Method, apparatus and device for estimating inlet pressure of mixing valve in low-pressure EGR system

Abstract

A method for estimating an inlet pressure of a mixing valve in a low-pressure EGR system. The low-pressure EGR system comprises a mixing valve, an air filtering apparatus and an EGR valve, an inlet of the mixing valve communicating with an output end of the air filtering apparatus, and an outlet of the mixing valve communicating with the EGR valve. The method comprises: on the basis of the atmospheric temperature, the atmospheric pressure, and the intake flow rate of the mixing valve, determining a pressure loss of air after passing through the air filtering apparatus (201); and, on the basis of the atmospheric pressure and the pressure loss, determining an inlet pressure of the mixing valve (202). The method avoids the addition of a pressure sensor, thereby reducing the production cost of products. Also disclosed are an apparatus and device for estimating the inlet pressure of the mixing valve in the low-pressure EGR system, and a computer storage medium.

Description

Method, device and equipment for estimating inlet pressure of mixing valve of low-pressure EGR system Technical Field

[0001] The present application belongs to the field of low-pressure EGR technology, and in particular relates to a method, device and equipment for estimating the inlet pressure of a mixing valve of a low-pressure EGR system. Background Art

[0002] To improve the thermal efficiency of gasoline engines, various companies have begun researching and mass-producing gasoline engines that utilize low-pressure exhaust gas recirculation (EGR) systems. Compared to traditional high-pressure EGR systems, low-pressure EGR systems significantly expand the engine's available EGR range, meeting the EGR requirements of common hybrid engine operating conditions and thus reducing fuel consumption.

[0003] Currently, the inlet pressure of the mixing valve of the low-pressure EGR system needs to be collected by a pressure sensor. This solution requires the installation of a pressure sensor in the low-pressure EGR system, thereby increasing the production cost of the product. Summary of the Invention

[0004] The embodiments of the present application provide a method, device and equipment for estimating the inlet pressure of a low-pressure EGR system mixing valve, thereby realizing the inlet pressure estimation of the low-pressure EGR system mixing valve and reducing the production cost of the product.

[0005] Other features and advantages of the present application will become apparent from the following detailed description, or may be learned in part by practice of the present application.

[0006] According to a first aspect of an embodiment of the present application, a method for estimating the inlet pressure of a mixing valve of a low-pressure EGR system is provided, wherein the low-pressure exhaust gas recirculation (EGR) system includes a mixing valve, an air filter device, and an EGR valve, wherein the inlet of the mixing valve is connected to the output end of the air filter device, and the outlet of the mixing valve is connected to the EGR valve. The inlet pressure estimation method includes:

[0007] determining the pressure loss of air after passing through the air filtration device according to the atmospheric temperature, atmospheric pressure and the air intake flow rate of the mixing valve;

[0008] An inlet pressure of the mixing valve is determined according to the atmospheric pressure and the loss pressure.

[0009] In some embodiments of the present application, based on the aforementioned solution, determining the inlet pressure of the mixing valve according to the atmospheric pressure and the loss pressure includes:

[0010] determining a pressure difference between the atmospheric pressure and the loss pressure;

[0011] The inlet pressure of the mixing valve is determined according to the pressure difference and the vehicle speed.

[0012] In some embodiments of the present application, based on the aforementioned solution, determining the inlet pressure of the mixing valve according to the pressure difference and the vehicle speed includes:

[0013] determining air density based on the atmospheric temperature and the atmospheric pressure;

[0014] determining a vehicle speed correction value according to the air density, the vehicle speed, and a preset vehicle speed correction coefficient;

[0015] The sum of the pressure difference and the vehicle speed correction value is determined as the inlet pressure.

[0016] In some embodiments of the present application, based on the aforementioned solution, determining the inlet pressure of the mixing valve according to the atmospheric pressure and the loss pressure includes:

[0017] The pressure difference between the atmospheric pressure and the loss pressure is determined as the inlet pressure of the mixing valve.

