Diesel engine plateau cold start control method and system

Abstract

The application discloses a diesel engine plateau cold start control method and system, and relates to the technical field of diesel engines.The method comprises the following steps: acquiring the running parameter information of the diesel engine in real time, and calculating the in-cylinder background temperature and the in-cylinder background pressure of the piston top dead center of the diesel engine; judging whether the diesel engine reaches the ignition condition under the current working condition according to the comparison between the engine running parameters and the diesel engine ignition critical MAP (mapping) diagram; if the diesel engine reaches the ignition condition, determining the optimal fuel injection pressure of the diesel engine under the current working condition based on the injection strategy MAP diagram, and controlling the fuel injection of the diesel engine; and if the diesel engine does not reach the ignition condition, determining the low-temperature start auxiliary measure of the diesel engine under the current working condition based on the diesel engine ignition critical MAP diagram, and controlling the operation until the diesel engine reaches the ignition condition.The application can more accurately judge whether the diesel engine reaches the ignition condition under the plateau cold start condition, more reasonably match the diesel fuel injection strategy and the auxiliary measure, and more efficiently and lowly consume improve the plateau cold start performance of the diesel engine.

Description

TECHNICAL FIELD

[0001] The application relates to the diesel engine technical field, in particular to a diesel engine plateau cold start control method and system. BACKGROUND

[0002] The diesel engine is a kind of engine which converts chemical energy (diesel fuel) into mechanical energy (power), and compared with the gasoline engine, it has good economy and high thermal efficiency, but the diesel engine is difficult to start under low temperature conditions, and poor starting performance restricts the wide application of the diesel engine. And China is vast in territory, and the plateau area accounts for about 37% of the land area, and the complex geographical conditions and climate characteristics will have a significant impact on the performance of the diesel engine.

[0003] Because of the small air density and low ambient temperature in the plateau area, when the diesel engine is cold started, the intake air temperature, intake air pressure, engine body temperature and circulating water temperature are all at a low level, the evaporation and mixing of the fuel will deteriorate and prolong the ignition delay period of the combustible mixture, once the piston starts to descend, the cylinder temperature starts to drop, and the ignition will become more difficult, and even misfire will occur. Therefore, how to improve the success rate of cold start of the diesel engine under complex plateau conditions and improve the cold start performance is an urgent problem to be solved. SUMMARY

[0004] The application provides a diesel engine plateau cold start control method and system, which constructs a cold start control strategy, more accurately controls the start and stop of the cold start auxiliary measures, more reasonably matches the low temperature starting auxiliary measures according to the engine operating state, realizes efficient and low-consumption improvement of the ignition success rate, and improves the cold start performance of the diesel engine.

[0005] The specific technical solutions are as follows:

[0006] In a first aspect, the application embodiment provides a diesel engine plateau cold start control method, which comprises the following steps:

[0007] Real-time acquisition of the operating parameter information of the diesel engine, and calculation of the cylinder background temperature and the cylinder background pressure of the piston top dead center of the diesel engine according to the operating parameter information, wherein the operating parameter information comprises the intake air temperature, the intake air pressure, the circulating water temperature and the injection pressure;

[0008] Extraction of the diesel engine ignition critical MAP, and judgment of whether the ignition condition is reached under the current working condition of the diesel engine according to the comparison between the cylinder background temperature, the cylinder background pressure, the circulating water temperature and the injection pressure and the diesel engine ignition critical MAP;

[0009] If the diesel engine reaches the ignition condition under the current working condition, an injection strategy MAP graph is extracted, the optimal injection pressure of the diesel engine under the current working condition is determined based on the injection strategy MAP graph, and the diesel engine is controlled to inject diesel oil according to the optimal injection pressure, wherein the injection strategy MAP graph is a curve graph of the ignition delay period varying with the injection pressure under different altitude conditions.

[0010] If the diesel engine does not reach the ignition condition under the current working condition, the low-temperature starting auxiliary measure of the diesel engine under the current working condition is determined based on the diesel engine ignition critical MAP graph, and the diesel engine is controlled to operate according to the low-temperature starting auxiliary measure until the diesel engine reaches the ignition condition; wherein the low-temperature starting auxiliary measure is one or both of the intake preheating measure and the circulating water heating measure.

[0011] In some embodiments of the present application, the calculation formula of the in-cylinder background temperature is:

[0012] T=T1 x ε k-1

[0013] The calculation formula of the in-cylinder background pressure is:

[0014] P=P1 x ε k

[0015] In the formula, T is the in-cylinder background temperature of the diesel engine piston at the top dead center; T1 is the intake temperature of the diesel engine; P is the in-cylinder background pressure of the diesel engine piston at the top dead center; P1 is the intake pressure of the diesel engine; ε is the compression ratio of the diesel engine; and k is the adiabatic compression index.

[0016] In some embodiments of the present application, the method further comprises:

[0017] Optical tests are performed in a constant volume combustion bomb to obtain spray characteristic data and ignition characteristic data under highland cold starting conditions, wherein the spray characteristic data includes gas / liquid phase penetration distance, spray cone angle and mixture concentration, and the ignition characteristic data includes ignition success rate and ignition delay period;

[0018] A three-dimensional simulation model of the constant volume combustion bomb is built, and the three-dimensional simulation model of the constant volume combustion bomb is calibrated according to the spray characteristic data and the ignition characteristic data;

[0019] Based on the calibrated three-dimensional simulation model of the constant volume combustion bomb, the temperature, pressure, fuel temperature and injection pressure in the constant volume combustion bomb are controlled respectively, the ambient temperature, ambient pressure, fuel temperature under different altitude conditions and the ignition delay period data of spray combustion under different injection pressures are obtained through three-dimensional simulation calculation, the injection strategy MAP graph is obtained according to the ignition delay period data, and the diesel engine ignition critical MAP graph under different injection pressures and fuel temperatures is obtained.

[0020] In some embodiments of the present application, the optical test in the constant volume combustion bomb, the spray characteristic data and the ignition characteristic data under high altitude cold start conditions are specifically as follows:

[0021] The fuel injector of the diesel engine is installed in the constant volume combustion bomb;

[0022] The temperature and pressure in the constant volume combustion bomb are adjusted to achieve the high altitude cold start conditions at different altitudes, the fuel injector is controlled to spray fuel, and the spray characteristic data and the ignition characteristic data corresponding to different altitude conditions are obtained.

[0023] In some embodiments of the present application, the method further comprises:

[0024] After the electric control system of the diesel engine is powered on, the sensors of the diesel engine are controlled to perform self-checking; wherein the sensors include an intake temperature sensor, an intake pressure sensor, a circulating water temperature sensor, and a high pressure oil rail pressure sensor;

[0025] If the sensor self-checking is abnormal, the ECU of the diesel engine reports a sensor fault code, and controls the diesel engine to stop, after troubleshooting, the electric control system is powered on again, and the sensors are controlled to perform self-checking until the sensor self-checking is normal;

[0026] If the sensor self-checking is normal, the ECU enters a waiting start signal state, when the ECU receives a start signal, the diesel engine is controlled to be powered on and started, and the diesel engine is dragged to reach a specified start speed, and the sensor monitors the operating parameter information of the diesel engine in real time.

[0027] In some embodiments of the present application, the extraction of the diesel engine ignition critical MAP and the comparison of the in-cylinder background temperature, the in-cylinder background pressure, the circulating water temperature, and the fuel injection pressure with the diesel engine ignition critical MAP to determine whether the diesel engine reaches the ignition condition under the current working condition specifically comprises:

[0028] The diesel engine ignition critical MAP is extracted, and the ignition area in the diesel engine ignition critical MAP corresponding to the circulating water temperature and the fuel injection pressure under the current working condition of the diesel engine is determined;

[0029] According to whether the in-cylinder background temperature and the in-cylinder background pressure under the current working condition of the diesel engine are in the ignition area of the diesel engine ignition critical MAP, it is determined whether the diesel engine reaches the ignition condition under the current working condition;

[0030] If the in-cylinder background temperature and the in-cylinder background pressure of the diesel engine under the current working condition are in the ignition region, it is determined that the ignition condition is reached under the current working condition of the diesel engine; if the in-cylinder background temperature and the in-cylinder background pressure of the diesel engine under the current working condition are not in the ignition region, it is determined that the ignition condition is not reached under the current working condition of the diesel engine.

