A control method of a dual-fuel methanol-diesel dual direct injection engine and a vehicle

Abstract

The application provides a control method of a dual-fuel methanol-diesel dual direct injection engine and a vehicle. The method comprises determining a temperature working condition of the vehicle according to an ambient temperature of the vehicle; in an extremely cold working condition, controlling a diesel nozzle to inject diesel according to first pre-injection, second pre-injection, third pre-injection and main injection per cycle, and the angle of the corresponding compression top dead center before the crankshaft rotation angle gradually decreases and the injection amount gradually increases during the successive injection process; in a cold working condition, controlling the diesel nozzle to inject diesel according to the injection parameters corresponding to the second pre-injection, the third pre-injection and the main injection; in a normal temperature working condition, controlling the diesel nozzle to inject diesel according to the injection parameters corresponding to the third pre-injection and the main injection; and in a high temperature working condition, directly entering a dual-fuel mode, controlling the diesel nozzle to inject diesel, and controlling a methanol nozzle to inject methanol. Through the control method, the problem of poor cold start performance caused by single diesel injection rate in the cold start stage is solved.

Description

Technical Field

[0001] This application relates to the field of internal combustion engine control technology, and in particular to a control method and vehicle for a dual-fuel methanol-diesel dual direct injection engine. Background Technology

[0002] The methanol-diesel dual direct injection engine achieves synergistic combustion of the two fuels through in-cylinder direct injection technology. Compared with single-fuel engines, it can reduce emissions while maintaining power performance and has a significant advantage in fuel cost. However, due to the physicochemical properties of methanol fuel, the methanol-diesel dual direct injection engine still faces technical bottlenecks during the cold start phase.

[0003] Methanol has a high latent heat of vaporization and low volatility, making it difficult for the fuel to form a combustible mixture in the cylinder at low temperatures, requiring diesel fuel for ignition. Traditional control strategies typically employ a fixed proportion of diesel pre-injection to utilize the heat of diesel combustion during the compression stroke to raise the cylinder temperature. However, this control strategy maintains the same number and amount of diesel injections regardless of ambient temperature, resulting in the following drawbacks: Insufficient preheating time: Under extremely cold conditions with low ambient temperatures, the heat released by the combustion of diesel fuel with a fixed injection volume is simply insufficient to effectively raise the cylinder temperature, resulting in incomplete methanol evaporation. A large amount of liquid methanol will then wash over the cylinder walls and dilute the lubricating oil, leading to a series of problems such as prolonged lag time, unstable combustion, and oil dilution.

[0004] Excessive preheating time: When the ambient temperature gradually increases, the amount of heat released by the combustion of diesel fuel with a fixed injection volume will lead to a series of problems such as excessively high combustion temperature, worsened emissions, and reduced fuel economy. Summary of the Invention

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

[0006] Firstly, this application proposes a control method for a dual-fuel methanol-diesel direct injection engine, and the technical solution adopted is as follows: A control method for a dual-fuel methanol-diesel direct injection engine, applied to a vehicle equipped with a dual-fuel engine, the dual-fuel engine being configured with a methanol nozzle for injecting methanol and a diesel nozzle for injecting diesel fuel; the method includes: Obtain the ambient temperature of the vehicle; From four preset temperature ranges, the target temperature range to which the ambient temperature belongs is determined; wherein, the four preset temperature ranges correspond to extreme cold conditions, cold conditions, normal temperature conditions and high temperature conditions, respectively. Under the extreme cold conditions corresponding to the target temperature range, the diesel nozzle is controlled to inject diesel fuel according to the injection parameters corresponding to the first pre-injection, second pre-injection, third pre-injection and main injection in each cycle. The injection parameters of the first pre-injection, second pre-injection, third pre-injection and main injection satisfy the following: the crankshaft angle before the corresponding compression top dead center gradually decreases and the injection quantity gradually increases. When the target temperature range corresponds to the cold operating condition, the diesel injector is controlled to inject diesel fuel with the injection parameters corresponding to the second pre-injection, the third pre-injection, and the main injection; Under normal temperature conditions corresponding to the target temperature range, the diesel nozzle is controlled to inject diesel fuel according to the injection parameters corresponding to the third pre-injection and the main injection. When the target temperature range corresponds to the high-temperature operating condition, the system directly enters the dual-fuel mode, controlling the diesel injector to inject diesel fuel and the methanol injector to inject methanol.

[0007] Optionally, the method further includes: Obtain the coolant temperature of the vehicle; Based on the completion status of the diesel nozzle injection, the methanol pressure is controlled to a preset pressure; Based on the temperature of the coolant after heating, determine whether the dual-fuel engine has entered dual-fuel mode; When the dual-fuel engine enters dual-fuel mode, a methanol substitution rate matching the corresponding preset coolant temperature is determined based on the coolant temperature and multiple preset coolant temperatures; wherein, the multiple preset coolant temperatures include a first coolant temperature, a second coolant temperature, and a third coolant temperature; When the coolant temperature rises to the first coolant temperature, the methanol nozzle is controlled to start injecting methanol, so that the initial methanol substitution rate is a first preset value. During the period when the coolant temperature gradually rises from the first coolant temperature to the second coolant temperature, the methanol nozzle is controlled to gradually increase the amount of methanol injected, so that the methanol substitution rate gradually increases to the second preset value. During the period when the coolant temperature gradually rises from the second coolant temperature to the third coolant temperature, the methanol nozzle is controlled to gradually increase the amount of methanol injected, so that the methanol substitution rate gradually increases to the third preset value. The first preset value, the second preset value, and the third preset value are arranged in ascending order.

[0008] Optionally, the injection parameters of the first pre-injection, second pre-injection, third pre-injection, and main injection satisfy the following: the crankshaft angle before the corresponding compression top dead center gradually decreases, and the injection quantity gradually increases, including: The diesel nozzle is controlled to inject diesel fuel at a crankshaft rotation angle of 120 degrees before the top dead center of the compression stroke and an injection quantity of 5 mg per cycle to complete the first pre-injection of the diesel fuel. The diesel nozzle is controlled to inject diesel fuel at a crankshaft rotation angle of 60 degrees before the top dead center of the compression stroke and an injection quantity of 8 mg per cycle, thus completing the second pre-injection of the diesel fuel. The diesel nozzle is controlled to inject diesel fuel at a crankshaft rotation angle of 30 degrees before the top dead center of the compression stroke and an injection quantity of 10 milligrams per cycle, thus completing the third pre-injection of the diesel fuel. The diesel nozzle is controlled to inject diesel fuel at a rate of 20 mg per cycle, with a crankshaft rotation angle of 10 degrees before the top dead center of the compression stroke, thus completing the main injection of the diesel fuel.

