A method of cold starting an engine and a vehicle

Abstract

The application provides a cold start method of an engine and a vehicle, and applies to the field of vehicles. The engine comprises direct injection nozzles and port injection nozzles. The method comprises the following steps: acquiring a current temperature of cooling liquid in an engine of a vehicle; in the case that the current temperature is less than or equal to a preset temperature threshold, acquiring a current rotating speed of the engine, and determining a first target fuel injection amount ratio between fuel injection amounts of the direct injection nozzles and the port injection nozzles of the engine based on the current temperature of the cooling liquid and the current rotating speed of the engine; and controlling the direct injection nozzles and the port injection nozzles to perform fuel injection according to the first target fuel injection amount ratio, so as to control the cold start of the engine. The method can help the engine to complete the cold start as soon as possible, and improve the success rate of the cold start of the engine.

Description

Technical Field

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

[0002] Currently, with the continuous development of the automotive industry, engine starting has gradually become a hot topic of concern. When vehicles are cold-started at extremely low temperatures, fuel economy is a primary consideration, and fuel is typically achieved through a gasoline direct injection (GDI) system that directly injects fuel into the engine cylinders. If a single GDI injection is ineffective, multiple GDI injections are usually employed to optimize the cold start process.

[0003] With a fully charged battery and good engine oil condition, cold starts at extremely low temperatures are highly reliable. However, compared to a good battery condition, the engine speed will decrease during a cold start when the battery charge is slightly lower, leading to reduced reliability and potential start-up failures. Summary of the Invention

[0004] This application provides a method for cold starting an engine and a vehicle, which can help the engine complete a cold start as quickly as possible and improve the success rate of engine cold starting.

[0005] In a first aspect, a cold start method for an engine is provided, the engine including a direct injection nozzle and a port injection nozzle, the method comprising: acquiring the current temperature of the coolant in the engine of a vehicle; if the current temperature is less than or equal to a preset temperature threshold, acquiring the current engine speed, and determining a first target fuel injection quantity ratio between the fuel injection quantities of the direct injection nozzle and the port injection nozzle when injecting fuel based on the current coolant temperature and the current engine speed; and controlling the direct injection nozzle and the port injection nozzle to inject fuel according to the first target fuel injection quantity ratio to control the cold start of the engine.

[0006] The above technical solution, by acquiring the current temperature of the coolant in the engine, can determine whether the engine is in a cold start scenario. If the engine is in a cold start scenario, the current engine speed can be acquired, and based on the current engine speed and the current coolant temperature, the target fuel injection ratio between the direct injection nozzle and the port injection nozzle can be determined. Then, the direct injection nozzle and the port injection nozzle are controlled to inject fuel according to the target fuel injection ratio, which can help the engine complete a cold start as quickly as possible. Because the fuel viscosity in the engine increases under low temperature conditions, which is not conducive to atomization, when the current temperature is determined to be less than or equal to a preset temperature threshold, a dual injection strategy using both direct injection nozzles and port injection nozzles can control the port injection nozzles in the intake manifold injection system to inject fuel into the intake manifold. With the help of the intake airflow, the fuel is better dispersed, forming a more uniform air-fuel mixture, improving combustion efficiency, and thus achieving faster engine start-up. Furthermore, it can reduce the demand for high-pressure fuel injection when using only direct injection nozzles, thereby avoiding start-up failures due to insufficient fuel pump output and improving the start-up success rate.

[0007] In conjunction with the first aspect, in some implementations of the first aspect, determining a first target fuel injection quantity ratio between the fuel injection quantities of the engine's direct injection nozzle and port injection nozzle when injecting fuel, based on the current temperature of the coolant and the current speed of the engine, includes: determining a first target fuel injection quantity ratio corresponding to the current temperature and the current speed based on a first preset correspondence; wherein the first preset correspondence is a correspondence between target parameters and target fuel injection quantity ratio; the target parameters include the temperature of the coolant and the speed of the engine; and the target fuel injection quantity ratio is the fuel injection quantity ratio when the direct injection nozzle and port injection nozzle inject fuel.

[0008] The aforementioned technical solution, by determining the first target fuel injection quantity ratio based on the current coolant temperature and the current engine speed, allows the fuel injection quantity of the direct injection nozzle and the port injection nozzle to better match the actual operating needs of the engine. This enables the air-fuel mixture to reach a more ideal state under different operating conditions, thereby improving fuel utilization and reducing fuel consumption. By rationally adjusting the fuel injection quantity ratio between the direct injection nozzle and the port injection nozzle, it is also possible to ensure that the engine receives appropriate fuel supply under various operating conditions, thus improving the engine's cold start success rate.

[0009] In conjunction with the first aspect and the above-described implementations, in some implementations of the first aspect, controlling the direct injection nozzle and the port injection nozzle to inject fuel according to the first target fuel injection quantity ratio includes: determining the total amount of fuel injection required for cold starting of the engine; determining the first fuel injection quantity corresponding to the direct injection nozzle and the second fuel injection quantity corresponding to the port injection nozzle based on the total fuel injection quantity and the first target fuel injection quantity ratio; wherein the sum of the first fuel injection quantity and the second fuel injection quantity is the total fuel injection quantity; controlling the direct injection nozzle to inject fuel according to the first fuel injection quantity and controlling the port injection nozzle to inject fuel according to the second fuel injection quantity.

[0010] In conjunction with the first aspect and the above-described implementations, in some implementations of the first aspect, controlling the direct injection nozzle to inject fuel according to the first injection quantity includes: when it is determined that the number of fuel injections by the direct injection nozzle is multiple, determining a second target injection quantity ratio corresponding to the current temperature of the coolant based on a second preset correspondence; wherein the second preset correspondence is the correspondence between the temperature of the coolant and the injection quantity ratio of each injection during multiple fuel injections; the second target injection quantity ratio is the ratio between the injection quantities of each injection during multiple fuel injections by the direct injection nozzle; determining the single injection quantity of the direct injection nozzle each time it injects fuel based on the first injection quantity and the second target injection quantity ratio; and controlling the direct injection nozzle to inject fuel according to the single injection quantity each time it injects fuel.

[0011] In conjunction with the first aspect and the above-described implementations, in some implementations of the first aspect, controlling the direct injection nozzle to inject fuel according to the first injection quantity and controlling the port injection nozzle to inject fuel according to the second injection quantity includes: determining a first injection time when the direct injection nozzle injects fuel and determining a second injection time when the port injection nozzle injects fuel; controlling the direct injection nozzle to inject fuel according to the first injection quantity at the first injection time and controlling the port injection nozzle to inject fuel according to the second injection quantity at the second injection time.

[0012] In conjunction with the first aspect and the above-described implementations, in some implementations of the first aspect, determining the first injection moment when the direct injection nozzle performs fuel injection includes: acquiring the current operating parameters of the engine; wherein the current operating parameters include the current engine speed and the current load; determining the target start time of fuel injection by the direct injection nozzle corresponding to the current operating parameters based on a third preset correspondence; wherein the third preset correspondence is the correspondence between the operating parameters and the start time of fuel injection by the direct injection nozzle; the operating parameters include the engine speed and the load; determining the target end time of fuel injection by the direct injection nozzle corresponding to the current operating parameters based on a fourth preset correspondence; wherein the fourth preset correspondence is the correspondence between the operating parameters and the end time of fuel injection by the direct injection nozzle; and when it is determined that the number of injections when the direct injection nozzle performs fuel injection is multiple, determining the first injection moment for each fuel injection by the direct injection nozzle based on the target start time and the target end time.

[0013] The above technical solution determines the target start and end times of fuel injection by the direct injection nozzle based on the engine's current speed and load, ensuring fuel is injected into the cylinder at the optimal time. When the direct injection nozzle is used for multiple injections, determining the first injection time for each injection based on the target start and end times allows for more precise fuel injection control. Furthermore, the injection timing of the direct injection nozzle is dynamically adjusted according to actual operating conditions, ensuring the engine performs optimally under various conditions and improving engine reliability.

[0014] In conjunction with the first aspect and the above-described implementations, in some implementations of the first aspect, determining the second injection timing when the port injection nozzle performs fuel injection includes: obtaining the opening time of the engine's intake valve and obtaining the injection delay angle when the port injection nozzle performs fuel injection; wherein the injection delay angle is the crankshaft angle between the start time of fuel injection by the port injection nozzle and the opening time of the intake valve; and determining the second injection timing when the port injection nozzle performs fuel injection based on the opening time of the intake valve and the injection delay angle.

[0015] The above technical solution determines the second injection time of fuel injection by the intake manifold injection nozzle based on the intake valve opening time and injection delay angle. This allows fuel to be injected into the intake manifold at the most appropriate time, fully mix with the intake airflow, and form a uniform air-fuel mixture. This ensures that the air-fuel mixture reaches its optimal state when it enters the cylinder, improves combustion efficiency, and thus increases the success rate of engine cold starts.

[0016] In combination with the first aspect and the above implementation methods, in some implementation methods of the first aspect, obtaining the injection delay angle when the air intake nozzle performs fuel injection includes: obtaining the current temperature of the coolant, the intake air temperature of the air entering the intake manifold of the engine, and the current engine speed; and determining the injection delay angle based on the current temperature of the coolant, the intake air temperature, and the current engine speed.

