Cold start method and device for engine, vehicle and storage medium

Abstract

Provided in the present application are a cold start method and device for an engine, a vehicle and a storage medium. The method is applied to the field of vehicles. The engine comprises a direct injection nozzle and a port fuel injection nozzle. The method comprises: acquiring a current temperature of cooling liquid in the engine of the vehicle; when the current temperature is less than or equal to a preset temperature threshold, acquiring a current rotational speed of the engine, and on the basis of the current temperature of the cooling liquid and the current rotational speed of the engine, determining a first target fuel injection quantity ratio between fuel injection quantities of the direct injection nozzle and the port fuel injection nozzle of the engine during fuel injection; and controlling the direct injection nozzle and the port fuel injection nozzle to perform fuel injection according to the first target fuel injection quantity ratio, so as to control the cold start of the engine. The method can help the engine complete the cold start as soon as possible, thereby improving the success rate of the cold start of the engine.

Description

Cold start method, device, vehicle and storage medium of engine

[0001] The present application claims priority to the Chinese patent application No. 202411335747.2, filed on September 24, 2024, and entitled "Cold start method and vehicle of engine", the content of which is incorporated herein by reference in its entirety. TECHNICAL FIELD

[0002] The present application relates to the field of vehicles, and in particular to a cold start method, device, vehicle and storage medium of engine. BACKGROUND

[0003] At present, with the continuous development of the automobile industry, the start of the engine has gradually become a hot issue of people's attention. When the vehicle is cold started at very low temperature, considering fuel economy, it is usually cold started by directly injecting fuel into the engine cylinder through the gasoline direct injection (GDI) system. If the GDI single injection start effect is poor, the GDI multiple injection method is usually used to optimize the cold start.

[0004] Under the conditions of sufficient battery power and good oil state, the cold start reliability at very low temperature is high. However, compared with the good state of the battery, the drag speed when cold starting under the condition of slightly low battery power will be poor, resulting in poor cold start reliability, and there may be a start failure. SUMMARY

[0005] The present application provides a cold start method, device, vehicle and storage medium of engine, which 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.

[0006] In a first aspect, a cold start method of engine is provided, the engine comprising a direct injection nozzle and a port injection nozzle, the method comprising: obtaining a current temperature of cooling liquid in the engine of the vehicle; in a case where the current temperature is less than or equal to a preset temperature threshold, obtaining a current speed of the engine, and determining a first target fuel injection amount ratio between fuel injection amounts of the direct injection nozzle and the port injection nozzle of the engine based on the current temperature of the cooling liquid and the current speed of the engine; and controlling the direct injection nozzle and the port injection nozzle to perform fuel injection according to the first target fuel injection amount ratio to control the cold start of the engine.

[0007] The technical solution disclosed in the above embodiment can determine whether the current engine belongs to a cold start scenario by obtaining the current temperature of the cooling liquid, and can obtain the current speed of the engine in the case of determining that the engine belongs to the cold start scenario, and determine the target fuel injection amount ratio between the direct injection nozzle and the port injection nozzle of the engine based on the current speed of the engine and the current temperature of the cooling liquid, and then control the direct injection nozzle and the port injection nozzle to perform fuel injection according to the target fuel injection amount ratio, which can help the engine to complete the cold start as soon as possible. Since the viscosity of the fuel in the engine increases under low-temperature conditions, which is not conducive to atomization, in the case of determining that the current temperature is less than or equal to the preset temperature threshold, the double-injection strategy of jointly injecting fuel by the direct injection nozzle and the port injection nozzle can control the port injection nozzle in the intake manifold injection system to inject fuel into the intake manifold, better disperse the fuel, form more uniform mixture, and improve the combustion efficiency, so as to realize the engine start more quickly. Moreover, the demand for high-pressure fuel injection amount when only the direct injection nozzle is used to inject fuel can be reduced, so that the start failure caused by insufficient fuel injection amount of the high-pressure fuel pump can be avoided, and the success rate of the start can be improved.

[0008] In a possible implementation manner, the first target fuel injection amount ratio between the fuel injection amounts of the direct injection nozzle and the port injection nozzle of the engine is determined based on the current temperature of the cooling liquid and the current speed of the engine, including: determining the first target fuel injection amount ratio corresponding to the current temperature and the current speed based on a first preset corresponding relationship; wherein the first preset corresponding relationship is a corresponding relationship between a target parameter and a target fuel injection amount ratio; the target parameter includes the temperature of the cooling liquid and the speed of the engine; and the target fuel injection amount ratio is the fuel injection amount ratio of the direct injection nozzle and the port injection nozzle.

[0009] In a possible implementation manner, the direct injection nozzle and the port injection nozzle are controlled to perform fuel injection according to the first target fuel injection amount ratio, including: determining the total fuel injection amount required for the cold start of the engine; determining the first fuel injection amount corresponding to the direct injection nozzle and the second fuel injection amount corresponding to the port injection nozzle based on the total fuel injection amount and the first target fuel injection amount ratio; wherein the sum of the first fuel injection amount and the second fuel injection amount is the total fuel injection amount; and controlling the direct injection nozzle to perform fuel injection according to the first fuel injection amount, and controlling the port injection nozzle to perform fuel injection according to the second fuel injection amount.

[0010] In a possible implementation manner, the method comprises: in a case where it is determined that the number of fuel injection times of the direct injection nozzle is multiple, determining a second target fuel injection amount ratio corresponding to the current temperature of the cooling liquid based on a second preset correspondence relationship, wherein the second preset correspondence relationship is a correspondence relationship between the temperature of the cooling liquid and the fuel injection amount ratio of each injection in the multiple fuel injection, and the second target fuel injection amount ratio is a ratio between the fuel injection amounts of each injection in the multiple fuel injection of the direct injection nozzle; and determining a single fuel injection amount of each fuel injection of the direct injection nozzle based on the first fuel injection amount and the second target fuel injection amount ratio; and controlling the direct injection nozzle to perform fuel injection according to the single fuel injection amount in each fuel injection.

[0011] In a possible implementation manner, the method comprises: determining a first injection time of the direct injection nozzle and a second injection time of the port injection nozzle; and controlling the direct injection nozzle to perform fuel injection according to the first fuel injection amount at the first injection time, and controlling the port injection nozzle to perform fuel injection according to the second fuel injection amount at the second injection time.

[0012] In a possible implementation manner, the method comprises: obtaining a current operating parameter of the engine, wherein the current operating parameter comprises a current speed and a current load; determining a target start time of fuel injection of the direct injection nozzle corresponding to the current operating parameter based on a third preset correspondence relationship, wherein the third preset correspondence relationship is a correspondence relationship between the operating parameter and the start time of fuel injection of the direct injection nozzle, and the operating parameter comprises the speed and the load; determining a target end time of fuel injection of the direct injection nozzle corresponding to the current operating parameter based on a fourth preset correspondence relationship, wherein the fourth preset correspondence relationship is a correspondence relationship between the operating parameter and the end time of fuel injection of the direct injection nozzle; and in a case where it is determined that the number of fuel injection times of the direct injection nozzle is multiple, determining the first injection time of each fuel injection of the direct injection nozzle based on the target start time and the target end time.

[0013] In a possible implementation manner, the method comprises: obtaining an opening time of an intake valve of the engine, and obtaining an injection delay angle of fuel injection of the port injection nozzle, wherein the injection delay angle is a crank angle between the start time of fuel injection of the port injection nozzle and the opening time of the intake valve; and determining the second injection time of fuel injection of the port injection nozzle based on the opening time of the intake valve and the injection delay angle.

[0014] In a possible implementation, the injection delay angle of the air path injection nozzle when performing fuel injection is obtained, including: obtaining the current temperature of the cooling liquid, the intake temperature of the air entering the intake manifold of the engine, and the current speed of the engine; determining the injection delay angle based on the current temperature of the cooling liquid, the intake temperature, and the current speed of the engine.

[0015] In a possible implementation, the direct injection nozzle and the air path injection nozzle are controlled to perform fuel injection according to the first target fuel injection ratio to control cold start of the engine, including: determining the target oil pressure corresponding to the current temperature of the cooling liquid based on the current temperature of the cooling liquid; controlling the fuel pump of the engine to adjust the fuel pressure inside the engine; and in a case where it is determined that the fuel pressure inside the engine reaches the target oil pressure, controlling the direct injection nozzle and the air path injection nozzle to perform fuel injection according to the first target fuel injection ratio to control cold start of the engine.

[0016] In a possible implementation, the fuel pump of the engine is controlled to adjust the fuel pressure inside the engine, including: detecting the current fuel pressure inside the engine, and comparing the current fuel pressure with the target oil pressure; if the current fuel pressure is less than the target oil pressure, controlling the fuel pump to increase the fuel pressure inside the engine; and if the current fuel pressure is greater than the target oil pressure, controlling the fuel pump to reduce the fuel pressure inside the engine.

[0017] In a possible implementation, the total fuel injection amount required for cold start of the engine is determined, including: obtaining a basic fuel injection amount required for normal start of the engine; determining a correction coefficient based on a current state parameter of the engine; and determining the total fuel injection amount required for cold start of the engine based on the basic fuel injection amount and the correction coefficient.