[0009] Optionally, after controlling the methanol nozzle to gradually and incrementally inject methanol, the method further includes: Obtain the operating parameters of the dual-fuel engine; the operating parameters include at least one of crankshaft speed, crankshaft angular acceleration, in-cylinder pressure rise rate, and methanol temperature; Determine whether the operating parameters are lower than the steady-state threshold parameter; When the operating parameters are lower than the steady-state threshold parameters, the output power of the dual-fuel engine is kept constant, the diesel injector is controlled to inject diesel in an incremental manner, and the methanol injector is controlled to inject methanol in a reduced manner, thereby reducing the methanol substitution rate.

[0010] Optionally, after controlling the methanol nozzle to gradually and incrementally inject methanol, the method further includes: The real-time operating parameters of the vehicle are obtained; the real-time operating parameters include at least one of the following: accelerator pedal position, intake pressure, and crankshaft speed of the dual-fuel engine. Based on the real-time operating parameters, the real-time operating conditions of the vehicle are identified; Obtain the load rate of the dual-fuel engine under the real-time operating conditions; Based on the load rate and multiple preset load ranges, a methanol substitution rate range matching the corresponding preset load range is determined; wherein, the multiple preset load ranges include a low load range, a medium load range, and a high load range divided according to the load rate range from low to high; Based on the low load range, the methanol nozzle is controlled to inject methanol within the first methanol substitution rate range; Based on the medium load range, the methanol nozzle is controlled to inject methanol within the second methanol substitution rate range; Based on the high load range, the methanol nozzle is controlled to spray methanol within the third methanol substitution rate range; Wherein, the upper limit of the first methanol substitution rate range is less than the lower limit of the second methanol substitution rate range, and the upper limit of the second methanol substitution rate range is less than the lower limit of the third methanol substitution rate range.

[0011] Optionally, after controlling the methanol nozzle to inject methanol within a corresponding methanol substitution rate range, the method further includes: Obtain the rate of change of accelerator pedal opening of the vehicle under the real-time operating conditions; Determine whether the rate of change of the accelerator pedal opening is greater than a threshold parameter. When the rate of change of the accelerator pedal opening is greater than the threshold operating parameter, the output power of the dual-fuel engine is kept constant, the diesel nozzle is controlled to inject diesel fuel instantaneously at a rate that increases by a preset amount per cycle, and the methanol nozzle is controlled to inject methanol at a reduced rate, so that the methanol substitution rate is reduced to the lower limit of the first methanol substitution rate range, and the actuator that increases the intake pressure is controlled to execute.

[0012] Optionally, the method further includes: Obtain the common rail pressure parameters, methanol nozzle inlet pressure parameters, and methanol temperature of the vehicle's methanol system; Determine whether the common rail pressure parameter and the methanol nozzle inlet pressure parameter are less than the preset injection pressure, and determine whether the methanol temperature is greater than the preset temperature; If the common rail pressure parameter and the methanol nozzle inlet pressure parameter are less than the preset injection pressure, or if the methanol temperature is greater than the preset temperature, the methanol system is determined to be faulty. Obtain the diesel injector current parameters and high-pressure common rail pressure parameters of the vehicle's diesel system; Determine whether the diesel injector current parameter is abnormal, and determine whether the high-pressure common rail pressure parameter exceeds the preset pressure range; If the diesel injector current parameter is abnormal, or the high-pressure common rail pressure parameter exceeds the preset pressure range, the diesel system is determined to be faulty. If 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 combined fault.

[0013] Optionally, after determining that the diesel system is faulty, the method further includes: In the event of a malfunction in the methanol system, the methanol nozzle is controlled to stop injecting, the diesel system is switched to operate independently, and methanol system malfunction information is output. After determining that the diesel system is faulty, the method further includes: In the event of a malfunction in the diesel injection system, the power of the dual-fuel engine is reduced to a preset power, the backup diesel injector is activated, and diesel system malfunction information is output. After determining that a fault is a compound fault, the method includes: In the event of a failure in both the methanol system and the diesel system, the dual-fuel engine will be shut down, and an audible and visual alarm will be displayed.

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

[0015] Optionally, the vehicle also includes a backup diesel injector for activation in the event of a failure in the diesel system.

[0016] This application has the following advantages: When implementing the control method for the dual-fuel methanol-diesel direct injection engine provided in this embodiment of the invention, four operating conditions are defined based on ambient temperature: extremely cold, cold, normal temperature, and high temperature. The number of pre-injections and injection parameters are adjusted in stages. At low temperatures, multiple small-volume pre-injections gradually raise the temperature, avoiding the wet-wall effect caused by low temperatures. As the temperature rises, the number of pre-injections is reduced or even eliminated to prevent excessively high combustion temperatures, emissions deterioration, and decreased fuel economy. This embodiment can dynamically adjust the injection parameters during the engine's cold start phase according to the actual ambient temperature, avoiding insufficient preheating or overheating problems under a fixed diesel injection quantity strategy, and significantly improving cold start performance.

[0017] The vehicles mentioned above all have the same advantages over the prior art as the control method described above, and will not be repeated here. Attached Figure Description

[0018] To more clearly illustrate the technical solution of this application, the drawings used in the description of this application will be briefly introduced below. Obviously, the drawings described below are only some embodiments of this application. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0019] Figure 1 This is a flowchart illustrating the steps of a control method for a dual-fuel methanol-diesel dual direct injection engine according to an embodiment of this application; Figure 2 This is a flowchart illustrating the control method of a dual-fuel methanol-diesel direct injection engine in the cold start phase according to an embodiment of this application. Figure 3 This is a flowchart illustrating the control method of a dual-fuel methanol-diesel dual direct injection engine under dynamic operating conditions, as shown in an embodiment of this application. Figure 4 This is a flowchart illustrating the control method of a dual-fuel methanol-diesel direct injection engine in the fault diagnosis stage, as shown in one embodiment of this application. Detailed Implementation

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

[0021] It should be noted that the existing control strategies for methanol-diesel dual direct injection engines have technical bottlenecks in many aspects, such as cold start, dynamic operating conditions, and fault diagnosis. These bottlenecks seriously affect the engine's performance and reliability.

[0022] During cold starts, due to the different combustion characteristics of methanol and diesel, and the significant impact of ambient temperature on fuel vaporization and combustion, if the diesel injection frequency and quantity are not adjusted according to the gradient changes in ambient temperature, insufficient preheating and incomplete methanol evaporation will occur under extremely cold conditions, while excess heat is likely to occur under higher temperatures, affecting fuel economy and emissions performance. Furthermore, after diesel ignition, the methanol substitution rate is unrelated to coolant temperature, resulting in insufficient precision in the dual-fuel ratio control of dual-fuel engines, making it difficult to balance combustion stability, fuel economy, and emissions performance under different thermal conditions.