[0017] In conjunction with the first aspect and the above-described implementations, in some implementations of the first aspect, controlling the direct injection nozzle and the port injection nozzle to inject fuel according to the first target fuel injection quantity ratio to control the engine cold start includes: determining a target oil pressure corresponding to the current temperature of the coolant; controlling the engine's fuel pump to adjust the fuel pressure inside the engine; and, when it is determined that the fuel pressure inside the engine has reached the target oil pressure, controlling the direct injection nozzle and the port injection nozzle to inject fuel according to the first target fuel injection quantity ratio to control the engine cold start.

[0018] The above technical solution, by determining the target fuel pressure based on the current temperature and controlling the fuel pump to adjust the fuel pressure, can achieve higher fuel pressure during injection, thereby improving fuel atomization. Better atomization allows for more thorough mixing of fuel and air, improving combustion stability and reliability, and helping the engine reach a stable operating state more quickly during cold starts. By precisely controlling the fuel pressure to achieve the target pressure, the direct injection nozzle and port injection nozzle can inject fuel according to the first target injection quantity ratio, ensuring the air-fuel mixture concentration is within an appropriate range and improving the success rate of engine cold starts.

[0019] Secondly, a cold start device for an engine is provided. The engine includes a direct injection nozzle and a port injection nozzle. The device includes: an acquisition module for acquiring the current temperature of the coolant in the engine of a vehicle; a determination module for acquiring the current engine speed when the current temperature is less than or equal to a preset temperature threshold, and determining a first target fuel injection quantity ratio between the fuel injection quantities of the direct injection nozzle and the port injection nozzle when injecting fuel based on the current coolant temperature and the current engine speed; and a control module for controlling the direct injection nozzle and the port injection nozzle to inject fuel according to the first target fuel injection quantity ratio to control the cold start of the engine.

[0020] In conjunction with the second aspect, in some implementations of the second aspect, the determining module is specifically used to: determine a first target fuel injection quantity ratio corresponding to the current temperature and the current engine speed based on a first preset correspondence; wherein, the first preset correspondence is the correspondence between target parameters and target fuel injection quantity ratio; the target parameters include the temperature of the coolant and the engine speed; the target fuel injection quantity ratio is the fuel injection quantity ratio when the direct injection nozzle and the port injection nozzle perform fuel injection.

[0021] In conjunction with the second aspect and the above implementation methods, in some implementation methods of the second aspect, the control module is specifically used to: determine the total amount of fuel injection required for cold starting of the engine; determine the first fuel injection quantity corresponding to the direct injection nozzle and the second fuel injection quantity corresponding to the port injection nozzle based on the ratio of the total fuel injection quantity and the first target fuel injection quantity; wherein the sum of the first fuel injection quantity and the second fuel injection quantity is the total fuel injection quantity; control the direct injection nozzle to inject fuel according to the first fuel injection quantity and control the port injection nozzle to inject fuel according to the second fuel injection quantity.

[0022] In conjunction with the second aspect and the above-described implementations, in some implementations of the second aspect, the control module includes a direct injection nozzle control unit, which is specifically used for: determining a second target injection quantity ratio corresponding to the current temperature of the coolant based on a second preset correspondence when it is determined that the number of fuel injections performed by the direct injection nozzle is multiple; wherein, the second preset correspondence is the correspondence between the temperature of the coolant and the injection quantity ratio of each injection during multiple fuel injections; the second target injection quantity ratio is the ratio between the injection quantities of each injection during multiple fuel injections performed by the direct injection nozzle; determining the single injection quantity of the direct injection nozzle each time it performs fuel injection based on the first injection quantity and the second target injection quantity ratio; and controlling the direct injection nozzle to perform fuel injection according to the single injection quantity each time it performs fuel injection.

[0023] In conjunction with the second aspect and the above-described implementations, in some implementations of the second aspect, the control module includes a control unit, which is specifically configured to: determine a first injection moment when the direct injection nozzle performs fuel injection, and determine a second injection moment when the port injection nozzle performs fuel injection; control the direct injection nozzle to perform fuel injection at the first injection moment according to the first injection quantity, and control the port injection nozzle to perform fuel injection at the second injection moment according to the second injection quantity.

[0024] In conjunction with the second aspect and the above-described implementations, in some implementations of the second aspect, the control unit includes a first determining unit, which is specifically configured to: acquire the current operating parameters of the engine; wherein the current operating parameters include the current speed and the current load; determine, based on a third preset correspondence, a target start time for fuel injection by the direct injection nozzle corresponding to the current operating parameters; wherein the third preset correspondence is a correspondence between the operating parameters and the start time for fuel injection by the direct injection nozzle; the operating parameters include the speed and the load; determine, based on a fourth preset correspondence, a target end time for fuel injection by the direct injection nozzle corresponding to the current operating parameters; wherein the fourth preset correspondence is a correspondence between the operating parameters and the end time for fuel injection by the direct injection nozzle; and, if it is determined that the number of injections by the direct injection nozzle is multiple, determine, based on the target start time and the target end time, a first injection time for each fuel injection by the direct injection nozzle.

[0025] In conjunction with the second aspect and the above-described implementations, in some implementations of the second aspect, the control unit includes a second determining unit, which is specifically used to: acquire the opening time of the intake valve of the engine, and acquire the injection delay angle when the port injection nozzle performs fuel injection; wherein the injection delay angle is the crankshaft angle between the start time of fuel injection by the port injection nozzle and the opening time of the intake valve; and determine a second injection time when the port injection nozzle performs fuel injection based on the opening time of the intake valve and the injection delay angle.

[0026] In conjunction with the second aspect and the above implementation methods, in some implementation methods of the second aspect, the second determining unit includes an acquisition unit, which is specifically used to: acquire the current temperature of the coolant, the intake air temperature of the air entering the intake manifold of the engine, and the current speed of the engine; and determine the injection delay angle based on the current temperature of the coolant, the intake air temperature, and the current speed of the engine.

[0027] In conjunction with the second aspect and the above implementation methods, in some implementation methods of the second aspect, the control module is specifically used to: determine the target oil pressure corresponding to the current temperature of the coolant; control the fuel pump of the engine to adjust the fuel pressure inside the engine; and when it is determined that the fuel pressure inside the engine reaches the target oil pressure, control the direct injection nozzle and the port injection nozzle to inject fuel according to the first target fuel injection quantity ratio, so as to control the cold start of the engine.

[0028] Thirdly, a vehicle is provided, including a memory and a processor. The memory is used to store executable program code, and the processor is used to call and run the executable program code from the memory, causing the vehicle to perform the cold start method of the engine in the first aspect and any possible implementation thereof.

[0029] Fourthly, a computer program product is provided, comprising: computer program code, which, when run on a computer, causes the computer to execute the cold start method of the engine in the first aspect and any possible implementation thereof.

[0030] Fifthly, a computer-readable storage medium is provided that stores computer program code, which, when executed on a computer, causes the computer to perform the cold start method of the engine described in the first aspect and any possible implementation thereof. Attached Figure Description

[0031] Figure 1 This is a schematic flowchart of a cold start method for an engine provided in an embodiment of this application;

[0032] Figure 2 This is a schematic flowchart of an engine starting method provided in an embodiment of this application;

[0033] Figure 3 This is a schematic diagram of the structure of a cold start device for an engine provided in an embodiment of this application;

[0034] Figure 4 This is a schematic diagram of the structure of a vehicle provided in an embodiment of this application. Detailed Implementation

[0035] The technical solutions in this application will be clearly and thoroughly described below with reference to the accompanying drawings. In the description of the embodiments of this application, unless otherwise stated, " / " means "or," for example, A / B can mean A or B. "And / or" in the text is merely a description of the relationship between related objects, indicating that three relationships can exist. For example, A and / or B can represent: A existing alone, A and B existing simultaneously, and B existing alone. Furthermore, in the description of the embodiments of this application, "multiple" refers to two or more than two.

[0036] Hereinafter, the terms "first" and "second" are used for descriptive purposes only and should not be construed as implying or suggesting relative importance or implicitly indicating the number of technical features indicated. Thus, a feature defined as "first" or "second" may explicitly or implicitly include one or more of that feature.

[0037] Currently, with the continuous development of the automotive industry, engine starting has gradually become a hot topic of concern. When vehicles are cold-started at extremely low temperatures, fuel economy is usually considered, and GDI (Gas Dioxide Injection) is typically used for cold starts. If a single GDI injection is ineffective, multiple GDI injections are usually employed to optimize cold starts.

[0038] With a fully charged battery and good engine oil condition, cold starts at extremely low temperatures are highly reliable. However, if the vehicle's 12V battery is not sufficiently charged, the starter motor may not provide enough power to start the engine.

[0039] If the engine coolant temperature is extremely low, such as below -30°C or -35°C, the internal engine parts harden, increasing resistance and causing the starter motor to reduce the engine's rotational speed. At lower engine speeds, the high-pressure fuel pump's efficiency is also lower, resulting in reduced pumping capacity. With this reduced pumping capacity, to ensure successful engine ignition, the GDI injection frequency may increase. However, if each injection exceeds the high-pressure pump's actual capacity, the fuel rail pressure will gradually decrease. When the fuel rail pressure drops to a certain level, high-pressure injection cannot be maintained, forcing the injection pump to operate in low-pressure injection mode. In low-pressure injection mode, fuel atomization is poor, leading to inadequate air-fuel mixture formation, which affects ignition success rate and ultimately causes cold start failure.

