Control method of dual-fuel methanol-diesel dual direct injection engine and vehicle

Abstract

The invention provides a control method of a dual-fuel methanol-diesel dual direct injection engine and a vehicle, and the method comprises the following steps: determining the temperature working condition of the vehicle according to the environment temperature of the vehicle; under the extremely cold working condition, a diesel oil nozzle is controlled to inject diesel oil according to the first-time pre-injection, the second-time pre-injection, the third-time pre-injection and the main injection of each cycle, in the successive injection process, the corresponding angle of a crank angle in front of a compression top dead center is gradually reduced, and the injection amount is gradually increased; under the cold working condition, a diesel oil nozzle is controlled to inject diesel oil according to injection parameters corresponding to second-time pre-injection, third-time pre-injection and main injection; under the normal-temperature working condition, a diesel oil nozzle is controlled to inject diesel oil according to injection parameters corresponding to third-time pre-injection and main injection; and under the high-temperature working condition, a dual-fuel mode is directly entered, the diesel nozzle is controlled to inject diesel, and the methanol nozzle is controlled to inject methanol. Through the control method provided by the invention, the problem of poor cold starting performance caused by adopting a single diesel injection rate in the cold starting stage is solved.

Description

TECHNICAL FIELD

[0001] The application relates to the technical field of internal combustion engine control, in particular to a control method of a dual-fuel methanol-diesel dual direct injection engine and a vehicle. BACKGROUND

[0002] The methanol-diesel dual direct injection engine realizes the collaborative combustion of two fuels by virtue of the in-cylinder direct injection technology, and compared with a single-fuel engine, can reduce emissions under the premise of guaranteeing power performance, and has obvious advantages in fuel cost. However, due to the physical and chemical properties of methanol fuel, the methanol-diesel dual direct injection engine still has technical bottlenecks in the cold start stage.

[0003] Methanol has high latent heat of vaporization and low volatility, so that in a low-temperature environment, it is difficult to form a combustible mixture in the cylinder, and needs to rely on diesel to ignite. The traditional control strategy usually adopts fixed proportion of diesel pre-injection, so as to use the heat of diesel combustion to improve the cylinder temperature in the compression stroke. However, the number of diesel injection and the injection amount under this control strategy are the same at different ambient temperatures, thus having the following disadvantages: Insufficient preheating time: under extremely cold conditions with too low ambient temperature, the heat released by the combustion of diesel with fixed injection amount cannot effectively improve the cylinder temperature, resulting in incomplete evaporation of methanol, a large amount of liquid methanol will flush the cylinder wall and dilute the lubricating oil, and then cause a series of problems such as prolonged idle period, unstable combustion and oil dilution.

[0004] Excessive preheating time: in the case of gradually increasing ambient temperature, the heat released by the combustion of diesel with fixed injection amount is too much, which will cause a series of problems such as high combustion temperature, deteriorated emissions and decreased fuel economy. SUMMARY

[0005] In view of the above problems, the application provides a control method of a dual-fuel methanol-diesel dual direct injection engine and a vehicle to solve the problem of poor cold start performance caused by single diesel injection rate in the cold start stage.

[0006] In a first aspect, the application provides a control method of a dual-fuel methanol-diesel dual direct injection engine, which adopts the technical scheme of: A control method of a dual-fuel methanol-diesel dual direct injection engine, applied to a vehicle with a dual-fuel engine, wherein the dual-fuel engine is configured with a methanol nozzle for injecting methanol and a diesel nozzle for injecting diesel; the method comprises: obtaining the ambient temperature of the vehicle; determining the target temperature interval to which the ambient temperature belongs from four preset temperature intervals; wherein the four preset temperature intervals correspond to extremely cold conditions, cold conditions, normal temperature conditions and high temperature conditions respectively; In a case where the target temperature range corresponds to the extremely cold working condition, the diesel nozzle is controlled to spray the diesel according to injection parameters corresponding to the first pre-injection, the second pre-injection, the third pre-injection and the main injection, and the injection parameters of the first pre-injection, the second pre-injection, the third pre-injection and the main injection satisfy that the angle of the corresponding compression top dead center before crank angle gradually decreases and the injection quantity gradually increases. In a case where the target temperature range corresponds to the cold working condition, the diesel nozzle is controlled to spray the diesel according to the injection parameters corresponding to the second pre-injection, the third pre-injection and the main injection. In a case where the target temperature range corresponds to the normal temperature working condition, the diesel nozzle is controlled to spray the diesel according to the injection parameters corresponding to the third pre-injection and the main injection. In a case where the target temperature range corresponds to the high temperature working condition, the dual-fuel mode is directly entered, the diesel nozzle is controlled to spray the diesel, and the methanol nozzle is controlled to spray the methanol.

[0007] Optionally, the method further comprises: acquiring a coolant temperature of the vehicle; controlling the methanol pressure to be a preset pressure according to the completion of the injection of the diesel nozzle; judging whether the dual-fuel engine enters the dual-fuel mode according to the coolant temperature after the temperature rise; in a case where the dual-fuel engine enters the dual-fuel mode, determining a methanol replacement rate matched with a preset coolant temperature corresponding to the preset coolant temperature according to the coolant temperature and a plurality of preset coolant temperatures, wherein the plurality of preset coolant temperatures include a first coolant temperature, a second coolant temperature and a third coolant temperature; in a case where the coolant temperature rises to the first coolant temperature, controlling the methanol nozzle to start spraying the methanol, so that an initial methanol replacement rate is a first preset value; during a period in which the coolant temperature gradually rises from the first coolant temperature to the second coolant temperature, controlling the methanol nozzle to gradually increase the injection of the methanol, so that the methanol replacement rate gradually increases to a second preset value; during a period in which the coolant temperature gradually rises from the second coolant temperature to the third coolant temperature, controlling the methanol nozzle to gradually increase the injection of the methanol, so that the methanol replacement rate gradually increases to a third preset value; wherein the first preset value, the second preset value and the third preset value increase from small to large.

[0008] Optionally, the injection parameters of the first pre-injection, the second pre-injection, the third pre-injection and the main injection satisfy that the corresponding compression top dead center crank angle gradually decreases and the injection quantity gradually increases, including: controlling the diesel nozzle to inject the diesel at a compression top dead center crank angle of 120 degrees, with an injection quantity of 5 mg per cycle, to complete the first pre-injection of the diesel; controlling the diesel nozzle to inject the diesel at a compression top dead center crank angle of 60 degrees, with an injection quantity of 8 mg per cycle, to complete the second pre-injection of the diesel; controlling the diesel nozzle to inject the diesel at a compression top dead center crank angle of 30 degrees, with an injection quantity of 10 mg per cycle, to complete the third pre-injection of the diesel; controlling the diesel nozzle to inject the diesel at a compression top dead center crank angle of 10 degrees, with an injection quantity of 20 mg per cycle, to complete the main injection of the diesel.

[0009] Optionally, after controlling the gradual increase of the methanol injection quantity of the methanol nozzle, the method further comprises: obtaining an operating parameter of the dual-fuel engine; the operating parameter includes at least one of a crankshaft speed, a crankshaft angular acceleration, an in-cylinder pressure rise rate and a methanol temperature; judging whether the operating parameter is lower than a steady-state threshold parameter; in the case that the operating parameter is lower than the steady-state threshold parameter, controlling the output power of the dual-fuel engine to be unchanged, controlling the diesel nozzle to increase the injection quantity of the diesel, and controlling the methanol nozzle to decrease the injection quantity of the methanol, so as to reduce the methanol replacement rate.

