EGR control method and apparatus, vehicle controller, and storage medium

Abstract

An EGR control method, comprising: on the basis of air flow data in an intake passage, a current EGR rate, and the temperature and pressure of a mixed gas at a specified position, determining an actual relative humidity of the mixed gas at the specified position; on the basis of working condition data of an engine and environmental state data, determining a target relative humidity of the mixed gas at the specified position; and on the basis of the actual relative humidity, the target relative humidity, and the current EGR rate, determining a target EGR rate. The method can reduce safety risks such as engine misfires and low-temperature icing, and improve the safety. Further provided are an EGR control apparatus, a vehicle controller, and a computer-readable storage medium.

Description

EGR control method, device, vehicle controller and storage medium

[0001] Cross-references to related applications

[0002] This application claims priority to Chinese Patent Application No. 202411910982.8, filed on December 23, 2024, entitled "EGR control method, apparatus, vehicle controller and storage medium", the entire contents of which are incorporated herein by reference. Technical Field

[0003] This disclosure relates to the field of engine technology, and in particular to an EGR control method, device, vehicle controller, and storage medium. Background Technology

[0004] EGR (Exhaust Gas Recirculation) refers to the process of returning a portion of the exhaust gas from the engine to the intake manifold, where it mixes with fresh air and re-enters the cylinders. Because exhaust gas contains a large amount of polyatomic gases such as carbon dioxide, which are non-combustible but absorb a significant amount of heat due to their high specific heat capacity, the maximum combustion temperature of the air-fuel mixture in the cylinder is lowered, thus reducing the amount of nitrogen oxides (NOx) generated. The EGR rate is the ratio of the recirculated exhaust gas volume to the total intake air volume. Proper control of the EGR rate is crucial for NOx purification and overall engine emissions.

[0005] In existing technologies, the EGR rate under different operating conditions is typically scanned on a test bench, and then calibrated in real vehicle tests to compensate for atmospheric pressure, water temperature, etc. The EGR rate during the use of each vehicle is then the calibrated fixed EGR rate.

[0006] Existing technologies use a fixed EGR rate for EGR control, without considering the impact of the environment, which poses safety risks such as engine misfire or icing. Summary of the Invention

[0007] This application provides an EGR control method, device, vehicle controller, and storage medium, which can accurately control the EGR rate, reduce safety risks such as fire or icing, and improve safety.

[0008] To address the aforementioned problems, in a first aspect, embodiments of this application provide an EGR control method, comprising:

[0009] The actual relative humidity of the gas mixture at the specified location is determined based on the airflow data in the intake passage, the current EGR rate, and the temperature and pressure of the mixed gas at the specified location.

[0010] Based on the engine's operating data and environmental condition data, determine the target relative humidity of the mixed gas at the designated location;

[0011] The target EGR rate is determined based on the actual relative humidity, the target relative humidity, and the current EGR rate.

[0012] Secondly, embodiments of this application provide an EGR control device, comprising:

[0013] The actual relative humidity determination module is used to determine the actual relative humidity of the mixed gas at the specified location based on the air flow data in the intake passage, the current EGR rate, and the temperature and pressure of the mixed gas at the specified location.

[0014] The target relative humidity determination module is used to determine the target relative humidity of the mixed gas at the specified location based on the engine's operating data and environmental condition data.

[0015] The target EGR rate determination module is used to determine the target EGR rate based on the actual relative humidity, the target relative humidity, and the current EGR rate.

[0016] Thirdly, embodiments of this application also provide a vehicle controller, including a memory, a processor, and a computer program stored in the memory and executable on the processor. When the processor executes the computer program, it implements the EGR control method described in embodiments of this application.

[0017] Fourthly, embodiments of this application provide a computer-readable storage medium storing a computer program thereon, which, when executed by a processor, represents the steps of the EGR control method disclosed in embodiments of this application.

[0018] The EGR control method, device, vehicle controller, and storage medium provided in this application determine the actual relative humidity of the gas mixture at a specified location based on airflow data in the intake passage, the current EGR rate, and the temperature and pressure of the gas mixture at a specified location. They then determine the target relative humidity of the gas mixture at the specified location based on engine operating data and environmental condition data. Finally, they determine the target EGR rate based on the actual relative humidity, the target relative humidity, and the current EGR rate. Since the actual and target relative humidity of the gas mixture can be determined based on airflow data and environmental condition data, and the actual relative humidity characterizes the state of condensate, the EGR rate can be dynamically adjusted based on the actual and target relative humidity. This dynamic adjustment of EGR fully considers the impact of the environment, reducing condensate production and effectively mitigating safety risks such as engine misfire and low-temperature icing caused by condensate, thereby improving safety. Attached Figure Description

[0019] To more clearly illustrate the technical solutions of the embodiments of this application, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of this application. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0020] Figure 1 is a layout diagram of the engine in an embodiment of this application;

[0021] Figure 2 is a flowchart of an EGR control method provided in an embodiment of this application;

[0022] Figure 3 is a flowchart of an EGR control method provided in an embodiment of this application;

[0023] Figure 4 is a flowchart of determining air state data based on air flow data in an embodiment of this application;

[0024] Figure 5 is a flowchart illustrating the determination of the volume percentage of water in the mixed gas in an embodiment of this application;

[0025] Figure 6 is a flowchart of an EGR control method provided in an embodiment of this application;

[0026] Figure 7 is a schematic diagram of an EGR control device provided in an embodiment of this application;

[0027] Figure 8 is a schematic diagram of the structure of a vehicle controller provided in an embodiment of this application. Specific Implementation

[0028] The technical solutions of the embodiments of this application will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of this application, not all embodiments. Based on the embodiments of this application, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of this application.