[0040] In summary, under extremely low temperature conditions, the engine cold start process will encounter problems such as low starter motor speed, limited oil pumping capacity of the high-pressure oil pump, and gradual decrease in oil pressure in the high-pressure oil rail, leading to engine cold start failure.

[0041] To address the aforementioned technical problems, this application provides a cold start method for an engine, wherein the executing entity of the method is a vehicle, specifically a controller within the vehicle.

[0042] The cold start method for an engine provided in this application embodiment is applied to a vehicle equipped with a dual injection system. The engine of the vehicle is a dual injection system engine, which includes a GDI system and a port fuel injection (PFI) system.

[0043] In the GDI system, fuel is injected directly into the engine cylinders using direct injection nozzles, where it mixes with air and is then burned. These direct injection nozzles are typically mounted on the engine cylinder head, near the combustion chamber.

[0044] The PFI (Port Injection Fuel) system uses port injection nozzles to inject fuel in front of the intake valves in the intake manifold, rather than injecting fuel directly into the cylinders. The port injection nozzles in the PFI system are typically installed in the engine's intake manifold, usually in front of the intake valves.

[0045] The aforementioned dual injection system ensures that the engine receives optimal fuel supply under various operating conditions, thereby improving the overall performance of the vehicle.

[0046] Figure 1 This is a schematic flowchart of a cold start method for an engine provided in an embodiment of this application.

[0047] For example, such as Figure 1 As shown, the method 100 includes:

[0048] S101, obtain the current temperature of the coolant in the vehicle's engine.

[0049] S102, when the current temperature is less than or equal to a preset temperature threshold, obtain the current engine speed, and based on the current coolant temperature and the current engine speed, determine the first target fuel injection quantity ratio between the fuel injection quantity of the engine's direct injection nozzle and the port injection nozzle when injecting fuel.

[0050] S103 controls the direct injection nozzle and the port injection nozzle to inject fuel according to the first target fuel injection quantity ratio in order to control the engine cold start.

[0051] In this embodiment, by acquiring the current temperature of the coolant in the engine, it can be determined whether the engine is in a cold start scenario. If the engine is determined to be in a cold start scenario, the current engine speed can be acquired, and based on the current engine speed and the current coolant temperature, the target fuel injection ratio between the direct injection nozzle and the port injection nozzle can be determined. Then, the direct injection nozzle and the port injection nozzle are controlled to inject fuel according to the target fuel injection ratio, which can help the engine complete a cold start as quickly as possible. Since the fuel viscosity in the engine increases under low temperature conditions, which is not conducive to atomization, when the current temperature is determined to be less than or equal to a preset temperature threshold, a dual injection strategy using both direct injection nozzles and port injection nozzles can be adopted. This can control the port injection nozzles in the intake manifold injection system to inject fuel into the intake manifold, utilizing the intake airflow to better disperse the fuel, forming a more uniform air-fuel mixture, improving combustion efficiency, and thus achieving faster engine start-up. Furthermore, it can reduce the demand for high-pressure fuel injection when using only direct injection nozzles, thereby avoiding start-up failures due to insufficient fuel pump output and improving the start-up success rate.

[0052] The following is about Figure 1 The specific implementation methods of each step in the illustrated embodiment are explained below:

[0053] Regarding S101 above, it can be understood that the current temperature of the coolant in the engine can also be referred to as the engine's starting water temperature.

[0054] The current temperature of the coolant in the aforementioned engine is typically measured using a coolant temperature sensor. This sensor is a thermistor whose resistance changes with temperature. It converts the temperature signal into an electrical signal and sends it to the engine controller.

[0055] For example, a coolant temperature sensor is typically installed in the engine water jacket or at the outlet of the engine radiator, in direct contact with the coolant. The coolant temperature sensor is a thermistor; its resistance decreases as the coolant temperature rises and increases as the coolant temperature falls. This resistance change is converted into a voltage signal and sent to the engine controller, which determines the current coolant temperature based on the received voltage signal.

[0056] During engine operation, coolant circulates through the engine, absorbing heat and transferring it to the radiator to maintain the engine's operating temperature within a suitable range. The coolant temperature directly affects engine performance and efficiency. For example, if the coolant temperature is too low, more fuel is needed to start the engine; if the coolant temperature is too high, the engine may trigger overheat protection, leading to decreased engine performance or even overheating damage.

[0057] Furthermore, after obtaining the current temperature of the coolant in the engine, the engine's fuel injection method can be adjusted based on the current coolant temperature.

[0058] Regarding S102 above, it is understood that the preset temperature threshold can be set according to actual needs, for example, the preset temperature threshold can be set to -20℃.

[0059] Furthermore, if the current temperature of the coolant is determined to be less than or equal to a preset temperature threshold, the engine can be considered to be at an extremely low temperature, and starting the engine at an extremely low temperature is called "engine cold start".

[0060] As mentioned earlier, if the starting effect of a single GDI injection is poor, multiple GDI injections are usually used to optimize cold starts. However, when using multiple GDI injections for cold starts, problems such as low starter motor speed, limited pumping capacity of the high-pressure oil pump, and gradual decrease in oil pressure in the high-pressure oil rail are encountered, which can lead to engine cold start failure.

[0061] The PFI (Pre-Injection Fuel) system injects fuel into the intake manifold instead of directly into the cylinders, utilizing the heat from the intake manifold to aid fuel evaporation. Furthermore, the PFI system typically doesn't require the high injection pressure of the GDI (Gas-Injection Difference) system, making it easier to achieve the necessary injection pressure even at low temperatures. Therefore, GDI+PFI injection can be used during engine cold starts to improve the success rate of cold starts.

[0062] Furthermore, engines currently equipped with dual-injection systems typically determine which injection method to use for fuel injection based on the engine's current speed.

[0063] Understandably, the current engine speed can usually be measured by a crankshaft position sensor, in revolutions per minute (RPM).

[0064] When the engine speed is low, the intake airflow velocity is relatively low. The PFI system can inject fuel into the intake manifold, allowing sufficient time for the fuel and air to mix thoroughly, forming a relatively homogeneous mixture. This homogeneous mixture is beneficial for stable combustion and improves combustion efficiency. In other words, when the engine speed is low, port fuel injection nozzles can be used for fuel injection.

[0065] When the engine's current speed is higher, the engine requires more air and fuel to produce greater power. The GDI system can inject fuel directly into the cylinders, achieving higher injection pressure, resulting in better fuel atomization and faster mixing with air. In other words, when the engine's current speed is higher, direct injection nozzles can be used for fuel injection.

[0066] It is understandable that when the engine is started at extremely low temperatures, fuel injection may be performed simultaneously using both port injection nozzles and direct injection nozzles. The ratio between the fuel injection quantities of the direct injection nozzles and port injection nozzles can be determined based on the current engine speed and the current coolant temperature, which is the aforementioned first target fuel injection quantity ratio.

[0067] In some embodiments, when the current engine speed and the current coolant temperature are both low, the proportion of fuel injection quantity from the port injection nozzles in the first target fuel injection quantity ratio can be increased. As the engine speed and coolant temperature increase, the proportion of fuel injection quantity from the direct injection nozzles in the first target fuel injection quantity ratio can be increased.

[0068] Understandably, as mentioned earlier, when engine speed is low, the intake airflow is relatively slow, and the mixture formation time is longer. At this time, the fuel injection ratio of the port injection nozzles can be appropriately increased to better atomize the fuel using the airflow within the intake manifold, thus promoting mixture formation. As engine speed increases, the intake airflow speed accelerates, and the mixture formation time shortens. Direct injection nozzles can inject fuel directly into the cylinder more quickly, improving combustion efficiency. Therefore, at high engine speeds, the fuel injection ratio of the direct injection nozzles can be appropriately increased.

[0069] When the coolant temperature is low, the engine is in a cold-start state. At this time, to ensure good combustion stability, the fuel injection ratio of the port injection nozzles can be increased. Port-injected fuel can be preheated within the intake manifold, helping to increase the temperature of the air-fuel mixture and promote combustion. As the coolant temperature rises to normal operating temperature, the engine's combustion conditions improve. The fuel injection ratio of the direct injection nozzles can be adjusted appropriately according to different operating conditions to improve the engine's power, economy, and emissions performance.

[0070] In other embodiments, a mapping relationship between engine speed, coolant temperature, and the fuel injection quantity ratio of direct injection nozzles and port injection nozzles can be established through experiments and data analysis. This relationship can be represented using methods such as two-dimensional tables and curve fitting.

[0071] In one possible implementation, determining a first target fuel injection quantity ratio between the fuel injection quantities of the engine's direct injection nozzle and port injection nozzle when injecting fuel, based on the current temperature of the coolant and the current engine speed, includes: determining a first target fuel injection quantity ratio corresponding to the current temperature and the current engine speed based on a first preset correspondence; wherein the first preset correspondence is a correspondence between target parameters and target fuel injection quantity ratio; the target parameters include the coolant temperature and the engine speed; and the target fuel injection quantity ratio is the fuel injection quantity ratio when the direct injection nozzle and port injection nozzle inject fuel.

[0072] It is understood that the aforementioned first preset correspondence can be obtained based on actual engine cold start tests, and this first preset correspondence can be stored in the engine controller.

[0073] For example, based on actual engine cold start tests, data on the best starting performance corresponding to different coolant temperatures and engine speeds can be obtained. The proportion of PFI fuel injection quantity corresponding to the current coolant temperature and current engine speed can be shown in Table 1:

[0074] Table 1

[0075]

[0076] As shown in Table 1 above, the proportion of PFI fuel injection can be determined based on the current temperature of the coolant and the current speed of the engine.