[0010] Optionally, after controlling the gradual increase of the methanol injection quantity of the methanol nozzle, the method further comprises: obtaining a real-time operating parameter of the vehicle; the real-time operating parameter includes at least one of a throttle pedal position, an intake pressure and a crankshaft speed of the dual-fuel engine; identifying a real-time operating condition of the vehicle based on the real-time operating parameter; obtaining a load rate of the dual-fuel engine under the real-time operating condition; determining a methanol replacement rate range corresponding to a preset load interval according to the load rate and a plurality of preset load intervals; wherein the plurality of preset load intervals include a low load interval, a medium load interval and a high load interval divided in the order of load rate range from low to high; controlling the methanol nozzle to inject the methanol in a first methanol replacement rate range based on the low load interval; control the methanol nozzle to inject the methanol in a second methanol replacement rate range based on the medium load range; control the methanol nozzle to inject the methanol in a third methanol replacement rate range based on the high load range; wherein, an upper limit of the first methanol replacement rate range is less than a lower limit of the second methanol replacement rate range, and an upper limit of the second methanol replacement rate range is less than a lower limit of the third methanol replacement rate range.

[0011] Optionally, after controlling the methanol nozzle to inject the methanol in the corresponding methanol replacement rate range, the method further comprises: obtaining a throttle opening degree change rate of the vehicle under the real-time operating condition; determining whether the throttle opening degree change rate is greater than a change threshold parameter; in the case that the throttle opening degree change rate is greater than the threshold operating parameter, controlling the output power of the dual-fuel engine to be unchanged, controlling the diesel nozzle to instantaneously inject the diesel with an injection amount that increases by a preset amount per cycle, controlling the methanol nozzle to inject the methanol in a reduced amount so as to reduce the methanol replacement rate to be less than the lower limit of the first methanol replacement rate range, and controlling the actuator that increases the intake air pressure to be executed.

[0012] Optionally, the method further comprises: obtaining a common rail pressure parameter, a methanol nozzle inlet pressure parameter and a methanol temperature of a methanol system of the vehicle; determining whether the common rail pressure parameter and the methanol nozzle inlet pressure parameter are less than a preset injection pressure, and determining whether the methanol temperature is greater than a preset temperature; in the case that the common rail pressure parameter and the methanol nozzle inlet pressure parameter are less than the preset injection pressure, or the methanol temperature is greater than the preset temperature, determining that the methanol system is faulty; obtaining a diesel nozzle current parameter and a high-pressure common rail pressure parameter of a diesel system of the vehicle; determining whether the diesel nozzle current parameter is abnormal, and determining whether the high-pressure common rail pressure parameter exceeds a preset pressure range; in the case that the diesel nozzle current parameter is abnormal, or the high-pressure common rail pressure parameter exceeds the preset pressure range, determining that the diesel system is faulty; in the case that the common rail pressure parameter and the methanol nozzle inlet pressure parameter are less than the preset injection pressure, and the diesel nozzle current parameter is abnormal, determining that it is a compound fault.

[0013] Optionally, after determining that the diesel system is faulty, the method further comprises: In the case of failure of the methanol system, the methanol nozzle is controlled to stop injection, the diesel system is switched to operate alone, and methanol system failure information is outputted; After determining the failure of the diesel system, the method further comprises: In the case of failure of the diesel injection system, the power of the dual-fuel engine is controlled to reduce to a preset power, a backup diesel nozzle is started, and diesel system failure information is outputted; After determining the compound failure, the method comprises: In the case of failure of both the methanol system and the diesel system, the dual-fuel engine is controlled to stop operating, and audible and visual alarm information is outputted.

[0014] The application also provides a vehicle configured with a dual-fuel engine comprising a methanol nozzle for injecting methanol and a diesel nozzle for injecting diesel, the vehicle further comprising: A methanol system configured with a first pressure sensor, a second pressure sensor and a temperature sensor, the first pressure sensor being used to acquire a common rail pressure parameter of the methanol system, the second pressure sensor being used to acquire a methanol nozzle inlet pressure parameter of the methanol system, and the temperature sensor being used to acquire a methanol temperature of the methanol system; A diesel system configured with a diesel nozzle, a diesel nozzle sensor and a high-pressure common rail pressure sensor, the diesel nozzle sensor being used to acquire a diesel nozzle current parameter of the diesel nozzle, and the high-pressure common rail pressure sensor being used to acquire a high-pressure common rail pressure parameter of the diesel system; A controller used to execute the control method of the dual-fuel methanol-diesel dual direct injection engine as described above.

[0015] Optionally, the vehicle further comprises a backup diesel nozzle used to start in the case of failure of the diesel system.

[0016] The application has the following advantages: When the control method of the dual-fuel methanol-diesel dual direct injection engine provided by the embodiment of the application is implemented, four working conditions of extreme cold, cold, normal temperature and high temperature are divided according to the ambient temperature, and the pre-injection frequency and injection parameters are adjusted in stages, the low-temperature multiple small-capacity pre-injection gently raises the temperature and avoids the wet wall effect caused by low temperature. As the temperature rises, the pre-injection frequency is reduced or even cancelled, avoiding high combustion temperature, deteriorated emissions and reduced fuel economy. The embodiment can dynamically adjust the injection parameters of the engine during the cold start stage according to the actual ambient temperature, avoiding the problems of insufficient or excessive preheating under the fixed diesel injection amount strategy, and significantly improving the cold start performance.

[0017] The vehicle has the same advantages as the control method described above has over the prior art, and thus will not be described here. BRIEF DESCRIPTION OF DRAWINGS

[0018] In order to more clearly illustrate the technical solutions of the present application, the following will briefly introduce the drawings needed to be used in the description of the present application. Obviously, the drawings in the following description are only some embodiments of the present application, and other drawings can be obtained by those skilled in the art without any creative labor.

[0019] Figure 1 is a step flow chart of the control method of the dual-fuel methanol-diesel dual direct injection engine according to an embodiment of the present application; Figure 2 is a flow principle diagram of the control method of the dual-fuel methanol-diesel dual direct injection engine according to an embodiment of the present application under the cold start link; Figure 3 is a flow principle diagram of the control method of the dual-fuel methanol-diesel dual direct injection engine according to an embodiment of the present application under the dynamic working condition link; Figure 4 is a flow principle diagram of the control method of the dual-fuel methanol-diesel dual direct injection engine according to an embodiment of the present application under the fault diagnosis link. DETAILED DESCRIPTION

[0020] The technical solutions in the embodiments of the present application will be described clearly and completely in the following with reference to the drawings in the embodiments of the present application. Obviously, the described embodiments are only some embodiments of the present application, not all the embodiments. Based on the embodiments in the present application, all the other embodiments obtained by those skilled in the art without any creative labor are within the scope of protection of the present application.

[0021] It should be noted that the control strategy of the existing methanol-diesel dual direct injection engine has technical bottlenecks in the links of cold start, dynamic working condition and fault diagnosis, which seriously affect the performance and reliability of the engine.

[0022] In the cold start link, due to the different combustion characteristics of methanol and diesel, and the great influence of environmental temperature on fuel vaporization and combustion, if the number of diesel injection and the injection amount are not adjusted according to the gradient change of the environmental temperature, it will lead to insufficient preheating in extremely cold conditions and incomplete evaporation of methanol, and in higher temperature conditions, it is easy to have excess heat, which affects fuel economy and emission performance. And after the diesel is ignited, there is no relationship between the replacement rate of methanol and the coolant temperature, which makes the precision of the dual-fuel engine fuel ratio control insufficient, and it is difficult to balance the combustion stability, fuel economy and emission performance under different thermal states.

[0023] During dynamic operating conditions, such as acceleration or under load, existing strategies mostly control the methanol substitution rate based on steady-state MAPs, which fail to track dynamic load changes in real time. For example, when the accelerator pedal position changes suddenly, the adjustment of the methanol injection rate lags, resulting in delayed power response. Furthermore, under high load, the methanol burns too quickly, which can easily cause knock.