[0029] Figure 1 is an engine layout diagram according to an embodiment of this application. As shown in Figure 1, a mass air flow (MAF) sensor is installed between the air filter and the mixing valve to collect air flow data in the intake passage. Temperature and pressure sensors are installed between the compressor and the intercooler, between the intercooler and the electronic throttle control (ETC), and between the electronic throttle control and the engine block. These temperature and pressure sensors are used to collect temperature and pressure data. The EGR control method provided in this embodiment relies on the mass air flow sensor and the temperature and pressure sensor in the engine intake passage.

[0030] Figure 2 is a flowchart of an EGR control method provided in an embodiment of this application. As shown in Figure 2, the method includes steps 210 to 230.

[0031] Step 210: Determine the actual relative humidity of the mixed gas at the specified location based on the airflow data in the intake passage, the current EGR rate, and the temperature and pressure of the mixed gas at the specified location.

[0032] In one exemplary embodiment, airflow data in the intake passage can be collected using an airflow sensor. The airflow sensor is positioned between the air filter and the mixing valve to collect flow data of the fresh air after it has passed through the air filter. The airflow data may include air temperature, air mass flow rate, and relative humidity.

[0033] In one exemplary embodiment, data characterizing the air humidity state can be determined from airflow data. Based on the data characterizing the air humidity state and the current EGR rate, humidity data in the air-exhaust gas mixture can be determined. Then, based on the humidity data in the gas mixture and the temperature and pressure of the gas mixture at a specified location, the actual relative humidity of the gas mixture at the specified location can be determined.

[0034] Step 220: Determine the target relative humidity of the mixed gas at the designated location based on the engine's operating data and environmental condition data.

[0035] In one exemplary embodiment, the engine's operating data may include engine speed and torque, and the environmental condition data may include ambient temperature and ambient humidity. The environmental condition data can be collected by sensors located at designated locations.

[0036] In one exemplary embodiment, the desired relative humidity is calculated based on engine operating data and environmental condition data, and is used as the target relative humidity (RH) of the gas mixture at a specified location. Dsire =F(speed, torque, ambient temperature, ambient humidity), for example, F(speed, torque, ambient temperature, ambient humidity) can represent a lookup table, that is, to determine the target relative humidity corresponding to the current speed, torque, ambient temperature and ambient humidity by looking up a table.

[0037] Step 230: Determine the target EGR rate based on the actual relative humidity, the target relative humidity, and the current EGR rate.

[0038] In an exemplary embodiment, when an engine with an EGR configuration is running, exhaust gas is introduced into the intake system and eventually participates in combustion. The exhaust gas contains a large amount of water. The mixture of exhaust gas and air is cooled by the cooling system. If the temperature is too low, liquid water will appear in the intake manifold. The water generated in this way is called condensate.

[0039] By comparing the actual relative humidity with the target relative humidity, if the actual relative humidity is greater than the target relative humidity, condensation may occur. In this case, the EGR rate can be reduced to avoid condensation; that is, the EGR rate is reduced by a certain amount from the current EGR rate to obtain the target EGR rate. If the actual relative humidity is less than the target relative humidity, the EGR rate can be increased; that is, the EGR rate is increased by a certain amount from the current EGR rate to obtain the target EGR rate. If the actual relative humidity is equal to the target relative humidity, no adjustment to the EGR rate is needed; that is, the target EGR rate equals the current EGR rate. After determining the target EGR rate, the current EGR rate can be adjusted to make the adjusted EGR rate the target EGR rate, and then EGR control can be performed based on the target EGR rate.

[0040] In one embodiment of this application, determining the target EGR rate based on the actual relative humidity, the target relative humidity, and the current EGR rate includes:

[0041] If the actual relative humidity is greater than the target relative humidity, then a first difference between the actual relative humidity and the target relative humidity is determined, and the target EGR rate is determined based on the first difference and the current EGR rate, wherein the target EGR rate is less than the current EGR rate; or

[0042] If the actual relative humidity is less than the target relative humidity, a second difference between the target relative humidity and the actual relative humidity is determined, and the target EGR rate is determined based on the second difference and the current EGR rate, wherein the target EGR rate is greater than the current EGR rate.

[0043] In an exemplary embodiment, if the actual relative humidity is greater than the target relative humidity, the EGR rate can be reduced to avoid the generation of condensation. In this case, a first difference between the actual relative humidity and the target relative humidity can be determined, and the first EGR rate change corresponding to the first difference can be determined by looking up a table based on the first difference. The target EGR rate is obtained by subtracting the first EGR rate change from the current EGR rate.