[0077] The aforementioned PFI injection quantity ratio refers to the proportion of the injection quantity of the PFI system's port injection nozzles to the total injection quantity required for engine starting. The total injection quantity required for engine starting is the sum of the injection quantity of the PFI system's port injection nozzles and the injection quantity of the GDI system's direct injection nozzles.

[0078] When the engine's current speed exceeds 1000 RPM, the GDI system's direct injection nozzles can use less fuel to maintain engine operation compared to the PFI system's port injection nozzles. Therefore, when the engine's current speed is greater than or equal to 1000 RPM, the PFI system's port injection nozzles can be discontinued for fuel injection.

[0079] When the current coolant temperature is -10°C, the engine is not at an extremely low temperature, so the GDI multi-injection strategy can be used, and there is no need to use the PFI system's port injection nozzles for fuel injection. When the current coolant temperature is greater than or equal to -10°C, the PFI system's port injection nozzles can no longer be used for fuel injection.

[0080] For example, if the current coolant temperature is -30°C and the current engine speed is 200 RPM, by referring to Table 1, the proportion of PFI fuel injection can be determined to be 0.4. Accordingly, the proportion of GDI fuel injection can be obtained as 0.6. That is, the first target fuel injection ratio between the fuel injection quantities of the direct injection nozzle and the port injection nozzle of the above engine is determined to be 3:2.

[0081] The above method, which determines the first target fuel injection quantity ratio based on the current coolant temperature and the current engine speed, allows the fuel injection quantity of the direct injection nozzle and the port injection nozzle to better match the actual operating needs of the engine. This enables the air-fuel mixture to reach a more ideal state under different operating conditions, thereby improving fuel utilization and reducing fuel consumption. By reasonably adjusting the fuel injection quantity ratio between the direct injection nozzle and the port injection nozzle, it is also possible to ensure that the engine receives a suitable fuel supply under various operating conditions, thereby improving the engine's cold start success rate.

[0082] Furthermore, after determining the aforementioned first target fuel injection quantity ratio, the engine can be controlled to inject fuel according to the first target fuel injection quantity ratio.

[0083] Regarding the above S103, it is understood that after determining the first target fuel injection quantity ratio, the engine controller can control the fuel injection pulse width of the direct injection nozzle and the air intake injection nozzle to make the direct injection nozzle and the air intake injection nozzle inject fuel according to the first target fuel injection quantity ratio.

[0084] The aforementioned injection pulse width refers to the duration for which the injector starts injecting fuel.

[0085] For example, the injection pulse width can be controlled by adjusting the opening and closing times of the injector.

[0086] To achieve optimal fuel injection and help the engine start smoothly, the fuel injector can be controlled to inject fuel only when the fuel pressure in the engine reaches a preset pressure.

[0087] In one possible implementation, controlling the direct injection nozzle and the port injection nozzle to inject fuel according to the first target fuel injection quantity ratio to control engine cold start includes: determining a target oil pressure corresponding to the current temperature of the coolant; controlling the engine's fuel pump to adjust the fuel pressure inside the engine; and, when it is determined that the fuel pressure inside the engine has reached the target oil pressure, controlling the direct injection nozzle and the port injection nozzle to inject fuel according to the first target fuel injection quantity ratio to control engine cold start.

[0088] It is understandable that the target oil pressure mentioned above refers to the fuel pressure value that the engine's fuel system is expected to achieve.

[0089] Furthermore, a correlation between coolant temperature and target oil pressure can be established in advance. After obtaining the current coolant temperature, the target oil pressure can be determined based on this correlation.

[0090] For example, the relationship between the temperature of the coolant and the target oil pressure can be shown in Table 2:

[0091] Table 2

[0092]

[0093] As shown in Table 2, the target oil pressure gradually increases as the current temperature of the coolant rises.

[0094] For example, if the current temperature of the coolant is -20°C, the target oil pressure corresponding to this temperature can be determined to be 14 MPa using Table 2 above.

[0095] Furthermore, after determining the target oil pressure, the engine controller can control the fuel pump to adjust the current fuel pressure inside the engine.

[0096] In some embodiments, after determining the target fuel pressure, the engine controller can detect the current internal fuel pressure of the engine using a fuel pressure sensor, and then compare the detected current fuel pressure with the target fuel pressure. If the current fuel pressure is lower than the target fuel pressure, it is determined that the fuel pump needs to be controlled to increase the fuel pressure; if the current fuel pressure is higher than the target fuel pressure, it is determined that the fuel pump needs to be controlled to decrease the fuel pressure.

[0097] Understandably, the aforementioned fuel pressure sensor can be installed on the fuel rail to monitor the fuel pressure in the fuel rail in real time.

[0098] The above-mentioned control of the fuel pump to increase or decrease fuel pressure can usually be achieved by controlling the speed of the fuel pump motor, or by controlling the amount of fuel returned by the return valve.

[0099] For example, if it is determined that it is necessary to control the fuel pump to increase fuel pressure, the speed of the fuel pump motor can be increased, thereby increasing the output pressure of the fuel pump. Alternatively, the return valve can be controlled to reduce the return fuel volume, thereby increasing the fuel pressure.

[0100] If it is determined that the fuel pump needs to be controlled to reduce fuel pressure, the pump speed can be reduced to decrease the output pressure. Alternatively, the return valve can be controlled to increase the return flow and reduce fuel pressure.

[0101] The above method, by determining the target fuel pressure based on the current temperature and controlling the fuel pump to adjust the fuel pressure, can achieve higher fuel injection pressure, thereby improving fuel atomization. Better atomization allows for more thorough mixing of fuel and air, improving combustion stability and reliability, and helping the engine reach a stable operating state more quickly during cold starts. By precisely controlling the fuel pressure to achieve the target pressure, the direct injection nozzle and port injection nozzle can inject fuel according to the first target injection quantity ratio, ensuring the air-fuel mixture concentration is within an appropriate range and improving the success rate of engine cold starts.

[0102] Furthermore, once it is determined that the fuel pressure inside the engine has reached the target fuel pressure, the direct injection nozzle and the port injection nozzle can be controlled to inject fuel according to the first target fuel injection quantity ratio.

[0103] In one possible implementation, controlling the direct injection nozzle and the port injection nozzle to inject fuel according to the first target fuel injection quantity ratio includes: determining the total amount of fuel injection required for cold starting of the engine; determining a first fuel injection quantity corresponding to the direct injection nozzle and a second fuel injection quantity corresponding to the port injection nozzle based on the total fuel injection quantity and the first target fuel injection quantity ratio; wherein the sum of the first fuel injection quantity and the second fuel injection quantity is the total fuel injection quantity; controlling the direct injection nozzle to inject fuel according to the first fuel injection quantity and controlling the port injection nozzle to inject fuel according to the second fuel injection quantity.

[0104] It is understandable that the total amount of fuel injection required for a cold start of the engine can be determined based on the engine's current state parameters. These parameters may include the current coolant temperature, engine speed, amount of air entering the engine, and air temperature.

[0105] In some embodiments, the basic fuel injection quantity required for normal engine start is obtained, a correction factor is determined based on the current state parameters of the engine, and then the total amount of fuel injection required for cold start of the engine is determined based on the basic fuel injection quantity and the correction factor.

[0106] Understandably, the above-mentioned basic fuel injection quantity can be determined based on the air quality entering the engine and the target air-fuel ratio.

[0107] The quality of air entering the engine can be estimated by the engine controller based on the intake manifold pressure or data from the air flow meter. For most gasoline engines, the standard stoichiometric air-fuel ratio is 14.7:1, meaning the target air-fuel ratio mentioned above can be 14.7:1.

[0108] Furthermore, with both the current coolant temperature and the intake air temperature entering the engine being low, the fuel volatility within the engine decreases, making it more difficult to form a fuel-air mixture. In this situation, it may be necessary to increase the amount of fuel injected compared to normal operating temperatures to ensure smooth engine starting.

[0109] For example, based on empirical data or pre-established models, the proportion of increased fuel injection required to ensure smooth engine start-up at the current operating temperature can be determined. For instance, based on the current coolant temperature and the intake air temperature, if it is determined that 10% more fuel injection is needed at the current operating temperature than at the normal operating temperature to ensure smooth engine start-up, then a temperature correction factor of 1.1 can be determined.

[0110] If the engine's current speed is too low, it means the engine needs more power to accelerate to its normal operating speed. In this situation, to ensure a smooth engine start, it may be necessary to increase the fuel injection volume by a certain percentage.

[0111] For example, based on empirical data or a pre-established model, the proportion of increased fuel injection required to ensure a smooth engine start at the current engine speed can be determined. For instance, if the engine's current speed indicates that 20% more fuel injection is needed than at normal speeds to ensure a smooth start, then a speed correction factor of 1.2 can be determined.

[0112] For example, if the mass of air entering the engine is 100 grams, the target air-fuel ratio is 14.7:1, and the gasoline density is 0.72 g / ml, the basic fuel injection quantity is calculated to be 9.444 ml. If the temperature correction factor is determined to be 1.1 and the speed correction factor is 1.2, then the comprehensive correction factor can be calculated to be 1.1 * 1.2 = 1.32. The corrected total fuel injection quantity is calculated to be 9.444 * 1.32 = 12.47 ml, meaning the total fuel injection quantity required for a cold start of the engine is 12.47 ml.