[0031] In some embodiments of the present application, the low-temperature starting auxiliary measure under the current working condition of the diesel engine is determined based on the diesel engine ignition critical MAP, and the diesel engine is controlled to operate according to the low-temperature starting auxiliary measure until the diesel engine reaches the ignition condition, specifically comprising:

[0032] The low-temperature starting auxiliary measure under the current working condition of the diesel engine is determined as the intake air preheating measure, and the diesel engine is controlled to perform the intake air preheating operation until the in-cylinder background temperature and the in-cylinder background pressure of the diesel engine are in the ignition region of the diesel engine ignition critical MAP;

[0033] If the in-cylinder background temperature and the in-cylinder background pressure of the diesel engine cannot be in the ignition region of the diesel engine ignition critical MAP after the intake air temperature of the diesel engine is increased to the intake air temperature heating limit, the low-temperature starting auxiliary measure under the current working condition of the diesel engine is re-determined as the circulating water heating measure, the diesel engine is controlled to stop the intake air preheating operation, and the diesel engine is controlled to perform the circulating water heating operation until the in-cylinder background temperature and the in-cylinder background pressure of the diesel engine are in the ignition region of the diesel engine ignition critical MAP;

[0034] If the in-cylinder background temperature and the in-cylinder background pressure of the diesel engine cannot be in the ignition region of the diesel engine ignition critical MAP after the circulating water temperature of the diesel engine is increased to the circulating water temperature heating limit, the low-temperature starting auxiliary measure under the current working condition of the diesel engine is re-determined as a combination of the intake air preheating measure and the circulating water heating measure, and the diesel engine is controlled to perform the intake air preheating operation and the circulating water heating operation until the in-cylinder background temperature and the in-cylinder background pressure of the diesel engine are in the ignition region of the diesel engine ignition critical MAP.

[0035] In some embodiments of the present application, the optimal injection pressure under the current working condition of the diesel engine is determined based on the injection strategy MAP, specifically comprising:

[0036] Based on the injection strategy MAP, the injection pressure corresponding to the shortest ignition delay period under the current working condition of the diesel engine is determined as the optimal injection pressure.

[0037] Through the above scheme, it can be known that the embodiment of the application collects the running parameters of the diesel engine in real time through the sensor, such as the intake temperature, the intake pressure, the circulating water temperature, the injection pressure and the like, and feeds back to the ECU, calculates the in-cylinder background temperature and the in-cylinder background pressure through the ECU, compares the calculated reference variable with the critical MAP graph of diesel engine ignition stored in the ECU, judges whether the low-temperature starting auxiliary measures need to be taken, if not, adjusts the injection pressure to the best according to the injection strategy MAP graph, if it cannot be started normally by adjusting the injection parameters, matches the best low-temperature starting auxiliary measures according to the critical MAP graph of diesel engine ignition, adopts one or several auxiliary measures combination, so as to improve the cold starting success rate, optimize the cold starting performance, and save energy and reduce emissions.

[0038] In the second aspect, the embodiment of the application provides a highland cold starting control system of a diesel engine, the system comprises:

[0039] A parameter acquisition module is configured to acquire running parameter information of the diesel engine in real time, and calculate in-cylinder background temperature and in-cylinder background pressure of the diesel engine piston top dead center according to the running parameter information, wherein the running parameter information comprises intake temperature, intake pressure, circulating water temperature and injection pressure.

[0040] An ignition condition judgment module is configured to extract a critical MAP graph of diesel engine ignition, judge whether the ignition condition is reached under the current working condition of the diesel engine according to comparison between the in-cylinder background temperature, the in-cylinder background pressure and the critical MAP graph of diesel engine ignition, and the circulating water temperature and the injection pressure.

[0041] A injection strategy determination module is configured to extract a injection strategy MAP graph when the ignition condition is reached under the current working condition of the diesel engine, determine the best injection pressure under the current working condition of the diesel engine based on the injection strategy MAP graph, and control the diesel engine to inject diesel according to the best injection pressure, wherein the injection strategy MAP graph is a curve graph of the ignition delay period changing with the injection pressure under different altitude conditions.

[0042] A low-temperature starting auxiliary module is configured to determine a low-temperature starting auxiliary measure under the current working condition of the diesel engine based on the critical MAP graph of diesel engine ignition when the ignition condition is not reached under the current working condition of the diesel engine, and control the diesel engine to operate according to the low-temperature starting auxiliary measure until the ignition condition of the diesel engine is reached, wherein the low-temperature starting auxiliary measure is one or both of the intake preheating measure and the circulating water heating measure.

[0043] In some embodiments of the application, the system further comprises:

[0044] An optical test module is configured to perform optical tests in a constant volume combustion bomb to obtain spray characteristic data and ignition characteristic data under high altitude cold start conditions, wherein the spray characteristic data includes gas / liquid phase penetration distance, spray cone angle and mixed gas concentration, and the ignition characteristic data includes ignition success rate and ignition delay period.

[0045] A MAP diagram acquisition module is configured to build a three-dimensional simulation model of the constant volume combustion bomb, calibrate the three-dimensional simulation model of the constant volume combustion bomb according to the spray characteristic data and the ignition characteristic data, and control the temperature, pressure, fuel temperature and fuel injection pressure in the constant volume combustion bomb based on the calibrated three-dimensional simulation model of the constant volume combustion bomb, so as to obtain the ambient temperature, ambient pressure, fuel temperature under different altitude conditions and the ignition delay period data of spray combustion under different fuel injection pressures through three-dimensional simulation calculation, and obtain the injection strategy MAP diagram and the diesel engine ignition critical MAP diagram under different fuel injection pressures and fuel temperatures according to the ignition delay period data.

[0046] In a third aspect, an embodiment of the present application provides a computing device, including a storage device and a processor, the storage device is configured to store a computer program, and the processor is configured to run the computer program to enable the computing device to perform the method in the first aspect.

[0047] In a fourth aspect, an embodiment of the present application provides a storage medium, which stores a computer program used in a computing device, and the computer program is executed by a processor to implement the method in the first aspect.

[0048] In a fifth aspect, an embodiment of the present application provides a computer program product, which includes instructions, and when the instructions are run on a computer or a processor, the computer or the processor performs the method in the first aspect.

[0049] The innovations of the embodiments of the present application include but are not limited to the following points:

[0050] 1. The diesel engine ignition critical MAP diagram and the injection strategy MAP diagram are obtained by combining optical tests and three-dimensional simulation of diesel ignition, and are stored in the ECU, and the diesel engine ignition critical MAP diagram and the injection strategy MAP diagram are used as a judgment basis for diesel engine high altitude cold start control, so that the start and stop of cold start auxiliary measures can be more accurately controlled, the best low temperature start auxiliary measure can be matched according to the engine operating state, and the low temperature cold start performance optimization can be efficiently and energy-savingly completed.

[0051] 2. The diesel engine's intake temperature, intake pressure, circulating water temperature, injection pressure and other operating parameters are obtained in real time by sensors, and the in-cylinder background temperature and pressure when the diesel engine piston is at the compression top dead center are calculated according to the operating parameters fed back by the sensors, so that the diesel engine's operating state is monitored in real time, the obtained engine operating parameters are more real-time and effective, and it can be more accurately judged whether the diesel engine reaches the ignition condition under the current working condition and whether auxiliary measures are needed, thereby solving the problem that the cold start control strategy in the prior art cannot cope with the influence of the coupling of multiple parameters in the cylinder on the starting performance under plateau conditions.

[0052] 3. Whether the diesel ignition condition is reached is judged by comparing the in-cylinder thermal state with the diesel ignition critical MAP, the diesel engine ignition critical MAP stored in the ECU is used as a judgment reference, various plateau environments can be adapted, the judgment is more convenient and accurate, and the practicality is strong.

[0053] 4. When the diesel engine's current working condition reaches the diesel ignition condition, the optimal injection pressure is selected according to the injection strategy MAP, the optimal injection pressure is determined with the shortest ignition delay as the target, the injection strategy MAP stored in the ECU is used to determine the optimal injection pressure, which is more efficient and convenient, the ignition success rate is higher, the diesel engine's cold start performance is better, the mixture burns completely, and the energy-saving and emission-reducing effect is achieved.

