the load of the crankshaft-piston and other moving parts is reduced, the engine friction resistance torque is reduced, the launch integrated motor has high speed, the starting is fast and stable, the decompression starting is realized, the comfort of the vehicle driver and passenger is improved, and the electric energy consumption is reduced.

[0050] In step S203, when it is detected that the engine speed is greater than the second preset engine speed, the engine is controlled to be injected and ignited, and when the engine is successfully ignited, the torque of the launch integrated motor is adjusted according to a preset torque unloading strategy, and when the torque of the launch integrated motor is adjusted to the preset torque, the engine starting is completed, wherein the second preset engine speed is greater than the first preset engine speed.

[0051] In the embodiment, during the process of starting the range extender system, and when it is determined that the engine speed is zero, the decompression rocker arm small piston of the engine valve train is controlled to be extended, the range extender system includes an engine, a launch integrated motor and an engine valve train, when the decompression rocker arm small piston is extended, the decompression rocker arm small piston contacts with the valve of the engine valve train to reduce the pressure of the compression cylinder of the engine, when it is determined that the decompression rocker arm small piston is extended, the launch integrated motor is powered to drag the engine backward to increase the engine speed, and when it is detected that the engine speed is greater than a first preset engine speed, the decompression rocker arm small piston is controlled to be retracted, when it is detected that the engine speed is greater than a second preset engine speed, the engine is controlled to be injected and ignited, and when the engine is successfully ignited, the torque of the launch integrated motor is adjusted according to a preset torque unloading strategy, and when the torque of the launch integrated motor is adjusted to the preset torque, the engine starting is completed, wherein the second preset engine speed is greater than the first preset engine speed. By controlling the exhaust valve to be opened during the compression stroke and the expansion stroke to release the compression pressure in the cylinder, the decompression starting is realized, the range extender starting is fast and stable, the vehicle NVH comfort is improved, the electric energy consumption is reduced, and the problem of the engine shaking during the stage of the launch integrated motor dragging the engine backward in the starting process of the existing range extender is solved.

[0052] In the implementation process, the torque of the start-integrated motor is adjusted according to the preset torque unloading strategy, and the engine starting is completed when the torque of the start-integrated motor is adjusted to the preset torque, including: adjusting the torque of the start-integrated motor to a first torque according to a step torque unloading strategy, wherein the step torque unloading strategy is a control strategy in which the torque decreases step by step over time; in a case where it is determined that the torque of the start-integrated motor reaches the first torque, the torque of the start-integrated motor is adjusted to the preset torque using a linear torque unloading strategy, wherein the linear torque unloading strategy is a control strategy in which the torque gradually decreases linearly over time; and in a case where it is determined that the torque of the start-integrated motor reaches the preset torque, it is determined that the engine starting operation is completed.

[0053] The step unloading of the method means that the motor torque decreases step by step in a ladder shape during the unloading process. The linear unloading strategy means that the motor torque gradually decreases linearly over time, quickly reduces the torque, and reduces the entire starting process time.

[0054] Specifically, in a case where it is determined that the torque of the start-integrated motor reaches the first torque, the torque of the start-integrated motor is adjusted to the preset torque using a linear torque unloading strategy, including: in a case where it is determined that the torque of the start-integrated motor reaches the first torque, determining a running time at which the torque of the start-integrated motor reaches the first torque; in a case where it is determined that the running time reaches a first preset time period, determining whether the torque fluctuation of the start-integrated motor is less than a fluctuation setting value; and in a case where the torque fluctuation of the start-integrated motor is less than the fluctuation setting value, adjusting the torque of the start-integrated motor to the preset torque using the linear torque unloading strategy.

[0055] The step unloading of the method means that the motor torque decreases step by step in a ladder shape during the unloading process, and then is stably maintained for a period of time (a first preset time period). The first preset time period is set to more finely control the exit timing of the motor.

[0056] More specifically, before the torque of the start-integrated motor is adjusted to the preset torque using the linear torque unloading strategy, the method further includes:

[0057] using the formula: ,

[0058] evaluating the speed fluctuation stability of the engine, wherein λ is the speed fluctuation stability, ω max is a maximum speed fluctuation value, ω min is a minimum speed fluctuation value, and ω mA difference value is preset for the speed fluctuation, and whether the linear torque unloading strategy is adopted to adjust the torque of the integrated starting motor is determined according to the speed fluctuation stability of the engine. The method determines whether the engine has started smoothly by evaluating the speed fluctuation stability of the engine.

[0059] Further, the first preset engine speed is determined according to the ambient temperature, the altitude, the coolant temperature, the oil temperature, the motor rotor moment of inertia, the motor efficiency curve and the battery power of the whole vehicle, and the second preset engine speed is determined according to the ambient temperature, the altitude, the coolant temperature, the oil temperature, the engine intake air volume and the fuel injection volume.