[0113] Furthermore, after determining the total amount of fuel injection required for the engine's cold start, the total amount of fuel injection can be allocated according to the previously determined first target fuel injection ratio.

[0114] For example, if the total amount of fuel injection required for a cold start of the engine is determined to be 10 ml, and the first target fuel injection ratio is determined to be 3:2, that is, the fuel injection amount injected by the direct injection nozzle accounts for 60% of the total fuel injection amount, and the fuel injection amount injected by the port injection nozzle accounts for 40% of the total fuel injection amount. Based on this total fuel injection amount and the first target fuel injection ratio, the first fuel injection amount corresponding to the direct injection nozzle can be determined to be 6 ml, and the second fuel injection amount corresponding to the port injection nozzle can be determined to be 4 ml.

[0115] Furthermore, after determining the first fuel injection quantity corresponding to the direct injection nozzle and the second fuel injection quantity corresponding to the port injection nozzle, the engine controller can control the direct injection nozzle to inject 6 ml of fuel and control the port injection nozzle to inject 4 ml of fuel, ensuring that the sum of the two is the required total fuel injection quantity of 10 ml.

[0116] During engine cold start, the GDI system can inject fuel either in a single injection or in multiple injections.

[0117] In some embodiments, the injection pattern of the GDI system can be determined based on the current temperature of the coolant and the current engine speed.

[0118] For example, if it is determined that the current temperature of the coolant is less than or equal to a preset temperature threshold and the current speed of the engine is less than or equal to a preset speed threshold, then the injection mode of the GDI system can be determined to be multiple injection.

[0119] The preset temperature threshold can be set according to actual needs, such as -20℃; the preset speed threshold can also be set according to actual needs, such as 600RPM.

[0120] In some embodiments, during engine cold start, the engine controller can set the initial injection frequency of the GDI system if the current coolant temperature is less than or equal to a preset temperature threshold and the current engine speed is less than or equal to a preset speed threshold. Then, it can be determined whether to adjust the initial injection frequency based on the engine's operating status.

[0121] For example, the initial number of sprays can be set according to actual needs; for instance, the initial number of sprays can be set to two.

[0122] If the engine experiences unstable combustion, large speed fluctuations, or unsatisfactory emission standards, the number of injections can be gradually increased from the initial number of injections. Specifically, an additional injection can be added each time the above situation occurs until the engine runs smoothly.

[0123] Conversely, if the engine experiences excessively high air-fuel mixture concentration, decreased combustion efficiency, or other abnormalities during combustion, the number of injections can be reduced from the initial number of injections. Specifically, one injection can be reduced each time the above situation occurs until the engine runs smoothly.

[0124] In other embodiments, an experimental data set from the engine and a pre-defined machine learning model are used to build a model that predicts the number of injections. This model can be stored in the vehicle's engine controller. During a cold start, the engine controller inputs the engine's current state parameters into this model, which then outputs a predicted number of injections.

[0125] It is understandable that the above-mentioned model for predicting the number of injections can be trained based on various engine state parameters such as engine temperature, speed, load, and fuel characteristics, as well as the number of injections corresponding to these various engine state parameters. Furthermore, this model has undergone extensive experimental verification and optimization.

[0126] For example, if the engine coolant temperature is -30°C, the gas temperature entering the engine is -25°C, the engine speed is 300 RPM, and the fuel in the engine is low-volatility fuel, inputting these parameters into the model for predicting the number of injections will result in a predicted number of injections of three.

[0127] It should be understood that as the engine operating status changes, the engine controller will continuously update the input parameters of the above-mentioned model for predicting the number of injections in order to adjust the number of injections of the GDI system in real time.

[0128] Furthermore, given that the injection method of the GDI system described above is multiple injection, the ratio between the fuel injection amounts injected by each injection from the direct injection nozzle can be determined.

[0129] In one possible implementation, controlling the direct injection nozzle to inject fuel according to the first injection quantity includes: when it is determined that the number of fuel injections by the direct injection nozzle is multiple, determining a second target injection quantity ratio corresponding to the current temperature of the coolant based on a second preset correspondence; wherein the second preset correspondence is the correspondence between the temperature of the coolant and the injection quantity ratio of each injection during multiple fuel injections; the second target injection quantity ratio is the ratio between the injection quantities of each injection during multiple fuel injections by the direct injection nozzle; determining the single injection quantity of the direct injection nozzle each time it injects fuel based on the first injection quantity and the second target injection quantity ratio; and controlling the direct injection nozzle to inject fuel according to the single injection quantity each time it injects fuel.

[0130] It is understandable that when the number of fuel injections by a direct injection nozzle is determined to be multiple, it means that the direct injection nozzle will perform multiple fuel injections within the current working cycle of the engine. The amount of fuel injected per injection by the direct injection nozzle can be determined based on the initial injection quantity.

[0131] The aforementioned second preset correspondence can be obtained based on the results of experimental testing. This second preset relationship can be a pre-set relationship table, which can be stored in the vehicle's engine controller.

[0132] For example, based on actual engine cold start tests, the ratio between the amount of fuel injected per injection when the starting effect is best under different coolant temperatures can be obtained.

[0133] The aforementioned second preset correspondence may include multiple sets of correspondences. Specifically, it may include the ratio between the amount of fuel injected in each injection during two fuel injections, and it may also include the ratio between the amount of fuel injected in each injection during three or more fuel injections.

[0134] Furthermore, based on the currently determined number of fuel injections by the direct injection nozzle, the corresponding number of injections can be found in the second preset relationship mentioned above.

[0135] For example, if it is determined that the direct injection nozzle injects fuel twice, the corresponding relationship between the current temperature of the coolant and the ratio of the amount of fuel injected in each of the two fuel injections can be found in the second preset relationship.

[0136] For example, the relationship between the current temperature of the coolant and the ratio of the amount of fuel injected in each of the two fuel injections can be shown in Table 3:

[0137] Table 3

[0138]

[0139] The injection ratio in Table 3 refers to the ratio between the amount of fuel injected by the direct injection nozzle for the first fuel injection and the amount of fuel injected by the direct injection nozzle for the second fuel injection.

[0140] Understandably, as the coolant temperature gradually increases, the fuel atomization effect improves, allowing for a slight increase in the proportion of fuel injected in the second injection to fully utilize the higher temperature and promote combustion. Therefore, as the current coolant temperature rises, the proportion of fuel injected by the direct injection nozzle for the second fuel injection tends to increase. However, when the current coolant temperature reaches 80℃, the fuel volatility is relatively good, and a single injection can provide sufficient fuel at the appropriate time to form a combustible mixture. Therefore, the direct injection nozzle no longer performs multiple fuel injections but instead injects fuel in a single injection.

[0141] For example, if it is determined that the GDI system performs fuel injection twice, the second preset relationship is used to find the correspondence between the current temperature of the coolant and the ratio of the amount of fuel injected in each of the two fuel injections. If the current temperature of the coolant is found to be -30°C, based on this correspondence, the ratio of the amount of fuel injected in the two fuel injections can be determined to be 8:2.

[0142] Furthermore, if the first injection amount corresponding to the determined direct injection nozzle is 10 ml, based on the injection amount ratio of the two fuel injections mentioned above, it can be determined that the first injection amount of the direct injection nozzle is 8 ml and the second injection amount of the direct injection nozzle is 2 ml. Therefore, it is possible to control the direct injection nozzle to inject 8 ml of fuel in the first injection and 2 ml of fuel in the second injection.

[0143] To improve the success rate of engine cold starts, the direct injection nozzle and the port injection nozzle can be controlled to inject fuel at the appropriate time.

[0144] In one possible implementation, controlling the direct injection nozzle to inject fuel according to the first injection quantity and controlling the port injection nozzle to inject fuel according to the second injection quantity includes: determining a first injection time when the direct injection nozzle injects fuel and determining a second injection time when the port injection nozzle injects fuel; controlling the direct injection nozzle to inject fuel according to the first injection quantity at the first injection time and controlling the port injection nozzle to inject fuel according to the second injection quantity at the second injection time.

[0145] It is understood that the first injection moment mentioned above refers to the moment when the direct injection nozzle begins to inject fuel; the second injection moment mentioned above refers to the moment when the airway injection nozzle begins to inject fuel.

[0146] The timing of fuel injection can be represented by the crankshaft's rotation angle relative to the compression top dead center (TDC). TDC is a specific position in the engine's working cycle; it's the position where the piston reaches its highest point during the compression stroke, at which point the piston is completely at the top of the cylinder. The crankshaft is the mechanical component in the engine that converts the piston's linear reciprocating motion into rotational motion. The crankshaft's rotation angle relative to TDC can be used to describe the timing of various events within the engine.

[0147] In some embodiments, a positive angle of rotation of the crankshaft relative to the compression top dead center indicates that the crankshaft has rotated a certain angle from the compression top dead center, that is, the crankshaft is at a certain position after the compression top dead center; a negative angle of rotation of the crankshaft relative to the compression top dead center indicates that the crankshaft has not yet reached the compression top dead center, that is, the crankshaft is at a certain position before the compression top dead center.

[0148] Furthermore, the first and second injection times can be set according to the actual operating conditions of the engine.