[0023] In dynamic operating conditions, such as acceleration or load operation, existing strategies mostly rely on steady-state MAP charts to control the methanol substitution rate, which cannot track changes in dynamic load in real time. For example, when the accelerator pedal opening changes abruptly, the adjustment of methanol injection quantity will lag, resulting in delayed power response. Moreover, under high loads, the methanol combustion rate is too fast, which can easily cause knocking.

[0024] In the fault diagnosis phase, existing systems rely on a relatively simplistic approach, often using a single sensor signal for fault determination, lacking the ability to independently diagnose methanol and diesel systems. For example, when methanol injection pressure is abnormal, it may be misdiagnosed as a methanol injection system fault, leading to an incorrect switch to pure diesel mode and affecting engine reliability. Furthermore, the ability to identify combined methanol-diesel faults is insufficient, making it difficult to quickly pinpoint the location of the combined fault.

[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 condition response, and enhances fault diagnosis logic, thereby balancing cold start stability, smooth dynamic operating conditions, and accurate fault detection.

[0026] Firstly, cold starting is a key challenge for methanol-diesel dual direct injection engines. The primary objective of this invention is to address the numerous problems encountered by dual-fuel engines during cold starting. The aim is to optimize cold starting performance by performing staged preheating of diesel fuel and methanol introduction based on different ambient temperatures. To achieve this objective, this invention specifically proposes a control method for a dual-fuel methanol-diesel dual direct injection engine, applicable to vehicles equipped with a dual-fuel engine, which includes a methanol nozzle for injecting methanol and a diesel nozzle for injecting diesel fuel. The dual-fuel methanol-diesel direct injection engine employs a dual-fuel combustion mode, which allows the engine's combustion state to be adjusted by the injection ratio of either fuel. A dual-fuel direct injection engine typically includes two independent diesel and methanol systems. Diesel and methanol injectors are arranged on the engine's combustion chamber. The two systems utilize a high-pressure common rail system to directly inject diesel fuel into the cylinders through the diesel injectors and methanol fuel through the methanol injectors.

[0027] like Figure 1 As shown, Figure 1 A flowchart illustrating the steps of a control method for a dual-fuel methanol-diesel direct injection engine according to an embodiment of the present invention is shown. The method includes the following steps: S1. Obtain the ambient temperature of the vehicle; Before starting the dual-fuel engine, ambient temperature sensors collect data on different ambient temperatures and divide the temperature range into multiple preset temperature zones, ordered from lowest to highest. These preset temperature zones correspond to different temperature conditions experienced by the vehicle. Injection parameters for the diesel injectors, such as the number of injections, injection timing, and injection quantity, are then set for each operating condition. This precise temperature zone classification provides a more accurate basis for subsequent preheating and fuel control.

[0028] S2. Determine the target temperature range to which the ambient temperature belongs from the four preset temperature ranges; wherein the four preset temperature ranges correspond to extreme cold conditions, cold conditions, normal temperature conditions and high temperature conditions, respectively. When setting multiple preset temperature ranges, the ambient temperature range can be divided into four preset temperature ranges in ascending order. Specifically, the first preset temperature range is ambient temperature ≤ -15℃, corresponding to extremely cold operating conditions; the second preset temperature range is -15℃ < ambient temperature ≤ 0℃, corresponding to cold operating conditions; the third preset temperature range is 0℃ < ambient temperature ≤ 15℃, corresponding to normal temperature operating conditions; and the fourth preset temperature range is ambient temperature > 15℃, corresponding to high temperature operating conditions.

[0029] After the four preset temperature ranges are set, when the dual-fuel engine starts, the ambient temperature, which is obtained in real time during the actual operation of the vehicle as described in step S1, is compared with the four preset temperature ranges to determine the target temperature range to which the ambient temperature belongs. This target temperature range is any one of the four preset temperature ranges. Since the four preset temperature ranges correspond to four operating conditions, once the target temperature range is obtained, it can be determined whether the vehicle is operating under extremely cold, cold, normal temperature, or high temperature conditions.

[0030] S3. Under the extremely cold conditions corresponding to the target temperature range, control the diesel nozzle to inject diesel according to the injection parameters corresponding to the first pre-injection, second pre-injection, third pre-injection and main injection in each cycle. The injection parameters of the first pre-injection, second pre-injection, third pre-injection and main injection shall meet the following: the crankshaft angle before the corresponding compression top dead center gradually decreases and the injection quantity gradually increases. When the ambient temperature is within the first preset temperature range, which is the target temperature range, the vehicle is in extreme cold operating conditions. Under these extremely cold conditions, methanol vaporization is very difficult. At the initial stage of starting, only diesel fuel is injected for in-cylinder preheating. The diesel injection adopts a strategy of "three pre-injections + main injection", totaling four injections per cycle.

[0031] In the three pre-injection processes, the first pre-injection is mainly used to preheat the combustion chamber and walls to form the ignition core. The second pre-injection is mainly used to increase the in-cylinder temperature and improve the uniformity of the mixture. The third pre-injection is mainly used to further preheat the combustion stability and provide a better ignition environment for the main injection. The main injection is mainly used to provide the main amount of fuel to complete the main work and achieve stable combustion.

[0032] To achieve the desired purpose for each pre-spray, this embodiment sets the injection parameters for the first pre-spray, second pre-spray, third pre-spray, and main spray to satisfy the following: the crankshaft angle before the corresponding compression top dead center gradually decreases, and the injection volume gradually increases.

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

[0034] The diesel injection quantity increases progressively from the first pre-injection to the third pre-injection and finally to the main injection, with the highest injection quantity during the main injection to ensure reliable ignition. Thus, the multiple pre-injections under extremely cold conditions create a gradual injection pattern of early small injections and late large injections, which gradually raises the temperature, reduces unburned fuel adhering to the cylinder wall, and ensures that the cylinder pressure and temperature have reached a high level by the time of the later main injection. This makes the high-volume diesel fuel easier to ignite, improving thermal efficiency.

[0035] It is worth mentioning that the injection parameters using this injection pattern can maintain a balance between combustion stability and power output in the other three operating conditions, except for extremely cold conditions. In particular, it can significantly shorten the start-up delay period and inhibit oil dilution in extremely cold and cold conditions.

[0036] S4. Under cold operating conditions corresponding to the target temperature range, control the diesel nozzle to inject diesel fuel with injection parameters corresponding to the second pre-injection, the third pre-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 in cold operating condition. In cold operating conditions, the temperature is already slightly higher, making methanol vaporization more difficult. Therefore, during the initial start-up, only diesel fuel is injected for cylinder preheating. Thus, compared to the injection strategy in extremely cold conditions, the total number of injections in cold operating conditions is reduced from four to three. Diesel injection adopts a strategy of "two pre-injections + main injection," totaling three injections per cycle.