[0044] In another exemplary embodiment, if the actual relative humidity is less than the target relative humidity, the EGR rate can be increased. In this case, a second difference between the target relative humidity and the actual relative humidity can be determined, and the second EGR rate change corresponding to the second difference can be determined by looking up a table based on the second difference. The current EGR rate is then added to the second EGR rate change to obtain the target EGR rate.

[0045] By determining the target EGR rate based on the relationship between the actual relative humidity and the target relative humidity, dynamic adjustment of the EGR rate is achieved, which can avoid the generation of condensation and reduce the risk of engine misfire or icing.

[0046] The EGR control method provided in this application determines the actual relative humidity of the gas mixture at a specified location based on airflow data in the intake passage, the current EGR rate, and the temperature and pressure of the gas mixture at that location. It then determines the target relative humidity of the gas mixture at that location based on engine operating data and environmental condition data. Finally, it determines the target EGR rate based on the actual relative humidity, the target relative humidity, and the current EGR rate. Since the actual and target relative humidity of the gas mixture can be determined based on airflow data and environmental condition data, and the actual relative humidity characterizes the state of condensate, the EGR rate can be dynamically adjusted based on these two values. This dynamic adjustment of the EGR rate fully considers the environmental impact, reducing condensate production and effectively mitigating safety risks such as engine misfires and low-temperature icing caused by condensate, thereby improving safety.

[0047] Figure 3 is a flowchart of an EGR control method provided in an embodiment of this application. This embodiment refines the steps for determining the actual relative humidity of the mixed gas at a specified location, based on the above embodiments. As shown in Figure 3, the method includes steps 310 to 360.

[0048] Step 310: Obtain airflow data in the intake passage through an airflow sensor. The airflow data is the flow rate data of the air after passing through the air filter.

[0049] In one exemplary embodiment, an air flow sensor is disposed between the air filter and the mixing valve to collect flow data of the fresh air after it has passed through the air filter.

[0050] Step 320: Determine air state data based on the air flow data, wherein the air state data is data characterizing the air humidity state.

[0051] In one exemplary embodiment, airflow data is calculated to determine data characterizing the air humidity state, thus obtaining air state data. Optionally, the air state data may include the partial pressure of water in the air, the molar flow rate of dry air, and the molar flow rate of water in the air. Dry air refers to air containing no moisture, i.e., with a relative humidity of 0.

[0052] Step 330: Determine the volume percentage of water in the mixture of air and exhaust gas based on the air state data and the current EGR rate.

[0053] In one exemplary embodiment, exhaust gas is the gas produced when air participates in combustion.

[0054] In an exemplary embodiment, air state data characterizes the humidity state of the air, while exhaust gas is produced when air participates in combustion. The humidity state data of the exhaust gas can be determined based on the combustion formula. Then, by combining the air state data, the humidity state data of the exhaust gas, and the current EGR rate, the volume percentage of water in the mixed gas produced by mixing air and exhaust gas at the current EGR rate can be determined.

[0055] Step 340: Determine the actual relative humidity of the mixed gas at the specified location based on the temperature and pressure of the mixed gas at the specified location and the volume percentage of water in the mixed gas.

[0056] In one exemplary embodiment, the designated location is a place where condensation may occur, typically between the intercooler and the engine block, such as between the intercooler and the electronic throttle, or between the electronic throttle and the engine block. If condensation enters the engine, it can cause misfires. At low temperatures, condensation can lead to engine freezing. By adjusting the EGR rate, condensation can be prevented, thus avoiding the risks of engine misfires or freezing.

[0057] In one exemplary embodiment, relative humidity is expressed as a percentage of the ratio of the actual water vapor pressure in the air to the saturated vapor pressure at the given temperature. The temperature and pressure of the mixed gas at a specified location can be collected by a sensor positioned at that location. Based on the temperature of the mixed gas, the saturated vapor pressure can be determined, and based on the pressure of the mixed gas and the volume percentage of water in the mixed gas, the pressure of the water in the mixed gas can be determined. Furthermore, based on the pressure of the water in the mixed gas and the saturated vapor pressure, the actual relative humidity of the mixed gas can be determined. The actual relative humidity of the mixed gas characterizes the state of the condensate in the mixed gas, thus quantifying the state of the condensate in the mixed gas.

[0058] In an optional embodiment of this application, determining the actual relative humidity of the mixed gas at a specified location based on the temperature and pressure of the mixed gas at a specified location, and the volume percentage of water in the mixed gas, includes: determining the saturated vapor pressure of the mixed gas based on the temperature of the mixed gas; determining the partial pressure of water in the mixed gas based on the pressure of the mixed gas and the volume percentage of water in the mixed gas; and determining the actual relative humidity of the mixed gas based on the saturated vapor pressure of the mixed gas and the partial pressure of water in the mixed gas.

