Oil injection control method and system for low-temperature starting of multi-cylinder diesel engine

Abstract

The invention provides an oil injection control method and system for low-temperature starting of a multi-cylinder diesel engine. The oil injection control method comprises the steps that the diesel engine is driven to operate to conduct zero-oil-injection reverse towing, and air inlet heating is conducted; the air inlet temperature of each cylinder is predicted according to an air inlet temperature prediction formula by collecting the temperature of an air inlet main pipe and structural parameters of an air inlet channel of the diesel engine; according to the air inlet temperature, the compression temperature of each air cylinder is predicted, and whether the compression temperature reaches the preset target compression temperature or not is judged; and performing trial oil injection on the cylinder reaching the target compression temperature, acquiring a rotating speed signal of the diesel engine at the moment, determining an oil injection strategy based on the acquired rotating speed signal, and controlling the cylinder to continuously inject oil according to the oil injection strategy so as to start the diesel engine at low temperature. According to the method, oil injection strategies of different air cylinders of the diesel engine are reasonably and differentially controlled, the time needed by low-temperature starting is shortened, and starting oil consumption and pollutant emission of the diesel engine are reduced.

Description

Technical Field

[0001] The present application belongs to the technical field of low-temperature starting of internal combustion engines, and in particular, relates to a fuel injection control method and system for low-temperature starting of a multi-cylinder diesel engine. Background Art

[0002] Diesel engines usually use direct injection compression ignition, which places high demands on the intake air temperature. Therefore, during the start-up of a diesel engine in a low-temperature environment, it is necessary to warm up the cylinder while idling to keep the engine temperature rising. At the same time, the fresh air is heated by intake air heating devices such as flame plugs and electric heating grids to achieve the ignition conditions of the diesel spray.

[0003] The compression temperature of the diesel engine cylinder continues to rise with the warm-up time. After the compression temperature reaches the ignition threshold, fuel is injected to make the diesel spray self-ignite in the cylinder to achieve the purpose of diesel engine starting. However, if the compression temperature does not reach the ignition threshold and the fuel is injected too early, it will not only cause the current ignition failure, but also hinder the ignition of subsequent cycles. On the one hand, this is because the diesel injected into the cylinder cannot ignite and burn, and a large amount of diesel accumulates in the cylinder, causing the diesel and air mixture ratio to be unbalanced. On the other hand, the evaporation and heat absorption process of the low-temperature diesel spray will cause the temperature in the cylinder to further decrease, making it more difficult for the diesel to ignite and burn, and prolonging the low-temperature starting time.

[0004] The prior art (CN103397968B-A Miller cycle diesel engine low temperature environment starting control method) uses the diesel engine temperature as a criterion, and when the diesel engine temperature is greater than the preset diesel engine starting temperature, fuel injection is performed, otherwise the fuel supply to the cylinder is 0. However, the prior art has two shortcomings: first, the measured diesel engine temperature is not the cylinder compression temperature, and no prediction method for the cylinder compression temperature is given; second, the arrangement position of the intake heating device will cause the actual intake temperature of each cylinder to be different; therefore, the control method cannot achieve reasonable differentiated control of the injection strategy, which will result in some cylinders of the multi-cylinder diesel engine successfully igniting, while some cylinders fail to ignite after injection, which ultimately leads to an extension of the overall starting time.

[0005] Therefore, during the low-temperature starting process of a multi-cylinder diesel engine using the intake air heating method, how to reasonably perform differentiated control on the injection strategies of different cylinders to avoid the situation where some cylinders fail to ignite is a technical problem that technical personnel in this field urgently need to solve. Summary of the invention

[0006] In view of this, the present application aims to propose a fuel injection control method and system for low-temperature starting of a multi-cylinder diesel engine, which can shorten the time required for low-temperature starting by performing reasonable and differentiated control on the fuel injection strategies of different cylinders of the diesel engine.