[0018] In some embodiments of the present application, based on the aforementioned solution, determining the pressure loss of air after passing through the air filtration device according to the atmospheric temperature, atmospheric pressure, and the intake air flow rate of the mixing valve includes:

[0019] Obtain the preset flow resistance coefficient and the preset air filter correction coefficient;

[0020] The loss pressure of air after passing through the air filtering device is determined according to the atmospheric temperature, the atmospheric pressure, the intake air flow rate of the mixing valve, the preset flow resistance coefficient, and the preset air filter correction coefficient.

[0021] In some embodiments of the present application, based on the above solution, testing the low-pressure EGR system includes testing a mixing valve and testing an air filtration device, and the inlet pressure estimation method further includes:

[0022] When the test low-pressure EGR system meets a preset condition, obtaining the outlet pressure of the test mixing valve, wherein the preset condition includes the test mixing valve being opened to a preset maximum opening;

[0023] An air filter correction coefficient corresponding to different test intake flow rates is obtained according to the outlet pressure, the atmospheric pressure, the atmospheric temperature, the test intake flow rate of the test mixing valve, the preset flow resistance coefficient and the test vehicle speed.

[0024] In some embodiments of the present application, based on the above solution, the inlet pressure estimation method further includes:

[0025] If the number of the air filter correction coefficients is greater than a first preset value within a preset period, obtaining a first average value of the air filter correction coefficients within the preset period and a second average value of the air filter correction coefficients within a previous period;

[0026] When the absolute value of the difference between the first average value and the second average value is greater than a second preset value, and the absolute value of the first average value is greater than a third preset value, a prompt message for replacing the test air filter device is output.

[0027] According to a second aspect of an embodiment of the present application, a device for estimating an inlet pressure of a mixing valve of a low-pressure EGR system is provided. The low-pressure EGR system includes a mixing valve, an air filter device, and an EGR valve. The inlet of the mixing valve is connected to the output end of the air filter device, and the outlet of the mixing valve is connected to the EGR valve. The inlet pressure estimating device includes:

[0028] a pressure loss calculation unit configured to determine the pressure loss of air after passing through the air filtering device based on the atmospheric temperature, the atmospheric pressure, and the air intake flow rate of the mixing valve;

[0029] An inlet pressure calculation unit is configured to determine an inlet pressure of the mixing valve according to the atmospheric pressure and the loss pressure.

[0030] According to a third aspect of an embodiment of the present application, an inlet pressure estimation device for a low-pressure EGR system mixing valve is provided, comprising a processor and a memory, wherein the memory stores computer program instructions that can be executed by the processor, and when the processor executes the computer program instructions, the steps of the method described in any one of the first aspects above are implemented.

[0031] According to a fourth aspect of an embodiment of the present application, a computer-readable storage medium is provided, in which computer program instructions are stored. When the computer program instructions are executed by a processor, the processor is prompted to implement the steps of the method described in any one of the first aspects above.

[0032] In the present application, the loss pressure of the air after passing through the air filtration device is determined based on the atmospheric temperature, atmospheric pressure and the intake flow rate of the mixing valve; the inlet pressure of the mixing valve is determined based on the atmospheric pressure and the loss pressure, thereby estimating the inlet pressure of the mixing valve in the low-pressure EGR system, avoiding the addition of a pressure sensor, and reducing the production cost of the product.

[0033] It should be understood that the foregoing general description and the following detailed description are exemplary and explanatory only and are not restrictive of the present application. BRIEF DESCRIPTION OF THE DRAWINGS

[0034] The accompanying drawings are incorporated into and constitute a part of the specification, illustrating embodiments consistent with the present application and, together with the specification, explaining the principles of the present application. Obviously, the drawings described below are only some embodiments of the present application, and those skilled in the art can derive other drawings based on these drawings without inventive effort. In the drawings:

[0035] FIG1 shows a schematic structural diagram of a low-pressure EGR system in one embodiment;

[0036] FIG2 is a schematic flow chart showing a method for estimating the inlet pressure of a mixing valve of a low-pressure EGR system according to one embodiment;

[0037] FIG3 shows a block diagram of an inlet pressure estimation device for a low-pressure EGR system mixing valve according to an embodiment;

[0038] FIG4 shows a schematic structural diagram of an inlet pressure estimation device for a mixing valve of a low-pressure EGR system according to an embodiment. DETAILED DESCRIPTION

[0039] The following will be combined with the drawings in the embodiments of this application to clearly and completely describe the technical solutions in the embodiments of this application. Obviously, the embodiments described are only part of the embodiments of this application, not all of the embodiments. Based on the embodiments in this application, all other embodiments obtained by ordinary technicians in this field without making creative efforts are within the scope of protection of this application.