[0149] For example, during the initial cold start phase of an engine, the coolant temperature and engine speed are both low. At this time, fuel has poor volatility and is not easily vaporized, making it difficult to form a homogeneous mixture with air. Port injection nozzles, on the other hand, typically inject fuel into the intake manifold or intake port, an area where the temperature is higher than inside the cylinder, which helps the fuel evaporate and atomize better. Furthermore, the port injection nozzles are positioned close to the intake port, allowing the fuel more time to mix with air before entering the cylinder, thus improving combustion efficiency.

[0150] Therefore, in the initial stage of engine cold start, fuel injection can be controlled by the intake manifold injectors. That is, the aforementioned second injection timing can be considered the starting moment of engine cold start.

[0151] As the coolant temperature rises, fuel volatility increases, making it easier to atomize. At this point, fuel injected directly into the cylinder via direct injection nozzles mixes thoroughly with air, improving combustion efficiency. Under high-temperature conditions, directly injected fuel more easily forms a homogeneous mixture with air, further enhancing combustion efficiency. Therefore, as the coolant temperature increases, the fuel injection from the direct injection nozzles can be controlled.

[0152] For example, a second preset temperature threshold can be set, and when the coolant temperature rises to a level greater than or equal to the second preset temperature threshold, the direct injection nozzle can be controlled to inject fuel. That is, the first injection moment can be the moment when the coolant temperature rises to a level greater than or equal to the second preset temperature threshold.

[0153] Furthermore, the injection timing of direct injection nozzles is usually affected by engine operating parameters, such as engine speed and load.

[0154] In one possible implementation, determining the first injection moment when the direct injection nozzle performs fuel injection includes: acquiring the current operating parameters of the engine; wherein the current operating parameters include the current engine speed and the current load; determining the target start moment of the direct injection nozzle performing fuel injection corresponding to the current operating parameters based on a third preset correspondence; wherein the third preset correspondence is the correspondence between the operating parameters and the start moment of the direct injection nozzle performing fuel injection; the operating parameters include the engine speed and the load; determining the target end moment of the direct injection nozzle performing fuel injection corresponding to the current operating parameters based on a fourth preset correspondence; wherein the fourth preset correspondence is the correspondence between the operating parameters and the end moment of the direct injection nozzle performing fuel injection; and if it is determined that the number of injections when the direct injection nozzle performs fuel injection is multiple, determining the first injection moment for each fuel injection by the direct injection nozzle based on the target start moment and the target end moment.

[0155] Understandably, as mentioned above, the engine speed is usually measured by a crankshaft position sensor, in revolutions per minute (RPM).

[0156] The current load mentioned above is usually estimated by the throttle position sensor, intake manifold absolute pressure sensor, etc., and is used to reflect the engine load status, usually expressed as a percentage.

[0157] The aforementioned third preset correspondence can be obtained based on the results of experimental testing. This third preset relationship can be a pre-set relationship table, which can be stored in the vehicle's engine controller.

[0158] The aforementioned third preset correspondence is used to represent the relationship between the engine's operating parameters (including engine speed and load) and the starting time of fuel injection by the direct injection nozzle.

[0159] For example, the third preset correspondence between the engine's operating parameters and the start time of fuel injection by the direct injection nozzle can be shown in Table 4:

[0160] Table 4

[0161]

[0162] As mentioned earlier, the timing of fuel injection can be represented by the crankshaft's rotation angle relative to the compression top dead center. The starting moment of fuel injection by the direct injection nozzle described above can actually be represented by the crankshaft's rotation angle relative to the compression top dead center. For example, if the starting moment of fuel injection is determined to be 310 degrees, it means that fuel injection begins when the crankshaft rotates to an angle of 310 degrees relative to the compression top dead center.

[0163] For example, after obtaining the engine's current speed and current load, the target start time for fuel injection can be queried from Table 4 above. For instance, if the engine's current speed is 400 RPM and the current load is 20%, it can be determined that fuel injection begins 300 degrees after the crankshaft has rotated to top dead center of the compression stroke.

[0164] Similarly, the aforementioned fourth preset correspondence can be obtained based on the results of experimental testing. This fourth preset relationship can be a pre-set relationship table, which can be stored in the vehicle's engine controller.

[0165] The aforementioned fourth preset correspondence is used to represent the relationship between the engine's operating parameters (including engine speed and load) and the end time of fuel injection by the direct injection nozzle.

[0166] For example, the fourth preset correspondence between the engine's operating parameters and the end time of fuel injection by the direct injection nozzle can be shown in Table 5:

[0167] Table 5

[0168]

[0169] As mentioned earlier, the timing of fuel injection can be represented by the crankshaft's rotation angle relative to the compression top dead center. Similarly, the end time of fuel injection by the direct injection nozzle can also be represented by the crankshaft's rotation angle relative to the compression top dead center. For example, if the end time of fuel injection is determined to be 100 degrees, it means that fuel injection ends when the crankshaft rotates to a position where the angle relative to the compression top dead center is 100 degrees.

[0170] For example, after obtaining the engine's current speed and current load, the target end time of fuel injection can be queried from Table 5 above. For instance, if the engine's current speed is 400 RPM and the current load is 20%, it can be determined that the fuel injection ends 80 degrees after the crankshaft rotates to top dead center of compression.

[0171] Furthermore, when it is determined that the number of injections when the direct injection nozzle performs fuel injection is multiple, the aforementioned target start time is actually the start time of the first fuel injection by the direct injection nozzle, and the aforementioned target end time is actually the end time of the last fuel injection by the direct injection nozzle.

[0172] Based on this, if it is determined that the number of injections when the direct injection nozzle performs fuel injection is multiple, the start time of each fuel injection by the direct injection nozzle can be determined according to the target start time and target end time mentioned above, that is, the first injection time of each fuel injection.

[0173] In some embodiments, the specific time of each injection by the direct injection nozzle can be allocated based on the time interval between the target start time and the target end time and the determined number of injections by the direct injection nozzle.

[0174] Specifically, the total time span is obtained by subtracting the target start time from the target end time, and then the total time span is divided by the number of sprays to obtain the average time interval between each spray.

[0175] For example, if the target start time is 300 degrees, meaning the fuel injection begins 300 degrees after the crankshaft has rotated to top dead center of compression, and the target end time is 80 degrees, meaning the fuel injection ends 80 degrees after the crankshaft has rotated to top dead center of compression, and the number of injections by the direct injection nozzle is determined to be 2, then first calculate the total angle span as 220 degrees, and then evenly distribute the two injections to obtain an average angle span of 110 degrees between each injection. Thus, it can be determined that the first fuel injection occurs 300 degrees after the crankshaft has rotated to top dead center of compression, and the position of the second fuel injection can be 300 degrees - 110 degrees = 190 degrees, meaning the second fuel injection occurs 190 degrees after the crankshaft has rotated to top dead center of compression.

[0176] In other embodiments, the correspondence between engine operating parameters and injection timing can be established in advance, and the start time of each direct injection nozzle injection can be determined based on the current operating parameters of the engine.

[0177] It is understandable that the specific establishment method is similar to the establishment method of the third and fourth preset correspondence relationships mentioned above, and will not be elaborated here.

[0178] The method described above determines the target start and end times of fuel injection by the direct injection nozzle based on the engine's current speed and load, ensuring fuel is injected into the cylinder at the optimal time. When the direct injection nozzle is used for multiple injections, determining the first injection time for each injection based on the target start and end times allows for more precise fuel injection control. Furthermore, the injection timing of the direct injection nozzle is dynamically adjusted according to actual operating conditions, ensuring the engine performs optimally under various conditions and improving engine reliability.

[0179] Furthermore, in addition to determining the first injection moment of the direct injection nozzle, the second injection moment of the airway injection nozzle can also be determined.

[0180] Understandably, if fuel is injected when the valve is open, the fuel will enter the cylinder directly, and the airflow within the cylinder at this time is not conducive to the proper mixing of fuel and air. Therefore, PFI systems typically avoid controlling the port fuel injector to inject fuel when the valve is open.

[0181] If the intake manifold injector sprays when the intake valve is closed, the fuel may not have enough time to mix fully with the air, thus affecting combustion efficiency. Therefore, when determining the second injection timing, a suitable point can be found between the opening and closing of the valve. This second injection timing ensures that the fuel and air are fully mixed and that a homogeneous mixture is formed when the fuel enters the cylinder.

[0182] In one possible implementation, determining the second injection time when the port injection nozzle performs fuel injection includes: acquiring the opening time of the engine's intake valve and acquiring the injection delay angle when the port injection nozzle performs fuel injection; wherein the injection delay angle is the crankshaft angle between the start time of fuel injection by the port injection nozzle and the opening time of the intake valve; and determining the second injection time when the port injection nozzle performs fuel injection based on the opening time of the intake valve and the injection delay angle.

[0183] Understandably, the opening timing of the intake valve can be represented by the crankshaft angle relative to the top dead center of the compression stroke. This intake valve opening timing can be determined using a camshaft position sensor.

[0184] The aforementioned injection delay angle refers to the crankshaft angle between the moment when the intake port injection nozzle begins to inject fuel and the moment when the intake valve opens.

[0185] The aforementioned injection delay angle can be determined based on the engine's current operating parameters, such as the current temperature of the coolant, the temperature of the air entering the engine, and the current engine speed.

[0186] In one possible implementation, obtaining the injection delay angle when the air intake nozzle performs fuel injection includes: obtaining the current temperature of the coolant, the intake air temperature of the air entering the intake manifold of the engine, and the current engine speed; and determining the injection delay angle based on the current temperature of the coolant, the intake air temperature, and the current engine speed.