[0059] In one exemplary embodiment, based on the temperature T of the mixed gas Mix By querying the water vapor pressure characteristics, the saturated vapor pressure P of the mixed gas can be obtained. Mix_Saturate Calculate the pressure P of the gas mixture. Mix and the volume percentage R of water in the gas mixture MixH2o The product of these terms represents the partial pressure of water in the gas mixture, specifically the partial pressure P of water in the gas mixture. Mix_H2o =P Mix *P MixH2o Calculate the ratio between the partial pressure of water in the gas mixture and the saturated vapor pressure of the gas mixture. This ratio is the actual relative humidity of the gas mixture, i.e., the actual relative humidity RH of the gas mixture. Mix =P Mix_H2o / P Mix_Saturate .

[0060] The saturated vapor pressure of the mixed gas can be accurately determined based on its temperature. The partial pressure of water in the mixed gas can be determined based on its pressure and the volume ratio of water in the mixed gas. Based on the saturated vapor pressure and the partial pressure of water in the mixed gas, the actual relative humidity of the mixed gas can be accurately determined, which can improve the accuracy of the actual relative humidity and thus improve the accuracy of EGR control.

[0061] Step 350: Determine the target relative humidity of the mixed gas at the designated location based on the engine's operating data and environmental condition data.

[0062] Step 360: Determine the target EGR rate based on the actual relative humidity, the target relative humidity, and the current EGR rate.

[0063] The EGR control method provided in this application acquires airflow data in the intake passage using an airflow sensor, determines air state data based on the airflow data, determines the volume percentage of water in the air-exhaust gas mixture based on the air state data and the current EGR rate, determines the actual relative humidity of the gas mixture at a specified location based on the temperature and pressure of the gas mixture and the volume percentage of water in the gas mixture, determines the target relative humidity of the gas mixture at the specified location based on engine operating data and environmental state data, and determines the target EGR rate based on the actual relative humidity, target relative humidity, and the current EGR rate. Since the actual relative humidity and target relative humidity of the gas mixture can be determined based on airflow data and environmental state data, this method is highly efficient. Humidity, specifically relative humidity, characterizes the state of condensation. Based on the actual and target relative humidity, the EGR rate can be dynamically adjusted. This dynamic adjustment fully considers environmental influences, reducing condensation generation and effectively mitigating safety risks such as engine misfires and low-temperature icing caused by condensation, thus improving safety. Furthermore, by determining air state data based on airflow data, and then using this data and the current EGR rate to determine the water volume percentage in the gas mixture, and combining this with the temperature and pressure of the gas mixture at a specified location and the water volume percentage, the actual relative humidity at that location can be determined. This improves the accuracy of the actual relative humidity determination, further enhancing safety.

[0064] Figure 4 is a flowchart of determining air state data based on air flow data in an embodiment of this application. As shown in Figure 4, the step of determining air state data based on the air flow data, i.e., step 320 mentioned above, includes:

[0065] Step 321: Determine the partial pressure of water in the air based on the air temperature and the relative humidity of the air.

[0066] In one exemplary embodiment, the partial pressure of water in the air refers to the pressure exerted by the moisture in the air.

[0067] In one embodiment of this application, determining the partial pressure of water in the air based on the air temperature and the air relative humidity includes: determining the saturated vapor pressure of the air based on the air temperature; and determining the partial pressure of water in the air based on the saturated vapor pressure of the air and the air relative humidity.

[0068] Based on the air temperature, look up the corresponding saturated vapor pressure from the water saturated vapor pressure table. Use this as the saturated vapor pressure of the air. Then, multiply the saturated vapor pressure by the relative humidity of the air. This product is used as the partial pressure of water in the air, determined by the following formula: P AirH2o =P Air _ Saturae*RH Air

[0069] Among them, P AirH2o P represents the partial pressure of water in the air. Air_Saturate RH represents the saturated vapor pressure of air. Air This indicates the relative humidity of the air.

[0070] By determining the saturated vapor pressure of air based on air temperature, and then determining the partial pressure of water in the air based on the saturated vapor pressure and relative humidity, the accuracy of the partial pressure of water in the air can be improved, thereby improving the accuracy of relative humidity and the accuracy of EGR control.

[0071] Step 322: Determine the molar flow rate of the dry air based on the air mass flow rate and the molar mass of the dry air.

[0072] The molar mass of dry air is a constant. The ratio of the mass flow rate of dry air to its molar mass is the molar flow rate of dry air, which can be determined using the following formula:

[0073] Where, N AirDry Q represents the molar flow rate of dry air. m_Air Indicates air mass flow rate, M AirDry This represents the molar mass of dry air.

[0074] Step 323: Determine the molar flow rate of water in the air based on the partial pressure of water in the air and the molar flow rate of the dry air.

[0075] Based on the partial pressure of water in the air and the molar flow rate of dry air, the molar flow rate of water in the air can be determined using the following formula:

[0076] Where, N AirH2o N represents the molar flow rate of water in the air. AirDry P represents the molar flow rate of dry air. baro It represents atmospheric pressure.

[0077] By using air temperature, relative humidity, and air mass flow rate, the partial pressure of water in the air, the molar flow rate of dry air, and the molar mass of water in the air can be accurately determined, thereby improving the accuracy of subsequent determination of actual relative humidity and improving the accuracy of EGR control.