[0037] During the two pre-spray processes, the first pre-spray in the cold operating condition is cancelled compared to the extremely cold operating condition. Meanwhile, the second pre-spray, originally performed in the extremely cold operating condition, is treated as the first pre-spray in the cold operating condition. That is, the injection timing (crankshaft angle before top dead center of the compression stroke) and injection volume of the first pre-spray are consistent with the second pre-spray in the extremely cold operating condition. Correspondingly, the injection timing and injection volume of the second pre-spray are consistent with the third pre-spray in the extremely cold operating condition.

[0038] S5. Under normal operating conditions corresponding to the target temperature range, control 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 within the third preset temperature range (which is also the target temperature range), the vehicle is operating under normal temperature conditions. Normal temperature conditions are already sufficiently high, and the ambient temperature has a relatively small impact on the fuel, allowing for earlier and more methanol injection. Therefore, compared to the injection strategy under extremely cold conditions, the total number of injections under normal temperature conditions is reduced from four to two. Diesel injection adopts a strategy of "one pre-injection + main injection," totaling two injections per cycle.

[0039] During the pre-spraying process, the first and second pre-sprays are cancelled under normal temperature conditions compared to the extreme cold conditions. At the same time, the third pre-spray, which was originally in the extreme cold conditions, is used as the first pre-spray under normal temperature conditions. That is, the spraying time and spray volume when starting the first pre-spray are the same as those of the third pre-spray under the extreme cold conditions.

[0040] S6. Under high-temperature conditions corresponding to the target temperature range, directly enter dual-fuel mode, control the diesel injector to inject diesel, and control the methanol injector to inject methanol.

[0041] When the ambient temperature is within the fourth preset temperature range (which is also the target temperature range), the vehicle is operating under high-temperature conditions. The temperature under these conditions is sufficiently high, allowing methanol to easily vaporize and better combust with diesel, enabling the direct use of dual-fuel mode. In dual-fuel mode, the onboard controller controls the injection quantity and timing of diesel and methanol. This can be achieved through simultaneous or staged injection of methanol and diesel directly into the cylinder; this embodiment does not impose any limitations on this.

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

[0043] In some embodiments, the injection parameters such as injection timing, injection quantity, and injection pressure for each pre-injection under each operating condition can be independently optimized based on various factors such as engine operating status, ambient temperature, coolant temperature, intake pressure, and methanol substitution rate, without needing to maintain consistency with the injection parameters used for a certain pre-injection under other operating conditions.

[0044] Of course, in other embodiments, the total number of injections per cycle by the diesel nozzle under each operating condition can also be selected. For example, a control strategy of four pre-injections + main injection can be adopted under extremely cold conditions. In this embodiment, each cycle refers to each compression stroke, which is the 180° crankshaft rotation segment from bottom dead center to top dead center.

[0045] Thus, this embodiment of the invention divides the operating conditions into four categories based on ambient temperature: extremely cold, cold, normal temperature, and high temperature. It then adjusts the number of pre-injections and injection parameters accordingly. At low temperatures, multiple small-volume pre-injections gradually raise the temperature, avoiding the wet-wall effect caused by low temperatures. As the temperature rises, the number of pre-injections is reduced or even eliminated to prevent excessively high combustion temperatures, worsened emissions, and decreased fuel economy. This embodiment can dynamically adjust the injection parameters during the engine's cold start phase according to the actual ambient temperature, avoiding insufficient or overheating problems under a fixed diesel injection quantity strategy, and significantly improving cold start performance.

[0046] In some embodiments, the gradually decreasing crankshaft angle before the compression top dead center corresponding to the three pre-injections and the main injection can be achieved by shifting the pre-injection time in the next pre-injection process relative to the previous pre-injection by a fixed crankshaft angle towards the compression top dead center, or by gradually decreasing the angle change between adjacent pre-injection processes. For example, the difference in crankshaft angle before the compression top dead center between the first and second pre-injections is the largest, while the difference between the second and third is smaller. Similarly, the gradually increasing injection quantity can be achieved by increasing the fuel quantity in the next pre-injection process by a fixed increment relative to the previous pre-injection; or by minimizing the difference in pre-injection quantity between the first and second pre-injections, while the increments from the second to the third, and from the third to the main injection, gradually increase.

[0047] In a preferred embodiment, step S3 further includes: S301: Control the diesel nozzle to inject diesel fuel at a crankshaft angle of 120 degrees before the top dead center of the compression stroke, with an injection quantity of 5 mg per cycle, to complete the first pre-injection of diesel fuel and form the ignition core.

[0048] S302: Control the diesel nozzle to inject diesel fuel at a crankshaft rotation angle of 60 degrees before the top dead center of the compression stroke, with an injection quantity of 8 mg per cycle, to complete the second pre-injection of diesel fuel and increase the cylinder temperature. S303: Control the diesel nozzle to inject diesel fuel at a crankshaft angle of 30 degrees before the top dead center of the compression stroke, with an injection quantity of 10 milligrams per cycle, to complete the third pre-injection of diesel fuel to further preheat the combustion chamber; S304. Control the diesel nozzle to inject diesel fuel at a rate of 20 mg per cycle with a crankshaft rotation angle of 10 degrees before the top dead center of the compression stroke to complete the main diesel fuel injection and achieve stable combustion.

[0049] Similarly, step S4 further includes: S401, Same as step S302, complete the first pre-injection of diesel fuel under cold conditions; S402, Same as step S303, complete the second pre-injection of diesel fuel under cold conditions; S403, Same as step S304, complete the main spray.

[0050] Similarly, step S5 further includes: S501, Same as step S303, complete the first pre-injection of diesel fuel under normal temperature conditions; S502, Same as step S304, complete the main spray.

[0051] like Figure 2 As shown, Figure 2 The flowchart illustrates the control method for a dual-fuel methanol-diesel direct injection engine of the present invention during the cold start phase. To further optimize cold start performance, another objective of this invention is to address the problem of insufficient methanol substitution rate control accuracy in the cold start phase of dual-fuel engines. A control strategy combining staged preheating and dynamic ramp-up of the methanol substitution rate is proposed. This method further includes: S7. Obtain the vehicle's coolant temperature; Coolant temperature directly reflects the engine block temperature and can be used to monitor engine thermal status, serving as a correlation factor for adjusting the methanol substitution rate. The methanol substitution rate is the percentage of chemical energy provided by methanol relative to the total chemical energy of all fuels during a complete working cycle of a dual-fuel (diesel-methanol) engine. In this embodiment, the coolant temperature can be acquired in real time using a coolant temperature sensor installed in the engine cooling system.

[0052] S8. Based on the completion of diesel injection, control the methanol pressure to the preset pressure; After diesel injection is completed under the corresponding operating conditions, the pre-injected diesel fuel directly heats the coolant, raising the coolant temperature to the preset start-up temperature, and the methanol pressure is maintained at 80MPa through the high-pressure common rail system.