[0024] Existing systems have a limited approach to fault diagnosis, often relying on a single sensor signal to determine faults. These systems lack the ability to independently diagnose both the methanol and diesel systems. For example, an abnormal methanol injection pressure could lead to a misdiagnosis of a methanol injection system failure, leading to a switch to pure diesel mode, impacting engine reliability. Furthermore, the system's ability to identify combined methanol-diesel faults is insufficient, making it impossible to quickly locate the fault point.

[0025] Therefore, there is an urgent need for a methanol-diesel dual direct injection engine control strategy and vehicle that optimizes cold start performance, improves dynamic operating response, and improves fault diagnosis logic, so as to take into account cold start stability, smooth dynamic operating conditions, and accurate fault detection.

[0026] First, cold starting is a key challenge facing methanol-diesel dual direct injection engines. The primary purpose of the present invention is to address the numerous issues inherent in cold starting with dual-fuel engines. This approach aims to optimize cold starting performance by implementing staged diesel preheating and methanol introduction according to varying ambient temperatures. To achieve this goal, the present invention specifically proposes a control method for a dual-fuel methanol-diesel dual direct injection engine. This method is applicable to vehicles equipped with a dual-fuel engine equipped with a methanol nozzle for injecting methanol and a diesel nozzle for injecting diesel. Dual-fuel methanol-diesel direct injection engines utilize a dual-fuel combustion mode, allowing the injection ratio of either fuel to be adjusted to control the engine's combustion state. Dual direct injection engines typically consist of two independent diesel and methanol systems, with diesel and methanol nozzles positioned in the engine combustion chambers. These two systems utilize a high-pressure common rail system to inject diesel directly into the cylinders through the diesel nozzle and methanol directly into the methanol nozzle.

[0027] like Figure 1 As shown, Figure 1 A flowchart showing the steps of a control method for a dual-fuel methanol-diesel dual direct injection engine according to an embodiment of the present invention; The method comprises the following steps: S1. Obtain the vehicle's ambient temperature; Before starting the dual-fuel engine, different ambient temperatures are collected by the ambient temperature sensor, and the temperature range is selected to divide it into multiple preset temperature intervals in order of temperature from small to large. The multiple preset temperature intervals correspond to different temperature conditions of the vehicle in turn. The injection parameters of the diesel nozzle are set for each condition, such as injection times, injection time, and injection amount. Through fine temperature interval grading, more accurate basis can be provided for subsequent preheating and fuel control.

[0028] S2, from the four preset temperature intervals, determine the target temperature interval to which the ambient temperature belongs; wherein the four preset temperature intervals correspond to extremely cold conditions, cold conditions, normal temperature conditions and high temperature conditions respectively; In the process of setting multiple preset temperature intervals, the ambient temperature range can be divided into four preset temperature intervals in order from small to large. Specifically, the ambient temperature ≤-15℃ is the first preset temperature interval, corresponding to the extremely cold condition; -15℃<ambient temperature≤0℃ is the second preset temperature interval, corresponding to the cold condition; 0℃<ambient temperature≤15℃ is the third preset temperature interval, corresponding to the normal temperature condition; and ambient temperature>15℃ is the fourth preset temperature interval, corresponding to the high temperature condition.

[0029] After the four preset temperature intervals are set, when the dual-fuel engine starts, the ambient temperature is compared with the four preset temperature intervals according to the ambient temperature obtained in real time during the actual operation of the vehicle in step S1, and the target temperature interval to which the ambient temperature belongs is determined. The target temperature interval is any one of the four preset temperature intervals. Since the four preset temperature intervals correspond to four conditions, after the target temperature interval is obtained, it can be determined whether the vehicle is in the extremely cold condition, the cold condition, the normal temperature condition or the high temperature condition.

[0030] S3, in the case that the target temperature interval corresponds to the extremely cold condition, the diesel nozzle is controlled to inject diesel according to the injection parameters corresponding to the first pre-injection, the second pre-injection, the third pre-injection and the main injection per cycle. The injection parameters of the first pre-injection, the second pre-injection, the third pre-injection and the main injection meet the following conditions: the angle of the corresponding compression top dead center crank angle gradually decreases, and the injection amount gradually increases; When the ambient temperature is in the first preset temperature interval, the first preset temperature interval is the target temperature interval, and the vehicle is in the extremely cold condition. Under such extremely cold conditions, it is very difficult for methanol to vaporize, so only diesel is injected for cylinder preheating at the initial stage of starting, and the diesel injection adopts a strategy of "three pre-injections + main injection" for a total of four injections per cycle.

[0031] During the three pilot injections, the first one preheats the combustion chamber and its walls to form an ignition core. The second one raises the in-cylinder temperature and improves mixing uniformity. The third one further preheats combustion stability, creating an optimal ignition environment for the main injection. The main injection delivers the primary fuel to achieve the primary work and stable combustion.

[0032] In order to achieve the corresponding purpose of each pilot injection, this embodiment sets the injection parameters of the first pilot injection, the second pilot injection, the third pilot injection and the main injection to meet the following requirements: the corresponding crankshaft angle before compression top dead center gradually decreases and the injection amount gradually increases.

[0033] During diesel injection, the gradual decrease in crankshaft angle before compression top dead center indicates that the injection timing is approaching ignition. The further away from the ignition timing, the longer the diesel has to mix with the air to form a combustible mixture, which helps stabilize the in-cylinder temperature. The closer to the ignition timing, the easier it is to ignite, which contributes to efficient power output. The crankshaft angle signal is measured by the crankshaft angle sensor.

[0034] The diesel injection rate also increases from the first pilot injection to the third pilot injection and finally to the main injection, with the highest injection rate during the main injection to ensure reliable ignition. In this way, multiple pilot injections in extremely cold conditions form a progressive injection pattern with small injections early and large injections later. This gradually increases the temperature, reduces unburned fuel adhesion to the cylinder wall, and ensures that the cylinder pressure and temperature reach high levels during the later main injection, making the high injection rate of diesel easier to ignite and improving thermal efficiency.

[0035] It is worth mentioning that the injection parameters using this injection law can maintain a balance between combustion stability and power output under the other three operating conditions except extreme cold conditions. In particular, it can significantly shorten the starting delay period and inhibit oil dilution under extreme cold conditions and cold conditions.

[0036] S4. When the target temperature range corresponds to a cold operating condition, controlling the diesel nozzle to inject diesel with injection parameters corresponding to the second pilot injection, the third pilot injection, and the main injection; When the ambient temperature is within the second preset temperature range, which is the target temperature range, the vehicle is considered to be operating in cold conditions. Cold temperatures are already slightly higher, making methanol vaporization more difficult. During the initial start, only diesel is injected to preheat the cylinder. Therefore, compared to the injection strategy for extremely cold conditions, the total number of injections in cold conditions is reduced from four to three. Diesel injection adopts a "two pre-injections + main injection" strategy, totaling three injections per cycle.

[0037] In the two pre-injection processes, the cold condition cancels the first pre-injection compared to the extremely cold condition, and the second pre-injection in the extremely cold condition is used as the first pre-injection in the cold condition, that is, the injection time (the angle of the compression top dead center before the crankshaft rotates) and the injection amount of the first pre-injection are consistent with the second pre-injection in the extremely cold condition. Correspondingly, the injection time and the injection amount of the second pre-injection are consistent with the third pre-injection in the extremely cold condition.

[0038] S5, in the case that the target temperature interval corresponds to the normal temperature condition, controlling the diesel nozzle to inject diesel according to the injection parameters corresponding to the third pre-injection and the main injection; When the ambient temperature is in the third preset temperature interval, the third preset temperature interval is the target temperature interval, and the vehicle corresponds to the normal temperature condition. The temperature in the normal temperature condition is high enough, and the influence of the ambient temperature on the fuel is relatively small, so the methanol can be introduced earlier and more. Therefore, compared with the injection strategy in the extremely cold condition, the total injection number in the normal temperature condition is reduced from four to two, and the diesel injection adopts the strategy of "one pre-injection + main injection" with a total of two injections per cycle.