[0018] In a possible implementation, before the direct injection nozzle is controlled to perform fuel injection according to the first fuel injection amount, the method further includes: determining a target injection mode of the direct injection nozzle based on the current temperature of the cooling liquid and the current speed of the engine; and if the current temperature of the cooling liquid 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, the target injection mode is determined as multiple injection.

[0019] In a second aspect, an engine cold start device is provided, the engine including a direct injection nozzle and an air path injection nozzle, and the device includes: an obtaining module configured to obtain a current temperature of a cooling liquid in an engine of a vehicle; a determining module configured to, in a case where the current temperature is less than or equal to a preset temperature threshold, obtain a current speed of the engine, and determine a first target fuel injection ratio between fuel injection amounts of the direct injection nozzle and the air path injection nozzle of the engine when performing fuel injection based on the current temperature of the cooling liquid and the current speed of the engine; and a control module configured to control the direct injection nozzle and the air path injection nozzle to perform fuel injection according to the first target fuel injection ratio to control cold start of the engine.

[0020] In a third aspect, the present application provides a vehicle comprising a memory and a processor. The memory is configured to store executable program code, and the processor is configured to invoke and run the executable program code from the memory, so that the vehicle executes the cold start method of the engine in the first aspect and any possible implementation of the first aspect.

[0021] In a fourth aspect, the present application provides a computer program product comprising computer program code, which, when executed on a computer, causes the computer to execute the cold start method of the engine in the first aspect and any possible implementation of the first aspect.

[0022] In a fifth aspect, the present application provides a computer-readable storage medium storing computer program code, which, when executed on a computer, causes the computer to execute the cold start method of the engine in the first aspect and any possible implementation of the first aspect. BRIEF DESCRIPTION OF DRAWINGS

[0023] FIG. 1 is a schematic flowchart of a cold start method of an engine according to an embodiment of the present application;

[0024] FIG. 2 is a schematic flowchart of a start method of an engine according to an embodiment of the present application;

[0025] FIG. 3 is a schematic structural diagram of a cold start device of an engine according to an embodiment of the present application;

[0026] FIG. 4 is a schematic structural diagram of a vehicle according to an embodiment of the present application. DETAILED DESCRIPTION

[0027] The technical solutions in the present application will be described in detail below with reference to the accompanying drawings. In the description of the embodiments of the present application, unless otherwise specified, " / " represents the meaning of or, for example, A / B can represent A or B: "and / or" in the text only describes the association relationship of the associated objects, which means that there can be three relationships, for example, A and / or B, which means that there are three cases of A alone, A and B together, and B alone. In addition, in the description of the embodiments of the present application, "multiple" means two or more than two.

[0028] Hereinafter, the terms "first" and "second" are only for descriptive purposes, and cannot be understood as implying or suggesting relative importance or implicitly indicating the number of indicated technical features. Therefore, the features defined with "first" and "second" can explicitly or implicitly include one or more features.

[0029] At present, with the continuous development of the automobile industry, the starting of the engine has gradually become a hot issue of concern. When the vehicle is cold started at very low temperature, considering fuel economy, cold start is usually performed by GDI injection. If the single injection of GDI has poor starting effect, the GDI multiple injection method is usually used to optimize the cold start.

[0030] Under the condition of sufficient battery power and good oil state, the cold start reliability of very low temperature is high. However, in the case that the power provided by the starter is insufficient due to the insufficient power of the 12V storage battery of the vehicle, the engine cannot be started.

[0031] If the coolant temperature of the engine is very low, such as below-30℃ or below-35℃, the internal parts of the engine become hard and the resistance increases, which also causes the rotation speed of the starter to decrease. In the case that the rotation speed of the engine is low, the working efficiency of the high-pressure oil pump is also low, which causes the oil pumping capacity to be poor. After the oil pumping capacity of the high-pressure oil pump is poor, in order to ensure the smooth ignition of the engine, the injection frequency of GDI may be increased, but if the injection amount of each injection exceeds the actual pumping amount of the high-pressure oil pump, the oil pressure in the oil rail will gradually decrease. When the oil pressure in the oil rail decreases to a certain extent, the high-pressure injection mode cannot be maintained, so that the injection pump can only work in the low-pressure injection mode. In the low-pressure injection mode, the fuel in the engine is poorly atomized, which causes the formation of mixed gas to be poor, thereby affecting the ignition success rate and causing the engine to fail to start.

[0032] In summary, under the condition of very low temperature, the engine cold start process will encounter problems such as low rotation speed of the starter, limited oil pumping capacity of the high-pressure oil pump, and gradual decrease of the oil pressure in the high-pressure oil rail, which causes the engine to fail to start.

[0033] In order to solve the above technical problems, the engine cold start method provided by the embodiment of the present application is provided, and the execution subject of the method is a vehicle, specifically a controller in the vehicle.

[0034] The engine cold start method provided by the embodiment of the present application is applied to a vehicle configured with a double injection system, and the engine of the vehicle is a double injection system engine, which includes a GDI system and a port fuel injection (PFI) system.

[0035] The GDI system uses a direct injection nozzle to directly inject fuel into the engine cylinder, which is mixed with air and then burned. The direct injection nozzle in the GDI system is usually installed on the cylinder head of the engine, close to the combustion chamber.

[0036] The PFI system sprays fuel into the intake manifold in front of the intake valve through air path injection nozzles instead of directly into the cylinder. The air path injection nozzles in the PFI system are usually installed in the intake manifold of the engine, usually in front of the intake valve.

[0037] The double injection system described above can ensure that the engine obtains the best fuel supply under various working conditions and improves the overall performance of the vehicle.

[0038] FIG. 1 is a schematic flowchart of an engine cold start method according to an embodiment of the present application.

[0039] For example, as shown in FIG. 1, the method 100 includes:

[0040] S101, obtaining the current temperature of the cooling liquid in the engine of the vehicle.

[0041] S102, in the case where the current temperature is less than or equal to a preset temperature threshold, obtaining the current speed of the engine, and determining a first target fuel injection amount ratio between the fuel injection amounts of the direct injection nozzle and the air path injection nozzle of the engine based on the current temperature of the cooling liquid and the current speed of the engine.

[0042] S103, controlling the direct injection nozzle and the air path injection nozzle to spray fuel according to the first target fuel injection amount ratio to control the cold start of the engine.

[0043] In the embodiment of the present application, by obtaining the current temperature of the cooling liquid in the engine, it can be determined whether the current engine belongs to a cold start scenario. In the case where it is determined that the engine belongs to a cold start scenario, the current speed of the engine can be obtained, and based on the current speed of the engine and the current temperature of the cooling liquid, the target fuel injection amount ratio between the direct injection nozzle and the air path injection nozzle of the engine is determined, and then the direct injection nozzle and the air path injection nozzle are controlled to spray fuel according to the target fuel injection amount ratio, which can help the engine to complete the cold start as soon as possible. Since the viscosity of the fuel in the engine increases under low temperature conditions, which is not conducive to atomization, in the case where the current temperature is less than or equal to a preset temperature threshold, the double injection strategy of using the direct injection nozzle and the air path injection nozzle together to spray fuel can control the air path injection nozzle in the intake manifold injection system to spray fuel into the intake manifold, which can better disperse the fuel and form more uniform mixture with the help of the intake air flow, thereby improving the combustion efficiency and achieving engine start faster. Moreover, it can reduce the demand for high-pressure fuel injection amount when using the direct injection nozzle alone to spray fuel, thereby avoiding start failure caused by insufficient pump oil amount of the high-pressure fuel pump, and improving the success rate of start.

[0044] The specific implementation of each step in the embodiment shown in FIG. 1 is described as follows:

[0045] For S101, it can be understood that the current temperature of the coolant in the engine can also be referred to as the starting water temperature of the engine.

[0046] The current temperature of the coolant in the engine is usually measured by a coolant temperature sensor. The coolant temperature sensor is a thermistor whose resistance value changes with temperature, which can convert the temperature signal into an electrical signal and send it to the engine controller.

[0047] For example, the coolant temperature sensor is usually installed in the engine water jacket or at the outlet of the engine radiator, directly in contact with the coolant. The coolant temperature sensor is a thermistor, and when the temperature of the coolant rises, the resistance value decreases; when the temperature of the coolant decreases, the resistance value increases. The coolant temperature sensor converts the resistance change into a voltage signal and sends the voltage signal to the engine controller, which determines the current temperature of the coolant according to the received voltage signal.

[0048] During engine operation, the coolant circulates through the engine interior, absorbs heat and conducts it to the radiator to maintain the engine operating temperature within an appropriate range. The temperature of the coolant usually directly affects the performance and efficiency of the engine. For example, if the current temperature of the coolant is too low, more fuel is needed to start the engine; if the current temperature of the coolant is too high, the engine may overheat and cause performance degradation or even overheating damage.