[0060] The first preset engine speed is the initial engine speed during starting, and the first preset engine speed is dynamically adjusted and corrected based on the initial value of the first preset engine speed, considering the parameters such as the ambient temperature, the altitude, the coolant temperature, the oil temperature, the motor rotor moment of inertia, the motor efficiency curve and the battery power of the whole vehicle, to adapt to different starting conditions. The initial value of the first preset engine speed is the crankshaft speed when the integrated starting motor can easily drive the engine and the efficiency of the integrated starting motor is high, which is found according to the friction work data of the engine bench engine at normal temperature.

[0061] The second preset engine speed is the critical value of the engine speed reaching the fuel injection ignition, and the second preset engine speed is dynamically adjusted and corrected based on the initial value of the second preset engine speed, considering the parameters such as the ambient temperature, the altitude, the coolant temperature, the oil temperature, the intake air volume and the fuel injection volume, to achieve better starting effect. The initial value of the second preset engine speed is the minimum crankshaft speed when the engine is stable combustion, which is found by considering the combustion characteristics of the engine bench engine at normal temperature.

[0062] Specifically, when the engine speed is greater than the first preset engine speed, the decompression rocker arm small piston is controlled to retract, including: detecting the engine speed after a second preset time period; and controlling the decompression rocker arm small piston to retract when the engine speed is greater than the first preset engine speed.

[0063] More specifically, the second preset time period is determined according to the ambient temperature, the altitude, the coolant temperature and the oil temperature.

[0064] The second preset time period is dynamically adjusted and corrected based on the initial value of the second preset time period, considering the parameters such as the ambient temperature, the altitude, the coolant temperature and the oil temperature. When the engine speed is greater than the first preset engine speed after the second preset time period, it indicates that the release of the cylinder compression pressure is completed, and the decompression rocker arm small piston is controlled to retract.

[0065] In order for those skilled in the art to more clearly understand the technical solutions of the present application, the implementation process of the engine starting control method of the present application will be described in detail below in conjunction with specific embodiments.

[0066] The present embodiment relates to a specific engine starting control method, which specifically includes the following contents:

[0067] The range extender starting process can be divided into two processes. The first process is that the integrated starter-generator quickly drags the engine to a certain speed, and the engine is reversed. In the second process, the engine is ignited, the integrated starter-generator gradually withdraws, and the engine attempts to ignite until the range extender shaft speed stabilizes.

[0068] The engine starting process resistance torque includes the gas torque generated by the in-cylinder gas, the inertia torque generated by the piston-rod system, and the friction torque generated by the main bearing, piston-cylinder liner sliding pair, connecting rod bearing, gear bearing, etc. The in-cylinder gas torque hinders the rotation of the shaft during the compression stroke of the engine. The greater the compression ratio of the engine piston, the greater the resistance torque generated by the compression gas during the compression stroke. The farther the piston is from the compression top dead center, the longer the compression stroke, and the greater the first cycle cylinder pressure peak, the greater the vehicle shaking. The lower the ambient temperature, the lower the cooling liquid temperature, and the lower the oil temperature during the engine reverse process, the greater the resistance torque.

[0069] The present embodiment proposes a range extender pressure reduction starting strategy. During the engine starting process, when the engine is reversed by the motor, the pressure reduction rocker small piston is extended to open the exhaust valve during the compression stroke and the expansion stroke, thereby releasing the compression pressure in the cylinder. In this way, the in-cylinder pressure is greatly reduced, the load on the crankshaft-piston and other moving parts is reduced, the engine friction resistance torque is reduced, and pressure reduction starting is achieved.

[0070] The pressure reduction release principle is shown in Figure 3 , which relies on the extension of the pressure reduction rocker small piston to actively open the exhaust valve to achieve pressure reduction function. During the compression stroke and the expansion stroke, the exhaust valve is opened, and the work done by the engine compression cylinder air is released to the exhaust system, and the expansion stroke does not have energy back pressure on the piston, thereby achieving pressure reduction function.

[0071] The exhaust valve control mode is shown in Figure 4 , Figure 5 and Table 1. The exhaust valve is opened during the compression stroke and the expansion stroke, and the piston is machined with a pit to ensure that the exhaust valve has a certain distance from the piston at the compression top dead center, thereby avoiding collision failure.

[0072] Table 1

[0073]

[0074] Figure 6 The control logic diagram of the control method for starting the specific engine specifically includes the following steps, as shown in Figure 6

[0075] Step 1: Determine whether the engine speed is zero. If yes, the small piston of the decompression rocker arm of the engine valve train is extended, the start-up integrated motor is powered, the start-up integrated motor drags the engine in reverse, and the reverse dragging duration is a set value 1.

[0076] Step 2: Determine whether the engine speed is greater than a set value 2. If yes, the small piston of the decompression rocker arm of the engine valve train is retracted.

[0077] Step 3: The start-up integrated motor drags the engine to a set value 3; the engine attempts to inject oil and ignite; the torque of the start-up integrated motor is gradually unloaded using a strategy 4, and after waiting for a set time 5, it is determined whether the engine speed fluctuation is less than a set value 6. If yes, the torque of the start-up integrated motor is quickly unloaded using a strategy 7, and the engine starts successfully. Otherwise, the torque unloading strategy 4 is adjusted again, and the above steps are repeated.