[0007] To achieve the above purpose, the technical solution of this application is implemented as follows:

[0008] In a first aspect, the present application provides a method for controlling low-temperature starting of a multi-cylinder diesel engine, including:

[0009] Driving the diesel engine to operate in zero-injection reverse towing and heating the intake air;

[0010] Collecting the temperature of the intake manifold of the diesel engine and the structural parameters of the intake passage, and predicting the intake temperature of each cylinder according to the intake temperature prediction formula;

[0011] Predicting the compression temperature of each cylinder according to the intake temperature respectively, and judging whether the compression temperature reaches a preset target compression temperature;

[0012] Performing trial fuel injection on the cylinders that reach the target compression temperature, collecting the diesel engine speed signal at this time, determining an injection strategy based on the collected speed signal, and controlling the cylinders to perform continuous fuel injection according to the injection strategy so that the diesel engine starts at low temperature.

[0013] In a second aspect, based on the same inventive concept, the present application further provides a low-temperature starting control system for a multi-cylinder diesel engine, including:

[0014] A preheating module configured to drive the diesel engine to operate in zero-injection reverse towing and heat the intake air;

[0015] A prediction module configured to collect the temperature of the intake manifold of the diesel engine and the structural parameters of the intake passage, and predict the intake temperature of each cylinder according to the intake temperature prediction formula;

[0016] A judgment module configured to predict the compression temperature of each cylinder according to the intake temperature respectively, and judge whether the compression temperature reaches a preset target compression temperature;

[0017] A control module configured to perform trial fuel injection on the cylinders that reach the target compression temperature, collect the diesel engine speed signal at this time, determine an injection strategy based on the collected speed signal, and control the cylinders to perform continuous fuel injection according to the injection strategy so that the diesel engine starts at low temperature.

[0018] In a third aspect, based on the same inventive concept, the present application further provides an electronic device, including a memory, a processor, and a computer program stored on the memory and executable on the processor, where the processor implements the method described in the first aspect when executing the program.

[0019] In a fourth aspect, based on the same inventive concept, the present application further provides a non-transitory computer-readable storage medium, where the non-transitory computer-readable storage medium stores computer instructions for causing the computer to execute the method described in the first aspect.

[0020] Compared with the prior art, the fuel injection control method and system for low-temperature starting of a multi-cylinder diesel engine according to the present application have the following beneficial effects:

[0021] The fuel injection control method and system for low-temperature starting of a multi-cylinder diesel engine according to the present application can predict the compression temperatures of different cylinders and use the cylinder compression temperature as a criterion to judge the fuel injection start time of each cylinder during the low-temperature starting process, realizing a reasonable differential fuel injection control strategy, avoiding the situation of fuel injection without ignition in some cylinders, and shortening the overall starting time required. BRIEF DESCRIPTION OF THE DRAWINGS

[0022] The drawings constituting a part of the present application are used to provide a further understanding of the present application. The schematic embodiments of the present application and their descriptions are used to explain the present application and do not constitute an improper limitation to the present application. In the drawings:

[0023] Figure 1 is a schematic flow chart of a fuel injection control method for low-temperature starting of a multi-cylinder diesel engine according to an embodiment of the present application;

[0024] Figure 2 is a schematic diagram for explaining a method for predicting the intake air temperature of different cylinders of a multi-cylinder diesel engine according to an embodiment of the present application;

[0025] Figure 3 is an application effect diagram of a differential delayed fuel injection strategy according to an embodiment of the present application;

[0026] Figure 4 is a schematic structural diagram of a low-temperature starting control system for a multi-cylinder diesel engine according to an embodiment of the present application;

[0027] Figure 5 is a schematic diagram of the hardware structure of an electronic device according to an embodiment of the present application. DETAILED DESCRIPTION OF THE EMBODIMENTS

[0028] In order to make the purpose, technical solutions and advantages of the present application clearer, the present application will be further described in detail below with reference to specific embodiments and the accompanying drawings.

