Method, equipment, medium and product for preventing engine from misfire

Abstract

The invention discloses a method, equipment, medium and product for preventing an engine from misfiring, and relates to the technical field of automobile engine emission control, the method comprises the following steps: when an exhaust gas recirculation system is in an open state, acquiring the temperature of mixed gas at the current moment; according to the mixed gas temperature at the current moment, calculating a mixed gas saturated steam theoretical density for preventing the engine from misfire; the first relative humidity of the detected air and the second relative humidity of the gas in the current exhaust gas recirculation system are obtained; according to the saturated gas steam theoretical density, the first relative humidity and the second relative humidity, the maximum safe opening rate of the exhaust gas recirculation system at the next moment is calculated; and controlling the opening rate of the exhaust gas recirculation system at the next moment according to the maximum opening rate so as to prevent the engine from misfire. According to the scheme, normal work of the engine is guaranteed, and maximization of the effect of the EGR system is achieved. The technical problem of how to prevent the engine from being on fire due to the EGR system is solved.

Description

Technical Field

[0001] The present application relates to the technical field of automobile engine emission control, and in particular to methods, equipment, media and products for preventing engine misfires. Background Art

[0002] With the development of social economy, people have higher and higher requirements for environmental protection and air quality, and automobile exhaust emission standards have become more and more stringent. In order to reduce the generation of harmful nitrogen oxides in automobile emissions, the existing technology widely adopts the EGR system. The EGR system can suppress the generation of nitrogen oxides by recycling part of the exhaust gas discharged by the engine and then introducing it into the intake duct to participate in combustion, thereby achieving the purpose of reducing automobile exhaust emissions.

[0003] Regarding the control of the EGR system, the existing technology mainly determines the opening rate of the EGR system according to the operating conditions of the engine, which is called the EGR rate. For example, as the engine load increases, the EGR rate is gradually increased to obtain a better nitrogen oxide emission reduction effect. However, the EGR system gas contains a large amount of water vapor, which is easy to condense when the temperature is low. Especially in cold weather in winter, the water vapor in the EGR system gas will produce a large amount of liquid water droplets when it is cooled. If these water droplets enter the engine combustion chamber, they will have a negative impact on the normal combustion process, causing misfires at the spark plugs and causing the entire engine to misfire.

[0004] However, when the existing EGR system is turned on, it lacks the function of judging and predicting the risk of water vapor in the EGR system gas, and cannot accurately judge whether the water vapor will condense into liquid excessively after the EGR system gas is mixed with the fresh air in the intake duct. Therefore, the existing EGR system cannot reasonably limit the EGR rate according to the degree of water vapor condensation in the EGR system gas, which can easily cause excessive water vapor condensation when a higher EGR rate is used, leading to serious engine misfire problems. Summary of the invention

[0005] The main purpose of this application is to provide a method, device, medium and product for preventing engine misfire, aiming to solve the technical problem of how to prevent engine misfire due to EGR system.

[0006] To achieve the above objectives, the present application proposes a method for preventing engine misfire, the method comprising:

[0007] When the exhaust gas recirculation system is in the on state, obtaining the mixed gas temperature at the current moment;

[0008] Calculating the theoretical density of saturated water vapor of the mixed gas for preventing engine misfire according to the mixed gas temperature at the current moment;

[0009] Acquire a first relative humidity of the detected air and a second relative humidity of gas in the current exhaust gas recirculation system;

[0010] Calculating a maximum safe opening rate of the exhaust gas recirculation system at a next moment according to the theoretical density of saturated gas water vapor, the first relative humidity, and the second relative humidity;

[0011] The exhaust gas recirculation system opening rate at the next moment is controlled according to the maximum opening rate to prevent the engine from misfiring.

[0012] In one embodiment, the step of obtaining the mixed gas temperature at the current moment specifically includes:

[0013] Obtain the air temperature and the exhaust gas recirculation system gas temperature through the temperature detector, and obtain the current exhaust gas recirculation system opening rate;

[0014] The current mixed gas temperature is determined based on the current exhaust gas recirculation system opening rate, the air temperature, and the exhaust gas recirculation system gas temperature.

[0015] In one embodiment, the step of calculating the theoretical density of saturated water vapor of the mixed gas for preventing engine misfire according to the mixed gas temperature at the current moment specifically includes:

[0016] Determine the saturated vapor pressure of the mixed gas based on the Antony equation and the mixed gas temperature at the current moment;

[0017] Measuring engine coefficients on a bench;

[0018] The theoretical density of saturated water vapor of the mixed gas is determined based on the saturated vapor pressure of the mixed gas and the engine coefficient.

[0019] In one embodiment, the step of calculating the maximum safe opening rate of the exhaust gas recirculation system at the next moment according to the theoretical density of the saturated gas water vapor, the first relative humidity and the second relative humidity specifically includes:

[0020] Acquire the first relative humidity and the second relative humidity by a temperature detector;

[0021] determining a mapping relationship between the maximum safe opening rate of the exhaust gas recirculation system at a next moment and the actual density of saturated water vapor of the mixed gas at the next moment according to the first relative humidity, the second relative humidity, the saturated vapor pressure of air, and the saturated vapor pressure of gas in the exhaust gas recirculation system;

[0022] The theoretical density of the saturated water vapor of the mixed gas is set equal to the actual density of the saturated water vapor of the mixed gas at the next moment, so as to determine the maximum safe opening rate of the exhaust gas recirculation system at the next moment.

[0023] In one embodiment, the step of determining the control index according to the control parameter comprises:

[0024] The step of determining the mapping relationship between the maximum safe opening rate of the exhaust gas recirculation system at the next moment and the actual density of saturated water vapor of the mixed gas at the next moment according to the first relative humidity, the second relative humidity, the saturated vapor pressure of the air, and the saturated vapor pressure of the exhaust gas recirculation system gas, before comprises:

[0025] Determining the saturated vapor pressure of the air based on the Antony equation and the air temperature;

[0026] Based on the Antony equation and the exhaust gas recirculation system gas temperature, the exhaust gas recirculation system gas saturation vapor pressure is determined.

[0027] In one embodiment, the step of controlling the opening rate of the exhaust gas recirculation system at the next moment according to the maximum opening rate specifically includes:

[0028] According to the vehicle operating conditions, determine the preset opening rate of the exhaust gas recirculation system at the next moment;

[0029] When the maximum safety opening rate is less than the preset opening rate, selecting the maximum safety opening rate as the opening rate of the exhaust gas recirculation system at the next moment;

[0030] When the preset opening rate of the exhaust gas recirculation system at the next moment is less than the maximum safe opening rate of the exhaust gas recirculation system at the next moment, the preset opening rate of the exhaust gas recirculation system at the next moment is selected as the opening rate of the exhaust gas recirculation system at the next moment.

[0031] In one embodiment, when the exhaust gas recirculation system is in the on state, the step of obtaining the mixed gas temperature at the current moment includes:

[0032] Detect whether the current vehicle speed is greater than or equal to the minimum opening speed and less than or equal to the maximum opening speed;

[0033] When the current vehicle speed is greater than or equal to the minimum opening vehicle speed and less than or equal to the maximum opening vehicle speed, it is determined that the exhaust gas recirculation system is in the opening state.