[0078] The engine cylinder pressure curve comparison diagram is shown in Figure 7 Using the embodiment, the in-cylinder pressure can be reduced by 40%, the engine jolt is reduced, and the vehicle NVH comfort is improved. The load of the crankshaft-piston and other moving parts is reduced, the engine starting torque is reduced, the starting time is shortened by about 30% under laboratory conditions, the engine starting time comparison diagram is shown in Figure 8 The starting resistance torque is reduced, the power consumption of the battery caused by the frequent starting of the start-up integrated motor is reduced, and the subjective NVH evaluation of the vehicle is improved from obvious jolt impact to very slight.

[0079] The control strategy of the embodiment integrates multiple parameters to construct an intelligent control decompression starting strategy. Figure 6 The set values of the parameters are not necessarily fixed and can be adaptively adjusted through accumulation of vehicle operating condition data, so that the strategy is more consistent with the actual use, and the starting efficiency and comfort are improved.

[0080] The set time 1 dynamic adjustment correction algorithm in Figure 6 is shown in Figure 9 : On the basis of the initial value, the environmental temperature, altitude, coolant temperature, oil temperature and other parameters are considered for dynamic adjustment and correction.

[0081] The engine starting initial speed dynamic adjustment correction algorithm is shown in Figure 10 ​The engine speed 2 preset value is dynamically adjusted and corrected on the basis of the initial value, considering parameters such as ambient temperature, altitude, coolant temperature, oil temperature, motor rotor moment of inertia, motor efficiency curve, and vehicle battery power, to adapt to different starting conditions.

[0082] The engine speed 2 initial value is found according to the friction work data of the engine on the engine test bench at normal temperature, when the crankshaft speed at which the starting and launching integrated machine can easily drag the engine and the efficiency of the starting and launching integrated machine is relatively high.

[0083] The engine speed set value 3 is the critical value of the engine speed reaching the fuel injection ignition, and is greater than the engine speed 2.

[0084] The engine speed 3 preset value is dynamically adjusted and corrected on the basis of the initial value, considering parameters such as ambient temperature, altitude, coolant temperature, oil temperature, intake air volume, and fuel injection volume, to achieve better starting effect. The dynamic adjustment and correction algorithm of the set speed 3 is as shown in Figure 11 .

[0085] The engine speed 3 initial value is the minimum crankshaft speed at which the engine stably combusts, considering the combustion characteristics of the engine on the engine test bench at normal temperature.

[0086] The torque unloading strategy 4 is a stepwise unloading strategy, which means that during the unloading process, the motor torque gradually decreases in steps, and then is stably maintained for a period of time (set time 5). The set time 5 is to more finely control the exit timing of the motor. The torque unloading strategy 7 is a linear unloading strategy. The linear unloading strategy means that the motor torque gradually decreases linearly over time, quickly reduces the torque, and reduces the entire starting process time. The starting and launching integrated motor torque unloading schematic diagram is as shown in Figure 12 .

[0087] The engine speed fluctuation set value 6 is used to judge whether the engine has been started smoothly. The engine speed fluctuation set value 6 is calculated from the crankshaft speed sensor signal in the engine electronic control unit, using the formula: to accurately judge the stability of the engine speed fluctuation, wherein ω max is the maximum value of the speed fluctuation, ω min is the minimum value of the speed fluctuation, and ω m is the preset difference value of the speed fluctuation.

[0088] The embodiment is applicable to the range extender product containing a multi-cylinder engine, has small changes to the engine body structure, and realizes pressure reduction starting by controlling the opening of the exhaust valve during the compression stroke and the expansion stroke to release the cylinder compression pressure. The range extender starts quickly and stably, improves the vehicle NVH comfort, and reduces the power consumption.

[0089] The embodiment increases the decompression rocker arm, has small change on the engine body structure of the range extender, lightens the load of the crankshaft-piston and other moving parts, reduces the engine starting torque, shortens the starting time by 30%, reduces the power consumption of the motor, greatly reduces the cylinder pressure, reduces the engine vibration, improves the comfort of the vehicle passengers, reduces the compression pressure peak of the motoring engine by 40%, reduces the friction work of the crankshaft-piston and other moving parts, reduces the engine vibration during the starting process, improves the comfort of the vehicle passengers, shortens the starting time by 30%, reduces the power consumption of the motor, and improves the subjective NVH evaluation of the vehicle from obvious vibration impact to very slight.

[0090] The embodiment of the application further provides an engine starting control device. It should be noted that the engine starting control device of the embodiment of the application can be used to execute the control method for engine starting provided by the embodiment of the application. The device is used to realize the above-mentioned embodiments and preferred embodiments, and the description has been made above. As used below, the term "module" can be a combination of software and / or hardware that realizes a predetermined function. Although the device described in the following embodiments is preferably realized in software, the realization of hardware or a combination of software and hardware is also possible and conceived.