[0029] It should be noted that, unless otherwise defined, the technical terms or scientific terms used in the embodiments of this application should have the ordinary meanings understood by those with ordinary skills in the field to which this application belongs. The "first", "second" and similar words used in the embodiments of this application do not indicate any order, quantity or importance, but are only used to distinguish different components. Words such as "including" or "comprising" mean that the elements or objects appearing before this word cover the elements or objects listed after this word and their equivalents, without excluding other elements or objects. Words such as "connected" or "linked" are not limited to physical or mechanical connections, but may include electrical connections, whether direct or indirect. "Up", "down", "left", "right", etc. are only used to represent relative position relationships. When the absolute position of the object being described changes, the relative position relationship may also change accordingly.

[0030] The embodiments of this application will be described in detail below with reference to the accompanying drawings.

[0031] Please refer to Figure 1 As shown, this embodiment provides a low-temperature starting control method for a multi-cylinder diesel engine. This method predicts the compression temperatures of different cylinders and uses the cylinder compression temperature as a criterion to judge the fuel injection start time of each cylinder during the low-temperature starting process, realizing a reasonable differential fuel injection control strategy, avoiding the situation of fuel injection and non-ignition in some cylinders, and shortening the overall starting time. This embodiment takes a certain V-type 12-cylinder engine as an example for illustration, and specifically includes the following steps:

[0032] Step S101: Drive the diesel engine to rotate in zero-injection reverse drag and perform intake air heating.

[0033] Specifically, in this embodiment, during the preheating stage, the diesel engine is driven to rotate by an electric motor in zero-injection reverse drag. The intake air is heated by means of flame intake air heating, electric heating grids, etc. As the heating device and the starting motor operate, the body temperature of the diesel engine, the coolant temperature, the lubricating oil temperature, and the intake air temperature gradually increase.

[0034] Step S102: Collect the intake main pipe temperature and intake duct structure parameters of the diesel engine, and predict the intake air temperature of each cylinder according to the intake air temperature prediction formula.

[0035] Specifically, in this embodiment, the V-type 12-cylinder engine has two rows of cylinders, with 6 cylinders in each row. The two rows of cylinders intake air separately, and the intake air heating devices are respectively arranged upstream of the first cylinder of the two rows of cylinders. The intake main pipe temperatures of the two rows of cylinders are respectively tested, collected and recorded, and one row is taken as an example for subsequent description. The air temperature at the intake main pipe is collected as T in .

[0036] Taking the intake situation of 6 cylinders in a single row as an example for illustration, the schematic diagram is as shown in the appendix Figure 2 The air temperature at the intake manifold is T in , and the average mass flow rate of the total intake of a single row is The wall temperature is T w , the convective heat transfer coefficient is h, the distance between intake valve 1 and the temperature measurement point is L in , the distance between intake valves is L, and the average mass flow rate and temperature at intake valve 1 are respectively T 1 , and the average mass flow rate and temperature at intake valve 2 are respectively T 2 , and so on.

[0037] During the prediction process of the intake air temperature at each intake valve, the flow process is regarded as quasi-steady state, and the intake air temperature of each cylinder is calculated in sequence. First, based on the air temperature T in at the intake manifold, the average mass flow rate , the structure parameters of the diesel engine intake port, etc., the intake air temperature T 1 at intake valve 1 is predicted. The relationship between T 1 and the above parameters is as follows:

[0038]

[0039] dA is the heat transfer area:

[0040] dA = πDdL

[0041] C p is the specific heat capacity at constant pressure, h is the convective heat transfer coefficient, and the Dittus-Boelter empirical formula is used to estimate h according to the air velocity:

[0042]

[0043] In the formula, Nu is the Nusselt number, D is the inner diameter of the pipe, k is the thermal conductivity of air, Re is the Reynolds number, Pr is the Prandtl number, and q is 0.3 when the fluid is cooled.

[0044] T gas is the local air temperature. During the intake process of diesel engines during cold start, the wall temperature is relatively low, and T gas gradually decreases as the air flow advances. Since the local air temperature T gas gradually decreases as the air flow advances and the degree of decrease is unknown, it is impossible to directly calculate the intake air temperature using conventional methods.