[0034] In addition, to achieve the above-mentioned purpose, the present application also proposes a device for preventing engine misfires, the device comprising: a memory, a processor, and a computer program stored in the memory and executable on the processor, the computer program being configured to implement the steps of the method for preventing engine misfires as described above.

[0035] In addition, to achieve the above-mentioned purpose, the present application also proposes a storage medium, which is a computer-readable storage medium, on which a computer program is stored, and when the computer program is executed by a processor, the steps of the method for preventing engine misfire as described above are implemented.

[0036] In addition, to achieve the above-mentioned purpose, the present application also provides a computer program product, which includes a computer program, and when the computer program is executed by a processor, the steps of the method for preventing engine misfire as described above are implemented.

[0037] One or more technical solutions proposed in this application have at least the following technical effects:

[0038] The present application obtains the mixed gas temperature at the current moment when the exhaust gas recirculation system is in the open state; calculates the theoretical density of saturated water vapor of the mixed gas to prevent engine misfire based on the mixed gas temperature at the current moment; then obtains the first relative humidity of the detected air and the second relative humidity of the gas in the current exhaust gas recirculation system; and calculates the maximum safe opening rate of the exhaust gas recirculation system at the next moment based on the theoretical density of saturated gas water vapor, the first relative humidity and the second relative humidity; finally, controls the opening rate of the exhaust gas recirculation system at the next moment based on the maximum opening rate to prevent engine misfire.

[0039] Since the current mixed gas temperature is obtained and the theoretical density of saturated water vapor in the mixed gas to prevent engine misfire is calculated based on the current mixed gas temperature, the theoretical saturation state of water vapor in the mixed gas under the current working condition can be accurately predicted. In addition, the relative humidity of the air and the EGR system gas is obtained, and the maximum safe opening rate allowed by the EGR system at the next moment is calculated based on these parameters. In this way, the saturation state that the water vapor will actually reach after the EGR system gas is mixed with fresh air at the next moment can be accurately predicted. The problem that the degree of condensation of water vapor cannot be accurately predicted in the prior art, and the EGR rate cannot be limited according to the degree of condensation, resulting in misfire, is effectively solved. Using the above method, it is possible to accurately judge whether excessive water vapor condensation will be generated in the EGR process at the next moment based on the comparison between the theoretical saturation state of water vapor and the actual mixed saturation state. It not only ensures the normal operation of the engine, but also maximizes the effect of the EGR system.

[0040] This method not only solves the technical problem of how to prevent engine misfires due to the EGR system, but also realizes more sophisticated and intelligent control and management of the EGR process. It maximizes the effect of the EGR system while ensuring stable operation of the engine. It greatly improves the control performance of the existing EGR system, making it better able to meet the requirements of future emission standards. BRIEF DESCRIPTION OF THE DRAWINGS

[0041] The accompanying drawings, which are incorporated in and constitute a part of this specification, illustrate embodiments consistent with the present application and, together with the description, serve to explain the principles of the present application.

[0042] In order to more clearly illustrate the embodiments of the present application or the technical solutions in the prior art, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, for ordinary technicians in this field, other drawings can be obtained based on these drawings without paying any creative labor.

[0043] Figure 1 A flow chart of the first embodiment of the method for preventing engine misfire provided in the present application;

[0044] Figure 2 A flow chart of the second embodiment of the method for preventing engine misfire provided in the present application;

[0045] Figure 3 A flow chart of the third embodiment of the method for preventing engine misfire of the present application;

[0046] Figure 4 Schematic diagram of the device structure of the hardware operating environment involved in the method for preventing engine misfire in the embodiment of the present application.

[0047] The purpose, features and advantages of this application will be further described in conjunction with the embodiments and with reference to the accompanying drawings. DETAILED DESCRIPTION

[0048] It should be understood that the specific embodiments described herein are only used to explain the technical solutions of the present application and are not used to limit the present application.

[0049] In order to better understand the technical solution of the present application, a detailed description will be given below in conjunction with the accompanying drawings and specific implementation methods.

[0050] It should be noted that the execution subject of this embodiment can be a computing service device with data processing, network communication and program running functions, such as a tablet computer, a personal computer, a mobile phone, etc., or an electronic device capable of realizing the above functions, etc. The following takes the engine misfire prevention system as an example to illustrate this embodiment and the following embodiments.

[0051] Based on this, the embodiment of the present application provides a method for preventing engine misfire, referring to Figure 1 , Figure 1 This is a flow chart of the first embodiment of the method for preventing engine misfire of the present application.

[0052] In this embodiment, the method for preventing engine misfire includes steps S10 to S50:

[0053] Step S10, when the exhaust gas recirculation system is in an on state, obtaining the current mixed gas temperature;

[0054] The mixed gas refers to the gas formed by mixing the exhaust gas recirculation system gas with the fresh air in the intake duct, and the mixed gas temperature is used to indicate the temperature of the mixed gas when the current EGR system is working.

[0055] Specifically, this step is performed when the exhaust gas recirculation (EGR) system is turned on. Its purpose is to prevent the engine from misfire. The system obtains the temperature parameters of the mixed gas at the current moment and provides input data for the subsequent calculation of the water vapor saturation state in the mixed gas. The temperature value of the current mixed gas can be obtained in real time through the mixed gas temperature detector as the output result of this step.

[0056] In some embodiments, this can be achieved in two ways:

[0057] Optionally, a mixed gas temperature detector can be pre-set, the detector is installed at the intake duct position after the exhaust gas recirculation system gas and air are mixed, and then the output value of the detector is directly read to obtain the mixed gas temperature at the current moment;

[0058] Optionally, an air temperature detector for detecting the fresh air temperature and an EGR system gas temperature detector for detecting the exhaust gas recirculation system gas temperature may be separately provided to know the current opening ratio of the EGR system in advance, and then the mixed gas temperature at the current moment may be obtained using a mixed gas temperature calculation formula based on the air temperature, the exhaust gas recirculation system gas temperature and the EGR opening ratio.

[0059] It is understandable that the current mixed gas temperature may also be acquired in other ways, which are not limited here.

[0060] Step S20, calculating the theoretical density of saturated water vapor of the mixed gas for preventing engine misfire according to the mixed gas temperature at the current moment;

[0061] Among them, the theoretical density of saturated water vapor in the mixed gas refers to the theoretical density value when the water vapor in the mixed gas reaches the saturated state under the current mixed gas temperature conditions, which is used to predict the limit state of water vapor changing from gas to liquid in the current mixed gas environment.

[0062] Specifically, this step is performed after obtaining the current mixed gas temperature. According to the laws of thermodynamics, when the mixed gas temperature is determined, the maximum saturated density value that the water vapor in the mixed gas can theoretically reach under the temperature condition can also be determined accordingly. The calculated saturated density value is the limit density value for complete condensation of water vapor under the current mixed gas conditions. The saturated vapor pressure at the mixed gas temperature can usually be calculated according to the vapor pressure formula, and the saturated water vapor density is further calculated from the saturated vapor pressure. The saturated density value will be used as a comparison benchmark to compare with the actual density of water vapor at the next moment to determine whether oversaturation will cause droplet condensation.