[0053] S9. Determine whether the dual-fuel engine has entered dual-fuel mode based on the coolant temperature after heating up. During the coolant heating process, it is determined whether the coolant temperature has reached the preset starting temperature. Once the diesel injector has completed its injection and the coolant temperature reaches the preset starting temperature, the engine can be considered to have entered normal operation. During normal operation, the engine enters dual-fuel mode, completing the cold start phase. Methanol injection can begin after entering dual-fuel mode. The preset starting temperature can be set to 20℃.

[0054] S10. When the dual-fuel engine enters dual-fuel mode, determine the methanol replacement rate that matches the corresponding preset coolant temperature based on the coolant temperature and multiple preset coolant temperatures; wherein, the multiple preset coolant temperatures include a first coolant temperature, a second coolant temperature, and a third coolant temperature. In this embodiment, multiple preset coolant temperatures are set based on varying coolant temperatures. Each preset coolant temperature corresponds to a specific methanol injection quantity, which in turn corresponds to a preset methanol substitution rate. The target preset coolant temperature is determined, and a specific preset methanol substitution rate matching that target preset coolant temperature is obtained. As the coolant temperature gradually increases from the preset start-up temperature to each preset coolant temperature, the methanol nozzle can be controlled to inject an incremental amount of methanol corresponding to the target preset coolant temperature, thereby increasing the methanol substitution rate to the corresponding preset value.

[0055] Specifically, in this embodiment, the coolant temperature is divided into a first coolant temperature, a second coolant temperature, and a third coolant temperature. The first coolant temperature corresponds to a methanol substitution rate with a first preset value; the second coolant temperature corresponds to a methanol substitution rate with a second preset value; and the third coolant temperature corresponds to a methanol substitution rate with a third preset value. The methanol substitution rates corresponding to the first, second, and third coolant temperatures increase from lowest to highest.

[0056] For example, the first coolant temperature is preferably 20°C, and the first preset value is 20%, which is the same as the preset start-up temperature. When the coolant temperature reaches 20°C, methanol can be injected, and the amount of methanol injected is controlled to maintain an initial methanol substitution rate of 20%. The second coolant temperature can be 50°C, and the second preset value is 50%. The third coolant temperature can be 80°C, and the third preset value is any value between 80% and 90%.

[0057] S11. When the coolant temperature rises to the first coolant temperature, control the methanol nozzle to start injecting methanol so that the initial methanol replacement rate is the first preset value. When the coolant temperature reaches 20°C, methanol is introduced, setting the initial methanol substitution rate to 20%. Since the diesel injector has completed its injection and the coolant has reached the preset start-up temperature, the cylinder temperature has already increased to a certain extent. Introducing methanol appropriately at this point can gradually bring out 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, the methanol nozzle is controlled to gradually increase the amount of methanol injected, so that the methanol substitution rate gradually increases to the second preset value. As the coolant temperature gradually rises, the methanol substitution rate is gradually increased, reaching 50% when the coolant temperature reaches 50°C. Specifically, as the coolant temperature gradually increases, the amount of methanol injected by the methanol nozzle gradually increases, resulting in a gradual increase in the methanol substitution rate. This gradual increase from a lower substitution rate in the lower temperature range to a higher substitution rate in the higher temperature range ensures continuity in the fuel switching process and stability in the combustion process.

[0059] In some embodiments, the methanol injection rate can be increased by a certain percentage for each increase in a preset temperature until a second preset value is reached. The preset temperature is 1°C, 2°C, or other temperatures; this embodiment does not limit this.

[0060] S13. During the period when the coolant temperature gradually rises from the second coolant temperature to the third coolant temperature, the methanol nozzle is controlled to gradually increase the amount of methanol injected, so that the methanol substitution rate gradually increases to the third preset value.

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

[0062] In yet another embodiment, after controlling the methanol nozzle to gradually and incrementally inject methanol, the method further includes: S14. Obtain the operating parameters of the dual-fuel engine; the operating parameters include at least one of crankshaft speed, crankshaft angular acceleration, in-cylinder pressure rise rate, and methanol temperature; S15. Determine whether the operating parameters are lower than the steady-state threshold parameters; S16. When the operating parameters are lower than the steady-state threshold parameters, control the output power of the dual-fuel engine to remain unchanged, control the diesel nozzle to inject diesel in an incremental manner, and control the methanol nozzle to inject methanol in a reduced manner, so as to reduce the methanol substitution rate.

[0063] In this embodiment, after the engine starts and during the period when the methanol substitution rate is dynamically adjusted according to the corresponding coolant temperature, the ECU monitors key operating parameters of the engine in real time to determine whether the engine is stable and responsive in the short period after starting. For example, the ECU can obtain the crankshaft speed of the dual-fuel engine through the crankshaft speed sensor, calculate the crankshaft angular acceleration by differentiating the speed signal, obtain the in-cylinder pressure rise rate through the in-cylinder pressure sensor, and obtain the methanol temperature through the methanol temperature sensor, among other parameters, to adjust the methanol injection quantity in real time.

[0064] By comparing various operating parameters with preset steady-state threshold parameters, it is determined whether the engine is currently in a stable combustion state. Each operating parameter corresponds to a steady-state threshold parameter, and the threshold ranges for crankshaft speed, crankshaft angular acceleration, in-cylinder pressure rise rate, and methanol temperature can be set separately. If any operating parameter falls below the steady-state threshold parameter, it indicates a decrease in combustion quality, and power output may fluctuate or decrease.

[0065] If the crankshaft speed is below the threshold, it indicates incomplete combustion and insufficient power output. To maintain the same output power, increase the diesel injection quantity while reducing the methanol injection ratio to ensure stable combustion and speed recovery.

[0066] If the crankshaft angular acceleration is below the threshold, it indicates unstable power output and engine jerking. While maintaining constant engine output power, the diesel injection quantity is automatically increased, while the methanol substitution rate is reduced.

[0067] If the rate of increase in cylinder pressure is below the threshold, it indicates that the combustion rate is not ideal, the combustion efficiency is low, and the flame propagation is weak. To maintain the same output power, increase the diesel injection quantity and reduce the methanol substitution rate to avoid methanol combustion lag at low temperatures and improve the combustion process.

[0068] If the methanol temperature is below the threshold, the surface methanol temperature will be too low, resulting in insufficient fuel vaporization and affecting ignition. Reducing the methanol injection quantity and increasing diesel injection improves combustion stability and heat output. Simultaneously, a methanol heating device can be activated to assist in raising the methanol temperature.

[0069] Thus, when engine combustion is unstable, the output power of the dual-fuel engine can be kept constant, the diesel injector can be controlled to inject more diesel, and the methanol injector can be controlled to inject less methanol, thereby reducing the methanol substitution rate until all operating parameters stabilize. This dynamic adjustment mechanism ensures that the engine maintains stable operation during the transition phase after startup.