[0054] 5. When the diesel engine's current working condition cannot reach the diesel ignition condition, the optimal low-temperature starting auxiliary measure is selected and operated according to the diesel engine ignition critical MAP until the ignition condition is reached, and the optimal injection pressure is selected for injection to start, the diesel engine ignition critical MAP stored in the ECU is used to determine the low-temperature starting auxiliary measure, which can comprehensively consider the heating efficiency, battery power consumption, drag speed and other factors, and quickly obtain the optimal low-temperature starting auxiliary measure, which is efficient and convenient and has strong practicality.

[0055] The beneficial effects of the embodiments of the present application are as follows:

[0056] By constructing a cold start control strategy, the start and stop of the cold start auxiliary measure are more accurately controlled, and the low-temperature starting auxiliary measure is more reasonably matched according to the engine operating state, so that the ignition success rate is improved efficiently and with low consumption, the diesel engine's cold start performance is improved, and the energy-saving and emission-reducing purpose is achieved. BRIEF DESCRIPTION OF DRAWINGS

[0057] In order to more clearly illustrate the technical solutions in the embodiments of the present application or the prior art, the drawings needed to be used in the embodiments or the prior art description will be briefly introduced below. 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 creating any inventive labor.

[0058] Figure 1 A flowchart of a diesel engine plateau cold start control method provided by the embodiment of the present application;

[0059] Figure 2 A spray strategy MAP provided by the embodiment of the present application;

[0060] Figure 3 A diesel engine ignition critical MAP provided by the embodiment of the present application;

[0061] Figure 4 An impact diagram of the intake preheating measure on the ignition condition at an altitude of 3000m provided by the embodiment of the present application;

[0062] Figure 5 An impact diagram of the single heating auxiliary on the ignition condition at an altitude of 4000m provided by the embodiment of the present application;

[0063] Figure 6 An impact diagram of the compound low-temperature start auxiliary measure on the ignition condition at an altitude of 4000m provided by the embodiment of the present application;

[0064] Figure 7 A running flowchart of the diesel engine plateau cold start control method provided by the embodiment of the present application;

[0065] Figure 8 A composition block diagram of the diesel engine plateau cold start control system provided by the embodiment of the present application;

[0066] Figure 9 A structure diagram of a computing device provided by the embodiment of the present application;

[0067] Figure 10 A structure diagram of a storage medium provided by the embodiment of the present application. DETAILED DESCRIPTION

[0068] The technical solutions in the embodiments of the present application will be clearly and completely described below with reference to the drawings in the embodiments of the present application. Obviously, the described embodiments are only some of the embodiments of the present application, but not all the embodiments of the present application. Based on the embodiments in the present application, all the other embodiments obtained by those of ordinary skill in the art without creative effort belong to the scope of protection of the present application.

[0069] It should be noted that the embodiments in the present application and the features in the embodiments can be combined with each other in the case of no conflict. The terms "comprising" and "having" and any variations thereof in the embodiments of the present application and the drawings are intended to cover non-exclusive inclusion. For example, the processes, methods, systems, products or devices including a series of steps or units are not limited to the listed steps or units, but can optionally further include steps or units not listed or can optionally further include other steps or units inherent to these processes, methods, products or devices.

[0070] Compared with the plain, the oxygen content decreases in the plateau environment, the cold start ignition success rate of the diesel engine decreases, and the improvement of the starting performance of the diesel engine mainly includes: optimizing the design parameters such as compression ratio and combustion chamber shape, optimizing the control parameters such as injection pressure and injection pulse width, valve timing and adopting auxiliary measures such as intake heating. However, due to the high cost and long cycle of the optimization of the design parameters, the adjustment of the control parameters also has limited effect on the optimization of the starting performance of the diesel engine, so it is necessary to improve the starting success rate of the diesel engine through auxiliary measures in the extreme environment of the plateau low temperature. However, in the prior art, the control of the low temperature auxiliary measures is mainly based on the reference of the environmental threshold, for example, if the environmental temperature or pressure is lower than the set threshold, the low temperature starting auxiliary measures are used. On the one hand, the above control strategy only uses the environmental parameters as the basis for judgment, and does not consider the spray ignition process dominated by the coupling of multiple parameters in the cylinder, and cannot accurately cope with the problem of cold start of the diesel engine under complex conditions such as variable altitude; on the other hand, the control strategy in the prior art cannot comprehensively arrange various auxiliary measures and injection strategies according to the environmental parameter threshold, and it is difficult to efficiently complete the optimization of the cold start performance.

[0071] In view of the above problems, the diesel engine plateau cold start control method is disclosed in the embodiments of the present application to achieve the purposes of improving the cold start success rate of the diesel engine on the plateau, optimizing the cold start performance of the diesel engine and saving energy and reducing emissions. The following will be described in detail.

[0072] In the embodiments of the present application, the cold start ignition success rate and the cold start performance are mainly improved from the following two aspects: the first aspect is to promote the formation of the mixture in the cylinder, such as optimizing the injection parameters; the second aspect is to improve the ignition condition of the mixture in the cylinder, such as intake preheating, circulating water heating and other auxiliary measures. For the complex plateau environment, the diesel engine plateau cold start control method designs a set of comprehensive and effective control strategy to comprehensively arrange the above optimization measures to achieve the best optimization effect and improve the cold start performance of the diesel engine.

[0073] Figure 1 A diesel engine plateau cold start control method is shown according to the embodiments of the present application. As shown in Figure 1 The diesel engine plateau cold start control method includes the following steps:

[0074] Step S110: Real-time acquisition of the operating parameter information of the diesel engine, and calculation of the in-cylinder background temperature and in-cylinder background pressure of the piston top dead center of the diesel engine according to the operating parameter information.

[0075] In the prior art, the low-temperature cold start method of the diesel engine uses a single environmental variable threshold as the basis for determining whether to use auxiliary heating measures. Although this method is simple and easy to operate, it is not accurate and effective. On the one hand, the in-cylinder thermal state of the engine near the compression top dead center is affected by the mutual coupling of the intake temperature, intake pressure, and circulating water temperature. Referring to only the threshold of the environmental parameter may overestimate the actual in-cylinder thermal state of the engine. For example, when the environmental parameter is higher than the determination threshold for starting the auxiliary measures, the in-cylinder thermal state at the compression top dead center may still not meet the in-cylinder ignition condition. In this case, auxiliary measures such as intake preheating are still needed, otherwise the diesel engine cannot be successfully started. On the other hand, when the environmental parameter is lower than the determination threshold for starting the auxiliary measures, the diesel engine may be successfully started by adjusting the fuel injection parameters. In this case, taking auxiliary measures will cause waste of battery power, which may lead to insufficient power supply of the starter motor, making it difficult to reverse the diesel engine to the starting speed, and further increasing the risk of cold start failure.

[0076] In the embodiments of the present application, the high-altitude cold start control method of the diesel engine acquires the operating parameter information of the diesel engine in real time through multiple sensors. Specifically, the operating parameter information includes the intake temperature, intake pressure, circulating water temperature, and fuel injection pressure. Then, the in-cylinder background temperature and in-cylinder background pressure of the piston top dead center of the diesel engine are obtained by calculation based on the operating parameter information fed back by the sensors. Thus, the cold start control strategy is constructed using real-time monitoring of environmental variables and engine operating parameters, and the high-altitude cold start control process of the diesel engine is optimized. The cold start control strategy can effectively and accurately determine whether the diesel engine meets the ignition condition under the current working condition and whether auxiliary measures are needed, solving the problem that the cold start control strategy in the prior art cannot cope with the influence of the coupling of multiple in-cylinder parameters under high-altitude conditions on the starting performance.

[0077] In some specific embodiments, the main components of the device applying the high-altitude cold start control method of the diesel engine include an intake temperature sensor, an intake pressure sensor, a circulating water temperature sensor, a high-pressure oil rail pressure sensor, an ECU (Electronic Control Unit), and an oil injector, etc. Each sensor is used to collect operating parameters such as intake temperature, intake pressure, circulating water temperature, and fuel injection pressure. The ECU calculates the background temperature and background pressure at the compression top dead center in the cylinder based on the data fed back by the multiple sensors. Specifically, the calculation formula of the in-cylinder background temperature at the compression top dead center is as follows:

[0078] T = T1 x ε k-1

[0079] The calculation formula of the cylinder background pressure at the compression top dead center is as follows:

[0080] P = P1 x ε k

[0081] In the above two formulas, T is the cylinder background temperature at the top dead center of the diesel engine piston; T1 is the intake temperature of the diesel engine; P is the cylinder background pressure at the top dead center of the diesel engine piston; P1 is the intake pressure of the diesel engine; ε is the compression ratio of the diesel engine; and k is the adiabatic compression index.