[0063] In some embodiments, this can be achieved in two ways:

[0064] Optionally, the corresponding saturation density value may be found in a preset temperature-saturation density correspondence table according to the current mixed gas temperature by looking up the table;

[0065] Optionally, the saturated vapor pressure at the current mixed gas temperature may be calculated using a thermodynamic formula, and then the corresponding theoretical density of saturated water vapor of the mixed gas may be obtained using a state equation.

[0066] It is understandable that other calculation methods may be used to obtain the saturation density, which is not limited here.

[0067] Step S30, obtaining a first relative humidity of the detected air and a second relative humidity of the gas in the current exhaust gas recirculation system;

[0068] The first relative humidity refers to the relative humidity of the air in the intake duct detected by the humidity detector; the second relative humidity refers to the relative humidity of the gas in the exhaust gas recirculation system detected. Relative humidity is used to indicate the ratio of the actual amount of water vapor in the gas to the saturated water vapor at that temperature.

[0069] Specifically, this step is performed after the theoretical density of saturated water vapor of the mixed gas is obtained. Its purpose is to obtain the relative humidity parameter describing the actual water vapor state in the gas, and provide input data for the subsequent calculation of the maximum opening rate of the EGR system at the next moment. The relative humidity can be detected by pre-setting humidity detectors in the air intake duct and the EGR duct, and the detected value is used as the output of this step.

[0070] In some embodiments, this can be achieved in two ways:

[0071] Optionally, a capacitive humidity sensor can be used to measure the degree to which the sensor capacitance value changes due to air and EGR system gas to detect its relative humidity;

[0072] Alternatively, a resistive or electrolyte humidity sensor can be used to detect the relative humidity of the gas by measuring the degree to which the gas causes the sensor's resistance or conductivity to change.

[0073] It is understandable that other types of humidity sensors or detection methods may also be used to obtain relative humidity, which is not limited here.

[0074] Step S40, calculating the maximum safe opening rate of the exhaust gas recirculation system at the next moment according to the theoretical density of the saturated gas water vapor, the first relative humidity and the second relative humidity;

[0075] Among them, the maximum safe opening rate refers to the maximum opening ratio that the EGR system can safely adopt at the next moment, determined based on the detection and comparison results of the theoretical saturation state of water vapor and the actual relative humidity state, so as to avoid the situation where water vapor in the mixed gas becomes oversaturated and condenses into droplets in large quantities.

[0076] Specifically, this step is performed after obtaining data describing the theoretical and actual state of water vapor (including the theoretical density of saturated water vapor of the mixed gas, and the relative humidity of air and EGR system gas). The engine misfire prevention system establishes a mathematical model of water vapor from a theoretical saturated state to an actual humidity state according to the physical law of the change of gas humidity state. Combined with the specific parameters of the EGR system, the maximum opening rate value of the EGR system at which the mixed gas water vapor will not be oversaturated under the current humidity conditions can be obtained through iterative calculation as the output result of step S40.

[0077] In some embodiments, step S40 can be implemented in two ways:

[0078] Optionally, based on a table lookup method, water vapor theory and actual saturation state may be used as index parameters to directly find the corresponding maximum safe opening rate in a pre-established index table;

[0079] Optionally, a physical model of water vapor humidity changes can be constructed, and the theoretical saturation density and actual relative humidity parameters can be brought into play. After iterative calculation, the maximum safe opening rate of the EGR system at the next moment when water vapor will not be oversaturated can be predicted.

[0080] It is understandable that the calculation of the maximum safe opening rate may also be achieved through other calculation means, which are not limited here.

[0081] Step S50, controlling the exhaust gas recirculation system opening rate at the next moment according to the maximum opening rate to prevent the engine from misfiring;

[0082] Specifically, this step is performed after calculating and obtaining the maximum safe opening rate of the EGR system at the next moment. First, the engine misfire prevention system determines the expected opening rate of the EGR system at the next moment according to the current engine operating conditions and speed state. Then, the expected opening rate is compared with the maximum safe opening rate calculated according to the water vapor saturation state, and the exhaust gas recirculation system opening rate at the next moment is adjusted in real time according to the comparison result. Through step S50, the specific opening rate control amount of the EGR system can be guided according to the maximum safe opening rate calculated according to the water vapor state, so that it can be dynamically maintained within a reasonable range to prevent engine misfires. Different from setting the opening rate directly according to the engine operating conditions, this method can actively prevent misfires caused by water vapor oversaturation problems, so that the EGR system can play the greatest emission reduction role under the premise of preventing misfires, better adapt to changes in operating conditions, and improve engine reliability and emission performance.

[0083] In some embodiments, step S50 can be implemented in two ways:

[0084] Optionally, a variable EGR opening rate valve can be set to adjust the valve opening according to the control signal to change the opening rate. After receiving the maximum safe opening rate, the control unit compares the output control signal and adjusts the valve to the corresponding opening;

[0085] Optionally, a mapping table of engine operating conditions and standard EGR opening rates can be pre-established. After the current operating conditions are detected, the standard opening rate is obtained by looking up the table, then limited to the maximum safe opening rate, and converted into a valve control signal.

[0086] It is understandable that step S50 may also control the specific opening rate of the EGR system according to the maximum safe opening rate in other ways, which is not limited here.

[0087] In summary, when the exhaust gas recirculation system is in the on state, the present embodiment obtains the mixed gas temperature at the current moment; calculates the theoretical density of saturated water vapor of the mixed gas to prevent engine misfire based on the mixed gas temperature at the current moment; then obtains the first relative humidity of the detected air and the second relative humidity of the gas in the current exhaust gas recirculation system; and calculates the maximum safe opening rate of the exhaust gas recirculation system at the next moment based on the theoretical density of saturated gas water vapor, the first relative humidity and the second relative humidity; finally, controls the opening rate of the exhaust gas recirculation system at the next moment based on the maximum opening rate to prevent engine misfire.

[0088] Since the current mixed gas temperature is obtained and the theoretical density of saturated water vapor in the mixed gas to prevent engine misfire is calculated based on the current mixed gas temperature, the theoretical saturation state of water vapor in the mixed gas under the current working condition can be accurately predicted. In addition, the relative humidity of the air and the EGR system gas is obtained, and the maximum safe opening rate allowed by the EGR system at the next moment is calculated based on these parameters. In this way, the saturation state that the water vapor will actually reach after the EGR system gas is mixed with fresh air at the next moment can be accurately predicted. The problem that the degree of condensation of water vapor cannot be accurately predicted in the prior art, and the EGR rate cannot be limited according to the degree of condensation, resulting in misfire, is effectively solved. Using the above method, it is possible to accurately judge whether excessive water vapor condensation will be generated in the EGR process at the next moment based on the comparison between the theoretical saturation state of water vapor and the actual mixed saturation state. It not only ensures the normal operation of the engine, but also maximizes the effect of the EGR system.

[0089] This method not only solves the technical problem of how to prevent engine misfires due to the EGR system, but also realizes more sophisticated and intelligent control and management of the EGR process. It maximizes the effect of the EGR system while ensuring stable operation of the engine. It greatly improves the control performance of the existing EGR system, making it better able to meet the requirements of future emission standards.