[0040] In addition, described feature, structure or characteristic can be combined in one or more embodiments in any suitable manner.In the following description, many specific details are provided so as to provide a full understanding of the embodiments of the present application. However, it will be appreciated by those skilled in the art that the technical scheme of the present application can be put into practice without one or more of the specific details, or other methods, components, devices, steps etc. can be adopted. In other cases, known methods, devices, implementations or operations are not shown or described in detail to avoid blurring the various aspects of the application.

[0041] The block diagrams shown in the accompanying drawings are merely functional entities and do not necessarily correspond to physically separate entities. That is, these functional entities may be implemented in software, in one or more hardware modules or integrated circuits, or in different networks and / or processor devices and / or microcontroller devices.

[0042] The flowcharts shown in the accompanying drawings are for illustrative purposes only and do not necessarily include all contents and operations / steps, nor must they be executed in the order described. For example, some operations / steps may be decomposed, while others may be combined or partially combined. Therefore, the actual execution order may vary depending on the actual situation.

[0043] In order to enable those skilled in the art to better understand the present application, the low-pressure EGR system involved in the present application is first briefly described with reference to FIG1 .

[0044] Figure 1 shows a schematic diagram of the low-pressure EGR system in one embodiment. As shown in Figure 1 , the low-pressure EGR system may include a throttle module, a mixing valve module, an EGR valve module, a supercharger module, an EGR cooler, an intercooler, a catalyst, a gasoline particulate filter (GPF), an air filter, and other components. The throttle module includes a throttle valve and its corresponding actuator, the mixing valve module includes a mixing valve and its corresponding actuator, the EGR valve module includes an EGR valve and its corresponding actuator, and the supercharger module includes a supercharger and its corresponding actuator.

[0045] The low-pressure EGR system extracts exhaust gas from the GPF, which then passes through the EGR cooler and EGR valve module before entering the compressor line. The air then passes through the air filter and mixing valve module, mixing with the exhaust gas in the compressor line. The air then enters the compressor, passing through the intercooler and throttle module and into the engine cylinders. The mixing valve module is installed between the air filter and the compressor, and the EGR valve module's outlet line is installed between the mixing valve and the compressor. When the low-pressure EGR system is required, the mixing valve needs to be closed to a smaller opening, creating a negative pressure downstream of the low-pressure EGR system. This creates a pressure differential across the EGR valve, allowing the mixed gas to enter the cylinders.

[0046] Figure 2 shows a flow chart of a method for estimating the inlet pressure of a low-pressure EGR system mixing valve in one embodiment. As shown in Figure 2 , a method for estimating the inlet pressure of a low-pressure EGR system mixing valve is provided. The method may include the following steps 201 to 202.

[0047] In step 201, the pressure loss of air after passing through the air filter device is determined based on the atmospheric temperature, atmospheric pressure, and the air flow rate of the mixing valve;

[0048] In step 202 , the inlet pressure of the mixing valve is determined based on the atmospheric pressure and the loss pressure.

[0049] It is understandable that the method for estimating the inlet pressure of a mixing valve of a low-pressure EGR system in the embodiment of the present application can be applied to an engine equipped with a low-pressure EGR system, and can ultimately be executed by an electronic control unit (ECU).

[0050] During the implementation process, the atmospheric temperature and atmospheric pressure can be detected by temperature and pressure sensors, and the intake flow of the mixing valve can be measured by a flow meter installed after the air filter equipment, or calculated by the engine main charging model.

[0051] In some embodiments, the loss pressure can be calculated according to the following formula 1:

[0052] Formula 1;

[0053] in, For loss pressure, The preset flow resistance coefficient, is the atmospheric temperature, is atmospheric pressure, is the intake air flow.