[0049] Further, after obtaining the current temperature of the coolant in the engine, the fuel injection mode of the engine can be adjusted according to the current temperature of the coolant.

[0050] For S102, it can be understood that the preset temperature threshold can be set according to actual needs, for example, the preset temperature threshold can be set to -20°C.

[0051] Further, in the case where the current temperature of the coolant is less than or equal to the preset temperature threshold, it can be considered that the engine is at an extremely low temperature, and the engine starting at an extremely low temperature is referred to as "engine cold start".

[0052] As described above, if the GDI single injection starting effect is poor, the GDI multiple injection method is usually used to optimize the cold start, but when the GDI multiple injection method is used for cold start, problems such as low starter drag speed, limited pump oil capacity of high-pressure oil pump, and gradual decrease of oil pressure in high-pressure oil rail are encountered, resulting in failure of the engine cold start.

[0053] The PFI system injects fuel into the intake manifold rather than directly into the cylinder, and can use the heat of the intake manifold to help vaporize the fuel. The PFI system also generally does not require as high a fuel injection pressure as the GDI system, so it can more easily achieve the required injection pressure even at low temperatures. Based on this, the GDI + PFI injection can be used when the engine is cold started, thereby improving the success rate of cold starting of the engine.

[0054] Further, the engine currently configured with the dual injection system generally determines which injection mode to use for fuel injection based on the current engine speed.

[0055] It can be understood that the current engine speed of the engine can generally be measured by a crank position sensor, and the unit is revolutions per minute (RPM).

[0056] When the current engine speed is low, the intake air flow speed is relatively low. The PFI system can inject fuel into the intake manifold, and there is enough time to mix the fuel and air to form a relatively uniform mixture. Such a uniform mixture is conducive to stable combustion and improves combustion efficiency. That is, when the current engine speed is low, the port injection nozzle can be used for fuel injection.

[0057] When the current engine speed of the engine is high, the engine needs more air and fuel to generate more power. The GDI system can inject fuel directly into the cylinder, and can achieve higher injection pressure to better atomize the fuel and mix it with air more quickly. That is, when the current engine speed is high, the direct injection nozzle can be used for fuel injection.

[0058] It can be understood that when the engine is started at an extremely low temperature, the port injection nozzle and the direct injection nozzle can be used for fuel injection at the same time, and the ratio between the fuel injection amount of the direct injection nozzle and the fuel injection amount of the port injection nozzle when the engine is injected by the direct injection nozzle and the port injection nozzle can be determined based on the current engine speed and the current coolant temperature, that is, the first target fuel injection amount ratio.

[0059] In some embodiments, when the current engine speed is low and the current coolant temperature is low, the proportion of the fuel injection amount of the port injection nozzle in the first target fuel injection amount ratio can be increased. As the engine speed increases and the coolant temperature increases, the proportion of the fuel injection amount of the direct injection nozzle in the first target fuel injection amount ratio can be increased.

[0060] It can be understood that, as described above, when the engine speed is low, the intake air flow speed is relatively slow, and the time for forming the mixture is relatively long. At this time, the fuel injection amount ratio of the port injection nozzle can be appropriately increased to better atomize the fuel by using the air flow in the port, so as to promote the formation of the mixture. As the engine speed increases, the intake air flow speed increases, and the time for forming the mixture is shortened. The direct injection nozzle can directly inject the fuel into the cylinder more quickly, thereby improving the combustion efficiency. Therefore, at high speed, the fuel injection amount ratio of the direct injection nozzle can be appropriately increased.

[0061] When the coolant temperature is low, the engine is in a cold start state. At this time, in order to ensure good combustion stability, the fuel injection amount ratio of the port injection nozzle can be increased. The fuel injected by the port injection can be preheated in the intake port, which helps to increase the temperature of the mixture and promote combustion. When the coolant temperature increases to the normal working temperature, the combustion condition of the engine is improved. The fuel injection amount ratio of the direct injection nozzle can be reasonably adjusted according to different working conditions, so as to improve the power, economy and emission performance of the engine.

[0062] In other embodiments, a mapping relationship between the engine speed, the coolant temperature and the fuel injection amount ratios of the direct injection nozzle and the port injection nozzle can also be established through experiments and data analysis. The relationship can be represented by using a two-dimensional table, curve fitting or the like.

[0063] In a possible implementation, the first target fuel injection amount ratio between the fuel injection amounts of the direct injection nozzle and the port injection nozzle of the engine is determined based on the current temperature of the coolant and the current speed of the engine, and the first target fuel injection amount ratio is determined based on a first preset corresponding relationship between a target parameter and a target fuel injection amount ratio. The target parameter includes the temperature of the coolant and the speed of the engine, and the target fuel injection amount ratio is the fuel injection amount ratio of the direct injection nozzle and the port injection nozzle.

[0064] It can be understood that the first preset corresponding relationship described above can be obtained according to actual engine cold start tests, and the first preset corresponding relationship can be stored in the engine controller.

[0065] For example, according to actual engine cold start tests, the data corresponding to the best start effect of different coolant temperatures and different engine speeds can be obtained, and the proportion of the PFI fuel injection amount corresponding to the current temperature of the coolant and the current speed of the engine can be as shown in Table 1:

[0066] Table 1

[0067] As shown in Table 1 above, the proportion of the PFI fuel injection amount can be determined according to the current temperature of the coolant and the current speed of the engine.

[0068] The proportion of the PFI fuel injection amount refers to the proportion of the fuel injection amount of the port injection nozzle of the PFI system in the total fuel injection amount required for starting the engine, and the total fuel injection amount required for starting the engine is the sum of the fuel injection amount of the port injection nozzle of the PFI system and the fuel injection amount of the direct injection nozzle of the GDI system.

[0069] When the current speed of the engine exceeds 1000 RPM, the direct injection nozzle of the GDI system can use less fuel injection amount to maintain the operation of the engine than the port injection nozzle of the PFI system, so when the current speed of the engine is greater than or equal to 1000 RPM, the port injection nozzle of the PFI system can no longer be used for fuel injection.

[0070] When the current temperature of the coolant is -10°C, the engine is at a non-extremely low temperature, the GDI multiple injection strategy can be used, and the port injection nozzle of the PFI system does not need to be used for fuel injection, so when the current temperature of the coolant is greater than or equal to -10°C, the port injection nozzle of the PFI system can no longer be used for fuel injection.

[0071] For example, if the current temperature of the coolant is -30°C and the current speed of the engine is 200 RPM, by querying Table 1, it can be determined that the proportion of the PFI fuel injection amount is 0.4. Accordingly, the proportion of the GDI fuel injection amount can be obtained as 0.6. That is, the first target fuel injection amount ratio between the fuel injection amounts of the direct injection nozzle and the port injection nozzle of the engine is determined as 3:2.

[0072] The method determines the first target fuel injection amount ratio based on the current temperature of the coolant and the current speed of the engine, which can make the fuel injection amounts of the direct injection nozzle and the port injection nozzle more suitable for the actual operation requirements of the engine, and can make the mixture in different working conditions reach a more ideal state, thereby improving the utilization rate of fuel and reducing fuel consumption. By reasonably adjusting the fuel injection amount ratio between the direct injection nozzle and the port injection nozzle, the engine can also obtain appropriate fuel supply in various working conditions, thereby improving the cold start success rate of the engine.

[0073] Further, after the first target fuel injection amount ratio is determined, the engine can be controlled to perform fuel injection according to the first target fuel injection amount ratio.

[0074] For S103, it can be understood that after the first target fuel injection ratio is determined, the engine controller can control the fuel injection pulse width of the direct injection nozzle and the port injection nozzle, so that the direct injection nozzle and the port injection nozzle inject fuel according to the first target fuel injection ratio.

[0075] The fuel injection pulse width refers to the length of time that the fuel injector is open.

[0076] For example, the control of the fuel injection pulse width can be achieved by adjusting the opening time and the closing time of the fuel injector.

[0077] In order to achieve the best fuel injection effect of the fuel injector and help the engine start smoothly, the fuel injector can be controlled to inject fuel when the fuel pressure in the engine reaches a preset pressure.

[0078] In one possible implementation, the control of the direct injection nozzle and the port injection nozzle to inject fuel according to the first target fuel injection ratio to control the cold start of the engine includes: determining a target oil pressure corresponding to the current temperature of the coolant based on the current temperature of the coolant; controlling the fuel pump of the engine to adjust the fuel pressure in the engine; and controlling the direct injection nozzle and the port injection nozzle to inject fuel according to the first target fuel injection ratio to control the cold start of the engine when it is determined that the fuel pressure in the engine reaches the target oil pressure.

[0079] It can be understood that the target oil pressure refers to the fuel pressure value that the fuel system of the engine hopes to reach.

[0080] Further, the correspondence between the temperature of the coolant and the target oil pressure can be established in advance, and after the current temperature of the coolant is obtained, the target oil pressure can be determined based on the correspondence.

[0081] For example, the correspondence between the temperature of the coolant and the target oil pressure can be as shown in Table 2:

[0082] Table 2

[0083] As shown in Table 2, as the current temperature of the coolant rises, the target oil pressure also gradually increases.