[0082] In an embodiment, before step S110, the diesel engine highland cold start control method further comprises:

[0083] A) After the electric control system of the diesel engine is powered on, the sensors of the diesel engine are controlled to perform self-checking.

[0084] The sensors include an intake temperature sensor, an intake pressure sensor, a circulating water temperature sensor, and a high-pressure oil rail pressure sensor.

[0085] If the sensor self-checking is abnormal, then step A is entered to step B.

[0086] B) The ECU of the diesel engine reports a sensor fault code, and controls the diesel engine to stop, after the fault is eliminated, the electric control system is powered on again, and the sensors are controlled to perform self-checking until the sensor self-checking is normal.

[0087] That is, when the sensor self-checking is abnormal, the ECU reports a sensor fault code, restricts the subsequent operation of the starter motor, stops, and after the fault is eliminated, the electric control system is powered on again and self-checking is performed until the self-checking is normal, and step B is entered to step C.

[0088] If the sensor self-checking is normal, then step A or step B is entered to step C.

[0089] C) The ECU enters a waiting start signal state, when the ECU receives a start signal, the diesel engine is controlled to be powered on and started, and the diesel engine is dragged to a specified start speed, and the sensors monitor the operating parameter information of the diesel engine in real time.

[0090] That is, when the sensor self-checking is normal, the start signal is waited for, after the diesel engine starts, the ECU receives the start signal, the starter motor is powered on, the engine is dragged to a specified start speed, and the sensors monitor the operating parameters such as the intake temperature, the intake pressure, the circulating water temperature, and the injection pressure during the operation of the starter motor.

[0091] Step S120: Extracting a diesel engine ignition critical MAP, and judging whether the ignition condition is reached under the current working condition of the diesel engine according to the comparison between the cylinder background temperature, the cylinder background pressure, the circulating water temperature, and the injection pressure and the diesel engine ignition critical MAP.

[0092] It should be noted that the ignition delay period in the present application refers to the time from the start of diesel injection to spray ignition. When the ignition delay period is extended to the piston downstroke phase, the in-cylinder temperature and pressure rapidly decrease and cannot be ignited. Generally, when the diesel ignition delay period exceeds 3 ms, the diesel engine is considered to be misfired.

[0093] In the embodiment of the present application, a diesel engine ignition critical MAP chart is stored in the ECU, and whether the ignition condition is reached under the current working condition of the diesel engine is judged by comparison with the actual in-cylinder temperature, in-cylinder pressure, circulating water temperature and injection pressure. If the ignition condition is reached under the current working condition of the diesel engine, step S120 enters step S130; if the ignition condition is not reached under the current working condition of the diesel engine, step S120 enters step S140.

[0094] In an embodiment, the specific acquisition method of the diesel engine ignition critical MAP chart includes the following steps:

[0095] a) Optical testing is performed in a constant volume combustion bomb to obtain spray characteristic data and ignition characteristic data under high-altitude cold start conditions.

[0096] Specifically, the optical testing in the constant volume combustion bomb obtains the ambient temperature, ambient pressure, circulating water temperature corresponding to different altitude conditions and the ignition delay period data of spray combustion under different injection pressures, i.e. spray characteristic data and ignition characteristic data, wherein the spray characteristic data mainly includes gas / liquid phase penetration distance, spray cone angle and mixture concentration, and the ignition characteristic data mainly includes ignition success rate and ignition delay period.

[0097] Further specifically, the fuel injector of the diesel engine is installed at the top of the constant volume combustion bomb; the circulating water temperature and the temperature and pressure in the constant volume combustion bomb are adjusted to achieve high-altitude cold start conditions at different altitudes, the fuel injector is controlled to inject fuel, and the spray characteristic data and ignition characteristic data corresponding to different altitude conditions are obtained.

[0098] Wherein, the high-altitude condition in the present application refers to the temperature and pressure under high-altitude environment, and for every 1000m increase in altitude, the air temperature decreases by about 5-6℃ and the air pressure decreases by about 0.1bar. The high-altitude cold start condition in the present application corresponds to the background temperature and background pressure in the cylinder when the engine starts under high-altitude conditions, and the high-altitude cold start generally refers to the case that the engine in-cylinder temperature and pressure are lower than those under plain condition, for example, based on a diesel engine with a compression ratio of about 14, when the altitude is 4000m, the ambient temperature is about 273K and the intake pressure is about 0.06MPa, at this time the engine compression top dead center in-cylinder background temperature and background pressure are 785K and 2.1MPa respectively, which are obviously lower than 840K and 3.4MPa under plain condition, at this time the engine is under high-altitude cold start condition.

[0099] b) Build a three-dimensional simulation model of the constant-volume incendiary bomb, and calibrate the three-dimensional simulation model of the constant-volume incendiary bomb based on spray characteristic data and ignition characteristic data.

[0100] Specifically, an in-cylinder ignition model (i.e., a three-dimensional simulation model of a constant-volume incendiary bomb) is established in CFD (Computational Fluid Dynamics) software, and the model is calibrated based on the optical test results obtained in step a) above.

[0101] c) Based on the calibrated three-dimensional simulation model of the constant-volume combustion bomb, the temperature, pressure, fuel temperature, and injection pressure inside the constant-volume combustion bomb are controlled respectively, and the critical ignition map of the diesel engine under different injection pressures and fuel temperatures is calculated through three-dimensional simulation.

[0102] Specifically, by controlling the operating parameters such as temperature, pressure, fuel temperature, and injection pressure within the constant-volume combustion bomb, and through three-dimensional simulation calculations, MAP diagrams of the diesel engine's ignition criticality under different injection pressures and fuel temperatures are obtained, such as... Figure 3 As shown, the obtained diesel engine ignition critical MAP is stored in the ECU. In practical applications, the fuel temperature, cylinder temperature, etc., can be changed by changing the circulating water temperature. In this embodiment, the constant volume combustion bomb three-dimensional simulation model can only change the fuel temperature. The data obtained by the three-dimensional simulation calculation are the ambient temperature, ambient pressure, fuel temperature, and ignition delay period of spray combustion under different altitude conditions, and the obtained diesel engine ignition critical MAP at different injection pressures and fuel temperatures. However, it should be noted and understood that the "fuel temperature" mentioned above is equivalent to the circulating water temperature. Therefore, the circulating water temperature under the current operating conditions of the diesel engine can be directly compared with the injection strategy MAP and the diesel engine ignition critical MAP obtained by the three-dimensional simulation.

[0103] In some specific embodiments, through the above step S110, the sensor collects operating parameters such as diesel engine intake air temperature, intake air pressure, and circulating water temperature in real time, and transmits the data collected by the sensor to the ECU. The ECU calculates reference variables (i.e., the in-cylinder background temperature and in-cylinder background pressure of the diesel engine) based on the data fed back by the sensor, and compares the reference variables with the diesel engine ignition critical MAP map stored in the ECU to determine whether cold start assistance measures are needed. Thus, based on the comparison result between the real-time thermal state in the cylinder and the diesel engine ignition critical MAP map, the most suitable cold start assistance measures are selected, which can improve the cold start ignition success rate with high efficiency and low consumption, improve cold start performance, and reduce cold start emission pollution.

[0104] In this embodiment, the low-temperature starting assistance measure is one or both of intake air preheating and circulating water heating. Intake air preheating heats the ambient gas entering the cylinder, thereby increasing the in-cylinder background temperature and pressure at top dead center of compression, promoting in-cylinder ignition. Circulating water heating increases the engine block temperature of the diesel engine, thereby increasing fuel temperature, reducing diesel viscosity, improving diesel flowability and atomization, and promoting diesel ignition.