[0054] In some embodiments, the pressure difference between the atmospheric pressure and the loss pressure can be determined as the inlet pressure of the mixing valve. That is, the inlet pressure of the mixing valve can be calculated according to the following formula 2:

[0055] Formula 2;

[0056] in, is the inlet pressure of the mixing valve.

[0057] The preset flow resistance coefficient can be obtained by bench test calibration. Specifically, the test low-pressure EGR system includes a test mixing valve and a test air filter device, and has the same other structural designs as the low-pressure EGR system. During the test, the pressure sensor at the inlet of the test mixing valve can be used to test the actual inlet pressure of the test mixing valve under different intake flow rates, and the flow resistance coefficient under different intake flow rates can be obtained by reverse calculation according to the inlet pressure calculation formula 2 of the mixing valve. When calculating the loss pressure, the corresponding flow resistance coefficient is determined as the preset flow resistance coefficient based on the intake flow rate of the mixing valve. Taking the atmospheric pressure of 101kpa, the atmospheric temperature of 25Deg, the intake flow rate of 117g / s, and the actual inlet pressure of 96.5kpa as an example, the flow resistance coefficient can be inferred to be 0.00012 through calculation.

[0058] It should be noted that due to the influence of vehicle speed, the inlet pressure of the air filtration device may be greater than the atmospheric pressure. Therefore, the inlet pressure of the mixing valve can be corrected according to the vehicle speed.

[0059] In some embodiments, a pressure difference between atmospheric pressure and loss pressure may be determined; and an inlet pressure of the mixing valve may be determined based on the pressure difference and the vehicle speed.

[0060] Specifically, the air density can be determined based on the atmospheric temperature and atmospheric pressure; the vehicle speed correction value can be determined based on the air density, vehicle speed and a preset vehicle speed correction coefficient; and the sum of the pressure difference and the vehicle speed correction value can be determined as the inlet pressure.

[0061] In some embodiments, the air density can be calculated according to the following formula 3:

[0062] Formula 3;

[0063] in, is the air density.

[0064] In some embodiments, the inlet pressure of the mixing valve can also be calculated according to the following formula 4:

[0065] Formula 4;

[0066] in, For vehicle speed, It is the preset vehicle speed correction factor.

[0067] The preset vehicle speed correction factor can be obtained through bench test calibration. The inlet pressure of the air filter device is related to the vehicle speed, atmospheric pressure, air density and atmospheric temperature. Specifically, the test low-pressure EGR system includes a test mixing valve and a test air filter device, and has the same other structural designs as the low-pressure EGR system. During the test, the pressure sensor at the inlet of the test air filter device can be used to test the inlet pressure of the test air filter device at different vehicle speeds, and the vehicle speed correction factor can be inferred based on the following formula 5:

[0068] Formula 5;

[0069] in, is the inlet pressure of the air filtration device. When calculating the mixing valve inlet pressure, the corresponding speed correction factor is determined based on the vehicle speed as the preset speed correction factor. For example, using an atmospheric pressure of 101 kPa, an atmospheric temperature of 25 degrees Celsius, a vehicle speed of 33.3 m / s, and an inlet pressure of 101.2 kPa for the test air filtration device, the speed correction factor can be inferred from Formula 5 to be 0.00015.

[0070] It should be noted that the resistance of the air filtration equipment will increase with the use time, so the preset air filtration correction coefficient can be used to correct the loss pressure.

[0071] In some embodiments, a preset flow resistance coefficient and a preset air filter correction coefficient can be obtained; the loss pressure of air after passing through the air filtration equipment is determined based on the atmospheric temperature, atmospheric pressure, the intake flow of the mixing valve, the preset flow resistance coefficient and the preset air filter correction coefficient.

[0072] During the implementation process, the loss pressure can also be calculated according to the following formula 6:

[0073] Formula 6;

[0074] Wherein, W is the preset air filter correction coefficient.

[0075] In some embodiments, the inlet pressure of the mixing valve can also be calculated according to the following formula 7:

[0076] Formula 7.