[0084] For example, if the current temperature of the coolant is -20℃, it can be determined from Table 2 that the target oil pressure corresponding to the temperature is 14Mpa.

[0085] Further, after the target oil pressure is determined, the engine controller can control the fuel pump to adjust the current fuel pressure in the engine.

[0086] In some embodiments, after determining the target oil pressure, the engine controller can detect the current fuel pressure inside the engine through the fuel pressure sensor, and then compare the detected current fuel pressure with the target oil pressure. If the current fuel pressure is lower than the target oil pressure, it is determined that the fuel pump needs to be controlled to increase the oil pressure; if the current fuel pressure is higher than the target oil pressure, it is determined that the fuel pump needs to be controlled to decrease the oil pressure.

[0087] It can be understood that the above-mentioned fuel pressure sensor can be installed on the fuel rail to monitor the oil pressure in the fuel rail in real time.

[0088] The above-mentioned control of the fuel pump to increase or decrease the oil pressure can be generally achieved by controlling the rotating speed of the motor of the fuel pump, and can also be achieved by controlling the oil return amount of the oil return valve.

[0089] For example, if it is determined that the fuel pump needs to be controlled to increase the oil pressure, the rotating speed of the motor of the fuel pump can be increased to increase the output pressure of the fuel pump, and the oil return amount of the oil return valve can be controlled to decrease to increase the oil pressure.

[0090] If it is determined that the fuel pump needs to be controlled to decrease the oil pressure, the rotating speed of the motor of the fuel pump can be decreased to decrease the output pressure of the fuel pump, and the oil return amount of the oil return valve can be controlled to increase to decrease the oil pressure.

[0091] The above-mentioned method, which determines the target oil pressure based on the current temperature and controls the fuel pump to adjust the fuel pressure, can make the fuel have a higher pressure when being injected, thereby improving the atomization effect of the fuel. Better atomization can make the fuel and air mix more fully, improve the stability and reliability of combustion, and help the engine reach a stable running state faster during cold start. By precisely controlling the fuel pressure to reach the target oil pressure, the direct injection nozzle and the port injection nozzle can be controlled to inject fuel according to the first target fuel injection amount ratio, so as to ensure that the mixture concentration is within a suitable range and improve the success rate of engine cold start.

[0092] Further, in the case where the fuel pressure inside the engine reaches the target oil pressure, the direct injection nozzle and the port injection nozzle can be controlled to inject fuel according to the first target fuel injection amount ratio.

[0093] In one possible implementation, the control of the direct injection nozzle and the port injection nozzle to inject fuel according to the first target fuel injection amount ratio includes: determining a total fuel injection amount required for the cold start of the engine; determining a first fuel injection amount corresponding to the direct injection nozzle and a second fuel injection amount corresponding to the port injection nozzle based on the total fuel injection amount and the first target fuel injection amount ratio; wherein the sum of the first fuel injection amount and the second fuel injection amount is the total fuel injection amount; and controlling the direct injection nozzle to inject fuel according to the first fuel injection amount and controlling the port injection nozzle to inject fuel according to the second fuel injection amount.

[0094] It can be understood that the total amount of fuel injection required for the cold start of the engine can be determined according to the current state parameters of the engine. The current state parameters of the engine can include the current temperature of the coolant, the speed of the engine, the amount of air entering the engine, and the air temperature, etc.

[0095] In some embodiments, the basic amount of fuel injection required for the normal start of the engine is obtained, a correction coefficient is determined based on the current state parameters of the engine, and then the total amount of fuel injection required for the cold start of the engine is determined based on the basic amount of fuel injection and the correction coefficient.

[0096] It can be understood that the basic amount of fuel injection can be determined according to the mass of air entering the engine and the target air-fuel ratio.

[0097] The mass of air entering the engine can be estimated by the engine controller according to the pressure of the intake manifold or the data of the air flow meter. For most gasoline engines, the standard theoretical air-fuel ratio is 14.7:1, i.e., the target air-fuel ratio can be 14.7:1.

[0098] Further, in the case that both the current temperature of the coolant and the intake temperature of the air entering the engine are low, the volatility of the fuel in the engine becomes poor, and the formation of the mixture becomes more difficult. In this case, more fuel injection than at normal operating temperature can be required to ensure the smooth start of the engine.

[0099] For example, according to empirical data or a pre-established model, the proportion of the increased amount of fuel injection required for the smooth start of the engine at the current operating temperature can be determined. For example, according to the current temperature of the coolant and the intake temperature of the air entering the engine, it is determined that 10% more fuel injection than at normal operating temperature is required to ensure the smooth start of the engine at the current operating temperature, i.e., the temperature correction coefficient can be determined as 1.1.

[0100] In the case that the current speed of the engine is too low, it means that the engine needs more power to accelerate to the normal operating speed. In this case, in order to ensure the smooth start of the engine, a certain proportion of the amount of fuel injection can be increased.

[0101] For example, according to empirical data or a pre-established model, the proportion of the increased amount of fuel injection required for the smooth start of the engine at the current speed can be determined. For example, according to the current speed of the engine, it is determined that 20% more fuel injection than at normal speed is required to ensure the smooth start of the engine at the current speed, i.e., the speed correction coefficient can be determined as 1.2.

[0102] For example, if the mass of air entering the engine is 100 grams, the target air-fuel ratio is 14.7:1, and the density of gasoline is 0.72 g / ml, the basic fuel injection amount is calculated to be 9.444 ml. If the temperature correction coefficient is determined to be 1.1 and the speed correction coefficient is determined to be 1.2, the comprehensive correction coefficient is calculated to be 1.1*1.2=1.32, and the corrected total fuel injection amount is calculated to be 9.444*1.32=12.47 ml, i.e., the total fuel injection amount required for cold start of the engine is 12.47 ml.

[0103] Further, after the total fuel injection amount required for cold start of the engine is determined, the total fuel injection amount can be distributed according to the previously determined first target fuel injection amount ratio.

[0104] For example, if the total fuel injection amount required for cold start of the engine is determined to be 10 ml, and the first target fuel injection amount ratio is determined to be 3:2, i.e., the fuel injection amount of the direct injection nozzle accounts for 60% of the total fuel injection amount, and the fuel injection amount of the port injection nozzle accounts for 40% of the total fuel injection amount. According to the total fuel injection amount and the first target fuel injection ratio, the first fuel injection amount corresponding to the direct injection nozzle is determined to be 6 ml, and the second fuel injection amount corresponding to the port injection nozzle is determined to be 4 ml.

[0105] Further, after the first fuel injection amount corresponding to the direct injection nozzle and the second fuel injection amount corresponding to the port injection nozzle are determined, 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 10 ml of total fuel injection amount.

[0106] During the cold start of the engine, the GDI system can use single injection to inject fuel, or can use multiple injections to inject fuel.

[0107] In some embodiments, the injection mode of the GDI system can be determined based on the current temperature of the coolant and the current speed of the engine.

[0108] For example, if the current temperature of the coolant is determined to be less than or equal to a preset temperature threshold and the current speed of the engine is determined to be less than or equal to a preset speed threshold, the injection mode of the GDI system can be determined to be multiple injections.

[0109] The above-mentioned preset temperature threshold can be set according to actual needs, such as -20°C; the above-mentioned preset speed threshold can also be set according to actual needs, such as 600 RPM.

[0110] In some embodiments, during the process of cold start of the engine, the engine controller can set the initial injection number of the GDI system when 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, whether to adjust the initial injection number can be determined according to the operating state of the engine.

[0111] For example, the initial injection number can be set to two according to actual needs.

[0112] If the engine has unstable combustion, large speed fluctuation or unsatisfactory emission indicators, the injection number can be gradually increased on the basis of the initial injection number. Specifically, the injection can be increased once each time the above-mentioned conditions occur until the engine runs smoothly.

[0113] On the contrary, if the engine has a too high concentration of mixed gas during combustion, a decrease in combustion efficiency or other abnormal conditions, the injection number can be reduced on the basis of the initial injection number. Specifically, the injection can be reduced once each time the above-mentioned conditions occur until the engine runs smoothly.

[0114] In other embodiments, an experimental data of the engine and a preset machine learning model are used to establish a model for predicting the injection number, which can be stored in the engine controller of the vehicle. During the process of cold start of the engine, the engine controller inputs the current state parameters of the engine into the model, and the model can output a predicted injection number.

[0115] It can be understood that the above-mentioned model for predicting the injection number can be trained based on the temperature, speed, load, fuel characteristics and other state parameters of the engine and the injection number corresponding to the state parameters of the engine, and the model has passed a large number of experimental verification and optimization.

[0116] For example, if the temperature of the coolant of the engine is -30°C, the temperature of the gas entering the engine is -25°C, the speed of the engine is 300 RPM, and the fuel in the engine is low-volatility fuel, these parameters are input into the model for predicting the injection number, and the predicted injection number can be obtained as three times.

[0117] It should be understood that as the operating state of the engine changes, the engine controller will constantly update the input parameters of the above-mentioned model for predicting the injection number to adjust the injection number of the GDI system in real time.