[0105] like Figure 3 As shown, the ignition zone is the area composed of the background temperature and background pressure that enable in-cylinder spray ignition. When the background temperature and background pressure are at... Figure 3 When the background temperature and pressure are outside the ignition zone, cold start ignition can be achieved directly without the need for low-temperature starting assistance. However, when the background temperature and pressure are outside the ignition zone, low-temperature starting assistance is necessary to achieve ignition. Figure 3 As shown in (a), an optimal injection pressure is most conducive to in-cylinder ignition, and the ignition zone area is largest at the optimal injection pressure. Intake air preheating can improve in-cylinder thermodynamic conditions, increasing background temperature and pressure to facilitate entry into the ignition zone. Heating circulating water can expand the ignition zone range in the diesel engine ignition criticality MAP, such as... Figure 3 (b) When the circulating water temperature is heated from 0℃ to 60℃, the area of ​​ignition zone a expands to ignition zone c. Intake air temperature and pressure are collected in real time by sensors and transmitted to the ECU to calculate the in-cylinder background temperature and pressure at the top dead center of the diesel engine compression stroke. The in-cylinder background temperature, in-cylinder background pressure, circulating water temperature, and injection pressure are compared with the diesel engine's critical ignition map to determine whether the diesel fuel injected into the engine cylinder can ignite. If the ignition conditions are met, no auxiliary measures are required; the optimal injection pressure is selected based on the variation of the ignition delay period with the injection pressure. If the diesel fuel cannot ignite, the optimal auxiliary measures are selected and implemented based on the comparison results, such as intake air preheating only, circulating water heating only, or both auxiliary measures operating simultaneously.

[0106] In another embodiment, the specific method for determining whether the diesel engine has reached the ignition condition under the current operating conditions includes the following steps:

[0107] 1) Extract the ignition critical MAP of the diesel engine, and determine the ignition zone corresponding to the circulating water temperature and injection pressure in the ignition critical MAP of the diesel engine under the current operating conditions.

[0108] Specifically, the ECU extracts the diesel engine ignition critical MAP map it stores, and determines the ignition zone in the diesel engine ignition critical MAP map corresponding to the circulating water temperature and injection pressure under the current operating conditions of the diesel engine as measured by the sensor in step S110 above.

[0109] 2) According to whether the in-cylinder background temperature and the in-cylinder background pressure under the current working condition of the diesel engine are in the ignition area of the ignition critical MAP graph of the diesel engine, it is judged whether the ignition condition under the current working condition of the diesel engine is reached.

[0110] Specifically, as shown in Figure 3 the in-cylinder background temperature and the in-cylinder background pressure under the current working condition of the diesel engine are compared with the ignition area of the ignition critical MAP graph of the diesel engine corresponding to the circulating water temperature and the injection pressure under the current working condition of the diesel engine obtained in step 1), and according to the comparison result, it is judged whether the ignition condition under the current working condition of the diesel engine is reached.

[0111] 3) If the in-cylinder background temperature and the in-cylinder background pressure under the current working condition of the diesel engine are in the ignition area, it is determined that the ignition condition under the current working condition of the diesel engine is reached; if the in-cylinder background temperature and the in-cylinder background pressure under the current working condition of the diesel engine are not in the ignition area, it is determined that the ignition condition under the current working condition of the diesel engine is not reached.

[0112] Specifically, as shown in Figure 3 If the in-cylinder background temperature and the in-cylinder background pressure under the current working condition of the diesel engine are in the ignition area, cold start ignition can be directly realized, at this time it is determined that the ignition condition under the current working condition of the diesel engine is reached; if the in-cylinder background temperature and the in-cylinder background pressure under the current working condition of the diesel engine are not in the ignition area, auxiliary measures must be started to expand the range of the ignition area in the ignition critical MAP graph of the diesel engine through low-temperature start auxiliary measures, at this time it is determined that the ignition condition under the current working condition of the diesel engine is not reached.

[0113] When the ignition condition under the current working condition of the diesel engine is reached, step S120 enters step S130:

[0114] Step S130: Extract the injection strategy MAP graph, determine the optimal injection pressure under the current working condition of the diesel engine based on the injection strategy MAP graph, and control the diesel engine to inject diesel fuel according to the optimal injection pressure.

[0115] In the embodiment of the present application, the ECU also stores the injection strategy MAP graph, which is a curve graph of the ignition delay period varying with the injection pressure under different altitude conditions. In the plateau cold start working condition, appropriately increasing the injection pressure will promote fuel atomization, shorten the ignition delay period, and be conducive to ignition. However, if the injection pressure continues to increase, it will lead to the increase of turbulent intensity and the intensification of fuel heat dissipation, which is not conducive to ignition. Therefore, the ignition delay period tends to shorten first and then lengthen with the increase of the injection pressure. The plateau cold start control method of the diesel engine is based on the injection strategy MAP graph, and takes the shortest ignition delay period as the optimization target. According to the variation law of the ignition delay period with the injection pressure, the optimal injection pressure can be obtained. With the increase of the altitude, the optimal injection pressure increases, as shown in Figure 2As shown, the plain and 2000m altitude working conditions can achieve in-cylinder ignition by adjusting the fuel injection pressure, and the 4000m altitude working condition must use low-temperature starting auxiliary measures. That is, the method optimizes the fuel injection strategy with the shortest ignition delay period as the target, determines the fuel injection pressure corresponding to the shortest delay period under the current working condition of the diesel engine as the optimal fuel injection pressure, and can achieve the purposes of improving the starting success rate, optimizing the cold starting performance, saving energy and reducing emissions.

[0116] In an embodiment, the specific acquisition method of the injection strategy MAP includes the following steps:

[0117] a) Perform optical tests in a constant volume combustion bomb to obtain spray characteristic data and ignition characteristic data under highland cold starting conditions.

[0118] b) Build a three-dimensional simulation model of the constant volume combustion bomb, and calibrate the three-dimensional simulation model of the constant volume combustion bomb according to the spray characteristic data and the ignition characteristic data.

[0119] d) Based on the calibrated three-dimensional simulation model of the constant volume combustion bomb, control the temperature, pressure, fuel temperature and fuel injection pressure in the constant volume combustion bomb respectively, obtain the ambient temperature, ambient pressure, fuel temperature and the delay period data of the spray combustion under different fuel injection pressures under different altitude conditions through three-dimensional simulation calculation, obtain the injection strategy MAP according to the delay period data, and store the obtained injection strategy MAP in the ECU.

[0120] When the diesel engine does not reach the ignition condition under the current working condition, go to step S140 from step S120:

[0121] Step S140: Determine the low-temperature starting auxiliary measures of the diesel engine under the current working condition based on the diesel engine ignition critical MAP, and control the diesel engine to operate according to the low-temperature starting auxiliary measures.

[0122] In the prior art, the diesel engine low-temperature cold start control strategy often selects a single auxiliary measure to improve the in-cylinder ignition condition after determining that the auxiliary measure needs to be enabled according to environmental parameters, which is low in efficiency and poor in effect. The diesel engine plateau cold start control method in the embodiments of the present application compares the reference variable calculated by the ECU according to the data fed back by the sensor with the diesel engine ignition critical MAP in the engine ECU to determine whether the low-temperature start auxiliary measure needs to be taken. If the diesel engine cannot be started normally by adjusting the fuel injection parameters, for example, the fuel injection timing corresponds to the in-cylinder thermal state, the fuel injection is closer to the top dead center, the in-cylinder temperature and pressure are higher, and it is more conducive to ignition, but at the same time, a large enough combustion chamber space is also needed to form the mixture. If the in-cylinder temperature and pressure are too low due to the cold start condition in the plateau environment, the diesel engine cannot be ignited by adjusting the fuel injection parameters. When the diesel engine cannot be started normally by adjusting the fuel injection parameters, the best low-temperature start auxiliary measure is matched according to the diesel engine ignition critical MAP, and one or a combination of auxiliary measures is adopted to improve the start success rate, optimize the cold start performance, and save energy and reduce emissions.