[0077] The preset air filter correction factor can be obtained through testing. Specifically, the test low-pressure EGR system includes a test mixing valve and a test air filter device, and has the same other structural designs as the low-pressure EGR system. The outlet pressure of the test mixing valve can be obtained when the test low-pressure EGR system meets preset conditions, including the test mixing valve being opened to a preset maximum opening. The air filter correction factor corresponding to different test intake flow rates is obtained based on the outlet pressure, atmospheric pressure, atmospheric temperature, the test intake flow rate of the test mixing valve, a preset flow resistance coefficient, and the test vehicle speed. When calculating the loss pressure, the air filter correction factor corresponding to the intake flow rate of the mixing valve is determined as the preset air filter correction factor.

[0078] It can be understood that when the test low-pressure EGR system is not working and the test mixing valve is opened to the preset maximum opening, the inlet pressure and outlet pressure of the test mixing valve can be considered to be consistent. By setting a pressure sensor at the outlet of the test mixing valve, the outlet pressure of the test mixing valve can be obtained. According to the outlet pressure, the intake flow rate of the test mixing valve, the vehicle speed and Formula 7, the air filter correction coefficient can be inverted.

[0079] The air filter correction factor is initially set to 1. When the low-pressure EGR system meets pre-set conditions during the test, a self-learning of the air filter correction factor is triggered. These pre-set conditions can include the engine being in steady-state operation, the test mixing valve intake flow rate being greater than 50g / s, and the test mixing valve being fully open for at least 2 seconds. Each time the low-pressure EGR system meets these pre-set conditions during the test, an air filter correction factor is calculated, stored, and the calculator is triggered to accumulate the result.

[0080] In some embodiments, within a preset period, if the number of air filter correction coefficients is greater than a first preset value, a first average value of the air filter correction coefficients within the preset period and a second average value of the air filter correction coefficients within the previous period are obtained; when the absolute value of the difference between the first average value and the second average value is greater than the second preset value, and the absolute value of the first average value is greater than the third preset value, a prompt message for replacing the test air filtration equipment is output.

[0081] Taking the preset cycle of 50 hours of driving time, the first preset value of 10, the second preset value of 1.5, and the third preset value of 3.5 as an example, every 50 hours is an update cycle. After 50 hours, if the number of air filter correction coefficients is greater than 10, and the difference between the first average value calculated within 50 hours and the second average value calculated last time is greater than 1.5, and the absolute value of the first average value is greater than 3.5, a prompt message is output and the test low-pressure EGR system is disabled.

[0082] If the number of air filter correction coefficients is greater than 10, the difference between the first average value calculated within 50 hours and the second average value calculated last time is less than 1, and the absolute value of the first average value is less than 4, the air filter correction coefficient is updated.

[0083] In some embodiments, after calculating the mixing valve inlet pressure, the EGR rate of the low-pressure EGR system can be calculated based on the mixing valve inlet pressure, and the engine can be controlled based on the EGR rate. Therefore, the estimated mixing valve inlet pressure can provide an indicator reference for engine control.

[0084] The embodiment of the present application determines the loss pressure of air after passing through the air filtration equipment based on the atmospheric temperature, atmospheric pressure and the intake flow rate of the mixing valve; determines the inlet pressure of the mixing valve based on the atmospheric pressure and the loss pressure, thereby estimating the inlet pressure of the mixing valve in the low-pressure EGR system, avoiding the addition of a pressure sensor, and reducing the production cost of the product.

[0085] In some embodiments, the inlet pressure estimation method of the low-pressure EGR system mixing valve may also include the following steps: obtaining a preset flow resistance coefficient and a preset air filter correction coefficient; determining the loss pressure of the air after passing through the air filtration equipment based on the atmospheric temperature, atmospheric pressure, the intake flow of the mixing valve, the preset flow resistance coefficient and the preset air filter correction coefficient; determining the pressure difference between the atmospheric pressure and the loss pressure; determining the air density based on the atmospheric temperature and atmospheric pressure; determining the vehicle speed correction value based on the air density, vehicle speed and the preset vehicle speed correction coefficient; and determining the sum of the pressure difference and the vehicle speed correction value as the inlet pressure.