[0091] The engine starting control device provided by the embodiment of the application is described below.

[0092] Figure 13 is a schematic diagram of the engine starting control device according to the embodiment of the application. As shown in Figure 13 , the device includes:

[0093] The first control unit 1301 is configured to control the decompression rocker arm small piston of the engine valve train to extend in the process of starting the range extender system and when the engine speed is determined to be zero, the range extender system including the engine, the start-integrated motor and the engine valve train, the decompression rocker arm small piston being in contact with the valve of the engine valve train to decompress the engine compression cylinder when the decompression rocker arm small piston extends;

[0094] The second control unit 1302 is configured to supply power to the start-integrated motor to adopt the start-integrated motor to motoring the engine to increase the engine speed when the decompression rocker arm small piston is determined to extend, and control the decompression rocker arm small piston to retract when the engine speed is detected to be greater than a first preset engine speed.

[0095] The third control unit 1303 is configured to control the engine to inject fuel and ignite in the case where the engine speed is detected to be greater than the second preset engine speed, and adjust the torque of the start-integrated motor according to a preset torque unloading strategy in the case where the engine ignites successfully, and complete engine starting in the case where the torque of the start-integrated motor is adjusted to the preset torque, wherein the second preset engine speed is greater than the first preset engine speed.

[0096] In this embodiment, the first control unit is configured to control the decompression rocker arm small piston of the engine valve train to extend in the case where the engine speed is determined to be zero during the starting of the range extender system, wherein the range extender system comprises an engine, a start-integrated motor and the engine valve train, and the decompression rocker arm small piston is in contact with the valve of the engine valve train to decompress the engine cylinder in the case where the decompression rocker arm small piston extends; the second control unit is configured to supply power to the start-integrated motor to adopt the start-integrated motor to drag the engine to increase the engine speed in the case where the decompression rocker arm small piston is determined to extend, and control the decompression rocker arm small piston to retract in the case where the engine speed is detected to be greater than the first preset engine speed; and the third control unit is configured to control the engine to inject fuel and ignite in the case where the engine speed is detected to be greater than the second preset engine speed, and adjust the torque of the start-integrated motor according to a preset torque unloading strategy in the case where the engine ignites successfully, and complete engine starting in the case where the torque of the start-integrated motor is adjusted to the preset torque, wherein the second preset engine speed is greater than the first preset engine speed. The problem that the engine shaking in the engine dragging stage of the start-integrated motor during the starting of the range extender affects the comfort of the passengers of the vehicle is solved.

[0097] As an optional solution, the third control unit comprises a first adjustment module, a second adjustment module and a first determination module. The first adjustment module is configured to adjust the torque of the start-integrated motor to the first torque according to a stepped torque unloading strategy, wherein the stepped torque unloading strategy is a control strategy in which the torque decreases step by step over time. The second adjustment module is configured to adjust the torque of the start-integrated motor to the preset torque according to a linear torque unloading strategy in the case where the torque of the start-integrated motor is determined to reach the first torque, wherein the linear torque unloading strategy is a control strategy in which the torque decreases linearly over time. The first determination module is configured to determine that the engine starting operation is completed in the case where the torque of the start-integrated motor is determined to reach the preset torque.

[0098] An optional solution, the second adjustment module includes a first determining submodule, a second determining submodule and an adjusting submodule; the first determining submodule is used to determine the running time of the torque of the above-mentioned starting motor to reach the above-mentioned first torque when it is determined that the torque of the above-mentioned starting motor reaches the above-mentioned first torque; the second determining submodule is used to determine whether the torque fluctuation of the above-mentioned starting motor is less than the fluctuation setting value when it is determined that the above-mentioned running time reaches a first preset time period; the adjusting submodule is used to adopt a linear torque unloading strategy to adjust the torque of the above-mentioned starting motor to the above-mentioned preset torque when the torque fluctuation of the above-mentioned starting motor is less than the above-mentioned fluctuation setting value.

[0099] In an optional solution, the third control unit includes an evaluation module and a third adjustment module; the evaluation module is used to use the formula: Evaluate the speed fluctuation stability of the above engine, where λ is the speed fluctuation stability, ω max is the maximum speed fluctuation, ω min is the minimum value of speed fluctuation, ω m A preset difference value is provided for the speed fluctuation; and a third adjustment module is used to determine whether to adopt the linear torque unloading strategy to adjust the torque of the starting-in-one motor according to the speed fluctuation stability.

[0100] In an optional solution, the device also includes a first determination unit and a second determination unit; the first determination unit is used to determine the above-mentioned first preset engine speed based on the ambient temperature, altitude, coolant temperature, oil temperature, motor rotor moment of inertia, motor efficiency curve and vehicle battery power; the second determination unit is used to determine the above-mentioned second preset engine speed based on the above-mentioned ambient temperature, altitude, coolant temperature, oil temperature, engine air intake volume and fuel injection volume.