[0045] Therefore, during the prediction process, the intake manifold is segmented to Figure 2For example, consider the section from the temperature measurement point to the intake valve 1 as the first section, with a pipe length of L in , and use the equivalent gas temperature T 等效 within this section to calculate the heat exchange quantity, obtaining:

[0046]

[0047] Estimate the equivalent gas temperature T 等效 by using the heat exchange characteristics during the air flow process and simulation calculations, establish the relationship between the equivalent temperature T 等效 and the main pipe air temperature and the intake air temperature at the intake valve 1. Finally, use the following formula to predict the intake air temperature at the intake valve 1:

[0048]

[0049] Furthermore, calculate T 2 using the same method, that is, the present invention uses the following formula to predict the intake air temperature at the intake valve 2:

[0050]

[0051] Among them, the sum of the average mass flow rates at the six intake valves is equal to the total intake average mass flow rate , and is regarded as one-sixth of the total mass flow rate during prediction.

[0052] Step S103: Predict the compression temperature of each cylinder according to the intake air temperature, and determine whether the compression temperature reaches the preset target compression temperature.

[0053] Specifically, in this embodiment, the diesel engine compression process is regarded as a polytropic process. Under adiabatic conditions, the polytropic index is 1.4. However, during the low-temperature starting process, the body temperature is low, the temperature difference is large, and the heat dissipation increases; at the same time, the rotational speed is low, the heat dissipation time per cycle is long, and the air leakage is large, further resulting in energy loss in the cylinder. Therefore, in the prediction process of this application, a polytropic index lower than the conventional level is used to predict the in-cylinder compression process. The polytropic index during the starting process can be estimated through a motoring test or simulation software, and is calculated using the following formula:

[0054]

[0055] In the formula, T comp1 is the compression temperature of cylinder 1, T 1 is the intake air temperature of cylinder 1, is the cylinder compression ratio, and n is the polytropic index.

[0056] Use the compression temperature of each cylinder as the fuel injection judgment basis, and the preset target compression temperature is T comp_set, the actual compression temperatures of different cylinders are T comp1 , T comp2 , …… T comp6 .

[0057] Step S104: Conduct a trial fuel injection on the cylinders that reach the target compression temperature, collect the diesel engine speed signal at this time, determine the fuel injection strategy based on the collected speed signal, and control the cylinders to conduct continuous fuel injection according to the fuel injection strategy so that the diesel engine can start at low temperatures.

[0058] Specifically, in this embodiment, the electronically controlled high-pressure common rail system is used to conduct a trial fuel injection on the cylinders that reach the target compression temperature (i.e., the actual compression temperature T compi > the preset value T comp_set ).

[0059] Collect the speed signal at this time and determine the subsequent fuel injection strategy based on the collected speed signal.

[0060] Among them, if the instantaneous speed of the diesel engine increases after the fuel injection of a certain cylinder, it means that the single-cylinder ignition of the fuel-injected cylinder is successful. In the subsequent cycles, keep the cylinder continuously fuel-injected and continue to monitor and judge the temperature of other cylinders that have not reached the preset temperature until the ignition of all cylinders is successful.

[0061] If the instantaneous speed does not increase after the fuel injection, it means that the single-cylinder ignition of the fuel-injected cylinder fails and the cylinder fuel injection criterion is incorrect. In this case, increase the starting preset target compression temperature of this cylinder, stop fuel injection into this cylinder in the subsequent cycles until the compression temperature exceeds the corrected compression temperature preset value.

[0062] The increase value ΔT comp_set of the starting preset target compression temperature is determined according to historical experience and the actual fuel injection volume:

[0063] ΔT comp_set = c × ΔT comp_set_his

[0064] In the formula, c is the fuel injection volume coefficient, and c takes 1 when the fuel injection volume is the calibrated value; ΔT comp_set_his is the correction value selected when the ignition is successful in the historical data. In the case of no experience of successful ignition, ΔT comp_set_his can be initially set as T 0 , T 0 is related to the diesel engine model and can be set by experience during the development and design process. The model used in this embodiment is about 5K.

[0065] The application effect of this method is as Figure 3 shown. Compared with the original fuel injection strategy, when the diesel engine adopts the differential delayed fuel injection strategy, the speed increases earlier and the starting time is shortened.