[0078] Figure 5 is a flowchart illustrating the process of determining the volume percentage of water in a gas mixture according to an embodiment of this application. As shown in Figure 5, step 330, which involves determining the volume percentage of water in the gas mixture of air and exhaust gas based on the air state data and the current EGR rate, includes:

[0079] Step 331: Determine the volume percentage of water in the exhaust gas produced when the air participates in combustion, based on the partial pressure of water in the air.

[0080] Based on the partial pressure of water in air and the combustion formula, the volume percentage of water in the exhaust gas produced when air participates in combustion can be calculated. The combustion formula can be expressed as follows:

[0081] Among them, C n H m This indicates the amount of hydrocarbons that participate in combustion in gasoline, where n and m represent the hydrocarbon ratio, and heat represents the heat generated during combustion.

[0082] For example, assuming 1 mol of air participates in combustion, the volume percentage of water in the exhaust gas is as follows:

[0083] Among them, R ExhaustH2o P represents the volume percentage of water in the exhaust gas. AirH2o P represents the partial pressure of water in the air. baro It represents atmospheric pressure.

[0084] Among them, R ExhaustH2o P represents the volume percentage of water in the exhaust gas. AirH2o P represents the partial pressure of water in the air. baro It represents atmospheric pressure.

[0085] Step 332: Determine the molar flow rate of the exhaust gas based on the molar flow rate of the dry air, the molar flow rate of the water in the air, and the current EGR rate.

[0086] EGR rate can be expressed as follows:

[0087] Among them, R EGR N represents the current EGR rate. EGR N represents the molar flow rate of the exhaust gas. AirH2o N represents the molar flow rate of water in the air. AirDry This represents the molar flow rate of dry air.

[0088] Based on the above formula for EGR rate, the formula for calculating the molar flow rate of exhaust gas can be obtained as follows:

[0089] The molar flow rate of the exhaust gas can be calculated using the formula for calculating the molar flow rate of the exhaust gas mentioned above.

[0090] Step 333: Determine the molar flow rate of water in the waste gas based on the molar flow rate of the waste gas and the volume percentage of water in the waste gas.

[0091] The molar flow rate of water in the waste gas is obtained by multiplying the molar flow rate of the waste gas by the volume percentage of water in the waste gas. Specifically, the molar flow rate of water in the waste gas is calculated using the following formula: N EGRH2o =N EGR *R ExhaustH2o

[0092] Where, N EGRH2o N represents the molar flow rate of water in the exhaust gas. EGR RE represents the molar flow rate of the exhaust gas. xhaustH2o This indicates the volume percentage of water in the exhaust gas.

[0093] Step 334: Determine the volume percentage of water in the mixed gas based on the molar flow rate of water in the exhaust gas, the molar flow rate of the exhaust gas, the molar flow rate of water in the air, and the molar flow rate of the dry air.

[0094] In one embodiment of this application, determining the volume percentage of water in the mixed gas based on the molar flow rate of water in the exhaust gas, the molar flow rate of the exhaust gas, the molar flow rate of water in the air, and the molar flow rate of dry air includes: determining the molar flow rate of water in the mixed gas based on the molar flow rate of water in the exhaust gas and the molar flow rate of water in the air; determining the molar flow rate of the mixed gas based on the molar flow rate of the exhaust gas, the molar flow rate of water in the air, and the molar flow rate of dry air; and determining the volume percentage of water in the mixed gas as the ratio of the molar flow rate of water in the mixed gas to the molar flow rate of the mixed gas.

[0095] The sum of the molar flow rates of water in the exhaust gas and the water in the air equals the molar flow rate of water mixed with other substances. The sum of the molar flow rates of the exhaust gas, the water in the air, and the dry air equals the molar flow rate of the mixed gas. The ratio of the molar flow rate of water in the mixed gas to the total molar flow rate of the mixed gas is calculated; this ratio represents the volume percentage of water in the mixed gas. In other words, the volume percentage of water in the mixed gas can be calculated using the following formula:

[0096] Among them, P MixH2o N represents the volume percentage of water in a gas mixture. AirH2o N represents the molar flow rate of water in the air. EGRH2o N represents the molar flow rate of water in the exhaust gas. EGR N represents the molar flow rate of the exhaust gas. AirDry This represents the molar flow rate of dry air.

[0097] By using the partial pressure of water in the air, the molar flow rate of dry air, the molar flow rate of water in the air, and the current EGR rate, the volume percentage of water in the gas mixture can be accurately determined, thereby improving the accuracy of the actual relative humidity determination and the accuracy of EGR control.

[0098] Figure 6 is a flowchart of an EGR control method provided in an embodiment of this application. As shown in Figure 6, the EGR control method may include the following steps:

[0099] Step 601: Obtain fresh air mass flow rate, fresh air temperature, fresh air humidity, and fresh air pressure through sensors.

[0100] The air pressure can be determined based on the fresh air pressure, which is the atmospheric pressure in the above embodiment. Fresh air is air that has been filtered.