[0118] Further, in the case where the injection mode of the above-mentioned GDI system is determined to be multiple injection, the ratio between the injection amount of each injection of the direct injection nozzle can be determined.

[0119] In a possible implementation, the control of the direct injection nozzle to spray fuel according to the first fuel injection amount comprises: in a case where it is determined that the number of fuel injection times of the direct injection nozzle is multiple, determining a second target fuel injection amount ratio corresponding to the current temperature of the coolant based on a second preset correspondence relationship; the second preset correspondence relationship is a correspondence relationship between the temperature of the coolant and the fuel injection amount ratio of each injection in multiple fuel injection; the second target fuel injection amount ratio is a ratio between the fuel injection amounts of each injection in multiple fuel injection of the direct injection nozzle; determining the single fuel injection amount of each fuel injection of the direct injection nozzle based on the first fuel injection amount and the second target fuel injection amount ratio; and controlling the direct injection nozzle to spray fuel according to the single fuel injection amount in each fuel injection.

[0120] It can be understood that, in a case where it is determined that the number of fuel injection times of the direct injection nozzle is multiple, it means that the direct injection nozzle will perform multiple fuel injection in the current working cycle of the engine. The single fuel injection amount of each fuel injection of the direct injection nozzle can be determined based on the first fuel injection amount.

[0121] The second preset correspondence relationship can be obtained according to the result of a test, and can be a preset relationship table stored in the engine controller of the vehicle.

[0122] For example, according to an actual engine cold start test, the ratio between the fuel injection amounts of each injection in multiple fuel injection of the direct injection nozzle when the start effect is best at different coolant temperatures can be obtained.

[0123] The second preset correspondence relationship can include multiple sets of correspondence relationships, and specifically can include the ratio between the fuel injection amounts of each injection in twice fuel injection, and can also include the ratio between the fuel injection amounts of each injection in three or more than three times fuel injection.

[0124] Further, according to the currently determined number of fuel injection times of the direct injection nozzle, the corresponding relationship of the corresponding number can be found in the second preset relationship.

[0125] For example, if it is determined that the number of fuel injection times of the direct injection nozzle is twice, the corresponding relationship between the current temperature of the coolant and the fuel injection amount ratio of each injection in twice fuel injection can be found in the second preset relationship.

[0126] For example, the corresponding relationship between the current temperature of the coolant and the fuel injection amount ratio of each injection in twice fuel injection can be as shown in Table 3.

[0127] Table 3

[0128] The injection ratio in Table 3 refers to the ratio between the injection amount of the first fuel injection of the direct injection nozzle and the injection amount of the second fuel injection of the direct injection nozzle.

[0129] It can be understood that as the coolant temperature gradually increases, the fuel atomization effect is better and better, and the injection amount ratio of the second injection can be appropriately increased to fully utilize the higher temperature to promote combustion. Therefore, as the current temperature of the coolant increases, the injection amount ratio of the second fuel injection of the direct injection nozzle tends to increase. However, when the current temperature of the coolant reaches 80℃, the volatility of the fuel is relatively good, and a single injection can provide sufficient fuel at the appropriate time to form combustible mixture, so the direct injection nozzle no longer performs multiple fuel injections, but performs fuel injection in the form of single injection.

[0130] For example, if it is determined that the GDI system performs fuel injection twice, the corresponding relationship between the current temperature of the coolant and the injection amount ratio of each injection during the two fuel injections is searched in the second preset relationship. If it is obtained that the current temperature of the coolant is -30℃, based on the corresponding relationship, it can be determined that the injection amount ratio of the two fuel injections is 8:2.

[0131] Further, if the determined first injection amount of the direct injection nozzle is 10 milliliters, based on the injection amount ratio of the two fuel injections, it can be determined that the first injection amount of the direct injection nozzle is 8 milliliters and the second injection amount of the direct injection nozzle is 2 milliliters, and the direct injection nozzle can be controlled to inject 8 milliliters of fuel for the first time and 2 milliliters of fuel for the second time.

[0132] In order to improve the success rate of engine cold start, the direct injection nozzle and the port injection nozzle can also be controlled to perform fuel injection at the appropriate time.

[0133] In one possible implementation, the control of the direct injection nozzle to perform fuel injection according to the first injection amount and the control of the port injection nozzle to perform fuel injection according to the second injection amount include: determining a first injection time when the direct injection nozzle performs fuel injection, and determining a second injection time when the port injection nozzle performs fuel injection; controlling the direct injection nozzle to perform fuel injection according to the first injection amount at the first injection time, and controlling the port injection nozzle to perform fuel injection according to the second injection amount at the second injection time.

[0134] It can be understood that the first injection time refers to the time when the direct injection nozzle starts to inject fuel, and the second injection time refers to the time when the port injection nozzle starts to inject fuel.

[0135] The time of injecting fuel can be represented by the rotation angle of the crankshaft relative to the compression top dead center. The compression top dead center is a specific position in the engine working cycle, in the compression stroke of the engine, the position where the piston moves to the highest point is called the compression top dead center, at this time, the piston is completely located at the top of the cylinder. The crankshaft is a mechanical component in the engine used to convert the linear reciprocating motion of the piston into rotary motion. The rotation angle of the crankshaft relative to the compression top dead center can be used to describe the occurrence time of various events inside the engine.

[0136] In some embodiments, when the rotation angle of the crankshaft relative to the compression top dead center is positive, it means 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; when the rotation angle of the crankshaft relative to the compression top dead center is negative, it means that the crankshaft has not reached the compression top dead center, that is, the crankshaft is at a certain position before the compression top dead center.

[0137] Further, the first injection time and the second injection time described above can be set according to the actual operation of the engine.

[0138] For example, in the initial stage of cold start of the engine, the current temperature of the coolant is low and the current speed of the engine is low, at this time, the volatility of the fuel is poor, it is not easy to become gaseous, so it is difficult to form a uniform mixture with air. The port injection nozzle usually injects fuel into the intake manifold or the air inlet, this part of the area is relatively high in temperature compared to the temperature in the cylinder, which helps the fuel to evaporate and atomize better. And the position of the port injection nozzle is close to the air inlet, the fuel has more time to mix with air before entering the cylinder, which helps to improve the combustion effect.

[0139] Therefore, in the initial stage of cold start of the engine, the port injection nozzle can be controlled to inject fuel. That is, the second injection time described above can be the starting time of the cold start of the engine.

[0140] As the temperature of the coolant increases, the volatility of the fuel increases, and it is easier to atomize, at this time, the fuel is directly injected into the cylinder through the direct injection nozzle, and the fuel in the cylinder can be fully mixed with air, thereby improving the combustion efficiency. Under high temperature conditions, fuel injected by direct injection is more likely to form a uniform mixture with air, which helps to improve the combustion efficiency. Therefore, as the temperature of the coolant increases, the direct injection nozzle can be controlled to inject fuel.

[0141] For example, a second preset temperature threshold can be set, and when the temperature of the coolant increases to 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 time described above can be the time when the temperature of the coolant increases to greater than or equal to the second preset temperature threshold.

[0142] Further, the injection timing of the direct injection nozzle is usually affected by the operating parameters of the engine, such as the engine speed and the engine load.

[0143] In a possible implementation, the first injection timing when the direct injection nozzle injects fuel is determined by: obtaining a current operating parameter of the engine; wherein the current operating parameter comprises a current speed and a current load; determining, based on a third preset correspondence relationship, a target start timing of fuel injection of the direct injection nozzle corresponding to the current operating parameter; wherein the third preset correspondence relationship is a correspondence relationship between an operating parameter and a start timing of fuel injection of the direct injection nozzle; the operating parameter comprises a speed and a load; determining, based on a fourth preset correspondence relationship, a target end timing of fuel injection of the direct injection nozzle corresponding to the current operating parameter; wherein the fourth preset correspondence relationship is a correspondence relationship between the operating parameter and an end timing of fuel injection of the direct injection nozzle; in a case where the number of fuel injection of the direct injection nozzle is multiple, determining, based on the target start timing and the target end timing, the first injection timing when the direct injection nozzle injects fuel each time.

[0144] It can be understood that, as described above, the speed of the engine is usually measured by a crank position sensor, and the unit is revolutions per minute (RPM).

[0145] The current load is usually estimated by a throttle position sensor, an intake manifold absolute pressure sensor, etc., and is used to reflect the load state of the engine, and is usually expressed by a percentage.

[0146] The third preset correspondence relationship can be obtained according to the results of experimental tests, and the third preset relationship can be a preset relationship table, which can be stored in the engine controller of the vehicle.

[0147] The third preset correspondence relationship is used to represent the relationship between the operating parameter of the engine (including the speed and the load of the engine) and the start timing of fuel injection of the direct injection nozzle.