[0086] This embodiment corrects the loss pressure by using a preset air filter correction coefficient, and corrects the pressure difference by using the vehicle speed and the preset vehicle speed correction coefficient, thereby improving the estimation accuracy of the inlet pressure.

[0087] The following describes an embodiment of the apparatus of the present application, which can be used to implement the method for estimating the inlet pressure of a low-pressure EGR system mixing valve described in the above-mentioned embodiment of the present application. For details not disclosed in the embodiment of the apparatus of the present application, please refer to the embodiment of the method for estimating the inlet pressure of a low-pressure EGR system mixing valve described in the above-mentioned embodiment of the present application.

[0088] Referring to FIG3 , a block diagram of an inlet pressure estimation device for a low-pressure EGR system mixing valve in an embodiment of the present application is shown. The low-pressure EGR system includes a mixing valve, an air filter device, and an EGR valve. The inlet of the mixing valve is connected to the output of the air filter device, and the outlet of the mixing valve is connected to the EGR valve. As shown in FIG3 , the inlet pressure estimation device for the low-pressure EGR system mixing valve may include: a loss pressure calculation unit 301, configured to determine the loss pressure of air after passing through the air filter device based on the atmospheric temperature, atmospheric pressure, and the intake flow rate of the mixing valve; and an inlet pressure calculation unit 302, configured to determine the inlet pressure of the mixing valve based on the atmospheric pressure and the loss pressure.

[0089] In some embodiments of the present application, based on the aforementioned solution, the inlet pressure calculation unit 302 is further configured to determine the pressure difference between the atmospheric pressure and the loss pressure; and determine the inlet pressure of the mixing valve according to the pressure difference and the vehicle speed.

[0090] In some embodiments of the present application, based on the aforementioned scheme, the inlet pressure calculation unit 302 is further configured to determine the air density based on the atmospheric temperature and atmospheric pressure; determine the vehicle speed correction value based on the air density, vehicle speed and a preset vehicle speed correction coefficient; and determine the sum of the pressure difference and the vehicle speed correction value as the inlet pressure.

[0091] In some embodiments of the present application, based on the above solution, the inlet pressure calculation unit 302 is further configured to determine the pressure difference between the atmospheric pressure and the loss pressure as the inlet pressure of the mixing valve.

[0092] In some embodiments of the present application, based on the aforementioned scheme, the loss pressure calculation unit 301 is also configured to obtain a preset flow resistance coefficient and a preset air filter correction coefficient; and determine the loss pressure of the air after passing through the air filtration equipment based on the atmospheric temperature, atmospheric pressure, the intake flow of the mixing valve, the preset flow resistance coefficient and the preset air filter correction coefficient.

[0093] In some embodiments of the present application, based on the aforementioned scheme, the test low-pressure EGR system includes a test mixing valve and a test air filtration device, and the loss pressure calculation unit 301 is also configured to obtain the outlet pressure of the test mixing valve when the test low-pressure EGR system meets preset conditions, and the preset conditions include the test mixing valve being opened to a preset maximum opening; according to the outlet pressure, atmospheric pressure, atmospheric temperature, the test intake flow of the test mixing valve, the preset flow resistance coefficient and the test vehicle speed, the air filter correction coefficient corresponding to different test intake flow rates is obtained.

[0094] In some embodiments of the present application, based on the aforementioned scheme, the pressure loss calculation unit 301 is also configured to obtain a first average value of the air filter correction coefficient within the preset period and a second average value of the air filter correction coefficient within the previous period if the number of air filter correction coefficients within the preset period is greater than a first preset value; and output a prompt message to replace the test air filter device when the absolute value of the difference between the first average value and the second average value is greater than the second preset value and the absolute value of the first average value is greater than the third preset value.