[0187] Understandably, the current temperature of the coolant can be measured using a coolant temperature sensor. The intake air temperature entering the engine's intake manifold can be measured using a temperature sensor. The current engine speed can be measured using a crankshaft position sensor.

[0188] Furthermore, a fifth preset correspondence between coolant temperature, intake air temperature, engine speed and injection delay angle can be established in advance. This fifth preset correspondence can be obtained through actual experimental data and simulation analysis.

[0189] For example, if the current temperature of the coolant is -20°C, the intake air temperature is -15°C, and the current engine speed is 200 RPM, based on the fifth preset correspondence mentioned above, the corresponding injection delay angle can be determined to be 10 degrees.

[0190] Furthermore, after determining the above-mentioned injection delay angle, the second injection time for fuel injection by the intake port injection nozzle can be determined based on the opening time of the intake valve and the injection delay angle.

[0191] For example, if the intake valve opens when the crankshaft rotates to an angle of -20 degrees relative to the top dead center of the compression stroke, and the aforementioned injection delay angle is 10 degrees, that is, the crankshaft angle between the moment when the port injection nozzle begins to inject fuel and the moment when the intake valve opens is 10 degrees, then it can be determined that the aforementioned port injection nozzle begins to inject fuel when the crankshaft rotates to an angle of -10 degrees relative to the top dead center of the compression stroke.

[0192] The above method, based on the intake valve opening time and injection delay angle, determines the second injection time of the fuel injection nozzle, which allows the fuel to be injected into the intake manifold at the most appropriate time, fully mix with the intake airflow, and form a uniform mixture. This ensures that the mixture reaches its optimal state when entering the cylinder, improves combustion efficiency, and thus increases the success rate of engine cold starts.

[0193] In some embodiments, after obtaining the current temperature of the coolant, different fuel injection methods can be adopted based on the current temperature of the coolant to control engine starting.

[0194] For example, Figure 2 This is a schematic flowchart of an engine starting method provided in an embodiment of this application.

[0195] like Figure 2 As shown, the method 200 includes:

[0196] S201, obtain the current temperature of the coolant in the vehicle's engine.

[0197] It is understandable that the current temperature of the coolant in the aforementioned engine can also be referred to as the engine's starting water temperature. The current temperature of the coolant in the aforementioned engine is typically measured using a coolant temperature sensor.

[0198] S202, when the current temperature of the coolant is less than or equal to the first preset temperature threshold, uses the GDI+PFI dual injection mode to inject fuel in order to control engine starting.

[0199] It is understood that the first preset temperature threshold mentioned above can be the same as the preset temperature threshold described above. This first preset temperature threshold can be set according to actual needs, such as being set to -20℃.

[0200] When the current temperature of the coolant is less than or equal to the first preset temperature threshold, the engine start is considered a cold start at extremely low temperatures.

[0201] S203, when the current temperature of the coolant is greater than the first preset temperature threshold and less than the second preset temperature threshold, fuel injection is performed using the GDI multiple injection method to control engine starting.

[0202] It is understandable that the second preset temperature threshold can also be set according to actual needs. The second preset temperature threshold can be set to be larger than the first temperature threshold, for example, set to 80℃.

[0203] If the current temperature is determined to be greater than the first preset temperature threshold and less than the second preset temperature threshold, the engine start is considered a cold start at a non-extremely low temperature.

[0204] S204: When the current temperature of the coolant is greater than or equal to the second preset temperature threshold, fuel injection is performed using the GDI single injection method to control engine starting.

[0205] Understandably, if the current temperature is greater than or equal to the second preset temperature threshold, the engine has approached or reached its normal operating temperature, and the engine can start smoothly using GDI single injection.

[0206] The above method, when the current temperature is determined to be less than or equal to a first preset temperature threshold, employs a dual-injection strategy (GDI+PFI dual injection mode) using both direct injection nozzles and port injection nozzles. This controls the port injection nozzles in the intake manifold injection system to inject fuel into the intake manifold, utilizing the intake airflow to better disperse the fuel, forming a more uniform air-fuel mixture, improving combustion efficiency, and thus achieving faster engine starting. When the current temperature is determined to be greater than the first preset temperature threshold but less than a second preset temperature threshold, a GDI multi-injection strategy (GDI multi-injection mode) is employed. This improves fuel atomization, resulting in a more uniform air-fuel mixture in the cylinder, which is more conducive to spark plug ignition and successful starting, and also improves fuel economy. When the current temperature is determined to be greater than or equal to the second preset temperature threshold, the fuel atomization effect is good, and a single injection is sufficient to form a good air-fuel mixture, eliminating the need for multiple injections. Furthermore, a single injection allows for better control of the injection quantity and timing, optimizing the combustion process and improving combustion efficiency.

[0207] Figure 3 This is a schematic diagram of the structure of a cold start device for an engine provided in an embodiment of this application.

[0208] For example, such as Figure 3 As shown, the device 300 includes:

[0209] The acquisition module 301 is used to acquire the current temperature of the coolant in the vehicle's engine.

[0210] The determining module 302 is used to obtain the current speed of the engine when the current temperature is less than or equal to a preset temperature threshold, and to determine a first target fuel injection quantity ratio between the fuel injection quantity of the engine's direct injection nozzle and port injection nozzle when the engine injects fuel based on the current temperature of the coolant and the current speed of the engine.

[0211] The control module 303 is used to control the direct injection nozzle and the airway injection nozzle to inject fuel according to the first target fuel injection quantity ratio in order to control the cold start of the engine.

[0212] In one possible implementation, the determining module is specifically used to: determine a first target fuel injection quantity ratio corresponding to the current temperature and the current engine speed based on a first preset correspondence; wherein, the first preset correspondence is the correspondence between target parameters and target fuel injection quantity ratio; the target parameters include the temperature of the coolant and the engine speed; the target fuel injection quantity ratio is the fuel injection quantity ratio when the direct injection nozzle and the port injection nozzle perform fuel injection.

[0213] In one possible implementation, the control module is specifically used to: determine the total amount of fuel injection required for cold starting of the engine; determine the first fuel injection quantity corresponding to the direct injection nozzle based on the ratio of the total fuel injection quantity to the first target fuel injection quantity, and determine the second fuel injection quantity corresponding to the port injection nozzle; wherein the sum of the first fuel injection quantity and the second fuel injection quantity is the total fuel injection quantity; control the direct injection nozzle to inject fuel according to the first fuel injection quantity, and control the port injection nozzle to inject fuel according to the second fuel injection quantity.

[0214] In one possible implementation, the control module includes a direct injection nozzle control unit, which is specifically configured to: when it is determined that the direct injection nozzle performs multiple fuel injections, determine a second target fuel injection quantity ratio corresponding to the current temperature of the coolant based on a second preset correspondence; wherein the second preset correspondence is the correspondence between the temperature of the coolant and the fuel injection quantity ratio of each injection during multiple fuel injections; the second target fuel injection quantity ratio is the ratio between the fuel injection quantities of each injection during multiple fuel injections by the direct injection nozzle; determine the single fuel injection quantity of each fuel injection by the direct injection nozzle based on the first fuel injection quantity and the second target fuel injection quantity ratio; and control the direct injection nozzle to inject fuel according to the single fuel injection quantity during each fuel injection.

[0215] In one possible implementation, the control module includes a control unit, which is specifically configured to: determine a first injection moment when the direct injection nozzle injects fuel, and determine a second injection moment when the port injection nozzle injects fuel; control the direct injection nozzle to inject fuel at the first injection moment according to the first injection quantity, and control the port injection nozzle to inject fuel at the second injection moment according to the second injection quantity.

[0216] In one possible implementation, the control unit includes a first determining unit, which is specifically configured to: acquire the current operating parameters of the engine; wherein the current operating parameters include the current speed and the current load; determine, based on a third preset correspondence, a target start time for fuel injection by the direct injection nozzle corresponding to the current operating parameters; wherein the third preset correspondence is a correspondence between the operating parameters and the start time for fuel injection by the direct injection nozzle; the operating parameters include the speed and the load; determine, based on a fourth preset correspondence, a target end time for fuel injection by the direct injection nozzle corresponding to the current operating parameters; wherein the fourth preset correspondence is a correspondence between the operating parameters and the end time for fuel injection by the direct injection nozzle; and, if it is determined that the number of injections by the direct injection nozzle is multiple, determine, based on the target start time and the target end time, a first injection time for each fuel injection by the direct injection nozzle.

[0217] In one possible implementation, the control unit includes a second determining unit, which is specifically used to: acquire the opening time of the intake valve of the engine, and acquire the injection delay angle when the port injection nozzle performs fuel injection; wherein the injection delay angle is the crankshaft angle between the start time of fuel injection by the port injection nozzle and the opening time of the intake valve; and determine a second injection time when the port injection nozzle performs fuel injection based on the opening time of the intake valve and the injection delay angle.

[0218] In one possible implementation, the second determining unit includes an acquisition unit, which is specifically used to: acquire the current temperature of the coolant, the intake air temperature of the air entering the intake manifold of the engine, and the current engine speed; and determine the injection delay angle based on the current temperature of the coolant, the intake air temperature, and the current engine speed.