[0148] For example, the third preset correspondence relationship between the operating parameter of the engine and the start timing of fuel injection of the direct injection nozzle can be as shown in Table 4:

[0149] Table 4

[0150] As described above, the injection timing of fuel can be represented by the angle of the crank relative to the compression top dead center. The start timing of fuel injection of the direct injection nozzle can actually be represented by the angle of the crank relative to the compression top dead center. For example, if it is determined that the start timing of fuel injection is 310 degrees, it means that the fuel injection starts when the crank rotates to an angle of 310 degrees relative to the compression top dead center.

[0151] For example, after obtaining the current speed and the current load of the engine, the target start time of fuel injection can be looked up in Table 4. For example, if the current speed of the engine is obtained as 400 RPM and the current load is obtained as 20%, it can be determined that the start of fuel injection occurs at a position 300 degrees after the compression top dead center.

[0152] Similarly, the fourth preset correspondence can be obtained according to test results, and the fourth preset correspondence can be a preset relationship table and can be stored in an engine controller of the vehicle.

[0153] The fourth preset correspondence is used to represent the relationship between the operating parameter of the engine (including the speed and the load of the engine) and the end time of fuel injection by the direct injection nozzle.

[0154] For example, the fourth preset correspondence between the operating parameter of the engine and the end time of fuel injection by the direct injection nozzle can be as shown in Table 5:

[0155] Table 5

[0156] As described above, the time of fuel injection can be represented by the rotation angle of the crankshaft relative to the compression top dead center. The end time of fuel injection by the direct injection nozzle can also be represented by the rotation angle of the crankshaft relative to the compression top dead center. For example, if the end time of fuel injection is determined as 100 degrees, it means that the fuel injection is ended when the rotation angle of the crankshaft relative to the compression top dead center is 100 degrees.

[0157] For example, after obtaining the current speed and the current load of the engine, the target end time of fuel injection can be looked up in Table 5. For example, if the current speed of the engine is obtained as 400 RPM and the current load is obtained as 20%, it can be determined that the end of fuel injection occurs at a position 80 degrees after the compression top dead center.

[0158] Further, in the case where the number of fuel injections by the direct injection nozzle is determined as multiple, the target start time is actually the start time of the first fuel injection by the direct injection nozzle, and the target end time is actually the end time of the last fuel injection by the direct injection nozzle.

[0159] Based on this, in the case where the number of fuel injections by the direct injection nozzle is determined as multiple, the start time of each fuel injection by the direct injection nozzle, i.e., the first injection time of each fuel injection, can be determined according to the target start time and the target end time.

[0160] In some embodiments, the specific time of each injection of the direct injection nozzle can be allocated according to the time interval between the target start time and the target end time and the determined number of injections of the direct injection nozzle.

[0161] Specifically, the total time span is obtained by subtracting the target start time from the target end time, and the average time interval between each injection is obtained by dividing the total time span by the number of injections.

[0162] For example, if the target start time is 300 degrees, i.e., the start of fuel injection occurs at a position 300 degrees after the compression top dead center, the target end time is 80 degrees, i.e., the end of fuel injection is determined to occur at a position 80 degrees after the compression top dead center, and the determined number of injections of the direct injection nozzle is 2, the total angle span is calculated to be 220 degrees, and the average angle span between the two injections is obtained by averaging the two injections, which is 110 degrees, and thus the first injection of fuel is determined to occur at a position 300 degrees after the compression top dead center, and the second injection of fuel can occur at a position 300 degrees-110 degrees=190 degrees after the compression top dead center.

[0163] In other embodiments, a correspondence between the operating parameters of the engine and the injection time can also be established in advance, and the start time of each injection of the direct injection nozzle is determined according to the current operating parameters of the engine.

[0164] It can be understood that the specific establishment method is similar to the establishment method of the third preset correspondence and the fourth preset correspondence described above, and will not be described here.

[0165] The above method determines the target start time and the target end time of fuel injection of the direct injection nozzle based on the current speed and the current load of the engine, which can make the fuel injected into the cylinder at the best time point. When the number of injections of the direct injection nozzle is determined to be multiple, the first injection time of each injection is determined based on the target start time and the target end time, which can achieve more precise fuel injection control. Moreover, the injection time of the direct injection nozzle is dynamically adjusted according to the actual working condition, which ensures that the engine can perform best in various working conditions and improves the reliability of the engine.

[0166] Further, in addition to determining the first injection time of fuel injection of the direct injection nozzle, the second injection time of fuel injection of the port injection nozzle can also be determined.

[0167] It can be understood that when fuel is injected during the opening of the valve, the fuel will directly enter the cylinder, and at this time, the airflow in the cylinder is not conducive to the full mixing of fuel and air. Therefore, the PFI system usually avoids controlling the port injection nozzle to inject fuel during the opening of the valve.

[0168] If the air path injection nozzle injects at the time when the intake valve is closed, the fuel can not have enough time to mix with the air sufficiently, thereby affecting the combustion effect. Based on this, when determining the second injection time, a suitable time between the opening and closing of the valve can be found, which can ensure that the fuel mixes with the air sufficiently and can form a uniform mixture when entering the cylinder.

[0169] In a possible implementation, the second injection time at which the air path injection nozzle injects fuel is determined by: obtaining an opening time of an intake valve of the engine, and obtaining an injection delay angle at which the air path injection nozzle injects fuel; wherein the injection delay angle is a crank angle between a start time of fuel injection by the air path injection nozzle and the opening time of the intake valve; and determining the second injection time at which the air path injection nozzle injects fuel based on the opening time of the intake valve and the injection delay angle.

[0170] It can be understood that the opening time of the intake valve can be represented by a crank angle relative to a compression top dead center. The opening time of the intake valve can be determined by a camshaft position sensor.

[0171] The injection delay angle refers to a crank angle between a start time of fuel injection by the air path injection nozzle and the opening time of the intake valve.

[0172] The injection delay angle can be determined according to current operating parameters of the engine, for example, can be determined according to a current temperature of the coolant, an intake temperature of air entering the engine, and a current speed of the engine.

[0173] In a possible implementation, the injection delay angle at which the air path injection nozzle injects fuel is obtained by: obtaining a current temperature of the coolant, an intake temperature of air entering an intake manifold of the engine, and a current speed of the engine; and determining the injection delay angle based on the current temperature of the coolant, the intake temperature of air, and the current speed of the engine.

[0174] It can be understood that the current temperature of the coolant can be measured by a coolant temperature sensor. The intake temperature of air entering the intake manifold of the engine can be measured by a temperature sensor. The current speed of the engine can be measured by a crankshaft position sensor.

[0175] Further, a fifth preset correspondence relationship between the coolant temperature, the intake temperature, and the engine speed and the injection delay angle can be established in advance, which can be obtained by actual experimental data and simulation analysis.

[0176] For example, if the current temperature of the coolant is -20℃, the intake air temperature is -15℃, and the current speed of the engine is 200 RPM, based on the fifth preset correspondence relationship, the corresponding injection delay angle can be determined as 10 degrees.

[0177] Further, after the injection delay angle is determined, a second injection time at which the port injection nozzle injects fuel can be determined based on the opening time of the intake valve and the injection delay angle.

[0178] For example, if the intake valve opens when the crankshaft rotates to -20 degrees relative to the compression top dead center, the injection delay angle is 10 degrees, and the crankshaft angle between the time at which the port injection nozzle starts to inject fuel and the opening time of the intake valve is 10 degrees, it can be determined that the port injection nozzle starts to inject fuel when the crankshaft rotates to -10 degrees relative to the compression top dead center.

[0179] The method determines the second injection time at which the port injection nozzle injects fuel based on the opening time of the intake valve and the injection delay angle, so that the fuel can be injected into the intake port at the most appropriate time, fully mixed with the intake air flow, and form a uniform mixture, thereby ensuring that the mixture reaches the best state when entering the cylinder, improving the combustion efficiency, and further improving the success rate of cold start of the engine.

[0180] In some embodiments, after the current temperature of the coolant is obtained, different fuel injection modes can be adopted based on the current temperature of the coolant to control the start of the engine.

[0181] For example, FIG. 2 is a schematic flowchart of an engine start method provided by an embodiment of the application.

[0182] As shown in FIG. 2, the method 200 includes:

[0183] S201, obtaining the current temperature of the coolant in the engine of the vehicle.

[0184] It can be understood that the current temperature of the coolant in the engine can also be referred to as the start water temperature of the engine. The current temperature of the coolant in the engine is usually measured by a coolant temperature sensor.

[0185] S202, in the case where the current temperature of the coolant is less than or equal to a first preset temperature threshold, adopting a GDI+PFI dual-injection injection mode to inject fuel to control the start of the engine.

[0186] It can be understood that the first preset temperature threshold can be the preset temperature threshold described above. The first preset temperature threshold can be set according to actual needs, for example, -20℃.

[0187] In a case where the current temperature of the coolant is less than or equal to the first preset temperature threshold, the engine start is a cold start at an extremely low temperature.

[0188] S203, in a case where the current temperature of the coolant is greater than the first preset temperature threshold and less than a second preset temperature threshold, fuel injection is performed in a GDI multiple injection mode to control the engine start.

[0189] It can be understood that the second preset temperature threshold can also be set according to actual needs, which can be set to be greater than the first temperature threshold, for example, 80℃.