[0101] An optional solution is that the second control unit includes a detection module and a control module; the detection module is used to detect the above-mentioned engine speed after a second preset time period; the control module is used to control the retraction of the above-mentioned decompression rocker arm small piston when the above-mentioned engine speed is greater than the above-mentioned first preset engine speed.

[0102] In an optional solution, the second control unit includes a second determination module, which is used to determine the above-mentioned second preset time period according to the ambient temperature, altitude, coolant temperature and oil temperature.

[0103] The control device for starting the engine includes a processor and a memory, and the first control unit, the second control unit and the third control unit are stored in the memory as program units, and the corresponding functions are realized by executing the program units stored in the memory by the processor. The modules are located in the same processor, or the modules are located in different processors in any combination.

[0104] The processor includes a core, and the core calls the corresponding program unit from the memory. One or more cores can be provided, and the problem of engine vibration affecting the comfort of vehicle passengers during the engine starting process of the existing range extender can be solved by adjusting the core parameters.

[0105] The memory can include non-permanent memory in a computer readable medium, random access memory (RAM) and / or non-volatile memory such as read-only memory (ROM) or flash memory (flash RAM), and the memory includes at least one memory chip.

[0106] The embodiment of the application provides a computer readable storage medium, and the computer readable storage medium includes a stored program, wherein the program controls the device where the computer readable storage medium is located to execute the control method for starting the engine when the program runs.

[0107] Specifically, the control method for starting the engine includes:

[0108] Step S201, during the starting process of a range extender system, and in the case where the engine speed is determined to be zero, a decompression rocker arm small piston of an engine valve train is controlled to extend, the range extender system includes an engine, an engine-starting integrated motor and the engine valve train, in the case where the decompression rocker arm small piston extends, the decompression rocker arm small piston contacts a valve of the engine valve train to reduce the pressure of an engine compression cylinder;

[0109] Step S202, in the case where the decompression rocker arm small piston is determined to extend, the engine-starting integrated motor is powered to adopt the engine-starting integrated motor to drag the engine in reverse, so as to increase the engine speed, and in the case where the engine speed is detected to be greater than a first preset engine speed, the decompression rocker arm small piston is controlled to retract;

[0110] Step S203, in the case where the engine speed is detected to be greater than a second preset engine speed, the engine is controlled to inject fuel and ignite, in the case where the engine ignites successfully, the torque of the engine-starting integrated motor is adjusted according to a preset torque unloading strategy, and in the case where the torque of the engine-starting integrated motor is adjusted to the preset torque, the starting of the engine is completed, wherein the second preset engine speed is greater than the first preset engine speed.

[0111] The embodiment of the present application provides a processor used for running a program, wherein the processor implements the control method for engine starting when running the program.

[0112] Specifically, the control method for engine starting comprises the following steps.

[0113] In step S201, in the process of starting the range extender system, and in the case that the engine speed is determined to be zero, the decompression rocker arm small piston of the engine valve train is controlled to extend, the range extender system comprises an engine, an integrated starter-generator and the engine valve train, in the case that the decompression rocker arm small piston extends, the decompression rocker arm small piston contacts the valve of the engine valve train, and is used for decompressing the engine compression cylinder.

[0114] In step S202, in the case that the decompression rocker arm small piston is determined to extend, the integrated starter-generator is powered, the integrated starter-generator is used to drag the engine in reverse, the engine speed is increased, and in the case that the engine speed is detected to be greater than a first preset engine speed, the decompression rocker arm small piston is controlled to retract.

[0115] In step S203, in the case that the engine speed is detected to be greater than a second preset engine speed, the second preset engine speed is greater than the first preset engine speed, the engine is controlled to inject fuel and ignite, in the case that the engine ignites successfully, the torque of the integrated starter-generator is adjusted according to a preset torque unloading strategy, and in the case that the torque of the integrated starter-generator is adjusted to the preset torque, the engine starting is completed.

[0116] The embodiment of the present application provides an electronic device, the device comprises a processor, a memory and a program stored in the memory and capable of running on the processor, and the processor implements at least the following steps when running the program:

[0117] In step S201, in the process of starting the range extender system, and in the case that the engine speed is determined to be zero, the decompression rocker arm small piston of the engine valve train is controlled to extend, the range extender system comprises an engine, an integrated starter-generator and the engine valve train, in the case that the decompression rocker arm small piston extends, the decompression rocker arm small piston contacts the valve of the engine valve train, and is used for decompressing the engine compression cylinder.

[0118] In step S202, in the case that the decompression rocker arm small piston is determined to extend, the integrated starter-generator is powered, the integrated starter-generator is used to drag the engine in reverse, the engine speed is increased, and in the case that the engine speed is detected to be greater than a first preset engine speed, the decompression rocker arm small piston is controlled to retract.

[0119] Step S203, in the case of detecting that the engine speed is greater than the second preset engine speed, controlling the engine to inject and ignite, and in the case of successful ignition of the engine, adjusting the torque of the start-integrated motor according to a preset torque unloading strategy, and in the case of the torque of the start-integrated motor being adjusted to the preset torque, completing engine starting, wherein the second preset engine speed is greater than the first preset engine speed.