[0039] In the pre-injection process, the normal temperature condition cancels the first pre-injection and the second pre-injection compared to the extremely cold condition, and the third pre-injection in the extremely cold condition is used as the first pre-injection in the normal temperature condition, that is, the injection time and the injection amount of the first pre-injection are consistent with the third pre-injection in the extremely cold condition.

[0040] S6, in the case that the target temperature interval corresponds to the high temperature condition, directly entering the dual-fuel mode, controlling the diesel nozzle to inject diesel, and controlling the methanol nozzle to inject methanol.

[0041] When the ambient temperature is in the fourth preset temperature interval, the fourth preset temperature interval is the target temperature interval, and the vehicle corresponds to the high temperature condition. The temperature in the high temperature condition is high enough, the methanol can be easily vaporized, and can better cooperate with diesel to burn, so the dual-fuel mode can be directly used. In the dual-fuel mode, the vehicle-mounted controller controls the injection amount and injection time of diesel and the injection amount and injection time of methanol, which can adopt the same cycle injection or phased injection of in-cylinder direct injection of methanol and in-cylinder direct injection of diesel, which is not limited in the embodiment.

[0042] It should be noted that the pre-injection can be used to improve the in-cylinder temperature, improve the formation of the mixture, and create better conditions for the ignition of the main injection. The fuel amount and injection time of the main injection directly determine the power output of the engine and the thermal efficiency of the main combustion stage. Therefore, the injection parameters of the diesel nozzle during the main injection in the four conditions in steps S3-S6 are preferably consistent, so that the engine can achieve high output performance in different conditions.

[0043] In some embodiments, the injection parameters of each pre-injection, such as the injection timing, injection quantity, and injection pressure, can also be independently optimized according to the engine operating state, ambient temperature, coolant temperature, intake pressure, and methanol replacement rate, without needing to be consistent with the injection parameters used at a certain pre-injection in other working conditions.

[0044] Of course, in other embodiments, the total number of injections per cycle of the diesel nozzle in each working condition can also be selected, for example, a control strategy of four pre-injections + main injection is used in extremely cold working conditions. In this embodiment, each cycle is each compression stroke, which is a 180° crank angle segment in which the piston moves from bottom dead center to top dead center.

[0045] In this way, the embodiments of the present application divide the extremely cold, cold, normal temperature, and high temperature working conditions according to the ambient temperature, and adjust the pre-injection quantity and injection parameters in stages. The low-temperature multiple small-capacity pre-injection gently raises the temperature and avoids the wet wall effect caused by low temperature. As the temperature rises, the number of pre-injections is reduced or even cancelled, avoiding high combustion temperature, deteriorating emissions, and fuel economy. The embodiments of the present application can dynamically adjust the injection parameters of the engine during the cold start stage according to the actual ambient temperature, avoiding the problem of insufficient or excessive heating under the fixed diesel injection quantity strategy, and significantly improving the cold start performance.

[0046] In some embodiments, the gradually decreasing angle of the compression top dead center before the crank angle corresponding to the three pre-injections and the main injection can be that the pre-injection timing in the next pre-injection process moves a fixed crank angle relative to the last pre-injection, or the angle change amount between adjacent two pre-injection processes can be gradually reduced, for example, the difference in the compression top dead center before the crank angle between the first pre-injection and the second pre-injection is the largest, and the difference between the second and the third is smaller. Similarly, the gradually increasing injection quantity can be that the fuel quantity in the next pre-injection process increases by a fixed increment relative to the last pre-injection, or the pre-injection quantity difference between the first pre-injection and the second pre-injection can be the smallest, and the increment between the second and the third, and the third and the main injection gradually increases.

[0047] In a preferred embodiment, step S3 further comprises: S301, controlling the diesel nozzle to inject five milligrams of diesel per cycle at a compression top dead center before a crank angle of 120 degrees to complete the first pre-injection of diesel to form an ignition core.

[0048] S302, controlling the diesel nozzle to inject eight milligrams of diesel per cycle at a compression top dead center before a crank angle of 60 degrees to complete the second pre-injection of diesel to raise the in-cylinder temperature; S303, controlling the diesel nozzle to inject ten milligrams of diesel per cycle at a compression top dead center before a crank angle of 30 degrees to complete the third pre-injection of diesel to further preheat the combustion chamber; S304, control the diesel nozzle to spray 20 milligrams per cycle of diesel before the compression top dead center ten degrees of crank angle, complete the main injection of diesel to realize stable combustion.

[0049] Similarly, step S4 further comprises: S401, the same as step S302, complete the first pre-injection of diesel under cold working condition; S402, the same as step S303, complete the second pre-injection of diesel under cold working condition; S403, the same as step S304, complete the main injection.

[0050] Similarly, step S5 further comprises: S501, the same as step S303, complete the first pre-injection of diesel under normal temperature working condition; S502, the same as step S304, complete the main injection.

[0051] As Figure 2 shown, Figure 2 the flow principle diagram of the control method of the dual-fuel methanol-diesel dual direct injection engine under the cold start link is shown. In order to further optimize the cold start performance, another purpose of the embodiment of the present application is to solve the problem of insufficient control accuracy of methanol replacement rate of dual-fuel engine under cold start link, and a control strategy of hierarchical preheating combined with dynamic climbing of methanol replacement rate is proposed. The method further comprises: S7, obtaining the cooling liquid temperature of the vehicle; The cooling liquid temperature directly reflects the engine body temperature and can be used to monitor the engine thermal state and as a correlation factor for adjusting the methanol replacement rate. The methanol replacement rate is the percentage of the chemical energy provided by methanol in the total chemical energy of all fuels in one complete working cycle of a dual-fuel (diesel-methanol) engine. In this embodiment, the cooling liquid temperature can be collected in real time by the cooling liquid temperature sensor installed in the engine cooling system.

[0052] S8, controlling the methanol pressure to be a preset pressure according to the injection completion of the diesel nozzle; After the diesel injection is completed under the corresponding working condition, the diesel pre-injection fuel directly heats the cooling liquid, raises the cooling liquid temperature to the preset starting temperature, and maintains the methanol pressure at 80MPa through the high-pressure common rail system.

[0053] S9, judging whether the dual-fuel engine enters the dual-fuel mode according to the temperature of the heated cooling liquid; In the process of heating the cooling liquid, it is determined whether the temperature of the heated cooling liquid reaches a preset starting temperature. After the diesel nozzle injection is completed and the temperature of the cooling liquid is the preset starting temperature, it is considered that the engine has entered a normal running stage. In the normal running stage, the engine enters a dual-fuel mode, and the cold start link is completed. After entering the dual-fuel mode, methanol can be started to be injected. The preset starting temperature can be set to 20°C.

[0054] S10, in the case that the dual-fuel engine enters the dual-fuel mode, according to the cooling liquid temperature and a plurality of preset cooling liquid temperatures, a methanol replacement rate matched with a corresponding preset cooling liquid temperature is determined; wherein the plurality of preset cooling liquid temperatures include a first cooling liquid temperature, a second cooling liquid temperature and a third cooling liquid temperature; In this embodiment, a plurality of preset cooling liquid temperatures are set according to the high and low of the cooling liquid temperature. Each preset cooling liquid temperature corresponds to a methanol injection amount, thereby corresponding to a certain preset value of the methanol replacement rate. The target preset cooling liquid temperature to which the cooling liquid temperature belongs is determined, and the specific preset value of the methanol replacement rate matched with the target preset cooling liquid temperature is obtained. When the cooling liquid temperature gradually rises from the preset starting temperature to each preset cooling liquid temperature, the methanol nozzle can be controlled to increase injection to the methanol injection amount corresponding to the target preset cooling liquid temperature, so that the methanol replacement rate is increased to the corresponding preset value.