[0070] The stability of each operating parameter is achieved by ensuring that the crankshaft speed, crankshaft angular acceleration, in-cylinder pressure rise rate, or methanol temperature is not lower than the steady-state threshold value obtained in real time, and that these parameters are maintained continuously for a certain period of time within the set steady-state range.

[0071] like Figure 3 As shown, Figure 3 The flowchart illustrates the control method for the dual-fuel methanol-diesel direct injection engine of the present invention under dynamic operating conditions. To address the engine's performance requirements under acceleration and different load conditions, another objective of this embodiment is to solve numerous problems existing in the dual-fuel engine under dynamic operating conditions. A dynamic coordinated control mechanism based on torque demand and combustion stability is proposed, and the method further includes the following steps: S17. Obtain the vehicle's real-time operating parameters; the real-time operating parameters include at least one of the following: accelerator pedal position, intake pressure, and crankshaft speed of the dual-fuel engine; Real-time vehicle operating parameters are collected to identify the current operating condition of the vehicle. This includes data such as accelerator pedal position from a accelerator pedal position sensor, intake pressure from an intake pressure sensor, and crankshaft speed from a crankshaft speed sensor, and the engine load rate is calculated in real time.

[0072] S18. Identify the real-time operating conditions of the vehicle based on real-time operating parameters; By collecting various real-time operating parameters, the real-time operating conditions of the vehicle can be determined. These real-time operating conditions can include specific conditions such as low-speed idling, high-speed cruising, acceleration, hill climbing, and load operation. Accurate condition identification is the foundation for achieving precise control.

[0073] S19. Obtain the load rate of the dual-fuel engine under real-time operating conditions; Real-time calculation of engine load is a key basis for adjusting the methanol substitution rate. The engine load rate reflects the current power demand of the engine, and the engine load status is determined by the load rate. The load rate can be calculated as the percentage of the required torque to the maximum torque at the current speed.

[0074] S20. Based on the load rate and multiple preset load ranges, determine the methanol substitution rate range that matches the corresponding preset load range; wherein, the multiple preset load ranges include low load range, medium load range and high load range divided according to the load rate range from low to high; In this embodiment, the engine load is divided into multiple preset load intervals, and each preset load interval corresponds to a methanol substitution rate range. By comparing the load rate with each preset load interval, the target load interval to which the load rate belongs is determined. The methanol substitution rate range that matches the target load interval is obtained.

[0075] Specifically, this embodiment divides the load rate range into low-load, medium-load, and high-load intervals, from low to high. The low-load interval corresponds to a first methanol substitution rate range; the medium-load interval corresponds to a second methanol substitution rate range; and the high-load interval corresponds to a third methanol substitution rate range. The low-load, medium-load, and high-load intervals are consecutively divided from low to high, and the corresponding methanol substitution rate ranges also increase from low to high. Furthermore, the methanol substitution rate ranges increase with the load intervals, and there is no overlap between the methanol substitution rate ranges of the different load intervals.

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

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

[0078] S21. Based on the low load range, control the methanol nozzle to inject methanol within the first methanol substitution rate range; When the load rate is in the low load range, the methanol substitution rate is limited to a low range. The methanol injector is controlled to reduce the amount of methanol injected, automatically reducing the methanol substitution rate to less than 30%-40%, while the main diesel injection quantity is increased and the injection timing is delayed to improve power output.

[0079] S22. Based on the medium load range, control the methanol nozzle to inject methanol within the second methanol substitution rate range; When the load rate is in the medium load range, the methanol substitution rate is limited to a medium range. The methanol injection nozzle is controlled to inject methanol to a methanol substitution rate of 50%-60%, and combined with exhaust gas recirculation technology, the in-cylinder temperature is reduced and nitrogen oxide emissions are suppressed.

[0080] S23. Based on the high load range, control the methanol nozzle to spray methanol within the third methanol substitution rate range; When the load rate is in the high load range, a high substitution rate strategy is adopted. The methanol nozzle is controlled to inject methanol to a methanol substitution rate of 70%-95%. Premixed air is formed by advancing the methanol injection timing (e.g., 40 degrees crankshaft rotation before the top dead center of the compressor), which reduces combustion noise.

[0081] In yet another embodiment, after controlling the methanol nozzle to inject methanol within a corresponding methanol substitution rate range, the method further includes: S24. Obtain the rate of change of accelerator pedal opening under real-time operating conditions of the vehicle; S25. Determine whether the rate of change of accelerator pedal opening is greater than the change threshold parameter; S26. When the rate of change of throttle pedal opening is greater than the threshold operating parameter, control the output power of the dual-fuel engine to remain unchanged, control the diesel nozzle to inject diesel instantaneously at a rate that increases by a preset amount per cycle, and control the methanol nozzle to reduce the amount of methanol injected, so that the methanol substitution rate is reduced to the lower limit of the first methanol substitution rate range, and control the actuator to increase the intake pressure.

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

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

[0084] Thus, in this embodiment, during acceleration or load operation, the engine load changes rapidly, allowing for real-time sensing of operating conditions and dynamic adjustment of the methanol substitution rate, while simultaneously performing dynamic response compensation to improve the response speed and stability under dynamic operating conditions.

[0085] like Figure 4 As shown, Figure 4 The flowchart illustrates the control method for a dual-fuel methanol-diesel direct injection engine under dynamic operating conditions. Another objective of this embodiment is to address numerous problems in the fault diagnosis stage of dual-fuel engines. It proposes an intelligent fault-tolerant mechanism with hierarchical diagnosis and redundancy switching to improve the accuracy of fault diagnosis and the reliability of the system. The method further includes: S27. Obtain the common rail pressure parameters, methanol nozzle inlet pressure parameters, and methanol temperature of the vehicle's methanol system. S28. Determine whether the common rail pressure parameter and the methanol nozzle inlet pressure parameter are less than the preset injection pressure, and determine whether the methanol temperature is greater than the preset temperature. S29. If 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, the methanol system is determined to be faulty. S30. Obtain the diesel injector current parameters and high-pressure common rail pressure parameters of the vehicle's diesel system. S31. Determine if the diesel injector current parameters are abnormal, and determine if the high-pressure common rail pressure parameters exceed the preset pressure range. S32. If the diesel injector current parameter is abnormal, or the high-pressure common rail pressure parameter exceeds the preset pressure range, the diesel system is determined to be faulty. S33. If 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 compound fault.

[0086] In this embodiment, steps S27-S29 employ dual pressure sensors. For example, a first pressure sensor collects common rail pressure parameters, and a second pressure sensor collects methanol nozzle inlet pressure parameters. The common rail pressure and nozzle inlet pressure parameters are combined to form the methanol injection pressure. Simultaneously, a temperature sensor is used to obtain the methanol temperature, avoiding misjudgments that might occur when using a single sensor signal for fault diagnosis. If the methanol injection pressure is less than 60 MPa, it is considered insufficient pressure; if the methanol temperature is greater than 80°C, it is considered overheating, thus directly determining a methanol system fault. After determining a methanol system fault, step S291 is initiated, controlling the methanol nozzle to stop injection, switching to diesel system operation alone, and outputting methanol system fault information. In this embodiment, only methanol system faults are classified as Level 1 faults. Methanol injection is immediately shut off, switching to pure diesel mode, and a fault code is sent via the CAN bus to indicate abnormal methanol injection pressure, ensuring the engine can continue operating and simultaneously reminding the user to perform maintenance.