[0120] The device herein can be a server, a PC, a PAD, a mobile phone, etc.

[0121] The application also provides a computer program product adapted to execute the program of initializing at least the following method steps when executed on a data processing device:

[0122] Step S201, in the process of starting the range extender system, and in the case of determining that the engine speed is zero, controlling the decompression rocker arm small piston of the engine valve train to extend, the range extender system comprising an engine, a start-integrated motor and the engine valve train, in the case of the decompression rocker arm small piston extending, the decompression rocker arm small piston contacts the valve of the engine valve train for decompression of the engine compression cylinder;

[0123] Step S202, in the case of determining that the decompression rocker arm small piston extends, powering the start-integrated motor to adopt the start-integrated motor to drag the engine in reverse to increase the engine speed, and in the case of detecting that the engine speed is greater than the first preset engine speed, controlling the decompression rocker arm small piston to retract;

[0124] Step S203, in the case of detecting that the engine speed is greater than the second preset engine speed, controlling the engine to inject and ignite, and in the case of successful ignition of the engine, adjusting the torque of the start-integrated motor according to a preset torque unloading strategy, and in the case of the torque of the start-integrated motor being adjusted to the preset torque, completing engine starting, wherein the second preset engine speed is greater than the first preset engine speed.

[0125] It should be apparent to those skilled in the art that the modules or steps of the application described above can be implemented with a general purpose computer, and can be centralized in a single computer or distributed among a network of computers, and can be implemented with program code executable by a computer, and thus can be stored in a storage device and executed by a computer, and in some cases, the steps shown or described can be executed in a different order than shown or described, or can be implemented as separate integrated circuit modules or as a single integrated circuit module, and thus the application is not limited to any particular combination of hardware and software.

[0126] Those skilled in the art will appreciate that embodiments of the application can be devised for a method, a system, or a computer program product. Accordingly, the application can be embodied in the form of an entirely hardware embodiment, an entirely software embodiment, or an embodiment combining software and hardware aspects. Furthermore, the application can be in the form of a computer program product on one or more computer-usable storage media (including, but not limited to, disk memory, CD-ROMs, optical storage media, etc.) embodying computer readable program code.

[0127] The present application is described herein with reference to the flowchart illustrations and / or block diagrams of the methods, apparatus (systems) and computer program products according to embodiments of the application. It will be understood that each block of the flowchart illustrations and / or block diagrams, and combinations of blocks in the flowchart illustrations and / or block diagrams, can be implemented by computer program instructions. These computer program instructions can be provided to a processor of a general purpose computer, special purpose computer, embedded processor, or other programmable data processing apparatus to produce a machine, such that the instructions, which execute via the processor of the computer or other programmable data processing apparatus, create means for implementing the functions specified in the flowchart illustrations and / or block diagrams. Figure 1 one or more functions specified in the flowchart illustrations and / or block diagrams. Figure 1 one or more functions specified in the flowchart illustrations and / or block diagrams.

[0128] These computer program instructions can also be stored in a computer- readable memory that can direct a computer or other programmable data processing apparatus to function in a particular manner, such that the instructions stored in the computer-readable memory produce an article of manufacture including instructions which implement the functions specified in the flowchart illustrations and / or block diagrams. Figure 1 one or more functions specified in the flowchart illustrations and / or block diagrams. Figure 1 one or more functions specified in the flowchart illustrations and / or block diagrams.

[0129] These computer program instructions can also be loaded onto a computer or other programmable data processing apparatus to cause a series of operational steps to be performed on the computer or other programmable apparatus to produce a computer-implemented process such that the instructions which execute on the computer or other programmable apparatus provide steps for implementing the functions specified in the flowchart illustrations and / or block diagrams.Figure 1 one or more processes and / or functions specified in one or more blocks Figure 1 one or more processes and / or functions specified in one or more blocks

[0130] In one typical arrangement, the computing device includes one or more processors (CPUs), input / output interfaces, network interfaces, and memory.

[0131] The memory can include non-persistent memory and / or volatile memory, such as random access memory (RAM) and / or cache memory, non-volatile memory, such as read-only memory (ROM), EPROM, and / or flash memory, etc. The memory is an example of computer readable media.

[0132] Computer readable media includes permanent and non-permanent, removable and non-removable media implemented in any method or technology for storage of information such as computer readable instructions, data structures, program modules or other data. Examples of computer storage media include, but are not limited to, phase change memory (PRAM), static random access memory (SRAM), dynamic random access memory (DRAM), other types of random access memory (RAM), read-only memory (ROM), electrically erasable programmable read-only memory (EEPROM), flash memory or other memory technology, compact disc read-only memory (CD-ROM), digital versatile disc (DVD), or other optical storage, magnetic cassettes, magnetic tapes, magnetic disk storage or other magnetic storage devices, or any other non-transmission medium that can be used to store information accessible to a computing device. According to the definition herein, computer readable media does not include transitory media, such as modulated data signals and carrier waves.