[0190] In a case where it is determined that the current temperature is greater than the first preset temperature threshold and less than the second preset temperature threshold, the engine start is a cold start at a non-extremely low temperature.

[0191] S204, in a case where the current temperature of the coolant is greater than or equal to the second preset temperature threshold, fuel injection is performed in a GDI single injection mode to control the engine start.

[0192] It can be understood that in a case where it is determined that the current temperature is greater than or equal to the second preset temperature threshold, the engine has approached or reached a normal working temperature, and at this time the engine can also be successfully started in the GDI single injection mode.

[0193] The above method, in a case where the current temperature is less than or equal to the first preset temperature threshold, adopts a double injection strategy of direct injection nozzles and port injection nozzles, that is, a GDI+PFI double injection mode, which can control the port injection nozzles in the intake manifold injection system to spray fuel into the intake manifold, disperse the fuel better with the help of the intake air flow, form more uniform mixture, improve the combustion efficiency, and thus faster realize the engine start. In a case where the current temperature is greater than the first preset temperature threshold and less than the second preset temperature threshold, a GDI multiple injection strategy is adopted, that is, a GDI multiple injection mode, which can improve the fuel atomization level, make the in-cylinder mixture uniform, be more conducive to the spark plug ignition and start successfully, and improve the fuel economy. In a case where the current temperature is greater than or equal to the second preset temperature threshold, the atomization effect of the fuel is good, single injection is sufficient to form good mixture, multiple injection is not needed, and single injection can better control the fuel injection amount and fuel injection time, optimize the combustion process, and improve the combustion efficiency.

[0194] FIG. 3 is a structural schematic diagram of a cold start device of an engine provided by an embodiment of the present application.

[0195] For example, as shown in FIG. 3, the device 300 includes:

[0196] The acquisition module 301 is configured to acquire a current temperature of cooling liquid in an engine of the vehicle.

[0197] The determination module 302 is configured to, in a case where the current temperature is less than or equal to a preset temperature threshold, acquire a current rotating speed of the engine, and determine a first target fuel injection amount ratio between fuel injection amounts of direct injection nozzles and port injection nozzles of the engine based on the current temperature of the cooling liquid and the current rotating speed of the engine.

[0198] The control module 303 is configured to control 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 cold start of the engine.

[0199] In a possible implementation, the determination module is specifically configured to: determine a first target fuel injection amount ratio corresponding to the current temperature and the current rotating speed based on a first preset correspondence relationship; the first preset correspondence relationship is a correspondence relationship between a target parameter and a target fuel injection amount ratio; the target parameter includes a temperature of cooling liquid and a rotating speed of an engine; and the target fuel injection amount ratio is a fuel injection amount ratio of direct injection nozzles and port injection nozzles.

[0200] In a possible implementation, the control module is specifically configured to: determine a total fuel injection amount required for cold start of the engine; determine a first fuel injection amount corresponding to the direct injection nozzles and a second fuel injection amount corresponding to the port injection nozzles based on the total fuel injection amount and the first target fuel injection amount ratio; the sum of the first fuel injection amount and the second fuel injection amount is the total fuel injection amount; and control the direct injection nozzles to perform fuel injection according to the first fuel injection amount, and control the port injection nozzles to perform fuel injection according to the second fuel injection amount.

[0201] In a possible implementation, the control module includes a direct injection nozzle control unit, which is specifically configured to: in a case where the number of times of fuel injection performed by the direct injection nozzles is multiple, determine a second target fuel injection amount ratio corresponding to the current temperature of the cooling liquid based on a second preset correspondence relationship; the second preset correspondence relationship is a correspondence relationship between a temperature of cooling liquid and a fuel injection amount ratio of each injection in multiple fuel injection; the second target fuel injection amount ratio is a ratio between fuel injection amounts of each injection in multiple fuel injection performed by the direct injection nozzles; determine a single fuel injection amount of each fuel injection performed by the direct injection nozzles based on the first fuel injection amount and the second target fuel injection amount ratio; and control the direct injection nozzles to perform fuel injection according to the single fuel injection amount in each fuel injection.

[0202] In a possible implementation manner, the control module comprises a control unit, which is specifically configured to: determine a first injection time when the direct injection nozzle performs fuel injection, and determine a second injection time when the air path injection nozzle performs fuel injection; control the direct injection nozzle to perform fuel injection according to the first fuel injection amount at the first injection time, and control the air path injection nozzle to perform fuel injection according to the second fuel injection amount at the second injection time.

[0203] In a possible implementation manner, the control unit comprises a first determination unit, which is specifically configured to: acquire a current operating parameter of the engine; wherein the current operating parameter comprises a current speed and a current load; determine a target starting time when the direct injection nozzle performs fuel injection corresponding to the current operating parameter based on a third preset corresponding relationship; wherein the third preset corresponding relationship is a corresponding relationship between an operating parameter and a starting time when the direct injection nozzle performs fuel injection; the operating parameter comprises a speed and a load; determine a target ending time when the direct injection nozzle performs fuel injection corresponding to the current operating parameter based on a fourth preset corresponding relationship; wherein the fourth preset corresponding relationship is a corresponding relationship between the operating parameter and an ending time when the direct injection nozzle performs fuel injection; in a case where the number of times when the direct injection nozzle performs fuel injection is multiple, determine a first injection time when the direct injection nozzle performs fuel injection each time based on the target starting time and the target ending time.

[0204] In a possible implementation manner, the control unit comprises a second determination unit, which is specifically configured to: acquire an opening time of an intake valve of the engine, and acquire an injection delay angle when the air path injection nozzle performs fuel injection; wherein the injection delay angle is a crank angle between a starting time when the air path injection nozzle performs fuel injection and the opening time of the intake valve; determine a second injection time when the air path injection nozzle performs fuel injection based on the opening time of the intake valve and the injection delay angle.

[0205] In a possible implementation manner, the second determination unit comprises an acquisition unit, which is specifically configured to: acquire a current temperature of the cooling liquid, an intake temperature of air entering an intake manifold of the engine, and a current speed of the engine; determine the injection delay angle based on the current temperature of the cooling liquid, the intake temperature, and the current speed of the engine.

[0206] In a possible implementation manner, the control module is specifically configured to: determine a target oil pressure corresponding to the current temperature of the cooling liquid based on the current temperature of the cooling liquid; control a fuel pump of the engine to adjust fuel pressure inside the engine; in a case where the fuel pressure inside the engine reaches the target oil pressure, control the direct injection nozzle and the air path injection nozzle to perform fuel injection according to the first target fuel injection amount ratio, to control cold start of the engine.

[0207] Fig. 4 is a structural schematic diagram of a vehicle provided by an embodiment of the present application.

[0208] For example, as shown in Fig. 4, 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 configured to invoke and execute the executable program code 4011 to execute an engine cold start method.

[0209] In addition, an apparatus provided by an embodiment of the present application can include a memory and a processor, wherein the memory stores executable program code, and the processor is configured to invoke and execute the executable program code to execute an engine cold start method provided by an embodiment of the present application.

[0210] The apparatus can be divided into functional modules according to the above method examples, for example, each functional module can be provided, or two or more functions can be integrated into one processing module, and the integrated module can be implemented in the form of hardware. It should be noted that the division of modules in the embodiment is illustrative, and is only a logical function division. In actual implementation, another division mode can be used.

[0211] In the case of dividing each functional module according to each function, the apparatus can further include an acquisition module, a determination module, a control module, and the like. It should be noted that all related contents of each step involved in the above method embodiments can be referred to the function description of the corresponding functional module, and will not be repeated here.

[0212] It should be understood that the apparatus provided by the embodiment is used to execute the above engine cold start method, and thus can achieve the same effect as the above implementation method.

[0213] In the case of using an integrated unit, the apparatus can include a processing module and a storage module. When the apparatus is applied to a vehicle, the processing module can be used to control and manage the actions of the vehicle. The storage module can be used to support the vehicle to execute related program codes and data.

[0214] The processing module can be a processor or a controller, which can realize or execute various exemplary logical blocks, modules and circuits shown in combination with the disclosure of the present application. The processor can also be a combination of computing functions, such as one or more microprocessor combinations, digital signal processing (DSP) and microprocessor combinations, etc. The storage module can be a memory.

[0215] In addition, the apparatus provided by the embodiments of the present application can be a chip, a component, or a module, and the chip can include a processor and a memory connected to each other. The memory is used to store instructions, and when the processor invokes and executes the instructions, the chip can perform the cold start method of the engine provided by the above embodiments.

[0216] The embodiments also provide a computer-readable storage medium having computer program codes stored therein, and when the computer program codes are run on a computer, the computer is caused to perform the above related method steps to implement the cold start method of the engine provided by the above embodiments.

[0217] The embodiments also provide a computer program product, and when the computer program product is run on a computer, the computer is caused to perform the above related steps to implement the cold start method of the engine provided by the above embodiments.