[0123] In a specific embodiment, the low-temperature start auxiliary measure is one or both of the intake air preheating measure and the circulating water heating measure. In the embodiments of the present application, the diesel engine plateau cold start control method reasonably matches the auxiliary measures according to the actual operating state of the engine. On the one hand, the appropriate auxiliary measure is preferentially selected to improve the heating efficiency and improve the start effect. Because the specific heat capacities of the heating mediums of the intake air preheating and the circulating water heating are different, the specific heat capacity of air is about 1.0 kJ / (kg·K), and the specific heat capacity of the common circulating water (ethylene glycol) is about 2.3 kJ / (kg·K). Therefore, under the same heating condition, the temperature rising effect of the intake air preheating is better, and the heating efficiency is higher. When only a single auxiliary measure is needed, the intake air preheating should be preferentially selected. On the other hand, the single auxiliary measure has a heating limit and limited optimization effect. For example, too high an intake air temperature will reduce the intake air density, resulting in a decrease in the intake air quality of the diesel engine and a decrease in the charging efficiency, which is not conducive to the in-cylinder ignition and start of the diesel engine. When the circulating water temperature exceeds its boiling point, the "boiling and opening" phenomenon is likely to occur, which seriously affects the normal operation of the diesel engine. Especially in a more severe environment (such as an altitude of 4000 m), only a single auxiliary measure is difficult to start, and multiple auxiliary measures need to be operated at the same time.

[0124] In the embodiments of the present application, the control strategy of the low-temperature start auxiliary measure considers the actual thermal state in the cylinder of the engine, more accurately determines whether the low-temperature start auxiliary measure needs to be taken, and more reasonably matches the diesel injection strategy and the auxiliary measure according to the characteristics of different low-temperature start auxiliary measures and the parameters of the diesel engine during operation, so that the cold start performance of the diesel engine can be more efficiently improved.

[0125] It should be noted and understood that in the present application, the in-cylinder background temperature and the in-cylinder background pressure are the background conditions for the engine oil injection ignition, and the "injection parameters" in the above-mentioned refer to the control parameters in the normal starting process of the diesel engine, i.e. the circulating water temperature and the injection pressure. After the in-cylinder background temperature and the in-cylinder background pressure of the diesel engine are calculated, the injection parameters are adjusted to optimize the ignition. If the injection parameters are still not optimized to ignite, the low-temperature starting auxiliary measures need to be started.

[0126] In a specific embodiment, based on the diesel engine ignition critical MAP, it is determined that the low-temperature starting auxiliary measure for the current working condition of the diesel engine is the intake air preheating measure, and the diesel engine is controlled to perform the intake air preheating operation until the in-cylinder background temperature and the in-cylinder background pressure of the diesel engine are in the ignition area of the diesel engine ignition critical MAP. If the intake air temperature of the diesel engine is increased to the intake air temperature heating limit, and the in-cylinder background temperature and the in-cylinder background pressure of the diesel engine still cannot be in the ignition area of the diesel engine ignition critical MAP, the low-temperature starting auxiliary measure for the current working condition of the diesel engine is determined again as the circulating water heating measure, the diesel engine is controlled to stop the intake air preheating operation, and the diesel engine is controlled to perform the circulating water heating operation until the in-cylinder background temperature and the in-cylinder background pressure of the diesel engine are in the ignition area of the diesel engine ignition critical MAP. If the circulating water temperature of the diesel engine is increased to the circulating water temperature heating limit, and the in-cylinder background temperature and the in-cylinder background pressure of the diesel engine still cannot be in the ignition area of the diesel engine ignition critical MAP, the low-temperature starting auxiliary measure for the current working condition of the diesel engine is determined again as the combination of the intake air preheating measure and the circulating water heating measure, and the diesel engine is controlled to perform the intake air preheating operation and the circulating water heating operation at the same time until the in-cylinder background temperature and the in-cylinder background pressure of the diesel engine are in the ignition area of the diesel engine ignition critical MAP.

[0127] As shown in the example of Figure 4 at an altitude of 3000m, the intake air temperature is increased by the intake air preheating measure, the diesel spray in this working condition reaches the ignition condition, the optimal injection pressure is selected for the shortest ignition delay period, and the injection is started. Figure 5 As shown in the example of Figure 6 at an altitude of 4000m, when the intake air temperature or the circulating water temperature is increased to the heating limit, the in-cylinder background temperature and the in-cylinder background pressure may still not be in the ignition area of the diesel engine ignition critical MAP. At this time, the intake air preheating measure and the circulating water heating measure need to be started at the same time, the intake air preheating operation and the circulating water heating operation are performed at the same time, the diesel spray in this working condition reaches the ignition condition, and the injection is started by selecting the optimal injection pressure.

[0128] In step S140, the optimal auxiliary measure is selected according to the diesel engine ignition critical MAP and is run, and then, from step S140, step S110 is entered, and from step S110, step S120 is entered, the operating parameter information of the diesel engine is re-acquired, the in-cylinder background temperature and the in-cylinder background pressure of the diesel engine are calculated according to the operating parameter information, and according to the comparison of the in-cylinder background temperature, the in-cylinder background pressure, the circulating water temperature, the fuel injection pressure and the diesel engine ignition critical MAP, it is judged whether the ignition condition is reached under the current working condition of the diesel engine, if the ignition condition is not reached under the current working condition of the diesel engine, step S120 is continuously entered from step S140, and the cycle is continued until the ignition condition is reached, and from step S120, step S130 is entered, and the starting is started.

[0129] The above is a detailed description of each step of the diesel engine plateau cold starting control method provided by the embodiment of the application, and the complete operation process of the diesel engine plateau cold starting is introduced as follows. Figure 7

[0130] 1. After the power of the diesel engine electronic control system is turned on, the sensor performs a self-checking process, if the sensor self-checking is normal, the starting signal is waited for, if the sensor self-checking appears abnormal, the ECU reports a sensor fault code, the subsequent starter motor work is limited, the machine is stopped, and after the fault is eliminated, the power is re-powered and self-checked.

[0131] 2. After the diesel engine starts, the ECU receives the starting signal, the starter motor is powered on, the engine is dragged to reach the specified starting speed, and during the working of the starter motor, the sensor monitors the intake temperature, intake pressure, circulating water temperature and fuel injection pressure in real time.

[0132] 3. According to the operating parameters detected by the sensor, the ECU calculates the in-cylinder background temperature and the in-cylinder background pressure of the diesel engine piston top dead center.

[0133] 4. The ECU imports the in-cylinder background temperature and the in-cylinder background pressure finally calculated, and the circulating water temperature and the fuel injection pressure measured by the sensor into the diesel engine ignition critical MAP and compares them to determine whether the ignition condition can be reached.

[0134] 5. If the ignition state is reached, the optimal injection strategy is selected according to the injection strategy MAP stored in the ECU to perform fuel injection, that is, the best fuel injection pressure is selected to perform diesel injection, and the starting process is started.

[0135] 6. If the ignition condition is not reached, the optimal low-temperature starting auxiliary measure is matched according to the diesel engine ignition critical MAP and is run until the ignition condition is reached, the best fuel injection pressure is selected to perform fuel injection, and the starting process is started.

[0136] ​In the embodiment of the present application, the diesel engine plateau cold start control method obtains the diesel spray ignition delay period data through optical testing in a constant volume combustion bomb and establishes a diesel engine ignition critical MAP graph, collects the diesel engine intake temperature, intake pressure, circulating water temperature and other operating parameters in real time through sensors, calculates the in-cylinder background temperature and in-cylinder background pressure of the engine compression top dead center corresponding to the intake temperature and intake pressure through the ECU, compares the reference variables monitored by the sensors and calculated by the ECU with the diesel engine ignition critical MAP graph in the engine ECU, and adjusts the injection pressure to the optimum according to the injection strategy MAP graph. If it still cannot be started at this time, the best low-temperature starting auxiliary measures are matched according to the diesel engine ignition critical MAP graph, one or a combination of several auxiliary measures is adopted, and the purpose of improving the cold start success rate is achieved.

[0137] The present application can more accurately determine whether the diesel engine reaches the ignition condition and whether the auxiliary measures need to be adopted under the plateau cold start condition. The environmental temperature and environmental pressure are mapped to the in-cylinder thermodynamic state of the diesel engine compression top dead center in the constant volume combustion bomb, the coupling of the circulating water temperature, the injection pressure and the in-cylinder background temperature and background pressure is considered, the diesel ignition delay period variation law under the plateau cold start condition is obtained through optical testing and the diesel engine ignition critical MAP graph is established, and whether the auxiliary measures need to be adopted is more accurately determined by comparing the reference variables during the diesel engine operation with the diesel engine ignition critical MAP graph.