[0101] Step 602: Calculate the molar flow rate of fresh air, the partial pressure of water in fresh air, and the saturated vapor pressure of fresh air.

[0102] Step 603: Calculate the volume percentage of water in the exhaust gas according to the combustion formula.

[0103] The volume percentage of water in the exhaust gas is the same as the molar percentage of water in the exhaust gas.

[0104] Step 604: Calculate EGR gas state data.

[0105] EGR gas is the exhaust gas. EGR gas state data includes the molar flow rate of the exhaust gas and the molar flow rate of water in the exhaust gas.

[0106] Step 605: Calculate the mixed gas state data.

[0107] The state data of the mixed gas includes the molar flow rate of the mixed gas and the volume percentage of water in the mixed gas.

[0108] Step 606: Obtain the pressure and temperature of the mixed gas using sensors.

[0109] Step 607: Calculate the actual relative humidity of the mixed gas.

[0110] Step 608: Determine whether the actual relative humidity is greater than the target relative humidity. If yes, proceed to step 609; otherwise, proceed to step 610.

[0111] Step 609: Reduce the EGR rate.

[0112] Step 610, increase the EGR rate.

[0113] The specific implementation process of each of the above steps can be referred to the above embodiments, and will not be repeated here.

[0114] This application proposes an algorithm for real-time calculation of the relative humidity of a mixed gas, which can quantify the state of condensate in the mixed gas in real time. By combining the state of condensate in the mixed gas, the EGR rate can be adjusted in real time, effectively reducing the risk of fire and low-temperature freezing caused by condensate. During the EGR operation, it is possible to determine in advance whether condensate may be generated, which provides the possibility of precise control of EGR and can effectively broaden the application range of EGR. It solves the problem in the prior art that EGR is turned off when the ambient temperature and water temperature are below a certain threshold in order to avoid the risk of low-temperature freezing.

[0115] Bench tests have proven that the actual relative humidity error of the mixed gas calculated in this application's embodiments is within 10%, making it applicable in engineering. In real-vehicle tests, the state of condensate in the intake manifold was observed using a camera, and the results showed that condensate production can be effectively reduced.

[0116] Figure 7 is a schematic diagram of an EGR control device provided in an embodiment of this application. As shown in Figure 7, the device includes:

[0117] The actual relative humidity determination module 710 is used to determine the actual relative humidity of the mixed gas at the specified location based on the air flow data in the intake passage, the current EGR rate, and the temperature and pressure of the mixed gas at the specified location.

[0118] The target relative humidity determination module 720 is used to determine the target relative humidity of the mixed gas at the specified location based on the engine's operating data and environmental condition data.

[0119] The target EGR rate determination module 730 is used to determine the target EGR rate based on the actual relative humidity, the target relative humidity, and the current EGR rate.

[0120] Optionally, the actual relative humidity determination module includes:

[0121] An airflow acquisition unit is used to acquire airflow data in the intake passage through an airflow sensor, wherein the airflow data is the flow data of the air after air filtration.

[0122] An air state determination unit is used to determine air state data based on the air flow data, wherein the air state data is data characterizing the air humidity state.

[0123] The water volume percentage determination unit is used to determine the water volume percentage in the mixture of air and exhaust gas based on the air state data and the current EGR rate.

[0124] The actual relative humidity determination unit is used to determine the actual relative humidity of the mixed gas at the specified location based on the temperature and pressure of the mixed gas at the specified location and the volume percentage of water in the mixed gas.

[0125] Optionally, the air flow data includes air temperature, air mass flow rate, and air relative humidity; the air state data includes the partial pressure of water in the air, the molar flow rate of dry air, and the molar flow rate of water in the air.

[0126] Optionally, the air state determination unit includes:

[0127] A water pressure determination subunit is used to determine the partial pressure of water in the air based on the air temperature and the air relative humidity;

[0128] A dry air molar flow rate determination subunit is used to determine the molar flow rate of the dry air based on the air mass flow rate and the molar mass of the dry air;

[0129] The air water molar flow rate determination subunit is used to determine the molar flow rate of water in the air based on the partial pressure of water in the air and the molar flow rate of dry air.

[0130] Optionally, the water pressure determination subunit is specifically used for:

[0131] Determine the saturated vapor pressure of the air based on the air temperature;

[0132] The partial pressure of water in the air is determined based on the saturated vapor pressure of the air and the relative humidity of the air.

[0133] Optionally, the water volume percentage determination unit includes:

[0134] The waste gas water volume ratio determination subunit is used to determine the water volume ratio in the waste gas generated when the air participates in combustion, based on the partial pressure of water in the air.

[0135] The exhaust gas molar flow rate determination subunit is used to determine the exhaust gas molar flow rate based on the dry air molar flow rate, the water molar flow rate in the air, and the current EGR rate.

[0136] The waste gas water molar flow rate determination subunit is used to determine the molar flow rate of water in the waste gas based on the molar flow rate of the waste gas and the volume ratio of water in the waste gas.

[0137] The subunit for determining the water volume percentage in the mixed gas is used to determine the water volume percentage in the mixed gas based on the molar flow rate of water in the exhaust gas, the molar flow rate of the exhaust gas, the molar flow rate of water in the air, and the molar flow rate of the dry air.