[0218] The apparatus, the computer-readable storage medium, the computer program product, or the chip provided by the embodiments can be used to execute the corresponding method provided above, and thus the beneficial effects achieved by the apparatus, the computer-readable storage medium, the computer program product, or the chip can refer to the beneficial effects of the corresponding method provided above, which will not be repeated here.

[0219] From the above description of the embodiments, those skilled in the art can understand that, for the convenience and brevity, only the division of the above functional modules is taken as an example for description, and in actual application, the above functions can be completed by different functional modules according to needs, that is, the internal structure of the apparatus is divided into different functional modules to complete all or part of the functions described above.

[0220] In the embodiments provided by the present application, it should be understood that the disclosed apparatus and method can be implemented in other ways. For example, the above-described apparatus embodiments are only schematic, and the division of the modules or units is only a logical function division, and there can be another division manner in actual implementation, for example, a plurality of units or components can be combined or integrated into another apparatus, or some features can be ignored or not executed. In addition, the displayed or discussed mutual coupling or direct coupling or communication connection can be indirect coupling or communication connection through some interfaces, apparatuses or units, and can be electrical, mechanical or other forms.

[0221] The above is only a specific implementation of the present application, but the protection scope of the present application is not limited thereto, and any person skilled in the art can easily think of changes or replacements within the technical range disclosed by the present application, which should be covered within the protection scope of the present application. Therefore, the protection scope of the present application should be subject to the protection scope of the claims.

Claims

1. A cold start method of an engine, wherein, The engine comprises a direct injection nozzle and a port injection nozzle, and the method comprises: obtaining a current temperature of coolant in an engine of a vehicle; in a case where the current temperature is less than or equal to a preset temperature threshold, obtaining a current speed of the engine, and determining a first target fuel injection amount ratio between fuel injection amounts of the direct injection nozzle and the port injection nozzle of the engine based on the current temperature of the coolant and the current speed of the engine; controlling the direct injection nozzle and the port injection nozzle to perform fuel injection according to the first target fuel injection amount ratio, so as to control cold start of the engine.

2. The method of claim 1, wherein, The determination of the first target fuel injection amount ratio between fuel injection amounts of the direct injection nozzle and the port injection nozzle of the engine based on the current temperature of the coolant and the current speed of the engine comprises: determining a first target fuel injection amount ratio corresponding to the current temperature and the current speed based on a first preset correspondence relationship; wherein the first preset correspondence relationship is a correspondence relationship between a target parameter and a target fuel injection amount ratio; the target parameter comprises a temperature of coolant and a speed of an engine; and the target fuel injection amount ratio is a fuel injection amount ratio of the direct injection nozzle and the port injection nozzle.

3. The method of claim 1 or 2, wherein, The control of the direct injection nozzle and the port injection nozzle to perform fuel injection according to the first target fuel injection amount ratio comprises: determining a total fuel injection amount required for cold start of the engine; determining a first fuel injection amount corresponding to the direct injection nozzle and a second fuel injection amount corresponding to the port injection nozzle based on the total fuel injection amount and the first target fuel injection amount ratio; wherein the sum of the first fuel injection amount and the second fuel injection amount is the total fuel injection amount; controlling the direct injection nozzle to perform fuel injection according to the first fuel injection amount, and controlling the port injection nozzle to perform fuel injection according to the second fuel injection amount.

4. The method of claim 3, wherein, The control of the direct injection nozzle to perform fuel injection according to the first fuel injection amount comprises: in a case where the number of fuel injection times of the direct injection nozzle is determined to be multiple, determining a second target fuel injection amount ratio corresponding to the current temperature of the coolant based on a second preset correspondence relationship; wherein the second preset correspondence relationship is a correspondence relationship between a temperature of coolant and a fuel injection amount ratio of each fuel injection in multiple fuel injection; and the second target fuel injection amount ratio is a ratio between fuel injection amounts of the direct injection nozzle in multiple fuel injection; determining a single fuel injection amount of the direct injection nozzle in each fuel injection based on the first fuel injection amount and the second target fuel injection amount ratio; controlling the direct injection nozzle to perform fuel injection according to the single fuel injection amount in each fuel injection.

5. The method of claim 3, wherein, The control of the direct injection nozzle to perform fuel injection according to the first fuel injection amount and the control of the port injection nozzle to perform fuel injection according to the second fuel injection amount comprise: determining a first injection time of the direct injection nozzle and a second injection time of the port injection nozzle; controlling the direct injection nozzle to perform fuel injection at the first injection time, and controlling the port injection nozzle to perform fuel injection at the second injection time. The direct injection nozzle is controlled to inject fuel at the first injection time according to the first fuel injection amount, and the air path injection nozzle is controlled to inject fuel at the second injection time according to the second fuel injection amount.

6. The method of claim 5, wherein, The first injection time when the direct injection nozzle injects fuel is determined, and the second injection time when the air path injection nozzle injects fuel is determined. A current operating parameter of the engine is acquired, wherein the current operating parameter includes a current speed and a current load. A target start time when the direct injection nozzle injects fuel is determined according to the current operating parameter based on a third preset correspondence relationship, wherein the third preset correspondence relationship is a correspondence relationship between an operating parameter and a start time when the direct injection nozzle injects fuel, and the operating parameter includes a speed and a load. A target end time when the direct injection nozzle injects fuel is determined according to the current operating parameter based on a fourth preset correspondence relationship, wherein the fourth preset correspondence relationship is a correspondence relationship between the operating parameter and an end time when the direct injection nozzle injects fuel. In a case where the injection times when the direct injection nozzle injects fuel are multiple, the first injection time when the direct injection nozzle injects fuel each time is determined based on the target start time and the target end time.

7. The method of claim 5, wherein, The second injection time when the air path injection nozzle injects fuel is determined, and the injection delay angle when the air path injection nozzle injects fuel is determined. An opening time of an intake valve of the engine is acquired, and an injection delay angle when the air path injection nozzle injects fuel is acquired, wherein the injection delay angle is a crankshaft angle between a start time when the air path injection nozzle injects fuel and the opening time of the intake valve. The second injection time when the air path injection nozzle injects fuel is determined based on the opening time of the intake valve and the injection delay angle.

8. The method of claim 7, wherein, The injection delay angle when the air path injection nozzle injects fuel is acquired, and the current temperature of the coolant, an intake temperature of air entering an intake manifold of the engine, and a current speed of the engine are acquired. The injection delay angle is determined based on the current temperature of the coolant, the intake temperature, and the current speed of the engine. The direct injection nozzle and the air path injection nozzle are controlled to inject fuel according to the first target fuel injection amount ratio to control cold start of the engine, and the current temperature of the coolant is acquired.

9. The method of any one of claims 1 to 8, wherein, A target oil pressure corresponding to the current temperature of the coolant is determined. A fuel pump of the engine is controlled to adjust fuel pressure inside the engine. In a case where the fuel pressure inside the engine reaches the target oil pressure, the direct injection nozzle and the air path injection nozzle are controlled to inject fuel according to the first target fuel injection amount ratio to control cold start of the engine. The fuel pump of the engine is controlled to adjust fuel pressure inside the engine, and the current fuel pressure inside the engine is detected and compared with the target oil pressure.

10. The method of claim 9, wherein, If the current fuel pressure is less than the target oil pressure, the fuel pump is controlled to increase the fuel pressure inside the engine. ​ ​ If the current fuel pressure is greater than the target fuel pressure, the fuel pump is controlled to reduce the fuel pressure inside the engine.

11. The method of claim 3, wherein, The total fuel injection amount required for the cold start of the engine is determined by: obtaining a basic fuel injection amount required for the normal start of the engine; determining a correction coefficient based on the current state parameter of the engine; and determining the total fuel injection amount required for the cold start of the engine based on the basic fuel injection amount and the correction coefficient.

12. The method of claim 3, wherein, Before the control of the direct injection nozzle to inject fuel according to the first fuel injection amount, the method further comprises: determining a target injection mode of the direct injection nozzle based on the current temperature of the coolant and the current speed of the engine; wherein if 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, the target injection mode is determined to be multiple injection.

13. An engine cold start device wherein, The engine comprises a direct injection nozzle and a port injection nozzle, and the device comprises: an obtaining module configured to obtain a current temperature of coolant in an engine of a vehicle; a determining module configured to, if the current temperature is less than or equal to a preset temperature threshold, obtain a current speed of the engine, and determine, based on the current temperature of the coolant and the current speed of the engine, a first target fuel injection amount ratio between fuel injection amounts of the direct injection nozzle and the port injection nozzle of the engine; a control module configured to control the direct injection nozzle and the port injection nozzle to inject fuel according to the first target fuel injection amount ratio, so as to control the cold start of the engine.

14. A vehicle, wherein, The vehicle comprises: a memory configured to store executable program code; a processor configured to call and run the executable program code from the memory, so that the vehicle performs the method according to any one of claims 1 to 12.

15. A computer readable storage medium, wherein, The computer readable storage medium stores a computer program, which, when executed, implements the method according to any one of claims 1 to 12. The computer readable storage medium stores a computer program, which, when executed, implements the method according to any one of claims 1 to 12.

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