[0055] Specifically, according to the cooling liquid temperature, the cooling liquid temperature is divided into a first cooling liquid temperature, a second cooling liquid temperature and a third cooling liquid temperature. The first cooling liquid temperature corresponds to a methanol replacement rate with a first preset value; the second cooling liquid temperature corresponds to a methanol replacement rate with a second preset value; and the third cooling liquid temperature corresponds to a methanol replacement rate with a third preset value. The first cooling liquid temperature, the second cooling liquid temperature and the third cooling liquid temperature are from small to large, and the corresponding methanol replacement rate is also from small to large.

[0056] Exemplarily, the first cooling liquid temperature is preferably 20°C, and the first preset value is 20%, which is the same as the preset starting temperature. When the temperature of the cooling liquid reaches 20°C, methanol can be started to be injected, and the injection amount of methanol is controlled to an initial methanol replacement rate of 20%. The second cooling liquid temperature can be 50°C, and the second preset value is 50%. The third cooling liquid temperature can be 80°C, and the third preset value is any one of 80%-90%.

[0057] S11, when the temperature of the cooling liquid rises to reach the first cooling liquid temperature, the methanol nozzle is controlled to start injecting methanol, so that the initial methanol replacement rate is the first preset value; When the coolant temperature reaches 20°C, the introduction of methanol begins, and the initial methanol replacement rate is set to 20%. After the diesel nozzle injection is completed and the coolant reaches the preset starting temperature, the in-cylinder temperature has been raised to a certain extent, and the appropriate introduction of methanol can gradually exert the advantages of methanol while ensuring stable combustion.

[0058] S12, during the period when the coolant temperature gradually rises from the first coolant temperature to the second coolant temperature, gradually increasing the injection of methanol by the methanol nozzle to gradually increase the methanol replacement rate to the second preset value; When the coolant temperature gradually rises, the methanol replacement rate is gradually increased, and when the coolant temperature reaches 50°C, the methanol replacement rate is increased to 50%. As the coolant temperature gradually rises, the methanol injected by the methanol nozzle gradually increases, so that the methanol replacement rate gradually increases. From a lower replacement rate in a lower temperature range to a higher replacement rate in a higher temperature range, the continuity of the fuel switching process and the stability of the combustion process are achieved.

[0059] In some embodiments, the methanol injection amount can be increased by a certain percentage for each preset temperature rise until the second preset value is reached. The preset temperature is 1°C, 2°C, or other temperatures, which are not limited in this embodiment.

[0060] S13, during the period when the coolant temperature gradually rises from the second coolant temperature to the third coolant temperature, gradually increasing the injection of methanol by the methanol nozzle to gradually increase the methanol replacement rate to the third preset value.

[0061] Similar to step S12, when the coolant temperature gradually rises, the methanol replacement rate is gradually increased, and when the coolant temperature reaches 80°C, the methanol replacement rate is increased to between 80% and 90%. When the coolant temperature continues to rise to greater than 80°C, the methanol replacement rate can also be controlled to be between 80% and 90%.

[0062] In yet another embodiment, after controlling the methanol nozzle to gradually increase the injection of methanol, the method further comprises: S14, obtaining an operating parameter of the dual-fuel engine; the operating parameter includes at least one of a crankshaft speed, a crankshaft angular acceleration, an in-cylinder pressure rise rate, and a methanol temperature; S15, determining whether the operating parameter is lower than a steady-state threshold parameter; S16, in the case where the operating parameter is lower than the steady-state threshold parameter, controlling the output power of the dual-fuel engine to remain unchanged, controlling the diesel nozzle to increase the injection of diesel, and controlling the methanol nozzle to decrease the injection of methanol to reduce the methanol replacement rate.

[0063] In the present embodiment, after the engine is started, and during the dynamic adjustment of the methanol replacement rate according to the corresponding coolant temperature, the ECU monitors the key operating parameters of the engine in real time, for judging whether the engine is stable and responds normally in the short stage after starting. For example, the ECU can obtain the crankshaft speed of the dual-fuel engine through the crankshaft speed sensor, obtain the crankshaft angular acceleration by differentiating the speed signal, obtain the in-cylinder pressure rise rate through the in-cylinder pressure sensor, obtain the methanol temperature through the methanol temperature sensor, and adjust the methanol injection amount in real time.

[0064] By comparing each operating parameter with the preset steady-state threshold parameter, it is judged whether the engine is currently in a stable combustion state. Each operating parameter has a corresponding steady-state threshold parameter, and the threshold ranges of the crankshaft speed, the crankshaft angular acceleration, the in-cylinder pressure rise rate, and the methanol temperature can be set respectively. If a certain operating parameter is lower than the steady-state threshold parameter, it indicates that the combustion quality is decreased, and the power output may fluctuate or decrease.

[0065] If the crankshaft speed is lower than the threshold, it indicates that the combustion is insufficient and the power output is insufficient. Under the target of keeping the output power unchanged, the diesel injection amount is increased, and the methanol injection proportion is reduced, to ensure stable combustion and speed recovery.

[0066] If the crankshaft angular acceleration is lower than the threshold, it indicates that the power output is unstable, and the engine operation is interrupted. Under the premise of ensuring the engine output power unchanged, the diesel injection amount is automatically increased, and the methanol replacement rate is reduced at this time.

[0067] If the in-cylinder pressure rise rate is lower than the threshold, it indicates that the combustion rate is not ideal, the combustion efficiency is low, and the flame propagation is weak. Under the target of keeping the output power unchanged, the diesel injection amount is increased, and the methanol replacement rate is reduced to avoid methanol combustion delay at low temperature and improve the combustion process.

[0068] If the methanol temperature is lower than the threshold, it indicates that the methanol temperature is too low, the fuel gasification is insufficient, and the ignition is affected. The methanol injection amount is reduced, the diesel injection is increased, the stability and heat output of combustion are improved, and the methanol heating device can be started to assist in increasing the methanol temperature.

[0069] In this way, when the engine combustion is unstable, the output power of the dual-fuel engine can be controlled unchanged, the diesel nozzle can be controlled to increase the diesel injection, and the methanol nozzle can be controlled to reduce the methanol injection, so that the methanol replacement rate is reduced until each operating parameter is stable. This dynamic adjustment mechanism can ensure stable operation of the engine in the transition stage after starting.

[0070] Among them, the stability of each operating parameter is that the crankshaft speed, the crankshaft angular acceleration, the in-cylinder pressure rise rate, or the methanol temperature obtained in real time is not lower than the steady-state threshold parameter, and is continuously maintained for more than a certain time in the set steady-state interval.

[0071] As Figure 3 shown, Figure 3 The flow principle diagram of the control method of the dual-fuel methanol-diesel dual direct injection engine of the application under dynamic working conditions is shown. In order to meet the performance requirements of the engine under acceleration and different loads, the embodiment further aims to solve many problems existing in the dynamic working condition of the dual-fuel engine, and proposes a dynamic collaborative control mechanism based on torque demand and combustion stability. The method further comprises the following steps: S17, obtaining real-time running parameters of the vehicle; the real-time running parameters include at least one of the position of the accelerator pedal, the intake pressure, and the crankshaft speed of the dual-fuel engine; The real-time running parameters of the vehicle are collected in real time, which are used to identify the real-time working condition of the vehicle. The position of the accelerator pedal can be obtained by an accelerator pedal position sensor, the intake pressure can be obtained by an intake pressure sensor, and the crankshaft speed can be obtained by a crankshaft speed sensor, and the engine load rate is calculated in real time.