[0133] It should also be noted that the terms "comprising", "containing", or any other variant thereof, are intended to cover a non-exclusive inclusion, such that a process, method, article or apparatus that comprises a list of elements does not only include those elements, but can also include other elements not expressly listed or inherent to such process, method, article or apparatus. Without more limitations, the element defined by the statement "comprising a" does not exclude the presence of additional identical elements in the process, method, article or apparatus that includes the element.

[0134] From the above description, it can be seen that the above-mentioned embodiments of the present application achieve the following technical effects:

[0135] 1) The application provides a control method for engine starting, comprising the following steps: in the process of starting a range extender system, and when it is determined that the engine speed is zero, a decompression rocker arm small piston of an engine valve train is controlled to extend, the range extender system comprises an engine, an integrated starter-generator and the engine valve train, when the decompression rocker arm small piston extends, the decompression rocker arm small piston is in contact with a valve of the engine valve train, and is used for decompressing a compression cylinder of the engine; when it is determined that the decompression rocker arm small piston extends, the integrated starter-generator is powered, the integrated starter-generator is used to drag the engine in reverse, the engine speed is increased, and when it is detected that the engine speed is greater than a first preset engine speed, the decompression rocker arm small piston is controlled to retract; when it is detected that the engine speed is greater than a second preset engine speed, the engine is controlled to inject fuel and ignite, and when the engine ignites successfully, the torque of the integrated starter-generator is adjusted according to a preset torque unloading strategy, and when the torque of the integrated starter-generator is adjusted to the preset torque, the engine starting is completed, wherein the second preset engine speed is greater than the first preset engine speed. The decompression starting is realized by controlling the exhaust valve to open in the compression stroke and the expansion stroke and releasing the compression pressure in the cylinder, the range extender starting is rapid and stable, the vehicle NVH comfort is improved, the electric energy consumption is reduced, and the problem that the engine shakes in the process of starting the existing range extender, the integrated starter-generator drags the engine in reverse, and the comfort of the vehicle passengers is affected is solved.

[0136] 2) The application provides a control device for engine starting, comprising: a first control unit, which is used for, in the process of starting a range extender system, and when it is determined that the engine speed is zero, controlling a decompression rocker arm small piston of an engine valve train to extend, the range extender system comprises an engine, an integrated starter-generator and the engine valve train, when the decompression rocker arm small piston extends, the decompression rocker arm small piston is in contact with a valve of the engine valve train, and is used for decompressing a compression cylinder of the engine; a second control unit, which is used for, when it is determined that the decompression rocker arm small piston extends, powering the integrated starter-generator, using the integrated starter-generator to drag the engine in reverse, increasing the engine speed, and when it is detected that the engine speed is greater than a first preset engine speed, controlling the decompression rocker arm small piston to retract; and a third control unit, which is used for, when it is detected that the engine speed is greater than a second preset engine speed, controlling the engine to inject fuel and ignite, and when the engine ignites successfully, adjusting the torque of the integrated starter-generator according to a preset torque unloading strategy, and when the torque of the integrated starter-generator is adjusted to the preset torque, completing the engine starting, wherein the second preset engine speed is greater than the first preset engine speed. The decompression starting is realized by controlling the exhaust valve to open in the compression stroke and the expansion stroke and releasing the compression pressure in the cylinder, the range extender starting is rapid and stable, the vehicle NVH comfort is improved, the electric energy consumption is reduced, and the problem that the engine shakes in the process of starting the existing range extender, the integrated starter-generator drags the engine in reverse, and the comfort of the vehicle passengers is affected is solved.

[0137] The above descriptions are only the preferred embodiment of the present application, but not for limiting the present application. For those skilled in the art, the present application can have various modifications and changes. Any modifications, equivalent replacements, improvements, etc. made within the spirit and principle of the present application shall be included in the protection scope of the present application.

Claims

1. A control method of engine start, characterized by, The method comprises: In the process of starting the range extender system, and in the case of determining that the engine speed is zero, the control engine valve train decompression rocker arm small piston extends, the range extender system comprises an engine, a motor-generator and the engine valve train, in the case of the decompression rocker arm small piston extending, the decompression rocker arm small piston contacts the valve of the engine valve train, for decompression of the engine compression cylinder; In the case of determining that the decompression rocker arm small piston extends, the motor-generator is powered to adopt the motor-generator to reverse drag the engine to increase the engine speed, and in the case of detecting that the engine speed is greater than a first preset engine speed, the decompression rocker arm small piston is controlled to retract; In the case of detecting that the engine speed is greater than a second preset engine speed, the engine is controlled to inject and ignite, and in the case of the engine ignition being successful, the torque of the motor-generator is adjusted according to a preset torque unloading strategy, and in the case of the torque of the motor-generator being adjusted to a preset torque, the engine starting is completed, wherein the second preset engine speed is greater than the first preset engine speed; Adjusting the torque of the motor-generator according to a preset torque unloading strategy, and in the case of the torque of the motor-generator being adjusted to a preset torque, the engine starting is completed, comprising: Adjusting the torque of the motor-generator to a first torque according to a step torque unloading strategy, wherein the step torque unloading strategy is a control strategy in which the torque decreases step by step with time; in the case of determining that the torque of the motor-generator reaches the first torque, the torque of the motor-generator is adjusted to the preset torque according to a linear torque unloading strategy, wherein the linear torque unloading strategy is a control strategy in which the torque gradually decreases linearly with time; in the case of determining that the torque of the motor-generator reaches the preset torque, it is determined that the engine starting operation is completed.