[0087] In steps S30-S32 of this embodiment, diesel injector current parameters and high-pressure common rail pressure parameters are obtained through diesel injector current waveform analysis and a high-pressure common rail pressure sensor, respectively, to detect diesel injection consistency. When the diesel injector drive current of a certain cylinder is abnormal, or the common rail pressure fluctuates by more than ±5%, a diesel system fault is determined. After determining the diesel system fault, the process proceeds to step S321. In the event of a diesel injection system fault, the power of the dual-fuel engine is reduced to a preset power, the backup diesel injector is activated, and diesel system fault information is output. In this embodiment, only diesel system faults are classified as Level 1 faults, limiting engine power to 50%, activating the backup diesel injector, and simultaneously sending a fault code to indicate a diesel injector fault, maintaining engine operation as much as possible while reducing power.

[0088] In step S33, when both abnormal methanol pressure and abnormal diesel injection current are detected simultaneously, it is determined to be a combined fault, and the process proceeds to step S331. In the event that both the methanol and diesel systems have failed, the dual-fuel engine is stopped, and an audible and visual alarm is issued. Simultaneous failure of both the methanol and diesel systems constitutes a level two fault, a serious fault. Therefore, an emergency shutdown procedure is triggered, cutting off all fuel supply and alerting the user with audible and visual alarms to prevent further damage caused by the combined fault.

[0089] Thus, in the fault diagnosis stage of this embodiment, due to the different structures and working principles of the methanol system and the diesel system, a single diagnostic method is difficult to accurately determine the fault. By using multi-sensor signals to determine the fault area, the accuracy of fault diagnosis and the reliability of the system are improved, ensuring the safe operation of the engine.

[0090] Secondly, this application also provides a vehicle equipped with a dual-fuel engine, the dual-fuel engine including a methanol nozzle for injecting methanol and a diesel nozzle for injecting diesel fuel. The vehicle further includes: a methanol system equipped with a first pressure sensor, a second pressure sensor, and a temperature sensor, the first pressure sensor being used to acquire the common rail pressure parameter of the methanol system, the second pressure sensor being used to acquire the methanol nozzle inlet pressure parameter of the methanol system, and the temperature sensor being used to acquire the methanol temperature of the methanol system; a diesel system equipped with a diesel nozzle, a diesel nozzle sensor, and a high-pressure common rail pressure sensor, the diesel nozzle sensor being used to acquire the diesel nozzle current parameter of the diesel nozzle, and the high-pressure common rail pressure sensor being used to acquire the high-pressure common rail pressure parameter of the diesel system; and a controller for executing the control method of the dual-fuel methanol-diesel direct injection engine described above.

[0091] Furthermore, the vehicle also includes a backup diesel injector, which is used to activate in the event of a diesel system failure.

[0092] As the vehicle embodiment is basically similar to the method embodiment, it is described in a relatively simple way. For relevant details, please refer to the description of the method embodiment.

[0093] The various embodiments in this specification are described in a progressive manner, with each embodiment focusing on the differences from other embodiments. The same or similar parts between the various embodiments can be referred to each other.

[0094] Those skilled in the art will understand that embodiments of this application can be provided as methods, apparatus, or computer program products. Therefore, embodiments of this application can take the form of entirely hardware embodiments, entirely software embodiments, or embodiments combining software and hardware aspects. Furthermore, embodiments of this application can take the form of computer program products implemented on one or more computer-usable storage media (including but not limited to disk storage, CD-ROM, optical storage, etc.) containing computer-usable program code.

[0095] This application describes embodiments with reference to flowchart illustrations and / or block diagrams of methods, terminal devices (systems), and computer program products according to embodiments of this application. It should be understood that each block of the flowchart illustrations and / or block diagrams, and combinations of blocks in the flowchart illustrations and / or block diagrams, can be implemented by computer program instructions. These computer program instructions can be provided to a processor of a general-purpose computer, special-purpose computer, embedded processor, or other programmable data processing terminal device to produce a machine, such that the instructions, which execute via the processor of the computer or other programmable data processing terminal device, generate instructions for implementing the flowchart illustrations. Figure 1 One or more processes and / or boxes Figure 1 A device that provides the functions specified in one or more boxes.

[0096] These computer program instructions may also be stored in a computer-readable storage medium that can direct a computer or other programmable data processing terminal device to operate in a particular manner, such that the instructions stored in the computer-readable storage medium produce an article of manufacture including instruction means, which are implemented in a process Figure 1 One or more 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 equipment, causing a series of operational steps to be performed on the computer or other programmable terminal equipment to produce a computer-implemented process, thereby providing instructions that execute on the computer or other programmable terminal equipment for implementing the process. Figure 1 One or more processes and / or boxes Figure 1 The steps of the function specified in one or more boxes.

[0098] Although preferred embodiments of the present application have been described, those skilled in the art, upon learning the basic inventive concept, can make other changes and modifications to these embodiments. Therefore, the appended claims are intended to be interpreted as including the preferred embodiments as well as all changes and modifications falling within the scope of the embodiments of the present application.

[0099] Finally, it should be noted that in this document, relational terms such as "first" and "second" are used only to distinguish one entity or operation from another, and do not necessarily require or imply any such actual relationship or order between these entities or operations. Furthermore, the terms "comprising," "including," or any other variations thereof are intended to cover non-exclusive inclusion, such that a process, method, article, or terminal device that comprises a list of elements includes not only those elements but also other elements not expressly listed, or elements inherent to such a process, method, article, or terminal device. Without further limitations, an element defined by the phrase "comprising one..." does not exclude the presence of other identical elements in the process, method, article, or terminal device that includes said element.

Claims

1. A control method for a dual-fuel methanol-diesel direct injection engine, applied to a vehicle equipped 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 fuel; characterized in that, The method includes: Obtain the ambient temperature of the vehicle; From four preset temperature ranges, the target temperature range to which the ambient temperature belongs is determined; wherein, the four preset temperature ranges correspond to extreme cold conditions, cold conditions, normal temperature conditions and high temperature conditions, respectively. Under the extreme cold conditions corresponding to the target temperature range, the diesel nozzle is controlled to inject diesel fuel according to the injection parameters corresponding to the first pre-injection, second pre-injection, third pre-injection and main injection in each cycle. The injection parameters of the first pre-injection, second pre-injection, third pre-injection and main injection satisfy the following: the crankshaft angle before the corresponding compression top dead center gradually decreases and the injection quantity gradually increases. When the target temperature range corresponds to the cold operating condition, the diesel injector is controlled to inject diesel fuel with the injection parameters corresponding to the second pre-injection, the third pre-injection, and the main injection; Under normal temperature conditions corresponding to the target temperature range, the diesel nozzle is controlled to inject diesel fuel according to the injection parameters corresponding to the third pre-injection and the main injection. When the target temperature range corresponds to the high-temperature operating condition, the system directly enters the dual-fuel mode, controlling the diesel injector to inject diesel fuel and the methanol injector to inject methanol.