[0072] S18, identifying the real-time running condition of the vehicle based on the real-time running parameters; The real-time running condition of the vehicle is determined by collecting various real-time running parameters. The real-time running condition can include low-speed idle, high-speed cruising, acceleration, climbing, load running, and other specific conditions. Accurate condition identification is the basis for precise control.

[0073] S19, obtaining the load rate of the dual-fuel engine under the real-time running condition; The engine load is calculated in real time, which is a key basis for adjusting the methanol replacement rate. The load rate of the engine reflects the size of the current power demand of the engine, and the load state of the engine is determined by the load rate. The load rate can be calculated by the percentage of the required torque and the maximum torque at the current speed.

[0074] S20, determining a methanol replacement rate range matched with a corresponding preset load interval according to the load rate and a plurality of preset load intervals, wherein the plurality of preset load intervals include a low load interval, a medium load interval, and a high load interval divided in order from low to high according to the load rate range; The engine load is divided into a plurality of preset load intervals in this embodiment, and each preset load interval corresponds to each methanol replacement rate range. By comparing the load rate and each preset load interval, the target load interval to which the load rate belongs is determined, and the methanol replacement rate range matched with the target load interval is obtained.

[0075] Specifically, the embodiment divides the load rate range from low to high into a low load interval, a medium load interval and a high load interval. The low load interval corresponds to a first methanol replacement rate range; the medium load interval corresponds to a second methanol replacement rate range; and the high load interval corresponds to a third methanol replacement rate range. The low load interval, the medium load interval and the high load interval are continuously divided from low to high, and the corresponding methanol replacement rate ranges are also from low to high. The methanol replacement rate range increases with the load interval, and there is no overlapping between the methanol replacement rate ranges of the load intervals.

[0076] For example, the low load interval can be a load rate ≤ 30%, and the first methanol replacement rate range is 30%-40%. The medium load interval can be 30% < load rate < 70%, and the second methanol replacement rate range is 50%-60%. The high load interval can be a load rate ≥ 70%, and the third methanol replacement rate range is 70%-95%.

[0077] Of course, the methanol replacement rate range of each load interval can also be continuously divided from low to high.

[0078] S21, based on the low load interval, controlling the methanol nozzle to spray methanol in the first methanol replacement rate range; When the load rate is in the low load interval, the methanol replacement rate is limited in a lower range. The methanol nozzle is controlled to reduce the amount of methanol sprayed, to automatically reduce the methanol replacement rate to less than 30%-40%, while increasing the main injection amount of diesel and delaying the injection timing to improve power output.

[0079] S22, based on the medium load interval, controlling the methanol nozzle to spray methanol in the second methanol replacement rate range; When the load rate is in the medium load interval, the methanol replacement rate is limited in a medium range. The methanol nozzle is controlled to spray methanol to a methanol replacement rate of 50%-60%, combined with the exhaust gas recirculation technology, to reduce the in-cylinder temperature and inhibit nitrogen oxide emissions.

[0080] S23, based on the high load interval, controlling the methanol nozzle to spray methanol in the third methanol replacement rate range; When the load rate is in the high load interval, a high replacement rate strategy is adopted. The methanol nozzle is controlled to spray methanol to a methanol replacement rate of 70%-95%, and a premixed gas is formed by advancing the methanol injection timing (such as forty degrees of crank angle before the compression top dead center) to reduce the combustion noise.

[0081] In yet another embodiment, after controlling the methanol nozzle to spray methanol in the corresponding methanol replacement rate range, the method further comprises: S24, obtaining a change rate of the accelerator pedal opening of the vehicle under the real-time operating condition; S25, judging whether the change rate of the accelerator pedal opening is greater than a change threshold parameter; S26. When the rate of change of the accelerator pedal opening is greater than a threshold operating parameter, the output power of the dual-fuel engine is controlled to remain unchanged, the diesel nozzle is controlled to instantaneously spray diesel according to an injection amount that increases by a preset amount per cycle, and the methanol nozzle is controlled to spray methanol in a reduced amount, so that the methanol substitution rate is reduced to a range lower than the lower limit of the first methanol substitution rate range, and the actuator for controlling the increase of the intake pressure is executed.

[0082] In this embodiment, the accelerator pedal position is collected in real time by the accelerator pedal position sensor, and the change in unit time is calculated to obtain the accelerator pedal opening change rate, so as to quickly identify the dynamic working condition, such as whether the real-time operating condition is in a rapid acceleration or rapid deceleration condition.

[0083] The rate of change of the accelerator pedal opening is compared with a preset threshold parameter to determine load stability. If the rate of change of the accelerator pedal opening exceeds the threshold parameter (e.g., 0.5 rad / s), it is considered a significant load fluctuation and dynamic compensation mode is triggered. In dynamic compensation mode, power output is maintained by instantaneously increasing the diesel injection rate, for example, by 5 mg per cycle, while simultaneously reducing the methanol substitution rate to 15%-20%. The boost pressure control module also increases intake pressure, shortening power response time until the load stabilizes and gradually returns to the normal methanol substitution rate range corresponding to the current load rate.

[0084] In this way, during the acceleration or load operation phase, this embodiment can sense the operating conditions in real time and dynamically adjust the methanol substitution rate due to the rapid changes in engine load, while performing dynamic response compensation to improve the response speed and stability of dynamic operating conditions.

[0085] like Figure 4 As shown, Figure 4 A schematic diagram of the control method for a dual-fuel methanol-diesel dual direct injection engine under dynamic operating conditions is shown. Another objective of this embodiment is to address numerous issues with fault diagnosis in dual-fuel engines. This embodiment proposes an intelligent fault-tolerant mechanism with hierarchical diagnosis and redundant switching to improve fault diagnosis accuracy and system reliability. The method further includes: S27, obtaining a common rail pressure parameter, a methanol nozzle inlet pressure parameter, and a methanol temperature of a methanol system of the vehicle; S28, determining whether the common rail pressure parameter and the methanol nozzle inlet pressure parameter are less than a preset injection pressure, and determining whether the methanol temperature is greater than a preset temperature; S29: If the common rail pressure parameter and the methanol nozzle inlet pressure parameter are less than a preset injection pressure, or the methanol temperature is greater than a preset temperature, it is determined that the methanol system is faulty; S30, obtaining a diesel nozzle current parameter and a high-pressure common rail pressure parameter of a diesel system of the vehicle; S31, judge whether the diesel nozzle current parameter is abnormal, and judge whether the high-pressure common rail pressure parameter exceeds the preset pressure range; S32, in the case that the diesel nozzle current parameter is abnormal or the high-pressure common rail pressure parameter exceeds the preset pressure range, determine that the diesel system fails; S33, in the case that the common rail pressure parameter and the methanol nozzle inlet pressure parameter are less than the preset injection pressure, and the diesel nozzle current parameter is abnormal, determine that it is a compound failure.

[0086] In steps S27-S29 of the embodiment, double pressure sensors are configured, for example, a first pressure sensor collects the common rail pressure parameter, and a second pressure sensor collects the methanol nozzle inlet pressure parameter. The common rail pressure parameter and the nozzle inlet pressure parameter are used as the methanol injection pressure together, and the temperature sensor is used to obtain the methanol temperature, so as to avoid misjudgment of the single sensor signal in the fault judgment. When the methanol injection pressure is less than 60 MPa, it is considered that the pressure supply is insufficient, or when the methanol temperature is greater than 80℃, it is considered that the temperature is too high, so the methanol system failure can be directly determined. After determining the methanol system failure, step S291 is entered, the methanol nozzle is controlled to stop injection, switched to diesel system alone, and the methanol system failure information is output. In the embodiment, only the methanol system failure is a primary failure, the methanol injection is immediately closed, switched to a pure diesel mode, and a fault code is sent through the CAN bus to express the methanol injection pressure abnormality, so as to ensure that the engine can continue to run, and at the same time remind the user to repair.