[0090] Based on the first embodiment of the present application, in the second embodiment of the present application, the same or similar contents as those in the above-mentioned embodiment 1 can be referred to the above introduction, and will not be repeated in the following. Figure 2 Based on the first embodiment, this embodiment provides a more specific method for preventing engine misfire, as follows:

[0091] Based on the solution of the first embodiment, this implementation provides a more specific method for obtaining the maximum safe opening rate, see Figure 2 :

[0092] Step S201, detecting whether the current vehicle speed is greater than or equal to the minimum opening vehicle speed and less than or equal to the maximum opening vehicle speed;

[0093] The current vehicle speed refers to the current real-time speed of the vehicle; the minimum start speed and the maximum start speed are the preset minimum speed threshold and maximum speed threshold for the EGR system to start working. The purpose of detecting the current vehicle speed is to determine whether the vehicle has reached the speed range in which the EGR system is ready to start working.

[0094] Specifically, this step needs to be executed at the beginning of the entire method to determine whether the current vehicle operating state meets the preconditions for starting the EGR system. The engine misfire prevention system can detect the current driving speed of the vehicle in real time through the speed sensor installed on the vehicle. The collected current speed value is compared with the set minimum and maximum start speed thresholds. If the current speed is between these two thresholds, it is determined that the vehicle has reached the speed range for the EGR system to start working, otherwise the EGR system start conditions are not met.

[0095] In some embodiments, step S201 can be implemented in two ways:

[0096] Optionally, an electromagnetic sensor may be used to detect the rotation speed of a gear or a transmission shaft and calculate and convert it into wheel rotation speed, i.e., vehicle speed;

[0097] Optionally, an annular sleeve sensor may be used to detect the frequency of the drive shaft periodically cutting the magnetic field lines and calculate the vehicle speed.

[0098] It is understandable that the detection of the current vehicle speed may also be achieved through other types of vehicle speed sensors, which are not limited here.

[0099] Step S202, when the current vehicle speed is greater than or equal to the minimum activation speed and less than or equal to the maximum activation speed, determining that the exhaust gas recirculation system is in an activation state;

[0100] The exhaust gas recirculation system is in the on state, which means that the EGR system will start to execute relevant control logic and operations to recycle exhaust gas to achieve the function of emission reduction. The EGR system on state is determined based on the vehicle speed detection result to determine whether the EGR system has started to work.

[0101] Specifically, this step is executed after the vehicle speed is detected to be within the specified range in the previous step. When the engine misfire prevention system detects that the vehicle speed meets the minimum opening speed and is less than or equal to the maximum opening speed, the software module will determine that the EGR system is ready, send a control signal to the EGR control unit, set the EGR system to the open state, and start the exhaust gas recovery operation. Otherwise, if the vehicle speed condition is not met, the EGR system is set to the closed state.

[0102] In some embodiments, step S202 can be implemented in two ways:

[0103] Optionally, after receiving the detection signal from the vehicle speed module, the EGR control unit autonomously determines whether the opening state condition is met and controls the system to be opened;

[0104] Optionally, the vehicle speed signal is input to the central controller, and the central controller sends a control command to the EGR control unit after comprehensive judgment, causing it to enter an open state.

[0105] It is understandable that determining the EGR system opening state may also be achieved through other methods, which are not limited here.

[0106] Step S203, obtaining the air temperature and the exhaust gas recirculation system gas temperature through the temperature detector, and obtaining the current exhaust gas recirculation system opening rate;

[0107] Among them, air temperature refers to the temperature of fresh air entering the engine combustion chamber; exhaust gas recirculation system gas temperature refers to the temperature of exhaust gas discharged from the engine and recovered through the EGR system; the current exhaust gas recirculation system opening rate (EGR opening rate) indicates the proportion of exhaust gas recovered by the EGR system to the total exhaust volume when the engine is working.

[0108] Specifically, this step is performed after the EGR system is turned on, and the purpose is to obtain parameters such as air temperature, EGR system gas temperature and current EGR opening rate required for mixed gas temperature calculation. By setting temperature detectors in the air intake duct and the EGR pipeline respectively, the temperature values ​​of the air and EGR system gas can be detected. The EGR opening rate can be obtained by reading the parameters of the EGR control unit. The output of step S203 includes air temperature, EGR system gas temperature and current EGR opening rate.

[0109] In some embodiments, step S203 can be implemented in two ways:

[0110] Optionally, a thermocouple or thermistor may be used as a temperature detector to obtain the temperature values ​​of the air and EGR system gas according to the electrical signal conversion;

[0111] Optionally, infrared thermal imaging technology can be used to directly obtain the temperature distribution of the gas when it flows through the pipeline and calculate the temperature. The EGR opening rate can be obtained by reading the control parameters of the EGR control unit through the CAN bus.

[0112] It is understandable that obtaining the air temperature, the EGR system gas temperature and the EGR opening rate may also be achieved through other types of temperature detectors or parameter reading interfaces, which are not limited here.

[0113] Step S204, determining the mixed gas temperature at the current moment based on the current exhaust gas recirculation system opening rate, the air temperature and the exhaust gas recirculation system gas temperature;

[0114] Specifically, this embodiment provides a specific calculation formula for the mixed gas temperature at the current moment:

[0115] T=(1-η 0 )*T 空 +η 0 *Tegr (1)

[0116] Among them, η 0 Indicates the current exhaust gas recirculation system opening rate, T 空 : Air temperature, T egr : EGR system gas temperature.

[0117] Among them, the current exhaust gas recirculation system opening rate indicates the proportion of the exhaust gas recovered by the current EGR system to the total exhaust gas volume; the air temperature refers to the temperature of the fresh air entering the engine combustion chamber; the exhaust gas recirculation system gas temperature refers to the temperature of the exhaust gas recovered through the EGR system pipeline after being discharged from the engine. The current mixed gas temperature refers to the temperature of the mixed gas after the EGR system gas and fresh air are mixed at the current moment.

[0118] Specifically, this step is performed after obtaining the air temperature, the EGR system gas temperature and the current EGR opening rate. According to the laws of thermodynamics, after gases of different temperatures are mixed in a certain proportion, the mixed temperature of the mixed gas can be calculated. Step S204 uses the current EGR opening rate, air temperature and EGR system gas temperature and other parameters into the calculation according to formula (1) to obtain the temperature value of the mixed gas at the current moment, which serves as the basis for the subsequent calculation of the water vapor parameters of the mixed gas.

[0119] Preferably, formula (1) is converted into program code by programming, and the parameters are substituted into the calculation to obtain the temperature of the mixed gas at the current moment.

[0120] Step S205, determining the saturated vapor pressure of the mixed gas based on the Antony equation and the mixed gas temperature at the current moment;

[0121] Specifically, this embodiment provides a specific calculation formula for the saturated vapor pressure of the mixed gas:

[0122] lgP=AB÷(T+C) (2)

[0123] Formula (2) is the general form of the Antony equation, where P represents the vapor pressure of the substance, T represents the temperature of the substance, and A, B and C are constants of the substance properties.

[0124] The saturated vapor pressure of the mixed gas indicates the maximum saturated water vapor pressure that the mixed gas can reach under the current mixed gas temperature conditions. The Antony equation describes the relationship between temperature and saturated vapor pressure.