2. The method of claim 1, wherein, In the case of determining that the torque of the motor-generator reaches the first torque, adjusting the torque of the motor-generator to the preset torque according to a linear torque unloading strategy, comprising: In the case of determining that the torque of the motor-generator reaches the first torque, determining the running time of the torque of the motor-generator reaching the first torque; In the case of determining that the running time reaches a first preset time period, determining whether the torque fluctuation of the motor-generator is less than a fluctuation setting value; In the case of the torque fluctuation of the motor-generator being less than the fluctuation setting value, adjusting the torque of the motor-generator to the preset torque according to a linear torque unloading strategy.

3. The method of claim 1, wherein, Before adjusting the torque of the motor-generator to the preset torque according to a linear torque unloading strategy, the method further comprises: The formula is used to evaluate the speed fluctuation stability of the engine, wherein, is the speed fluctuation stability, is the maximum speed fluctuation, is the minimum speed fluctuation, is the preset difference value of the speed fluctuation.​ According to the speed fluctuation stability, it is determined whether to adjust the torque of the motor-generator according to the linear torque unloading strategy.

4. The method of claim 1, wherein, The method further comprises: According to the ambient temperature, the altitude, the coolant temperature, the oil temperature, the motor rotor moment of inertia, the motor efficiency curve and the vehicle battery power, the first preset engine speed is determined; The second preset engine speed is determined according to the ambient temperature, the altitude, the coolant temperature, the engine oil temperature, an engine air intake amount, and a fuel injection amount.

5. The method of claim 1, wherein, In a case where the engine speed is greater than a first preset engine speed, the control unit controls the decompression rocker arm small piston to retract. The engine speed is detected after a second preset time period. In a case where the engine speed is greater than the first preset engine speed, the control unit controls the decompression rocker arm small piston to retract.

6. The method of claim 5, wherein, The method further comprises: The second preset time period is determined according to an ambient temperature, an altitude, a coolant temperature, and an engine oil temperature.

7. An engine start control device characterized by comprising: The method further comprises: A first control unit is configured to, in a process in which a range extender system is started and in a case where an engine speed is determined to be zero, control a decompression rocker arm small piston of an engine valve train to extend, the range extender system comprising an engine, an integrated starter-generator, and the engine valve train, the decompression rocker arm small piston being in contact with a valve of the engine valve train to decompress a compression cylinder of the engine in a case where the decompression rocker arm small piston extends; A second control unit is configured to, in a case where the decompression rocker arm small piston is determined to extend, supply power to the integrated starter-generator to adopt the integrated starter-generator to freewheel the engine to increase the engine speed, and in a case where the engine speed is detected to be greater than a first preset engine speed, control the decompression rocker arm small piston to retract; A third control unit is configured to, in a case where the engine speed is detected to be greater than a second preset engine speed, control the engine to inject fuel and ignite, the second preset engine speed being greater than the first preset engine speed, and in a case where the engine is successfully ignited, adjust a torque of the integrated starter-generator according to a preset torque unloading strategy, and in a case where the torque of the integrated starter-generator is adjusted to a preset torque, complete engine starting. The third control unit comprises a first adjusting module, a second adjusting module, and a first determining module, the first adjusting module is configured to adjust the torque of the integrated starter-generator to a first torque according to a stepped torque unloading strategy, the stepped torque unloading strategy being a control strategy in which the torque is stepped down over time, the second adjusting module is configured to, in a case where the torque of the integrated starter-generator is determined to reach the first torque, adjust the torque of the integrated starter-generator to the preset torque according to a linear torque unloading strategy, the linear torque unloading strategy being a control strategy in which the torque is gradually linearly reduced over time, and the first determining module is configured to, in a case where the torque of the integrated starter-generator is determined to reach the preset torque, determine that the engine starting operation is completed.

8. A computer-readable storage medium, characterized in that, The computer readable storage medium comprises a stored program, wherein the program, when executed, controls a device in which the computer readable storage medium is located to perform the control method for engine starting according to any one of claims 1 to 6.

9. An electronic device, comprising: The computer readable storage medium comprises a stored program, wherein the program, when executed, controls a device in which the computer readable storage medium is located to perform the control method for engine starting according to any one of claims 1 to 6. one or more processors, a memory, and one or more programs, wherein the one or more programs are stored in the memory and configured to be executed by the one or more processors, the one or more programs including programs for performing the control method of starting the engine according to any one of claims 1 to 6.

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