[0095] Based on the same inventive concept, embodiments of the present application also provide a device for estimating the inlet pressure of a low-pressure EGR system mixing valve. Referring to FIG. 4 , a schematic diagram of the structure of the device for estimating the inlet pressure of a low-pressure EGR system mixing valve in an embodiment of the present application is shown. The device for estimating the inlet pressure of a low-pressure EGR system mixing valve includes one or more memories 404, one or more processors 402, and at least one computer program (computer program instructions) stored in the memories 404 and executable on the processors 402. When the processors 402 execute the computer program, the method described above is implemented.

[0096] In FIG4 , a bus architecture (represented by bus 400) is shown. Bus 400 may include any number of interconnected buses and bridges. Bus 400 links various circuits, including one or more processors represented by processor 402 and memory represented by memory 404. Bus 400 may also link various other circuits, such as peripherals, voltage regulators, and power management circuits. These are well known in the art and are therefore not described further herein. Bus interface 405 provides an interface between bus 400 and receiver 401 and transmitter 403. Receiver 401 and transmitter 403 may be the same component, namely a transceiver, which provides a means for communicating with various other devices over a transmission medium. Processor 402 is responsible for managing bus 400 and general processing, while memory 404 may be used to store data used by processor 402 when performing operations.

[0097] Based on the same inventive concept, an embodiment of the present application provides a computer-readable storage medium, in which computer program instructions are stored. When the computer program instructions are executed by a processor, the processor is prompted to implement the steps of the method as described above.

[0098] The functions described herein may be implemented in hardware, software executed by a processor, firmware, or any combination thereof. If implemented in software executed by a processor, the functions may be stored as one or more instructions or codes on or transmitted via a computer-readable medium. Other examples and implementations are within the scope and spirit of this application and the appended claims. For example, due to the nature of software, the functions described above may be implemented using software executed by a processor, hardware, firmware, hardwiring, or a combination of any of these. Furthermore, the functional units may be integrated into a single processing unit, each unit may exist physically separately, or two or more units may be integrated into a single unit.

[0099] In the several embodiments provided in this application, it should be understood that the disclosed technical content can be implemented in other ways. Among them, the device embodiments described above are only exemplary. For example, the division of the units can be a logical function division. In actual implementation, there may be other division methods, such as multiple units or components can be combined or integrated into another system, or some features can be ignored or not executed. Another point is that the mutual coupling or direct coupling or communication connection shown or discussed can be through some interfaces, indirect coupling or communication connection of units or modules, which can be electrical or other forms.

[0100] The units described as separate components may or may not be physically separate, and the components of the control device may or may not be physical units, that is, they may be located in one place or distributed across multiple units. Some or all of the units may be selected according to actual needs to achieve the purpose of the present embodiment.

[0101] If the integrated unit is implemented in the form of a software functional unit and sold or used as an independent product, it can be stored in a computer-readable storage medium. Based on this understanding, the technical solution of the present application is essentially or the part that contributes to the prior art or all or part of the technical solution can be embodied in the form of a software product, and the computer software product is stored in a storage medium, including a number of instructions for enabling a computer device (which can be a personal computer, a server or a network device, etc.) to execute all or part of the steps of the method described in each embodiment of the present application. The aforementioned storage medium includes: U disk, read-only memory (ROM, Read-Only Memory), random access memory (RAM, Random Access Memory), mobile hard disk, magnetic disk or optical disk, etc. Various media that can store computer program instructions.

[0102] The foregoing is merely an embodiment of the present application and is not intended to limit the present application. Various modifications and variations are possible for those skilled in the art. Any modifications, equivalent substitutions, or improvements made within the spirit and principles of the present application shall be included within the scope of the claims of the present application.

Claims

1. A method for estimating the inlet pressure of a mixing valve in a low-pressure EGR system, characterized in that, The low-pressure exhaust gas recirculation (EGR) system includes a mixing valve, an air filtering device, and an EGR valve. The inlet of the mixing valve is communicated with the output end of the air filtering device, and the outlet of the mixing valve is communicated with the EGR valve. The inlet pressure estimation method includes: Determine the pressure loss of air after passing through the air filtering device according to the atmospheric temperature, atmospheric pressure, and the intake air flow rate of the mixing valve. Determine the inlet pressure of the mixing valve according to the atmospheric pressure and the pressure loss.