[0087] In steps S30-S32 of the embodiment, the diesel nozzle current parameter and the high-pressure common rail pressure parameter are obtained by diesel nozzle current waveform analysis and high-pressure common rail pressure sensor respectively, so as to detect the diesel injection consistency. When the diesel nozzle driving current of a certain cylinder is abnormal, or the common rail pressure fluctuation exceeds ±5%, it is determined that the diesel system fails. After determining the diesel system failure, step S321 is entered, in the case that the diesel injection system fails, the power of the dual-fuel engine is controlled to reduce to a preset power, the standby diesel nozzle is started, and the diesel system failure information is output. In the embodiment, only the diesel system failure is a primary failure, the engine power is limited to 50%, and the standby diesel nozzle is enabled, and a fault code is sent to express the diesel injector failure, so as to maintain the engine operation as much as possible under the condition of reducing the power.

[0088] In step S33, when the methanol pressure abnormality and the diesel injection current abnormality are detected at the same time, it is determined that it is a compound failure, step S331 is entered, in the case that the methanol system and the diesel system both fail, the dual-fuel engine is controlled to stop running, and the audible and visual alarm information is output. The methanol system and the diesel system fail at the same time, which is a secondary failure, belonging to a serious failure, so an emergency shutdown program is triggered immediately, all fuel supplies are cut off, and the user is prompted through the audible and visual alarm to avoid more serious damage caused by the compound failure.

[0089] Thus, in the fault diagnosis link, due to the difference in structure and working principle between the methanol system and the diesel system, a single diagnosis mode is difficult to accurately determine the fault, the multi-sensor signal is used to determine the fault area, the accuracy of fault diagnosis and the reliability of the system are improved, and the safe operation of the engine is ensured.

[0090] In a second aspect, the application also provides a vehicle configured with a dual-fuel engine, the dual-fuel engine comprising a methanol nozzle for injecting methanol and a diesel nozzle for injecting diesel, the vehicle further comprising: a methanol system configured with a first pressure sensor, a second pressure sensor and a temperature sensor, the first pressure sensor being configured to acquire a common rail pressure parameter of the methanol system, the second pressure sensor being configured to acquire a methanol nozzle inlet pressure parameter of the methanol system, and the temperature sensor being configured to acquire a methanol temperature of the methanol system; a diesel system configured with a diesel nozzle, a diesel nozzle sensor and a high-pressure common rail pressure sensor, the diesel nozzle sensor being configured to acquire a diesel nozzle current parameter of the diesel nozzle, and the high-pressure common rail pressure sensor being configured to acquire a high-pressure common rail pressure parameter of the diesel system; and a controller configured to execute the control method of the dual-fuel methanol-diesel dual direct injection engine as described above.

[0091] Further, the vehicle further comprises a backup diesel nozzle configured to be started when the diesel system fails.

[0092] For the vehicle embodiment, since it is basically similar to the method embodiment, the description is relatively simple, and the relevant parts are described in the part of the method embodiment.

[0093] Each embodiment in the specification is described in a progressive manner, and each embodiment focuses on the difference from other embodiments. The same and similar parts between the embodiments can be referred to each other.

[0094] Those skilled in the art should understand that the embodiments of the application can be provided as a method, device or computer program product. Therefore, the embodiments of the application can be in the form of a complete hardware embodiment, a complete software embodiment or an embodiment combining software and hardware aspects. Moreover, the embodiments of the application can be in the form of a computer program product implemented on one or more computer usable storage media (including but not limited to magnetic disk storage, CD-ROM, optical storage, etc.) containing computer usable program code.

[0095] The embodiments of the present application are described with reference to the flowcharts and / or block diagrams of the methods, terminal devices (systems), and computer program products according to the embodiments of the present application. It should be understood that each process and / or box in the flowchart and / or block diagram, as well as the combination of the processes and / or boxes in the flowchart and / or block diagram, can be implemented by computer program instructions. These computer program instructions can be provided to a processor of a general-purpose computer, a special-purpose computer, an embedded processor, or other programmable data processing terminal device to produce a machine, so that the instructions executed by the processor of the computer or other programmable data processing terminal device generate instructions for implementing the steps in the process. Figure 1 a process or multiple processes and / or boxes Figure 1 A device that provides the functions specified in a block or multiple blocks.

[0096] These computer program instructions may also be stored in a computer readable memory that can direct a computer or other programmable data processing terminal device to operate in a specific manner, so that the instructions stored in the computer readable memory produce a manufactured product including an instruction device, which implements the process Figure 1 a process or multiple processes and / or boxes Figure 1 The function specified in one or more boxes.

[0097] These computer program instructions can also be loaded onto a computer or other programmable data processing terminal device so that a series of operating steps are executed on the computer or other programmable terminal device to produce a computer-implemented process, thereby providing instructions for executing on the computer or other programmable terminal device to implement the process. Figure 1 a process or multiple processes and / or boxes Figure 1 A step that specifies a function in one or more boxes.

[0098] Although preferred embodiments of the present invention have been described, those skilled in the art may make additional changes and modifications to these embodiments once they become aware of the basic inventive concepts. Therefore, the appended claims are intended to be interpreted as including the preferred embodiments and all changes and modifications that fall within the scope of the embodiments of the present invention.

[0099] Finally, it needs to be mentioned that in this document, relational terms such as first and second and the like can only be used to distinguish one entity or action from another entity or action, without necessarily requiring or implying any actual such relationship or order between or among the entities or actions. Moreover, the terms "comprises", "comprising", or any other variations thereof, are intended to cover a non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements does not include only those elements but can include other elements not expressly listed or inherent to such process, method, article, or apparatus. An element proceeded by "comprises... a" does not, without more constraints, exclude the presence of additional identical elements in the process, method, article, or apparatus that comprises the element.

Claims

1. A control method for a dual-fuel methanol-diesel dual direct injection engine, applied to a vehicle having a dual-fuel engine, wherein the dual-fuel engine is equipped with a methanol nozzle for injecting methanol and a diesel nozzle for injecting diesel; characterized in that: The method comprises: obtaining the ambient temperature of the vehicle; Determining a target temperature range to which the ambient temperature belongs from four preset temperature ranges; wherein the four preset temperature ranges correspond to an extremely cold operating condition, a cold operating condition, a normal temperature operating condition, and a high temperature operating condition, respectively; When the target temperature range corresponds to the extremely cold operating condition, the diesel nozzle is controlled to inject the diesel according to injection parameters corresponding to a first pilot injection, a second pilot injection, a third pilot injection, and a main injection in each cycle, and the injection parameters of the first pilot injection, the second pilot injection, the third pilot injection, and the main injection satisfy that the corresponding crankshaft angle before compression top dead center gradually decreases and the injection amount gradually increases; When the target temperature range corresponds to the cold operating condition, controlling the diesel nozzle to inject the diesel with the injection parameters corresponding to the second pilot injection, the third pilot injection, and the main injection; When the target temperature range corresponds to the normal temperature operating condition, controlling the diesel nozzle to inject the diesel according to the injection parameters corresponding to the third pilot injection and the main injection; When the target temperature range corresponds to the high temperature operating condition, the dual fuel mode is directly entered to control the diesel nozzle to inject the diesel, and to control the methanol nozzle to inject the methanol.