2. The control method for a dual-fuel methanol-diesel direct injection engine according to claim 1, characterized in that, The method further includes: Obtain the coolant temperature of the vehicle; Based on the completion status of the diesel nozzle injection, the methanol pressure is controlled to a preset pressure; Based on the temperature of the coolant after heating, determine whether the dual-fuel engine has entered dual-fuel mode; When the dual-fuel engine enters dual-fuel mode, a methanol substitution rate matching the corresponding preset coolant temperature is determined based on the coolant temperature and multiple preset coolant temperatures; wherein, the multiple preset coolant temperatures include a first coolant temperature, a second coolant temperature, and a third coolant temperature; When the coolant temperature rises to the first coolant temperature, the methanol nozzle is controlled to start injecting methanol, so that the initial methanol substitution rate is a first preset value. During the period when the coolant temperature gradually rises from the first coolant temperature to the second coolant temperature, the methanol nozzle is controlled to gradually increase the amount of methanol injected, so that the methanol substitution rate gradually increases to the second preset value. During the period when the coolant temperature gradually rises from the second coolant temperature to the third coolant temperature, the methanol nozzle is controlled to gradually increase the amount of methanol injected, so that the methanol substitution rate gradually increases to the third preset value. The first preset value, the second preset value, and the third preset value are arranged in ascending order.

3. The control method for a dual-fuel methanol-diesel direct injection engine according to claim 1, characterized in that, The injection parameters for the first pre-injection, second pre-injection, third pre-injection, and main injection satisfy the following: the crankshaft angle before the corresponding compression top dead center gradually decreases, and the injection quantity gradually increases, including: The diesel nozzle is controlled to inject diesel fuel at a crankshaft rotation angle of 120 degrees before the top dead center of the compression stroke and an injection quantity of 5 mg per cycle to complete the first pre-injection of the diesel fuel. The diesel nozzle is controlled to inject diesel fuel at a crankshaft rotation angle of 60 degrees before the top dead center of the compression stroke and an injection quantity of 8 mg per cycle, thus completing the second pre-injection of the diesel fuel. The diesel nozzle is controlled to inject diesel fuel at a crankshaft rotation angle of 30 degrees before the top dead center of the compression stroke and an injection quantity of 10 milligrams per cycle, thus completing the third pre-injection of the diesel fuel. The diesel nozzle is controlled to inject diesel fuel at a rate of 20 mg per cycle, with a crankshaft rotation angle of 10 degrees before the top dead center of the compression stroke, thus completing the main injection of the diesel fuel.

4. The control method for a dual-fuel methanol-diesel direct injection engine according to claim 2, characterized in that, After controlling the methanol nozzle to gradually and incrementally inject methanol, the method further includes: Obtain the operating parameters of the dual-fuel engine; the operating parameters include at least one of crankshaft speed, crankshaft angular acceleration, in-cylinder pressure rise rate, and methanol temperature; Determine whether the operating parameters are lower than the steady-state threshold parameter; When the operating parameters are lower than the steady-state threshold parameters, the output power of the dual-fuel engine is kept constant, the diesel injector is controlled to inject diesel in an incremental manner, and the methanol injector is controlled to inject methanol in a reduced manner, thereby reducing the methanol substitution rate.

5. The control method for a dual-fuel methanol-diesel direct injection engine according to claim 2, characterized in that, After controlling the methanol nozzle to gradually and incrementally inject methanol, the method further includes: The real-time operating parameters of the vehicle are obtained; the real-time operating parameters include at least one of the following: accelerator pedal position, intake pressure, and crankshaft speed of the dual-fuel engine. Based on the real-time operating parameters, the real-time operating conditions of the vehicle are identified; Obtain the load rate of the dual-fuel engine under the real-time operating conditions; Based on the load rate and multiple preset load ranges, a methanol substitution rate range matching the corresponding preset load range is determined; wherein, the multiple preset load ranges include a low load range, a medium load range, and a high load range divided according to the load rate range from low to high; Based on the low load range, the methanol nozzle is controlled to inject methanol within the first methanol substitution rate range; Based on the medium load range, the methanol nozzle is controlled to inject methanol within the second methanol substitution rate range; Based on the high load range, the methanol nozzle is controlled to spray methanol within the third methanol substitution rate range; Wherein, the upper limit of the first methanol substitution rate range is less than the lower limit of the second methanol substitution rate range, and the upper limit of the second methanol substitution rate range is less than the lower limit of the third methanol substitution rate range.

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

7. The control method for a dual-fuel methanol-diesel direct injection engine according to claim 1, characterized in that, The method further includes: Obtain the common rail pressure parameters, methanol nozzle inlet pressure parameters, and methanol temperature of the vehicle's methanol system; Determine whether the common rail pressure parameter and the methanol nozzle inlet pressure parameter are less than the preset injection pressure, and determine whether the methanol temperature is greater than the preset temperature; If the common rail pressure parameter and the methanol nozzle inlet pressure parameter are less than the preset injection pressure, or if the methanol temperature is greater than the preset temperature, the methanol system is determined to be faulty. Obtain the diesel injector current parameters and high-pressure common rail pressure parameters of the vehicle's diesel system; Determine whether the diesel injector current parameter is abnormal, and determine whether the high-pressure common rail pressure parameter exceeds the preset pressure range; If the diesel injector current parameter is abnormal, or the high-pressure common rail pressure parameter exceeds the preset pressure range, the diesel system is determined to be faulty. If 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 combined fault.

8. The control method for a dual-fuel methanol-diesel 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 malfunction in the methanol system, the methanol nozzle is controlled to stop injecting, the diesel system is switched to operate independently, and methanol system malfunction information is output. After determining that the diesel system is faulty, the method further includes: In the event of a malfunction in the diesel injection system, the power of the dual-fuel engine is reduced to a preset power, the backup diesel injector is activated, and diesel system malfunction information is output. After determining that a fault is a compound fault, the method includes: In the event of a failure in both the methanol system and the diesel system, the dual-fuel engine will be shut down, and an audible and visual alarm will be displayed.

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

10. The vehicle according to claim 9, characterized in that, The vehicle also includes a backup diesel injector for activation in the event of a failure in the diesel system.

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