[0138] Optionally, the subunit for determining the water volume percentage in the mixed gas is specifically used for:

[0139] The molar flow rate of water in the mixed gas is determined based on the molar flow rate of water in the exhaust gas and the molar flow rate of water in the air.

[0140] The molar flow rate of the mixed gas is determined based on the molar flow rate of the exhaust gas, the molar flow rate of water in the air, and the molar flow rate of the dry air.

[0141] The ratio of the molar flow rate of water in the mixed gas to the molar flow rate of the mixed gas is determined as the volume percentage of water in the mixed gas.

[0142] Optionally, the actual relative humidity determination unit is specifically used for:

[0143] The saturated vapor pressure of the mixed gas is determined based on the temperature of the mixed gas.

[0144] The partial pressure of water in the mixed gas is determined based on the pressure of the mixed gas and the volume percentage of water in the mixed gas.

[0145] The actual relative humidity of the mixed gas is determined based on the saturated vapor pressure of the mixed gas and the partial pressure of water in the mixed gas.

[0146] Optionally, the target EGR rate determination module is specifically used for:

[0147] If the actual relative humidity is greater than the target relative humidity, then a first difference between the actual relative humidity and the target relative humidity is determined, and the target EGR rate is determined based on the first difference and the current EGR rate, wherein the target EGR rate is less than the current EGR rate; or

[0148] If the actual relative humidity is less than the target relative humidity, a second difference between the target relative humidity and the actual relative humidity is determined, and the target EGR rate is determined based on the second difference and the current EGR rate, wherein the target EGR rate is greater than the current EGR rate.

[0149] The EGR control device provided in this application embodiment is used to implement the steps of the EGR control method described in this application embodiment. The specific implementation of each module of the device is described in the corresponding steps, and will not be repeated here.

[0150] The EGR control device provided in this application determines the actual relative humidity of the gas mixture at a specified location based on airflow data in the intake passage, the current EGR rate, and the temperature and pressure of the gas mixture at that location. It then determines the target relative humidity of the gas mixture at that location based on engine operating data and environmental condition data. Finally, it determines the target EGR rate based on the actual relative humidity, the target relative humidity, and the current EGR rate. Since the actual and target relative humidity of the gas mixture can be determined based on airflow data and environmental condition data, and the actual relative humidity characterizes the state of condensate, the EGR rate can be dynamically adjusted based on the actual and target relative humidity. This dynamic adjustment of the EGR rate fully considers the impact of the environment, reducing condensate production and effectively mitigating safety risks such as engine misfires and low-temperature icing caused by condensate, thereby improving safety.

[0151] Figure 8 is a schematic diagram of a vehicle controller according to an embodiment of this application. As shown in Figure 8, the vehicle controller 800 may include one or more processors 810 and one or more memories 820 connected to the processors 810. The vehicle controller 800 may also include an input interface 830 and an output interface 840 for communicating with another device or system. The program code executed by the processor 810 may be stored in the memory 820.

[0152] The processor 810 in the vehicle controller 800 calls the program code stored in the memory 820 to execute the EGR control method in the above embodiment.

[0153] This application also provides a computer-readable storage medium storing a computer program thereon, which, when executed by a processor, implements the steps of the EGR control method as described in this application.

[0154] This application also provides a computer program product that, when executed by a processor, implements the steps of the EGR control method as described in this application.

[0155] The various embodiments in this specification are described in a progressive manner, with each embodiment focusing on its differences from other embodiments. Similar or identical parts between embodiments can be referred to interchangeably. For the apparatus embodiments, since they are fundamentally similar to the method embodiments, the description is relatively simple; relevant parts can be referred to the descriptions in the method embodiments.

[0156] The above provides a detailed description of an EGR control method, device, vehicle controller, and storage medium provided in the embodiments of this application. Specific examples have been used to illustrate the principles and implementation methods of this application. The descriptions of the above embodiments are only for the purpose of helping to understand the method and core ideas of this application. At the same time, for those skilled in the art, there will be changes in the specific implementation methods and application scope based on the ideas of this application. Therefore, the content of this specification should not be construed as a limitation of this application.

[0157] Through the above description of the embodiments, those skilled in the art can clearly understand that each embodiment can be implemented by means of software plus necessary general-purpose hardware platforms, and of course, it can also be implemented by hardware. Based on this understanding, the above technical solutions, in essence or the part that contributes to the prior art, can be embodied in the form of a software product. This computer software product can be stored in a computer-readable storage medium, such as ROM / RAM, magnetic disk, optical disk, etc., and includes several instructions to cause a computer device (which may be a personal computer, server, or network device, etc.) to execute the methods described in the various embodiments or some parts of the embodiments.

Claims

1. An EGR control method, comprising: The actual relative humidity of the gas mixture at the specified location is determined based on the airflow data in the intake passage, the current EGR rate, and the temperature and pressure of the mixed gas at the specified location. Based on the engine's operating data and environmental condition data, determine the target relative humidity of the mixed gas at the designated location; The target EGR rate is determined based on the actual relative humidity, the target relative humidity, and the current EGR rate.