[0125] Specifically, this step is performed after the mixed gas temperature at the current moment is calculated. To prevent the engine misfire system, first query the corresponding material characteristic constant, and then convert the mixed gas temperature T 混Substituting the corresponding material characteristic constants into the formula, we can get the saturated water vapor pressure corresponding to the mixed gas at this temperature. The saturated vapor pressure is the limit pressure value that water vapor may reach in the current mixed gas environment, and is used to subsequently calculate the theoretical limit saturation state of water vapor in the mixed gas.

[0126] Preferably, the Antony equation is converted into program code by programming, and the execution parameters are substituted into the program code to calculate the saturated vapor pressure of the mixed gas.

[0127] Step S206, measuring the engine coefficient by a test bench;

[0128] The engine coefficient refers to the empirical coefficient for the conversion between water vapor pressure and density in the engine mixed gas. This coefficient is related to the engine model and structural parameters.

[0129] Specifically, this step needs to be carried out during the engine design phase. The dynamic test bench is used to collect the pressure and density data of the mixed gas under different working conditions of the engine. According to the corresponding relationship between pressure and density, the average value is obtained after multiple tests to determine the engine coefficient k. This coefficient will be used in the subsequent water vapor density calculation.

[0130] In some embodiments, measuring the engine coefficient can be achieved in two ways:

[0131] Optionally, under steady-state engine conditions, the pressure and density of the mixed gas are measured respectively, and the coefficient k is determined by taking the average value of multiple tests;

[0132] Optional, during engine transient conditions The changing process of pressure and density is measured in a state, the corresponding relationship between pressure and density is obtained through correlation analysis, and the coefficient k is determined.

[0133] Step S207, determining the theoretical density of saturated water vapor of the mixed gas based on the saturated vapor pressure of the mixed gas and the engine coefficient;

[0134] Specifically, this embodiment provides a specific calculation formula for the theoretical density of saturated water vapor of the mixed gas:

[0135] ρ 理论 =(k*k 0 )*e lgp 混 (3)

[0136] Among them, ρ 理论 represents the theoretical density of saturated water vapor of the mixed gas, k represents the engine coefficient, k 0 The coefficient for converting saturated vapor pressure to density is a constant, e lgp 混 Indicates the saturated vapor pressure of the mixed gas.

[0137] The theoretical density of saturated water vapor in the mixed gas refers to the maximum saturated density that the water vapor in the mixed gas can theoretically reach under the current temperature conditions of the mixed gas.

[0138] Specifically, this step is performed after obtaining the saturated vapor pressure of the mixed gas and the engine coefficient. The engine misfire prevention system, according to formula (3), brings the saturated vapor pressure and the engine coefficient into the calculation to accurately obtain the theoretical saturated density limit value of water vapor under the current mixed gas environment. The theoretical density will serve as the basis for subsequent judgment of the actual saturation level of water vapor.

[0139] Preferably, formula (3) is converted into a program code implementation, and the execution parameters are substituted to obtain the theoretical density;

[0140] Step S208, obtaining the first relative humidity and the second relative humidity through a temperature detector;

[0141] The first relative humidity refers to the ratio of the amount of water vapor in the fresh air entering the engine combustion chamber to the amount of saturated water vapor under the temperature of the air, which can be expressed as the actual content of water vapor in the air; the second relative humidity refers to the ratio of the amount of water vapor in the exhaust gas entering the engine combustion chamber through the EGR system to the amount of saturated water vapor under the temperature of the exhaust gas, which can be expressed as the actual content of water vapor in the EGR system gas. The relative humidity parameter reflects the actual existence state of water vapor in the gas.

[0142] Specifically, this step is performed after the maximum saturation state of water vapor in the mixed gas under theoretical conditions is calculated. The purpose of step S208 is to obtain the actual state parameters describing the water vapor from the two parts of the mixed gas, air and EGR system gas, for reference in the subsequent steps of calculating and controlling the EGR system, and to determine whether the water vapor in the mixed gas is oversaturated under actual conditions.

[0143] In some embodiments, step S208 of obtaining relative humidity can be implemented in two ways:

[0144] Optionally, a capacitive humidity sensor can be used to measure the relative humidity of the gas based on the electrical parameters of the capacitance change caused by the adsorption of gas molecules on the sensor electrode surface;

[0145] Optionally, a resistive humidity sensor can be used to measure the relative humidity of the air and EGR system gas based on an electrical parameter that causes the sensor resistance value to change when the gas flows through.

[0146] It should be noted that obtaining the first and second relative humidities in step S208 may also be achieved by selecting other types of humidity sensors, which are not limited here.

[0147] Step S209, determining the saturated vapor pressure of the air based on the Antony equation and the air temperature;

[0148] The air saturated vapor pressure refers to the maximum saturated pressure state value that water vapor in the air can reach under the detected air temperature conditions. The Antony equation describes the relationship between gas temperature and saturated vapor pressure.

[0149] Specifically, reference may be made to formula (2) and step S205, which is performed on the basis of the obtained air flow temperature data. According to the Antony equation, the air temperature data is substituted into the equation to calculate the water vapor pressure value when the air is saturated at the temperature, i.e., the saturated vapor pressure of the air. The air saturated vapor pressure obtained here represents the maximum pressure that the water vapor in the air can theoretically reach.

[0150] In some embodiments, step S209 can be implemented in the following two ways:

[0151] Optionally, the formula of the Antony equation is converted into a table lookup program code, and the air saturated vapor pressure is looked up in a preset temperature-saturated pressure table according to the air temperature as an index value;

[0152] Optionally, the Antony equation formula is converted into a calculation program code, the air temperature variable is input, and the air saturated vapor pressure result is obtained through computer calculation.

[0153] Step S210, determining the saturated vapor pressure of the exhaust gas recirculation system gas based on the Antony equation and the exhaust gas recirculation system gas temperature;

[0154] The saturated vapor pressure of the EGR system gas refers to the theoretical maximum saturated pressure value that water vapor in the EGR system gas can reach under the known EGR system gas temperature conditions. The relationship between the EGR system gas temperature and the saturated vapor pressure also conforms to the Antony equation.

[0155] Specifically, reference may be made to formula (2) and step S205, which is performed after obtaining the EGR system gas temperature data. Similarly, according to the Antony equation, the EGR system gas temperature value is substituted into the calculation to solve the water vapor pressure of the EGR system gas at the saturated state under the temperature condition, that is, the saturated vapor pressure of the EGR system gas. The saturated vapor pressure of the EGR system gas obtained here represents the maximum pressure value that the water vapor in the EGR system gas may theoretically reach.

[0156] In some embodiments, step S210 can be implemented in the following two ways:

[0157] Optionally, the saturated vapor pressure of the EGR system gas is searched in a preset temperature-saturated pressure lookup table according to the EGR system gas temperature;

[0158] Optionally, the EGR system gas temperature variable is substituted into a computer calculation to obtain the EGR system gas saturated vapor pressure based on the Antony equation.

[0159] It is understandable that the calculation of the saturated vapor pressure of the EGR system gas may also be achieved by other methods, which are not limited here.