2. The control method of the dual-fuel methanol-diesel dual direct injection engine according to claim 1, characterized in that: The method further comprises: obtaining a coolant temperature of the vehicle; According to the completion of the injection of the diesel nozzle, the methanol pressure is controlled to be a preset pressure; determining whether the dual-fuel engine enters a dual-fuel mode according to the increased coolant temperature; When the dual-fuel engine enters the dual-fuel mode, determining a methanol substitution rate that matches the preset coolant temperature based on the coolant temperature and a plurality of preset coolant temperatures; wherein the plurality of preset coolant temperatures include a first coolant temperature, a second coolant temperature, and a third coolant temperature; When the coolant temperature rises to reach the first coolant temperature, controlling the methanol nozzle to start spraying the methanol so that the initial methanol replacement rate is a first preset value; During the period when the coolant temperature gradually increases from the first coolant temperature to the second coolant temperature, controlling the methanol nozzle to gradually increase the injection of the methanol so that the methanol substitution rate gradually increases to a second preset value; When the coolant temperature gradually increases from the second coolant temperature to the third coolant temperature, controlling the methanol nozzle to gradually increase the injection of methanol so that the methanol replacement rate gradually increases to a third preset value; The first preset value, the second preset value and the third preset value are arranged from small to large.

3. The control method of a dual-fuel methanol-diesel dual direct injection engine according to claim 1, characterized in that: The injection parameters of the first pilot injection, the second pilot injection, the third pilot injection and the main injection satisfy: the corresponding crankshaft angle before compression top dead center gradually decreases and the injection amount gradually increases, including: Controlling the diesel nozzle to inject the diesel at a crankshaft angle of 120 degrees before compression top dead center and an injection amount of 5 mg per cycle to complete the first pilot injection of the diesel; Controlling the diesel nozzle to inject the diesel at a crankshaft angle of 60 degrees before compression top dead center and an injection amount of 8 mg per cycle to complete the second pilot injection of the diesel; Controlling the diesel nozzle to inject the diesel at a crankshaft angle of thirty degrees before compression top dead center and an injection amount of ten milligrams per cycle, thereby completing the third pilot injection of the diesel; The diesel injection nozzle is controlled to inject the diesel at a crankshaft angle of ten degrees before compression top dead center and an injection amount of 20 mg per cycle to complete the main injection of the diesel.

4. The control method of a dual-fuel methanol-diesel dual direct injection engine according to claim 2, characterized in that: After controlling the methanol nozzle to gradually increase the injection of the methanol, the method further includes: Acquiring operating parameters of the dual-fuel engine; the operating parameters including at least one of crankshaft speed, crankshaft angular acceleration, cylinder pressure rise rate, and methanol temperature; determining whether the operating parameter is lower than a steady-state threshold parameter; When the operating parameter is lower than the steady-state threshold parameter, the output power of the dual-fuel engine is controlled to remain unchanged, the diesel nozzle is controlled to increase the injection of diesel, and the methanol nozzle is controlled to reduce the injection of methanol, so as to reduce the methanol substitution rate.

5. The control method of a dual-fuel methanol-diesel dual direct injection engine according to claim 2, characterized in that: After controlling the methanol nozzle to gradually increase the injection of the methanol, the method further includes: Acquiring real-time operating parameters of the vehicle; the real-time operating parameters include at least one of an accelerator pedal position, an intake pressure, and a crankshaft speed of the dual-fuel engine; identifying a real-time operating condition of the vehicle based on the real-time operating parameters; Obtaining a load rate of the dual-fuel engine under the real-time operating condition; Determining a methanol substitution rate range that matches the preset load interval based on the load rate and a plurality of preset load intervals; wherein the plurality of preset load intervals include a low load interval, a medium load interval, and a high load interval divided from low to high according to the load rate range; Based on the low load range, controlling the methanol nozzle to inject the methanol within a first methanol substitution rate range; Based on the medium load range, controlling the methanol nozzle to inject the methanol within a second methanol substitution rate range; Based on the high load range, controlling the methanol nozzle to inject the methanol within a third methanol substitution rate range; Among them, the upper limit of the first methanol substitution rate range is smaller than the lower limit of the second methanol substitution rate range, and the upper limit of the second methanol substitution rate range is smaller than the lower limit of the third methanol substitution rate range.

6. The control method of the dual-fuel methanol-diesel dual direct injection engine according to claim 5, characterized in that: After controlling the methanol nozzle to inject the methanol within the corresponding methanol replacement rate range, the method further includes: Obtaining a rate of change of an accelerator pedal opening of the vehicle under the real-time operating condition; Determining whether the accelerator pedal opening change rate is greater than a change threshold parameter; When the accelerator pedal opening change rate is greater than the threshold operating parameter, the output power of the dual-fuel engine is controlled to remain unchanged, the diesel nozzle is controlled to instantaneously spray the diesel according to the injection amount increasing by a preset amount per cycle, and the methanol nozzle is controlled to reduce the amount of methanol injection, so that the methanol substitution rate is reduced to a range lower than the lower limit of the first methanol substitution rate range, and the actuator for increasing the intake pressure is controlled to execute.

7. The control method of a dual-fuel methanol-diesel dual direct injection engine according to claim 1, characterized in that: The method further comprises: obtaining a common rail pressure parameter, a methanol nozzle inlet pressure parameter, and a methanol temperature of a methanol system of the vehicle; determining whether the common rail pressure parameter and the methanol nozzle inlet pressure parameter are less than a preset injection pressure, and determining whether the methanol temperature is greater than a preset temperature; When the common rail pressure parameter and the methanol nozzle inlet pressure parameter are less than the preset injection pressure, or the methanol temperature is greater than the preset temperature, determining that the methanol system is faulty; Obtaining a diesel nozzle current parameter and a high-pressure common rail pressure parameter of a diesel system of the vehicle; Determining whether the diesel nozzle current parameter is abnormal, and determining whether the high-pressure common rail pressure parameter exceeds a preset pressure range; When the diesel nozzle current parameter is abnormal, or the high-pressure common rail pressure parameter exceeds the preset pressure range, determining that the diesel system is faulty; When the common rail pressure parameter and the methanol nozzle inlet pressure parameter are less than the preset injection pressure, and the diesel nozzle current parameter is abnormal, it is determined to be a composite fault.

8. The control method of a dual-fuel methanol-diesel dual direct injection engine according to claim 7, characterized in that: After determining that the diesel system is faulty, the method further includes: In the event of a failure in the methanol system, the methanol nozzle is controlled to stop spraying, the diesel system is switched to operate alone, and methanol system failure information is output; After determining that the diesel system is faulty, the method further includes: In the event of a failure in the diesel injection system, controlling the power of the dual-fuel engine to be reduced to a preset power, starting a backup diesel injection nozzle, and outputting diesel system failure information; After determining that a complex fault occurs, the method includes: In the event that both the methanol system and the diesel system fail, the dual-fuel engine is controlled to stop running and an audible and visual alarm message is output.

9. A vehicle equipped with a dual-fuel engine, the dual-fuel engine comprising a methanol nozzle for injecting methanol and a diesel nozzle for injecting diesel, characterized in that: The vehicle further comprises: A methanol system is equipped with a first pressure sensor, a second pressure sensor, and a temperature sensor. The first pressure sensor is used to obtain a common rail pressure parameter of the methanol system. The second pressure sensor is used to obtain a methanol nozzle inlet pressure parameter of the methanol system. The temperature sensor is used to obtain a methanol temperature of the methanol system. A diesel system is equipped with a diesel nozzle, a diesel nozzle sensor, and a high-pressure common rail pressure sensor. The diesel nozzle sensor is used to collect the diesel nozzle current parameter of the diesel nozzle, and the high-pressure common rail pressure sensor is used to collect the high-pressure common rail pressure parameter of the diesel system. A controller for executing the control method of a dual-fuel methanol-diesel dual direct injection engine according to any one of claims 1 to 8.

10. The vehicle according to claim 9, characterized in that The vehicle further comprises a backup diesel injection nozzle, which is used to start when a failure occurs in the diesel system.

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