2. The method of claim 1, wherein, The step of determining the actual relative humidity of the mixed gas at the specified location based on airflow data in the intake passage, the current EGR rate, and the temperature and pressure of the mixed gas at the specified location includes: Airflow data in the intake passage is obtained through an airflow sensor, and the airflow data is the flow rate of air after passing through an air filter. Based on the air flow data, air state data is determined, which is data characterizing the air humidity state; Based on the air state data and the current EGR rate, determine the volume percentage of water in the mixture of air and exhaust gas; The actual relative humidity of the mixed gas at the specified location is determined based on the temperature and pressure of the mixed gas at the specified location, as well as the volume percentage of water in the mixed gas.

3. The method of claim 2, wherein, The air flow data includes air temperature, air mass flow rate, and air relative humidity; the air state data includes the partial pressure of water in the air, the molar flow rate of dry air, and the molar flow rate of water in the air.

4. The method of claim 3, wherein, The step of determining air state data based on the air flow data includes: The partial pressure of water in the air is determined based on the air temperature and the relative humidity of the air. The molar flow rate of the dry air is determined based on the air mass flow rate and the molar mass of the dry air. The molar flow rate of water in the air is determined based on the partial pressure of water in the air and the molar flow rate of the dry air.

5. The method of claim 4, wherein, Determining the partial pressure of water in the air based on the air temperature and the relative humidity includes: Determine the saturated vapor pressure of the air based on the air temperature; The partial pressure of water in the air is determined based on the saturated vapor pressure of the air and the relative humidity of the air.

6. The method according to any one of claims 3-5, wherein, The step of determining the volume percentage of water in the air-exhaust gas mixture based on the air state data and the current EGR rate includes: Based on the partial pressure of water in the air, determine the volume percentage of water in the exhaust gas produced when the air participates in combustion; The molar flow rate of the exhaust gas is determined based on the molar flow rate of the dry air, the molar flow rate of the water in the air, and the current EGR rate. The molar flow rate of water in the waste gas is determined based on the molar flow rate of the waste gas and the volume percentage of water in the waste gas. The volume percentage of water in the mixed gas is determined based on the molar flow rate of water in the exhaust gas, the molar flow rate of the exhaust gas, the molar flow rate of water in the air, and the molar flow rate of the dry air.

7. The method of claim 6, wherein, Determining the volume percentage of water in the mixed gas based on the molar flow rate of water in the exhaust gas, the molar flow rate of the exhaust gas, the molar flow rate of water in the air, and the molar flow rate of the dry air includes: The molar flow rate of water in the mixed gas is determined based on the molar flow rate of water in the exhaust gas and the molar flow rate of water in the air. The molar flow rate of the mixed gas is determined based on the molar flow rate of the exhaust gas, the molar flow rate of water in the air, and the molar flow rate of the dry air. The ratio of the molar flow rate of water in the mixed gas to the molar flow rate of the mixed gas is determined as the volume percentage of water in the mixed gas.

8. The method according to any one of claims 2-7, wherein, Determining the actual relative humidity of the mixed gas at a specified location based on the temperature and pressure of the mixed gas at the specified location, and the volume percentage of water in the mixed gas, includes: The saturated vapor pressure of the mixed gas is determined based on the temperature of the mixed gas. The partial pressure of water in the mixed gas is determined based on the pressure of the mixed gas and the volume percentage of water in the mixed gas. The actual relative humidity of the mixed gas is determined based on the saturated vapor pressure of the mixed gas and the partial pressure of water in the mixed gas.

9. The method according to any one of claims 1-7, wherein, The step of determining the target EGR rate based on the actual relative humidity, the target relative humidity, and the current EGR rate includes: If the actual relative humidity is greater than the target relative humidity, then a first difference between the actual relative humidity and the target relative humidity is determined, and the target EGR rate is determined based on the first difference and the current EGR rate, wherein the target EGR rate is less than the current EGR rate; or If the actual relative humidity is less than the target relative humidity, a second difference between the target relative humidity and the actual relative humidity is determined, and the target EGR rate is determined based on the second difference and the current EGR rate, wherein the target EGR rate is greater than the current EGR rate.

10. An EGR control device, comprising: The actual relative humidity determination module is used to determine the actual relative humidity of the mixed gas at the specified location based on the air flow data in the intake passage, the current EGR rate, and the temperature and pressure of the mixed gas at the specified location. The target relative humidity determination module is used to determine the target relative humidity of the mixed gas at the specified location based on the engine's operating data and environmental condition data. The target EGR rate determination module is used to determine the target EGR rate based on the actual relative humidity, the target relative humidity, and the current EGR rate.

11. A vehicle controller, comprising a memory, a processor, and a computer program stored in the memory and executable on the processor, wherein the processor, when executing the computer program, implements the EGR control method according to any one of claims 1 to 9.

12. A computer-readable storage medium having a computer program stored thereon, which, when executed by a processor, implements the steps of the EGR control method according to any one of claims 1 to 9.

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