[0160] Step S211, determining a mapping relationship between the maximum safe opening rate of the exhaust gas recirculation system at a next moment and the actual density of saturated water vapor of the mixed gas at the next moment according to the first relative humidity, the second relative humidity, the saturated vapor pressure of the air, and the saturated vapor pressure of the exhaust gas recirculation system gas;

[0161] Specifically, this embodiment provides a specific calculation formula for the actual density of saturated water vapor of the mixed gas:

[0162] ρ 实际 =k 0 (1-η max )*RH 空 *e lgp 空 +k 0 *η max *RH egr *e lgp egr (4)

[0163] Among them, ρ 实际 Indicates the actual density of saturated water vapor in the mixed gas at the next moment, η max Indicates the maximum safe opening rate, RH 空 Indicates the first relative humidity, RH egr Indicates the second relative humidity, lgp 空 Indicates the saturated vapor pressure of air, lgp egr Indicates the saturated vapor pressure of the exhaust gas recirculation system gas.

[0164] Among them, the maximum safe opening rate refers to the highest opening rate that the EGR system can safely adopt at the next moment calculated based on the theoretical and actual state of water vapor; the actual density of saturated water vapor in the mixed gas refers to the saturated density that the water vapor in the mixed gas may actually reach at the next moment. The mapping relationship refers to the mathematical correspondence model between the two.

[0165] Specifically, this step is performed after obtaining the first and second relative humidities and the saturated vapor pressures of the air and EGR system gas. According to the law of the change of the gas water vapor state, a mathematical model between the maximum safe opening rate and the actual saturated density of the mixed gas can be established. For example, the formula for calculating the actual density of the mixed gas given by formula (4) includes parameters such as the maximum safe opening rate and relative humidity, saturated vapor pressure, etc. By determining the functional relationship between the two, a mapping model between the maximum safe opening rate and the actual saturated density of the mixed gas is obtained.

[0166] In some embodiments, step S211 can be implemented in the following two ways:

[0167] Optionally, a lookup table is pre-established based on the parameters to directly obtain the mapping relationship between the maximum safe opening rate and the actual density;

[0168] Optionally, a mathematical model of the two is established through multiple iterative calculations to obtain a mapping relationship function.

[0169] It is understandable that the mapping relationship may be determined by other methods, which are not limited here.

[0170] Step S212, setting the theoretical density of the saturated water vapor of the mixed gas equal to the actual density of the saturated water vapor of the mixed gas at the next moment, so as to determine the maximum safe opening rate of the exhaust gas recirculation system at the next moment;

[0171] Specifically, this embodiment provides a specific maximum safe opening rate calculation formula:

[0172] Let ρ 理论 =ρ 实际 ,Right now:

[0173] η max =(k*e lgp 混 -RH 空 *e lgp 空 )÷(RH egr *e lgp egr -RH 空 *lgp 空 ) (5)

[0174] Specifically, step S212 is performed based on the mapping relationship between the actual density of saturated water vapor of the mixed gas, the theoretical density of saturated water vapor of the mixed gas and the maximum safe opening rate. The purpose is to keep the theoretical saturation state consistent with the actual saturation state to avoid water vapor oversaturation and thus calculate the maximum safe opening rate that the EGR system can achieve at the next moment.

[0175] The engine misfire prevention system first establishes a mathematical model between the theoretical density and actual density of water vapor according to the law of gas state change, and includes the variable of the maximum safe opening rate to obtain a mapping relationship model between the theoretical-actual density and the maximum safe opening rate. Then, the theoretical density expression is equal to the actual density expression, and is brought into the mapping relationship model. Through calculation and solution, the highest safe opening rate value that the EGR system can achieve under the premise of making the theoretical saturation equal to the actual saturation to avoid oversaturation can be directly obtained under the current water vapor state.

[0176] For example, according to formula (4) and formula (5), the theoretical density ρtheoretical and the actual density ρactual are set equal, and the maximum safe opening rate η is included. max The mapping relationship expression of the EGR system can be directly obtained by conversion calculation under the current water vapor state at the next moment. max .

[0177] In some embodiments, step S212 can be implemented in two ways:

[0178] Optionally, after substituting the relationship between theoretical density and actual density into the mapping function, a programming operation is performed to solve the maximum safe opening rate;

[0179] Optionally, in a pre-established theoretical-actual density-opening rate mapping table, the maximum safe opening rate that satisfies the condition that the theoretical density is equal to the actual density is searched.

[0180] It is understandable that the maximum safe opening rate may be obtained in step S212 by other calculation means, which is not limited here.

[0181] In summary, the method for preventing engine misfires provided in the second embodiment of the present application first detects the vehicle speed and confirms that the EGR system is in the open state. Then the air temperature, the EGR system gas temperature and the EGR system opening rate are measured to calculate the current mixed gas temperature; the saturated vapor pressure of the mixed gas is calculated using the Antony equation according to the mixed gas temperature; the theoretical saturated density of water vapor in the mixed gas is obtained in combination with the engine coefficient. The relative humidity of the air and EGR system gas is detected at the same time. The saturated vapor pressures of the air and EGR system gas are calculated respectively using the air and EGR system gas temperatures. According to the law of water vapor state change, a mathematical mapping model between theoretical density, actual density and maximum safe opening rate is established. Then, by making the theoretical density equal to the actual density, the maximum safe opening rate is solved. Finally, compared with the standard opening rate obtained based on the operating conditions, the smaller value of the two is selected to determine the actual opening rate of the EGR system at the next moment.

[0182] In this embodiment, the temperature of the mixed gas is detected, the theoretical saturation state of water vapor in the mixed gas is calculated, and the actual humidity data of the air and the EGR system gas are obtained, and a mathematical model between the theoretical and actual saturation states of water vapor is established, as well as a mapping relationship with the maximum safe opening rate. On this basis, the theoretical saturation is made equal to the actual saturation, and the optimal opening rate that the EGR system can achieve at the next moment without causing water vapor oversaturation can be accurately obtained. This prevents misfires and maximizes the EGR effect. It effectively solves the problem that the existing EGR system may use an excessively large opening rate, resulting in serious misfires, when it is unable to accurately judge the saturation state of water vapor.

[0183] Based on the first and second embodiments of the present application, in the third embodiment of the present application, the same or similar contents as those of the above-mentioned first and second embodiments can be referred to the above introduction, and will not be repeated in the following. Figure 3 Based on the harmonic current injection control index, this embodiment provides a solution for identifying the optimal harmonic current control parameter according to the control index, as follows:

[0184] Step S301, determining a preset opening rate of the exhaust gas recirculation system at the next moment according to the vehicle operating condition;

[0185] Among them, the vehicle operating condition refers to the current working state of the vehicle, including parameters such as engine speed, load, and throttle opening; the preset opening rate refers to the standard opening ratio of the EGR system at the next moment, estimated based on the engine operating condition.

[0186] Specifically, this step is performed after calculating the maximum safe opening rate of the EGR system at the next moment. The engine misfire prevention system will detect the current operating conditions of the engine, and determine the opening rate that needs to be adopted by the EGR system under standard conditions at the next moment under the current operating conditions, i.e., the preset opening rate, based on the mapping relationship between the operating conditions and the standard EGR opening rate established in advance. The preset opening rate is mainly obtained based on the engine operating conditions, with the purpose of enabling the EGR system to play a regular emission reduction role.