[0138] In addition, the present application more reasonably matches the diesel injection strategy and the auxiliary measures according to the characteristics of different auxiliary measures and the reference variables during the diesel engine operation, and more efficiently and lowly consumes to improve the plateau cold start performance of the diesel engine. Under the same heating condition, the intake preheating has a better heating effect and a higher heating efficiency, and the single auxiliary measure preferentially selects the intake preheating. Considering that the intake preheating has a heating limit and that the too high intake temperature reduces the diesel engine intake amount, the intake preheating and the circulating water heating auxiliary measures need to be simultaneously started in the more severe high-altitude environment. Therefore, according to the comparison results of the intake temperature, the intake pressure, the circulating water temperature of the diesel engine and the critical ignition MAP graph, the intake preheating alone or the two auxiliary measures are simultaneously performed can be selected.

[0139] Corresponding to the method embodiment, the embodiment of the present application also provides a diesel engine plateau cold start control system for executing the diesel engine plateau cold start control method steps in the above embodiment. As shown in Figure 8 The diesel engine plateau cold start control system 200 mainly includes a parameter acquisition module 210, an ignition condition judgment module 220, an injection strategy determination module 230, a low-temperature start auxiliary module 240, an optical testing module 250 and a MAP graph acquisition module 260.

[0140] Specifically, the parameter acquisition module 210 is configured to acquire real-time operation parameter information of the diesel engine, and calculate the in-cylinder background temperature and the in-cylinder background pressure of the diesel engine piston top dead center according to the operation parameter information, wherein the operation parameter information includes intake air temperature, intake air pressure, circulating water temperature and fuel injection pressure.

[0141] The ignition condition judgment module 220 is configured to extract a diesel engine ignition critical MAP, and judge whether the ignition condition is met under the current working condition of the diesel engine according to the comparison between the in-cylinder background temperature, the in-cylinder background pressure, the circulating water temperature and the fuel injection pressure and the diesel engine ignition critical MAP.

[0142] The injection strategy determination module 230 is configured to extract an injection strategy MAP when the ignition condition is met under the current working condition of the diesel engine, determine the optimal fuel injection pressure under the current working condition of the diesel engine based on the injection strategy MAP, and control the diesel engine to perform diesel injection according to the optimal fuel injection pressure, wherein the injection strategy MAP is a curve graph of the ignition delay period varying with the fuel injection pressure under different altitude conditions.

[0143] The low-temperature starting auxiliary module 240 is configured to determine a low-temperature starting auxiliary measure under the current working condition of the diesel engine based on the diesel engine ignition critical MAP when the ignition condition is not met under the current working condition of the diesel engine, and control the diesel engine to operate according to the low-temperature starting auxiliary measure until the ignition condition is met; wherein the low-temperature starting auxiliary measure is one or both of an intake air preheating measure and a circulating water heating measure.

[0144] The optical test module 250 is configured to perform optical tests in a constant volume combustion bomb to obtain spray characteristic data and ignition characteristic data under highland cold starting conditions, wherein the spray characteristic data includes gas / liquid phase penetration distance, spray cone angle and mixture concentration, and the ignition characteristic data includes ignition success rate and ignition delay period.

[0145] The MAP acquisition module 260 is configured to build a constant volume combustion bomb three-dimensional simulation model, calibrate the constant volume combustion bomb three-dimensional simulation model according to the spray characteristic data and the ignition characteristic data, and control the temperature, pressure, fuel temperature and fuel injection pressure in the constant volume combustion bomb based on the calibrated constant volume combustion bomb three-dimensional simulation model, so as to obtain the ambient temperature, ambient pressure, fuel temperature under different altitude conditions and the ignition delay period data of spray combustion under different fuel injection pressures through three-dimensional simulation calculation, obtain the injection strategy MAP according to the ignition delay period data, and obtain the diesel engine ignition critical MAP under different fuel injection pressures and fuel temperatures.

[0146] It should be noted that the diesel engine plateau cold start control system provided by the embodiments of the present application has the same technical effects as the diesel engine plateau cold start control method embodiments of the present application based on the same concept, and the specific content can be referred to the description of the diesel engine plateau cold start control method embodiments of the present application, which will not be repeated here.

[0147] In summary, the present application discloses a diesel engine plateau cold start control method and system, which collects the operating parameters of the diesel engine such as intake temperature, intake pressure, circulating water temperature, and injection pressure in real time through a sensor and feeds back to the ECU, calculates the in-cylinder background temperature and in-cylinder background pressure through the ECU, compares the calculated reference variable with the diesel engine ignition critical MAP stored in the ECU, judges whether to take low-temperature starting auxiliary measures, if not, adjusts the injection pressure to the best according to the injection strategy MAP, if it cannot be started normally by adjusting the injection parameters, matches the best low-temperature starting auxiliary measures according to the diesel engine ignition critical MAP, adopts one or several auxiliary measures combination, and achieves the purpose of improving the cold start success rate, optimizing the cold start performance, and saving energy and reducing emissions.

[0148] In addition, based on the above method embodiments, as shown in Figure 9 Another embodiment of the present application provides a computing device 300, which includes a storage device 310 for storing a computer program and a processor 320 for running the computer program to make the computing device 300 execute the method of the above diesel engine plateau cold start control method embodiments.

[0149] Based on the above method embodiments, as shown in Figure 10 Another embodiment of the present application provides a storage medium 400, which stores a computer program 410 used in a computing device, and the computer program 410 is executed by a processor to implement the method of the above diesel engine plateau cold start control method embodiments.

[0150] Based on the above embodiments, another embodiment of the present application provides a computer program product, which contains instructions, and when the instructions are run on a computer or a processor, the computer or the processor executes the method of the above diesel engine plateau cold start control method embodiments.

[0151] Those skilled in the art can understand that the drawings are only schematic diagrams of an embodiment, and the modules or flows in the drawings are not necessarily necessary for implementing the present application.

[0152] Those skilled in the art can understand that the modules in the device in the embodiments can be distributed in the device in the embodiments as described in the embodiments, or can be located in one or more devices different from the embodiments. The modules in the above embodiments can be combined into one module, or can be further split into multiple sub-modules.

[0153] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present application, and not to limit them; although the present application has been described in detail with reference to the above embodiments, those skilled in the art should understand that the technical solutions recorded in the above embodiments can be modified, or some technical features can be replaced by equivalents; and these modifications or replacements do not make the essence of the corresponding technical solutions deviate from the spirit and scope of the technical solutions of the embodiments of the present application.

Claims

1. A control method of a diesel engine highland cold start-up, characterized by, The method comprises: real-time acquisition of operation parameter information of the diesel engine, and calculation of in-cylinder background temperature and in-cylinder background pressure of the diesel engine piston top dead center based on the operation parameter information, wherein the operation parameter information comprises intake air temperature, intake air pressure, circulating water temperature and fuel injection pressure; extraction of a diesel engine ignition critical MAP, and determination of whether the diesel engine reaches an ignition condition under the current working condition based on comparison of the in-cylinder background temperature, the in-cylinder background pressure, the circulating water temperature and the fuel injection pressure with the diesel engine ignition critical MAP; if the diesel engine reaches the ignition condition under the current working condition, extraction of a fuel injection strategy MAP, determination of optimal fuel injection pressure of the diesel engine under the current working condition based on the fuel injection strategy MAP, and control of the diesel engine for diesel fuel injection based on the optimal fuel injection pressure, wherein the fuel injection strategy MAP is a curve graph of variation of a delay period with fuel injection pressure under different altitude conditions; if the diesel engine does not reach the ignition condition under the current working condition, determination of low-temperature starting auxiliary measures of the diesel engine under the current working condition based on the diesel engine ignition critical MAP, and control of the diesel engine operation based on the low-temperature starting auxiliary measures until the diesel engine reaches the ignition condition, wherein the low-temperature starting auxiliary measures are one or both of intake air preheating measures and circulating water heating measures.

2. The diesel highland cold start control method according to claim 1, characterized by, The calculation formula of the in-cylinder background temperature is: T = T1 x ε k-1 The calculation formula of the in-cylinder background pressure is: P = P1 x ε k In the formula, T is the in-cylinder background temperature of the diesel engine piston top dead center, T1 is the intake air temperature of the diesel engine, P is the in-cylinder background pressure of the diesel engine piston top dead center, P1 is the intake air pressure of the diesel engine, ε is the compression ratio of the diesel engine, and k is the adiabatic compression index.