2. The method for estimating the inlet pressure of the mixing valve of the low-pressure EGR system according to claim 1, characterized in that, The step of determining the inlet pressure of the mixing valve according to the atmospheric pressure and the pressure loss includes: Determine the pressure difference between the atmospheric pressure and the pressure loss. Determine the inlet pressure of the mixing valve according to the pressure difference and the vehicle speed.

3. The method for estimating the inlet pressure of the mixing valve of the low-pressure EGR system according to claim 2, characterized in that The step of determining the inlet pressure of the mixing valve according to the pressure difference and the vehicle speed includes: Determine the air density according to the atmospheric temperature and the atmospheric pressure. Determine the vehicle speed correction value according to the air density, the vehicle speed, and a preset vehicle speed correction coefficient. Determine the sum of the pressure difference and the vehicle speed correction value as the inlet pressure.

4. The method for estimating the inlet pressure of the mixing valve of the low-pressure EGR system according to claim 1, wherein The step of determining the inlet pressure of the mixing valve according to the atmospheric pressure and the pressure loss includes: Determine the pressure difference between the atmospheric pressure and the pressure loss as the inlet pressure of the mixing valve.

5. The method for estimating the inlet pressure of the mixing valve of the low-pressure EGR system according to claim 1, characterized in that, The step of determining the pressure loss of air after passing through the air filtering device according to the atmospheric temperature, atmospheric pressure, and the intake air flow rate of the mixing valve includes: Obtain a preset flow resistance coefficient and a preset air filter correction coefficient. Determine the pressure loss of air after passing through the air filtering device according to the atmospheric temperature, the atmospheric pressure, the intake air flow rate of the mixing valve, the preset flow resistance coefficient, and the preset air filter correction coefficient.

6. The method for estimating the inlet pressure of the mixing valve of the low-pressure EGR system according to claim 5, wherein The test low-pressure EGR system includes a test mixing valve and a test air filtering device. The inlet pressure estimation method further includes: When the test low-pressure EGR system meets the preset conditions, obtain the outlet pressure of the test mixing valve. The preset conditions include that the test mixing valve is opened to a preset maximum opening degree. Obtain the air filter correction coefficients corresponding to different test intake air flow rates according to the outlet pressure, the atmospheric pressure, the atmospheric temperature, the test intake air flow rate of the test mixing valve, the preset flow resistance coefficient, and the test vehicle speed.

7. The method for estimating the inlet pressure of the mixing valve of the low-pressure EGR system according to claim 6, wherein The inlet pressure estimation method further includes: Within a preset period, if the number of the air filter correction coefficients is greater than a first preset value, obtain a first average value of the air filter correction coefficients within the preset period and a second average value of the air filter correction coefficients in the previous period. When the absolute value of the difference between the first average value and the second average value is greater than a second preset value, and the absolute value of the first average value is greater than a third preset value, output a prompt message for replacing the test air filtering device.

8. An inlet pressure estimation device for a mixing valve of a low-pressure EGR system, characterized in that, The low-pressure EGR system includes a mixing valve, an air filtering device, and an EGR valve. The inlet of the mixing valve is communicated with the output end of the air filtering device, and the outlet of the mixing valve is communicated with the EGR valve. The inlet pressure estimation device includes: A loss pressure calculation unit configured to determine a loss pressure of air after passing through the air filtering device according to an atmospheric temperature, an atmospheric pressure, and an intake air flow rate of the mixing valve; An inlet pressure calculation unit configured to determine an inlet pressure of the mixing valve according to the atmospheric pressure and the loss pressure.

9. An inlet pressure estimation device for a mixing valve of a low-pressure EGR system, comprising a processor and a memory, characterized in that, The memory stores computer program instructions executable by the processor, and when the processor executes the computer program instructions, steps of the method according to any one of claims 1 to 7 are implemented.

10. A computer-readable storage medium, characterized in that, Computer program instructions are stored in the computer-readable storage medium, and when the computer program instructions are executed by a processor, the processor is caused to implement steps of the method according to any one of claims 1 to 7.

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