[0066] The method described in this embodiment can predict the intake air temperature of different cylinders and the cylinder compression temperature respectively according to the intake manifold temperature of the diesel engine, the structural parameters of the intake pipeline of the diesel engine, and by combining calculation methods such as thermodynamics, fluid mechanics, and heat transfer. Taking the cylinder compression temperature as a criterion, it judges when each cylinder starts fuel injection during the low-temperature starting process.

[0067] The system adopts a high-pressure common rail fuel supply method, supports separate control of the fuel injection strategies of different injectors to achieve a reasonable differential fuel injection control strategy. At the same time, it uses the method of trial fuel injection to correct the strategy, avoids the situation of misfire of fuel injection in some cylinders, shortens the overall starting time required, and reduces the starting fuel consumption and pollutant emissions of the diesel engine.

[0068] It should be noted that some embodiments of the present application are described above. Other embodiments are within the scope of the appended claims. In some cases, the actions or steps recited in the claims can be performed in a different order than in the above embodiments and still achieve the desired result. Additionally, the processes depicted in the figures do not necessarily require the particular order or sequential order shown to achieve the desired result. In certain embodiments, multitasking and parallel processing are also possible or may be advantageous.

[0069] Based on the same inventive concept, corresponding to the method of any of the above embodiments, an embodiment of the present application also provides a low-temperature starting control system for a multi-cylinder diesel engine.

[0070] As Figure 4 shown, the low-temperature starting control system for the multi-cylinder diesel engine includes:

[0071] A preheating module 11, configured to drive the diesel engine to run in zero fuel injection reverse drag and perform intake air heating;

[0072] A prediction module 12, configured to collect the intake manifold temperature and intake duct structure parameters of the diesel engine, and predict the intake air temperature of each cylinder according to the intake air temperature prediction formula;

[0073] A judgment module 13, configured to predict the compression temperature of each cylinder respectively according to the intake air temperature, and judge whether the compression temperature reaches a preset target compression temperature;

[0074] A control module 14, configured to perform trial fuel injection on the cylinders that reach the target compression temperature, collect the diesel engine speed signal at this time, determine the fuel injection strategy based on the collected speed signal, and control the cylinders to perform continuous fuel injection according to the fuel injection strategy so that the diesel engine starts at low temperature.

[0075] For the convenience of description, when describing the above system, it is divided into various modules according to functions and described separately. Of course, when implementing the embodiments of the present application, the functions of each module can be implemented in the same or multiple software and / or hardware.

[0076] The system of the above embodiment is used to implement the corresponding method in any of the foregoing embodiments, and has the beneficial effects of the corresponding method embodiments, which will not be elaborated here.

[0077] Based on the same inventive concept, corresponding to the method of any of the above embodiments, an embodiment of the present application further provides an electronic device, including a memory, a processor, and a computer program stored on the memory and executable on the processor. When the processor executes the program, it implements the method described in any of the above embodiments.

[0078] Figure 5 FIG. shows a more specific schematic diagram of the hardware structure of the electronic device provided in this embodiment. The device may include: a processor 1010, a memory 1020, an input / output interface 1030, a communication interface 1040, and a bus 1050. Among them, the processor 1010, the memory 1020, the input / output interface 1030, and the communication interface 1040 are communicatively connected to each other inside the device through the bus 1050.

[0079] The processor 1010 can be implemented in a general-purpose CPU (Central Processing Unit), a microprocessor, an application-specific integrated circuit (ASIC), or one or more integrated circuits, etc., and is used to execute relevant programs to implement the technical solutions provided in the embodiments of this specification.

[0080] The memory 1020 can be implemented in the form of a ROM (Read Only Memory), a RAM (Random Access Memory), a static storage device, a dynamic storage device, etc. The memory 1020 can store an operating system and other application programs. When implementing the technical solutions provided in the embodiments of this specification through software or firmware, the relevant program codes are stored in the memory 1020 and called and executed by the processor 1010.