3. The diesel high altitude cold start control method of claim 1, wherein The method further comprises: optical testing in a constant volume combustion bomb to obtain spray characteristic data and ignition characteristic data under plateau cold starting conditions, wherein the spray characteristic data comprises gas / liquid phase penetration distance, spray cone angle and mixture concentration, and the ignition characteristic data comprises ignition success rate and delay period; establishment of a constant volume combustion bomb three-dimensional simulation model, and calibration of the constant volume combustion bomb three-dimensional simulation model based on the spray characteristic data and the ignition characteristic data; based on the calibrated constant volume combustion bomb three-dimensional simulation model, control of temperature, pressure, fuel temperature and fuel injection pressure in the constant volume combustion bomb, three-dimensional simulation calculation of corresponding ambient temperature, ambient pressure, fuel temperature under different altitude conditions and delay period data of spray combustion under different fuel injection pressures, and obtaining of the fuel injection strategy MAP based on the delay period data and obtaining of the diesel engine ignition critical MAP under different fuel injection pressures and fuel temperatures.

4. The diesel high altitude cold start control method according to claim 3, characterized by, The optical testing in the constant volume combustion bomb to obtain the spray characteristic data and the ignition characteristic data under plateau cold starting conditions specifically comprises: installation of a fuel injector of the diesel engine in the constant volume combustion bomb; adjustment of circulating water temperature and temperature and pressure in the constant volume combustion bomb to achieve plateau cold starting conditions under different altitudes, control of the fuel injector for fuel injection, and obtaining of the spray characteristic data and the ignition characteristic data corresponding to different altitude conditions.

5. The diesel high altitude cold start control method of claim 1 wherein, The method further comprises: After the electric control system of the diesel engine is powered on, the sensors of the diesel engine are controlled to perform self-checking; wherein the sensors include an intake temperature sensor, an intake pressure sensor, a circulating water temperature sensor, and a high-pressure oil rail pressure sensor; If the sensors are abnormal in self-checking, the ECU of the diesel engine reports a sensor fault code, and controls the diesel engine to stop running, after the fault is eliminated, the electric control system is powered on again, and the sensors are controlled to perform self-checking until the sensors are normal in self-checking; If the sensors are normal in self-checking, the ECU enters a waiting start signal state, when the ECU receives a start signal, the diesel engine is controlled to be powered on and started, and the diesel engine is dragged to reach a specified starting speed, and the sensors monitor the operating parameter information of the diesel engine in real time.

6. The diesel high altitude cold start control method of claim 1 wherein, The extraction of the diesel engine ignition critical MAP graph, according to the comparison of the in-cylinder background temperature, the in-cylinder background pressure, the circulating water temperature, and the injection pressure with the diesel engine ignition critical MAP graph, whether the diesel engine reaches the ignition condition under the current working condition specifically comprises: Extracting the diesel engine ignition critical MAP graph, determining the ignition area corresponding to the circulating water temperature and the injection pressure in the diesel engine ignition critical MAP graph according to the circulating water temperature and the injection pressure under the current working condition of the diesel engine; According to whether the in-cylinder background temperature and the in-cylinder background pressure under the current working condition of the diesel engine are in the ignition area of the diesel engine ignition critical MAP graph, whether the diesel engine reaches the ignition condition under the current working condition is determined; If the in-cylinder background temperature and the in-cylinder background pressure under the current working condition of the diesel engine are in the ignition area, it is determined that the diesel engine reaches the ignition condition under the current working condition; if the in-cylinder background temperature and the in-cylinder background pressure under the current working condition of the diesel engine are not in the ignition area, it is determined that the diesel engine does not reach the ignition condition under the current working condition.

7. The diesel high altitude cold start control method according to claim 6, characterized by, The determination of the low-temperature starting auxiliary measure of the diesel engine under the current working condition based on the diesel engine ignition critical MAP graph, and the control of the diesel engine according to the low-temperature starting auxiliary measure until the diesel engine reaches the ignition condition specifically comprises: Determining that the low-temperature starting auxiliary measure of the diesel engine under the current working condition is the intake preheating measure, controlling the diesel engine to perform intake preheating operation until the in-cylinder background temperature and the in-cylinder background pressure of the diesel engine are in the ignition area of the diesel engine ignition critical MAP graph; If the in-cylinder background temperature and the in-cylinder background pressure of the diesel engine cannot be in the ignition area of the diesel engine ignition critical MAP graph after the intake temperature of the diesel engine rises to the intake temperature heating limit, the low-temperature starting auxiliary measure of the diesel engine under the current working condition is determined again as the circulating water heating measure, the diesel engine is controlled to stop intake preheating operation, and the diesel engine is controlled to perform circulating water heating operation until the in-cylinder background temperature and the in-cylinder background pressure of the diesel engine are in the ignition area of the diesel engine ignition critical MAP graph; If the cylinder background temperature and the cylinder background pressure of the diesel engine cannot be in the ignition region of the diesel engine ignition critical MAP after the circulating water temperature of the diesel engine is raised to the circulating water temperature heating limit, the low-temperature starting auxiliary measure of the diesel engine under the current working condition is re-determined as the combination of the intake preheating measure and the circulating water heating measure, and the diesel engine is controlled to perform intake preheating operation and circulating water heating operation until the cylinder background temperature and the cylinder background pressure of the diesel engine are in the ignition region of the diesel engine ignition critical MAP.

8. The diesel high altitude cold start control method of claim 1 wherein, The method further includes: The method further includes:

9. A diesel high altitude cold start control system characterized by, The system includes: A parameter acquisition module, configured to acquire running parameter information of the diesel engine in real time, and calculate the cylinder background temperature and the cylinder background pressure of the diesel engine piston top dead center according to the running parameter information, wherein the running parameter information includes intake temperature, intake pressure, circulating water temperature, and injection pressure; An ignition condition judgment module, configured to extract a diesel engine ignition critical MAP, and judge whether the ignition condition is met under the current working condition of the diesel engine according to comparison between the cylinder background temperature, the cylinder background pressure, and the circulating water temperature, the injection pressure, and the diesel engine ignition critical MAP; A injection strategy determination module, configured to extract a injection strategy MAP when the ignition condition is met under the current working condition of the diesel engine, determine the optimal injection pressure under the current working condition of the diesel engine based on the injection strategy MAP, and control the diesel engine to perform diesel injection according to the optimal injection pressure, wherein the injection strategy MAP is a curve graph of the ignition delay period changing with the injection pressure under different altitude conditions; A low-temperature starting auxiliary module, configured to determine the low-temperature starting auxiliary measure under the current working condition of the diesel engine based on the diesel engine ignition critical MAP when the ignition condition is not met under the current working condition of the diesel engine, and control the diesel engine to operate according to the low-temperature starting auxiliary measure until the ignition condition is met, wherein the low-temperature starting auxiliary measure is one or both of the intake preheating measure and the circulating water heating measure.

10. The diesel high altitude cold start control system of claim 9, wherein, The system further includes: An optical test module, configured to perform optical test in a constant volume combustion bomb to obtain spray characteristic data and ignition characteristic data under highland cold starting conditions, wherein the spray characteristic data includes gas / liquid phase penetration distance, spray cone angle, and mixed gas concentration, and the ignition characteristic data includes ignition success rate and ignition delay period; The MAP graph acquisition module is configured to build a three-dimensional simulation model of a constant volume combustion bomb, calibrate the three-dimensional simulation model of the constant volume combustion bomb according to the spray characteristic data and the ignition characteristic data, and control the temperature, pressure, fuel temperature and fuel injection pressure in the constant volume combustion bomb respectively based on the calibrated three-dimensional simulation model of the constant volume combustion bomb, so as to obtain the ambient temperature, ambient pressure, fuel temperature corresponding to different altitudes and the ignition delay period data of spray combustion under different fuel injection pressures through three-dimensional simulation calculation, obtain the injection strategy MAP graph according to the ignition delay period data, and obtain the critical MAP graph of diesel engine ignition under different fuel injection pressures and fuel temperatures.

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