[0187] In some embodiments, step S301 can be implemented in two ways:

[0188] Optionally, by looking up a table, according to the current engine operating condition, the corresponding preset opening rate is searched in a preset operating condition-opening rate mapping table;

[0189] Optionally, a mathematical model is established for the mapping relationship between the operating condition and the opening rate through programming operation, and the current operating condition is brought into calculation to calculate the preset opening rate.

[0190] Step S302, when the maximum safety opening rate is less than the preset opening rate, selecting the maximum safety opening rate as the opening rate of the exhaust gas recirculation system at the next moment;

[0191] Specifically, this step is performed after obtaining the preset opening rate and the maximum safe opening rate. The engine misfire prevention system will determine the size relationship between the two. If the maximum safe opening rate is smaller, the maximum safe opening rate will be taken as the actual opening rate of the EGR system at the next moment. The reason for this is that the maximum safe opening rate can ensure that the water vapor in the mixed gas will not be oversaturated, thereby preventing the engine from misfire. Therefore, when the preset opening rate is greater than the maximum safe opening rate, the maximum safe opening rate should be used first to comprehensively consider the EGR effect and engine reliability.

[0192] Step S303, when the preset opening rate of the exhaust gas recirculation system at the next moment is less than the maximum safe opening rate of the exhaust gas recirculation system at the next moment, selecting the preset opening rate of the exhaust gas recirculation system at the next moment as the opening rate of the exhaust gas recirculation system at the next moment;

[0193] Specifically, this step is also performed after obtaining the two opening rates. At this time, the engine misfire prevention system determines that the preset opening rate is less than the maximum safe opening rate, that is, the preset opening rate is within the allowable safety range, and the preset opening rate is directly used as the EGR opening rate at the next moment. In this way, the normal emission control strategy of the engine can be guaranteed, and there will be no fire hazard.

[0194] In summary, the method for preventing engine misfire provided in the third embodiment of the present application will detect the current working condition of the engine after calculating the maximum safe opening rate, and determine the standard preset opening rate according to the pre-established mapping relationship between the working condition and the opening rate. Then, the maximum safe opening rate is compared with the preset opening rate. If the maximum safe opening rate is smaller, the maximum safe opening rate is taken as the actual opening rate of the EGR system at the next moment, which can prevent the risk of misfire; if the preset opening rate is smaller, the preset opening rate is directly taken as the opening rate at the next moment, which can ensure the normal emission control strategy of the engine.

[0195] In the embodiment of the present application, since the maximum safe opening rate is obtained, the standard opening rate required based on the engine operating conditions is also considered and a choice is made between the two, which not only prevents the risk of misfire caused by supersaturation of water vapor, but also takes into account the emission control requirements of the engine rules. In the case where the water vapor saturation state cannot be accurately judged, this method can avoid using an excessively large EGR opening rate and effectively prevent misfire problems. At the same time, controlling the EGR system in combination with the standard operating conditions can ensure the emission reduction effect of the engine.

[0196] It should be noted that the above examples are only used to understand the present application and do not constitute a limitation on the method for preventing engine misfires of the present application. More simple transformations based on this technical concept are all within the protection scope of the present application.

[0197] The present application provides an engine misfire prevention device, which includes: at least one processor; and a memory communicatively connected to the at least one processor; wherein the memory stores instructions executable by the at least one processor, and the instructions are executed by the at least one processor so that the at least one processor can execute the engine misfire prevention method in the above-mentioned embodiment one.

[0198] Reference below Figure 4 , which shows a schematic diagram of the structure of the engine fire prevention device suitable for implementing the embodiment of the present application. The engine fire prevention device in the embodiment of the present application may include but is not limited to mobile terminals such as mobile phones, laptop computers, digital broadcast receivers, PDAs (Personal Digital Assistants), PADs (Portable Application Descriptions), PMPs (Portable Media Players), vehicle-mounted terminals (such as vehicle-mounted navigation terminals), etc., and fixed terminals such as digital TVs, desktop computers, etc. Figure 4 The engine misfire prevention device shown is only an example and should not bring any limitation to the functions and scope of use of the embodiments of the present application.

[0199] like Figure 4As shown, the engine misfire prevention device may include a processing device 1001 (e.g., a central processing unit, a graphics processor, etc.), which can perform various appropriate actions and processes according to a program stored in a read-only memory (ROM: Read Only Memory) 1002 or a program loaded from a storage device 1003 to a random access memory (RAM: Random Access Memory) 1004. In RAM1004, various programs and data required for the operation of the engine misfire prevention device are also stored. The processing device 1001, ROM1002, and RAM1004 are connected to each other through a bus 1005. An input / output (I / O) interface 1006 is also connected to the bus. Generally, the following systems can be connected to the I / O interface 1006: an input device 1007 including, for example, a touch screen, a touch pad, a keyboard, a mouse, an image sensor, a microphone, an accelerometer, a gyroscope, etc.; an output device 1008 including, for example, a liquid crystal display (LCD: Liquid Crystal Display), a speaker, a vibrator, etc.; a storage device 1003 including, for example, a magnetic tape, a hard disk, etc.; and a communication device 1009. The communication device 1009 can allow the engine misfire prevention device to communicate wirelessly or wired with other devices to exchange data. Although the figure shows an engine misfire prevention device with various systems, it should be understood that it is not required to implement or have all the systems shown. More or fewer systems can be implemented or have alternatively.

[0200] In particular, according to the embodiments disclosed in the present application, the process described above with reference to the flowchart can be implemented as a computer software program. For example, the embodiments disclosed in the present application include a computer program product, which includes a computer program carried on a computer-readable medium, and the computer program includes a program code for executing the method shown in the flowchart. In such an embodiment, the computer program can be downloaded and installed from a network through a communication device, or installed from a storage device 1003, or installed from a ROM 1002. When the computer program is executed by the processing device 1001, the above-mentioned functions defined in the method of the embodiment disclosed in the present application are executed.

[0201] The engine misfire prevention device provided by the present application adopts the engine misfire prevention method in the above-mentioned embodiment, and can solve the technical problem of how to prevent the engine from misfiring due to the EGR system. Compared with the prior art, the beneficial effects of the engine misfire prevention device provided by the present application are the same as the beneficial effects of the engine misfire prevention method provided by the above-mentioned embodiment, and the other technical features of the engine misfire prevention device are the same as the features disclosed in the method of the previous embodiment, which will not be repeated here.

[0202] It should be understood that the various parts disclosed in this application can be implemented by hardware, software, firmware or a combination thereof. In the description of the above embodiments, specific features, structures, materials or characteristics can be combined in any one or more embodiments or examples in a suitable manner.

[0203] The above is only a specific implementation of the present application, but the protection scope of the present application is not limited thereto. Any person skilled in the art who is familiar with the present technical field can easily think of changes or substitutions within the technical scope disclosed in the present application, which should be included in the protection scope of the present application. Therefore, the protection scope of the present application should be based on the protection scope of the claims.

[0204] The present application provides a computer-readable storage medium having computer-readable program instructions (ie, computer programs) stored thereon, and the computer-readable program instructions are used to execute the engine misfire prevention method in the above-mentioned embodiment.