[0081] The input / output interface 1030 is used to connect to the input / output module to achieve information input and output. The input / output module can be configured as a component in the device (not shown in the figure) or externally connected to the device to provide corresponding functions. Among them, the input device can include a keyboard, a mouse, a touch screen, a microphone, various sensors, etc., and the output device can include a display, a speaker, a vibrator, an indicator light, etc.

[0082] The communication interface 1040 is used to connect to the communication module (not shown in the figure) to achieve communication interaction between this device and other devices. Among them, the communication module can achieve communication through wired means (such as USB, network cable, etc.) or through wireless means (such as mobile network, WIFI, Bluetooth, etc.).

[0083] The bus 1050 includes a path for transmitting information between various components of the device (such as the processor 1010, the memory 1020, the input / output interface 1030, and the communication interface 1040).

[0084] It should be noted that although the above device only shows the processor 1010, the memory 1020, the input / output interface 1030, the communication interface 1040, and the bus 1050, in the specific implementation process, the device may also include other components necessary for normal operation. In addition, those skilled in the art can understand that the above device may also only include the components necessary to implement the solution of the embodiments of this specification, and do not necessarily include all the components shown in the figure.

[0085] The electronic device of the above embodiment is used to implement the corresponding method in any of the foregoing embodiments, and has the beneficial effects of the corresponding method embodiments, which will not be elaborated here.

[0086] Based on the same inventive concept, corresponding to the method of any of the above embodiments, the present application also provides a non-transitory computer-readable storage medium. The non-transitory computer-readable storage medium stores computer instructions, and the computer instructions are used to make the computer execute the method described in any of the above embodiments.

[0087] The computer-readable medium of this embodiment includes both permanent and non-permanent, removable and non-removable media, and information storage can be implemented by any method or technology. The information can be 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 technologies, compact disc read-only memory (CD-ROM), digital versatile disc (DVD) or other optical storage, magnetic cassette tapes, magnetic disk storage or other magnetic storage devices, or any other non-transmission medium that can be used to store information that can be accessed by a computing device.

[0088] The computer instructions stored in the storage medium of the above embodiment are used to cause the computer to execute the method described in any of the above embodiments, and have the beneficial effects of the corresponding method embodiments, which will not be elaborated here.

[0089] Those of ordinary skill in the art should understand that: The discussion of any of the above embodiments is only exemplary and is not intended to imply that the scope of the present application (including the claims) is limited to these examples; Under the concept of the present application, the technical features in the above embodiments or different embodiments can also be combined, the steps can be implemented in any order, and there are many other variations in different aspects of the embodiments of the present application as described above, which are not provided in detail for the sake of brevity.

[0090] In addition, for simplicity of explanation and discussion, and so as not to make the embodiments of the present application difficult to understand, the well-known power / ground connections to integrated circuit (IC) chips and other components may or may not be shown in the provided drawings. Furthermore, the devices may be shown in block diagram form to avoid making the embodiments of the present application difficult to understand, and this also takes into account the fact that the details of the implementation of these block diagram devices are highly dependent on the platform on which the embodiments of the present application are to be implemented (i.e., these details should be fully within the understanding of those skilled in the art). In cases where specific details (such as circuits) are set forth to describe the exemplary embodiments of the present application, it will be apparent to those skilled in the art that the embodiments of the present application can be implemented without these specific details or with variations of these specific details. Therefore, these descriptions should be considered illustrative rather than restrictive.

[0091] Although the present application has been described in connection with specific embodiments thereof, many alternatives, modifications, and variations of these embodiments will be apparent to those of ordinary skill in the art in light of the foregoing description. For example, other memory architectures (e.g., dynamic RAM (DRAM)) may be used with the embodiments discussed.

[0092] Embodiments of the present application are intended to cover all such alternatives, modifications, and variations that fall within the broad scope of the appended claims. Accordingly, any omissions, modifications, equivalent substitutions, improvements, etc. made within the spirit and principles of the embodiments of the present application shall be included within the protection scope of the present application.