[0219] In one possible implementation, the control module is specifically used to: determine a target oil pressure corresponding to the current temperature of the coolant; control the engine's fuel pump to adjust the internal fuel pressure of the engine; and, when it is determined that the internal fuel pressure of the engine has reached the target oil pressure, control the direct injection nozzle and the port injection nozzle to inject fuel according to the first target fuel injection quantity ratio, so as to control the engine cold start.

[0220] Figure 4 This is a schematic diagram of the structure of a vehicle provided in an embodiment of this application.

[0221] For example, such as Figure 4 As shown, the vehicle 400 includes a memory 401 and a processor 402, wherein the memory 401 stores executable program code 4011, and the processor 402 is used to call and execute the executable program code 4011 to perform a cold start method for an engine.

[0222] Furthermore, embodiments of this application also protect an apparatus that may include a memory and a processor, wherein the memory stores executable program code, and the processor is used to call and execute the executable program code to perform a cold start method for an engine provided in embodiments of this application.

[0223] This embodiment can divide the device into functional modules based on the above method example. For example, each module can correspond to a separate function, or two or more functions can be integrated into one processing module. The integrated module can be implemented in hardware. It should be noted that the module division in this embodiment is illustrative and only represents one logical functional division. In actual implementation, there may be other division methods.

[0224] When the functional modules are divided according to their respective functions, the device may also include an acquisition module, a determination module, and a control module. It should be noted that all relevant content regarding the steps involved in the above method embodiments can be referenced from the functional descriptions of the corresponding functional modules, and will not be repeated here.

[0225] It should be understood that the device provided in this embodiment is used to perform the above-described cold start method for an engine, and therefore can achieve the same effect as the above-described implementation method.

[0226] When using an integrated unit, the device may include a processing module and a storage module. When the device is applied to a vehicle, the processing module can be used to control and manage the vehicle's movements. The storage module can be used to support the vehicle in executing relevant program code and data.

[0227] The processing module may be a processor or a controller, which can implement or execute various exemplary logic blocks, modules, and circuits shown in conjunction with the disclosure of this application. The processor may also be a combination of functions that implement computing capabilities, such as a combination of one or more microprocessors, a combination of digital signal processing (DSP) and microprocessors, etc., and the storage module may be a memory.

[0228] In addition, the device provided in the embodiments of this application may specifically be a chip, component or module. The chip may include a connected processor and a memory. The memory is used to store instructions. When the processor calls and executes the instructions, the chip can execute a cold start method for an engine provided in the above embodiments.

[0229] This embodiment also provides a computer-readable storage medium storing computer program code. When the computer program code is run on a computer, the computer executes the above-described related method steps to implement the engine cold start method provided in the above embodiment.

[0230] This embodiment also provides a computer program product that, when run on a computer, causes the computer to perform the aforementioned steps to implement the cold start method for an engine provided in the above embodiment.

[0231] In this embodiment, the device, computer-readable storage medium, computer program product, or chip are all used to execute the corresponding methods provided above. Therefore, the beneficial effects they can achieve can be referred to the beneficial effects in the corresponding methods provided above, and will not be repeated here.

[0232] Through the above description of the embodiments, those skilled in the art will understand that, for the sake of convenience and brevity, only the division of the above functional modules is used as an example. In actual applications, the above functions can be assigned to different functional modules as needed, that is, the internal structure of the device can be divided into different functional modules to complete all or part of the functions described above.

[0233] In the embodiments provided in this application, it should be understood that the disclosed apparatus and methods can be implemented in other ways. For example, the apparatus embodiments described above are merely illustrative; for instance, the division of modules or units is only a logical functional division, and in actual implementation, there may be other division methods. For example, multiple units or components may be combined or integrated into another device, or some features may be ignored or not executed. Furthermore, the coupling or direct coupling or communication connection shown or discussed may be through some interfaces; the indirect coupling or communication connection between devices or units may be electrical, mechanical, or other forms.

[0234] The above description is merely a specific embodiment of this application, but the scope of protection of this application is not limited thereto. Any variations or substitutions that can be easily conceived by those skilled in the art within the scope of the technology disclosed in this application should be included within the scope of protection of this application. Therefore, the scope of protection of this application should be determined by the scope of the claims.

Claims

1. A cold start method for an engine, characterized in that, The engine includes a direct injection nozzle and a port injection nozzle, and the method includes: Obtain the current temperature of the coolant in the vehicle's engine; When the current temperature is less than or equal to a preset temperature threshold, the current speed of the engine is obtained, and based on the current temperature of the coolant and the current speed of the engine, a first target fuel injection quantity ratio between the fuel injection quantity of the engine's direct injection nozzle and port injection nozzle when performing fuel injection is determined. Determine the total amount of fuel injection required for a cold start of the engine; Based on the total fuel injection quantity and the first target fuel injection quantity ratio, the first fuel injection quantity corresponding to the direct injection nozzle is determined, and the second fuel injection quantity corresponding to the air intake injection nozzle is determined; wherein, the sum of the first fuel injection quantity and the second fuel injection quantity is the total fuel injection quantity; The engine is controlled to cold start by controlling the direct injection nozzle to inject fuel according to the first injection quantity and the port injection nozzle to inject fuel according to the second injection quantity. The control of the direct injection nozzle to inject fuel according to the first injection quantity includes: when the number of fuel injections by the direct injection nozzle is determined to be multiple, determining a second target injection quantity ratio corresponding to the current temperature of the coolant based on a second preset correspondence; the second preset correspondence is the relationship between the coolant temperature and the injection quantity ratio of each injection during multiple fuel injections; the second target injection quantity ratio is the ratio between the injection quantities of each injection during multiple fuel injections by the direct injection nozzle; determining the single injection quantity of the direct injection nozzle each time it injects fuel based on the first injection quantity and the second target injection quantity ratio; and controlling the direct injection nozzle to inject fuel according to the single injection quantity each time it injects fuel.

2. The method according to claim 1, characterized in that, Determining the first target fuel injection quantity ratio between the fuel injection quantities of the engine's direct injection nozzles and port injection nozzles, based on the current temperature of the coolant and the current engine speed, includes: Based on a first preset correspondence, a first target fuel injection quantity ratio corresponding to the current temperature and the current engine speed is determined; wherein, the first preset correspondence is the correspondence between target parameters and target fuel injection quantity ratio; the target parameters include the temperature of the coolant and the engine speed; the target fuel injection quantity ratio is the fuel injection quantity ratio when the direct injection nozzle and the port injection nozzle perform fuel injection.

3. The method according to claim 1, characterized in that, The method of controlling the direct injection nozzle to inject fuel according to the first injection quantity and controlling the port injection nozzle to inject fuel according to the second injection quantity includes: Determine the first injection time when the direct injection nozzle performs fuel injection, and determine the second injection time when the airway injection nozzle performs fuel injection; The direct injection nozzle is controlled to inject fuel at the first injection time according to the first fuel injection quantity, and the air intake injection nozzle is controlled to inject fuel at the second injection time according to the second fuel injection quantity.

4. The method according to claim 3, characterized in that, Determining the first injection moment when the direct injection nozzle performs fuel injection includes: Obtain the current operating parameters of the engine; wherein, the current operating parameters include the current speed and the current load; Based on a third preset correspondence, the target start time for fuel injection by the direct injection nozzle corresponding to the current operating parameters is determined; wherein, the third preset correspondence is the correspondence between the operating parameters and the start time for fuel injection by the direct injection nozzle; the operating parameters include speed and load; Based on the fourth preset correspondence, the target end time for fuel injection by the direct injection nozzle corresponding to the current operating parameters is determined; wherein, the fourth preset correspondence is the correspondence between the operating parameters and the end time for fuel injection by the direct injection nozzle; If it is determined that the number of injections when the direct injection nozzle performs fuel injection is multiple, the first injection time for each fuel injection by the direct injection nozzle is determined based on the target start time and the target end time.

5. The method according to claim 3, characterized in that, Determining the second injection moment when the airway injection nozzle performs fuel injection includes: The engine obtains the opening time of the intake valve and the injection delay angle when the port injection nozzle performs fuel injection; wherein the injection delay angle is the crankshaft angle between the start time of fuel injection by the port injection nozzle and the opening time of the intake valve. Based on the opening time of the intake valve and the injection delay angle, the second injection time when the airway injection nozzle performs fuel injection is determined.

6. The method according to claim 5, characterized in that, The step of obtaining the injection delay angle when the airway injection nozzle performs fuel injection includes: The current temperature of the coolant, the intake air temperature of the air entering the intake manifold of the engine, and the current engine speed are obtained. The injection delay angle is determined based on the current temperature of the coolant, the intake air temperature, and the current engine speed.

7. The method according to claim 1, characterized in that, The method of controlling the direct injection nozzle to inject fuel according to the first injection quantity and controlling the port injection nozzle to inject fuel according to the second injection quantity to control the engine cold start includes: Based on the current temperature of the coolant, determine the target oil pressure corresponding to the current temperature; Control the engine's fuel pump to adjust the fuel pressure inside the engine; When the fuel pressure inside the engine reaches the target fuel pressure, the direct injection nozzle is controlled to inject fuel according to the first injection quantity, and the port injection nozzle is controlled to inject fuel according to the second injection quantity, so as to control the cold start of the engine.

8. A vehicle, characterized in that, The vehicles include: Memory, used to store executable program code; A processor for calling and running the executable program code from the memory, causing the vehicle to perform the method as described in any one of claims 1 to 7.

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