[0205] The computer-readable storage medium provided in the present application may be, for example, a USB flash drive, but is not limited to electrical, magnetic, optical, electromagnetic, infrared, or semiconductor systems, systems or devices, or any combination of the above. More specific examples of computer-readable storage media may include, but are not limited to: an electrical connection with one or more wires, a portable computer disk, a hard disk, a random access memory (RAM), a read-only memory (ROM), an erasable programmable read-only memory (EPROM or flash memory), an optical fiber, a portable compact disk read-only memory (CD-ROM), an optical storage device, a magnetic storage device, or any suitable combination of the above. In this embodiment, the computer-readable storage medium may be any tangible medium containing or storing a program that can be used by or in combination with an instruction execution system, system or device. The program code contained on the computer-readable storage medium may be transmitted using any appropriate medium, including but not limited to: wires, optical cables, RF (Radio Frequency), etc., or any suitable combination of the above.

[0206] The computer-readable storage medium may be included in the engine misfire prevention device; or may exist independently without being assembled into the engine misfire prevention device.

[0207] The modules involved in the embodiments described in this application may be implemented by software or hardware, wherein the name of the module does not constitute a limitation on the unit itself in some cases.

[0208] The readable storage medium provided by the present application is a computer-readable storage medium, which stores computer-readable program instructions (i.e., computer programs) for executing the above-mentioned method for preventing engine misfires, and can solve the technical problem of how to prevent engine misfires due to the EGR system. Compared with the prior art, the beneficial effects of the computer-readable storage medium provided by the present application are the same as the beneficial effects of the method for preventing engine misfires provided by the above-mentioned embodiment, and will not be repeated here.

[0209] The present application also provides a computer program product, comprising a computer program, wherein when the computer program is executed by a processor, the steps of the method for preventing engine misfire as described above are implemented.

[0210] The computer program product provided by the present application can solve the technical problem of how to prevent the engine from misfiring due to the EGR system. Compared with the prior art, the beneficial effects of the computer program product provided by the present application are the same as the beneficial effects of the method for preventing engine misfire provided by the above embodiment, and will not be described in detail here.

[0211] The above descriptions are only some embodiments of the present application, and are not intended to limit the patent scope of the present application. All equivalent structural changes made using the contents of the present application specification and drawings under the technical concept of the present application, or direct / indirect applications in other related technical fields are included in the patent protection scope of the present application.

Claims

1. A method for preventing engine misfire, characterized in that: The method for preventing engine misfire comprises: When the exhaust gas recirculation system is in the on state, obtaining the mixed gas temperature at the current moment; Calculating the theoretical density of saturated water vapor of the mixed gas for preventing engine misfire according to the mixed gas temperature at the current moment; Acquire a first relative humidity of the detected air and a second relative humidity of gas in the current exhaust gas recirculation system; Calculating a maximum safe opening rate of the exhaust gas recirculation system at a next moment according to the theoretical density of saturated gas water vapor, the first relative humidity, and the second relative humidity; The exhaust gas recirculation system opening rate at the next moment is controlled according to the maximum opening rate to prevent the engine from misfiring.

2. The method according to claim 1, characterized in that The step of obtaining the mixed gas temperature at the current moment specifically includes: Obtain the air temperature and the exhaust gas recirculation system gas temperature through the temperature detector, and obtain the current exhaust gas recirculation system opening rate; The current mixed gas temperature is determined based on the current exhaust gas recirculation system opening rate, the air temperature, and the exhaust gas recirculation system gas temperature.

3. The method according to claim 2, characterized in that The step of calculating the theoretical density of saturated water vapor of the mixed gas for preventing engine misfire according to the mixed gas temperature at the current moment specifically includes: Determine the saturated vapor pressure of the mixed gas based on the Antony equation and the mixed gas temperature at the current moment; Measuring engine coefficients on a bench; The theoretical density of saturated water vapor of the mixed gas is determined based on the saturated vapor pressure of the mixed gas and the engine coefficient.

4. The method according to claim 3, characterized in that The step of calculating the maximum safe opening rate of the exhaust gas recirculation system at the next moment according to the theoretical density of the saturated gas water vapor, the first relative humidity and the second relative humidity specifically includes: Acquire the first relative humidity and the second relative humidity by a temperature detector; determining a mapping relationship between the maximum safe opening rate of the exhaust gas recirculation system at a next moment and the actual density of saturated water vapor of the mixed gas at the next moment according to the first relative humidity, the second relative humidity, the saturated vapor pressure of air, and the saturated vapor pressure of gas in the exhaust gas recirculation system; The theoretical density of the saturated water vapor of the mixed gas is set equal to the actual density of the saturated water vapor of the mixed gas at the next moment, so as to determine the maximum safe opening rate of the exhaust gas recirculation system at the next moment.

5. The method according to claim 4, characterized in that The step of determining the mapping relationship between the maximum safe opening rate of the exhaust gas recirculation system at the next moment and the actual density of saturated water vapor of the mixed gas at the next moment according to the first relative humidity, the second relative humidity, the saturated vapor pressure of the air, and the saturated vapor pressure of the exhaust gas recirculation system gas, before comprises: Determining the saturated vapor pressure of the air based on the Antony equation and the air temperature; Based on the Antony equation and the exhaust gas recirculation system gas temperature, the exhaust gas recirculation system gas saturation vapor pressure is determined.

6. The method according to claim 5, characterized in that The step of controlling the exhaust gas recirculation system opening rate at the next moment according to the maximum opening rate specifically includes: According to the vehicle operating conditions, determine the preset opening rate of the exhaust gas recirculation system at the next moment; When the maximum safety opening rate is less than the preset opening rate, selecting the maximum safety opening rate as the opening rate of the exhaust gas recirculation system at the next moment; When the preset opening rate of the exhaust gas recirculation system at the next moment is less than the maximum safe opening rate of the exhaust gas recirculation system at the next moment, the preset opening rate of the exhaust gas recirculation system at the next moment is selected as the opening rate of the exhaust gas recirculation system at the next moment.

7. The method according to claim 1, characterized in that The step of obtaining the mixed gas temperature at the current moment when the exhaust gas recirculation system is in the on state previously includes: Detect whether the current vehicle speed is greater than or equal to the minimum opening speed and less than or equal to the maximum opening speed; When the current vehicle speed is greater than or equal to the minimum opening vehicle speed and less than or equal to the maximum opening vehicle speed, it is determined that the exhaust gas recirculation system is in the opening state.

8. An engine fire prevention device, characterized in that: The engine misfire prevention device comprises: a memory, a processor, and a computer program stored in the memory and executable on the processor, wherein the computer program is configured to implement the steps of the engine misfire prevention method according to any one of claims 1 to 7.

9. A storage medium, characterized in that: The storage medium is a computer-readable storage medium, and a computer program is stored on the storage medium. When the computer program is executed by a processor, the steps of the method for preventing engine misfire according to any one of claims 1 to 7 are implemented.

10. A computer program product, characterized in that The computer program product comprises a computer program, and when the computer program is executed by a processor, the steps of the method for preventing engine misfire according to any one of claims 1 to 7 are implemented.

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