Claims

1. A multi-cylinder diesel engine low temperature starting control method, characterized in that: include: Drive the diesel engine to reverse without fuel injection and heat the intake air; By collecting the intake manifold temperature and intake duct structural parameters of the diesel engine, the intake temperature of each cylinder is predicted according to the intake temperature prediction formula; Predicting the compression temperature of each cylinder according to the intake air temperature, and determining whether the compression temperature reaches a preset target compression temperature; A test fuel injection is performed on the cylinder that has reached the target compression temperature, and the diesel engine speed signal at this time is collected. The fuel injection strategy is determined based on the collected speed signal, and the cylinder is controlled to perform continuous fuel injection according to the fuel injection strategy to start the diesel engine at low temperature.

2. The method according to claim 1, characterized in that The intake air temperature prediction formula is: In the formula, represents the average mass flow rate of the total intake air in a single row, C p is the isobaric specific heat capacity, T in represents the air temperature at the intake manifold, h represents the convective heat transfer coefficient, T w represents the wall temperature, D represents the inner diameter of the pipe, L in Indicates the distance between the intake valve and the temperature measuring point.

3. The method according to claim 1, characterized in that The compression temperature prediction formula is: Where, T comp1 represents the compression temperature of cylinder 1, T1 represents the intake temperature of cylinder 1, represents the cylinder compression ratio and n represents the polynomial index.

4. The method according to claim 1, characterized in that: The compression temperature of each cylinder is used as the basis for judging fuel injection, and the actual compression temperature of different cylinders is compared with the preset target compression temperature. The cylinders that reach the target compression temperature are injected with fuel through the electronically controlled high-pressure common rail system.

5. The method according to claim 1, characterized in that The injection strategy includes: In response to the instantaneous increase in the speed of the diesel engine after the cylinder is injected with fuel, it is determined that the single cylinder of the injected cylinder has been successfully ignited, and the cylinder continues to be injected with fuel, and the cylinders that have not reached the target compression temperature are continuously monitored and the temperature is judged until all cylinders are successfully ignited.

6. The method according to claim 1, characterized in that The injection strategy also includes: In response to the fact that the instantaneous speed does not increase after the cylinder is injected with fuel, it is determined that the single cylinder ignition of the injected cylinder has failed and the cylinder injection judgment criterion is incorrect. At this time, the target compression temperature of the cylinder is increased and fuel injection to the cylinder is stopped until the compression temperature exceeds the corrected target compression temperature.

7. The method according to claim 6, characterized in that The target compression temperature increase value is determined based on historical experience and actual fuel injection quantity, specifically: ΔT comp_set =c×ΔT comp_set_his ; Where, c represents the fuel injection coefficient, and when the fuel injection amount is the calibrated value, c is 1; ΔT comp_set_his Indicates the correction value selected when the ignition is successful in the historical data. In the case of no successful ignition experience, ΔT comp_set_his Let T0, ΔT comp_set Indicates the target compression temperature increase value.

8. A multi-cylinder diesel engine low temperature starting control system, characterized in that: include: A preheating module is configured to drive the diesel engine to perform zero fuel injection reverse drag and perform intake air heating; The prediction module is configured to collect the intake manifold temperature and intake duct structural parameters of the diesel engine and predict the intake temperature of each cylinder according to the intake temperature prediction formula; a judgment module, configured to predict the compression temperature of each cylinder according to the intake air temperature, and judge whether the compression temperature reaches a preset target compression temperature; The control module is configured to perform a test injection on the cylinder that reaches the target compression temperature, collect the diesel engine speed signal at this time, and determine the injection strategy based on the collected speed signal, and control the cylinder to continuously inject fuel according to the injection strategy to start the diesel engine at low temperature.

9. An electronic device, comprising a memory, a processor, and a computer program stored in the memory and executable on the processor, wherein the processor implements the method according to any one of claims 1 to 7 when executing the program.

10. A non-transitory computer-readable storage medium, characterized in that: in, The non-transitory computer-readable storage medium stores computer instructions, and the computer instructions are used to cause a computer to execute the method according to any one of claims 1 to 7.

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