Method for detecting leakage of engine exhaust gas recirculation system and leakage detection system

Abstract

The application belongs to the technical field of engines, and particularly relates to a method and system for detecting air leakage of an engine exhaust gas recirculation system, comprising the following steps: confirming whether a detection unit is working normally; judging the relationship between actual supercharging pressure of the engine and required supercharging pressure of the engine according to the normal working of the detection unit and the working condition that the engine is under a preset load, the supercharger is in a working state, and the EGR valve is in an open state; closing the EGR valve according to the condition that the actual supercharging pressure is lower than the required supercharging pressure and the difference between the actual supercharging pressure and the required supercharging pressure is greater than a preset deviation value, and determining that air leakage occurs in an air inlet pipeline according to the condition that the flow of gas in an exhaust gas recirculation pipeline is zero; and determining that air leakage occurs in the exhaust gas recirculation pipeline according to the condition that gas backflow occurs in the exhaust gas recirculation pipeline. The method for detecting air leakage of the engine exhaust gas recirculation system can determine the position of air leakage, is helpful to improve the efficiency of later maintenance, and is convenient to operate.

Description

TECHNICAL FIELD

[0001] The present application belongs to the technical field of engines, and particularly relates to a method and system for detecting air leakage of an engine exhaust gas recirculation system. BACKGROUND

[0002] The main function of the exhaust gas recirculation (EGR) system is to introduce part of the exhaust gas generated during the engine combustion process back into the cylinder for secondary utilization. This approach is one of the key measures to reduce engine exhaust pollutant emissions.

[0003] If the exhaust gas recirculation system leaks, it will cause a series of serious problems. Specifically, when the intake pipe leaks, the concentration of combustible mixture will become thin, which will make it difficult for the mixture to reach the ideal state required for vehicle starting. In this case, the engine may experience power deficiency, making it extremely difficult to start the vehicle. In addition, the thin combustible mixture is prone to generate nitrogen oxides during combustion, which not only increases the emission of pollutants and harmful gases, but also causes greater pollution to the environment. In the case of exhaust gas recirculation pipe leakage, the exhaust gas cannot be effectively guided back to the combustion chamber, which may have a negative impact on the engine combustion process. Due to the ineffective use of exhaust gas, the engine combustion efficiency will be reduced, which may lead to oil leakage problems. At the same time, due to the reduction of temperature and combustion speed in the combustion chamber, the idle speed of the engine may become unstable, and even the idle speed may rise. These problems not only affect the overall performance of the engine, but also increase fuel consumption, further affecting the economy and environmental performance of the vehicle. More seriously, the leakage of the exhaust gas recirculation pipe may cause the exhaust gas to be unable to undergo secondary combustion treatment, resulting in more and more accumulation of exhaust gas inside the engine. Once these accumulated exhaust gases are discharged to the external environment, they will cause serious pollution to the environment. Therefore, the air leakage problem of the exhaust gas recirculation system not only affects the performance and economy of the vehicle, but also has a significant negative impact on the environment. Therefore, regular inspection and maintenance of the exhaust gas recirculation system to ensure its normal operation is of great significance to maintaining vehicle performance and protecting the environment.

[0004] In an exhaust gas recirculation system, in order to ensure the normal operation of the system and accurately measure the parameters of the exhaust gas, some sensors are usually installed in the pipeline to monitor the pressure or flow of the exhaust gas. These sensors are crucial to the stability and efficiency of the system. However, due to the vibration generated by the exhaust gas recirculation pipeline during operation, these vibrations may cause damage to the sensors. To prevent this from happening, a rubber hose is usually used to connect the pipeline to absorb and buffer the impact force caused by the vibration. Although the recirculated exhaust gas has been cooled by the cooling system before being reintroduced into the cylinder, it still maintains a high temperature and pressure. This high-temperature and high-pressure environment makes the rubber hose prone to aging and cracking after long-term use. Since the rubber hose is usually installed in a relatively hidden location inside the engine compartment, it is not easy to detect the leakage in a timely manner. This makes the problem more complicated, as the leakage may cause the engine performance to decline, but the driver and maintenance personnel may not be able to detect it. The existing exhaust gas recirculation system leakage detection method can detect whether the system has a leakage problem, but it often cannot accurately locate the specific position of the leakage. This brings great inconvenience to maintenance work, as maintenance personnel cannot accurately find the problem, so they cannot target repair and replace parts.

[0005] Therefore, it is urgent to propose an engine exhaust gas recirculation system leakage detection method and a leakage detection system to solve the above problems. SUMMARY

[0006] The purpose of the present application is to at least solve the problem of being unable to accurately determine the leakage position of the EGR system. This purpose is achieved by the following technical solutions:

[0007] The first aspect of the present application proposes an engine exhaust gas recirculation system leakage detection method, the engine exhaust gas recirculation system comprising an engine, a supercharger, an intake pipeline, and an exhaust gas recirculation pipeline, the outlet end of the intake pipeline being in communication with the air inlet of the engine, the inlet end of the exhaust gas recirculation pipeline being in communication with the exhaust port of the engine, the outlet end of the exhaust gas recirculation pipeline being in communication with the intake pipeline, an EGR valve being provided on the exhaust gas recirculation pipeline, the supercharger being in communication with the intake pipeline for increasing the intake pressure, the engine exhaust gas recirculation system leakage detection method comprising the following steps:

[0008] S100: confirming whether the detection unit in the engine exhaust gas recirculation system is working normally;

[0009] S200: judging the relationship between the actual supercharging pressure of the engine and the required supercharging pressure of the engine according to the normal working of the detection unit in the engine exhaust gas recirculation system and the working condition of the engine under the preset load, making the supercharger work and the EGR valve open;

[0010] S300: closing the EGR valve according to the actual supercharging pressure being lower than the required supercharging pressure and the difference between the actual supercharging pressure and the required supercharging pressure being greater than a preset deviation value, determining that the air leakage occurs on the intake pipeline according to the flow of the gas in the exhaust gas recirculation pipeline being zero, and determining that the air leakage occurs on the exhaust gas recirculation pipeline according to the gas backflow occurring in the exhaust gas recirculation pipeline.

[0011] In the case that the engine's exhaust gas recirculation system is functioning properly, the engine is started and adjusted to a predetermined load condition. During this process, the supercharger begins to operate, significantly increasing the intake air pressure in the intake air line. At this time, the EGR valve is open, allowing the engine's exhaust gases to flow smoothly from the intake port to the exhaust port of the exhaust gas recirculation line, i.e., the gases can recirculate from the engine's exhaust port to the intake air line and then back to the engine's cylinders, achieving the purpose of exhaust gas recirculation. The engine exhaust gas recirculation system leak detection method proposed in this embodiment can accurately determine the relationship between the actual supercharging pressure of the engine and the required supercharging pressure of the engine to determine whether a leak has occurred in the engine exhaust gas recirculation system. In addition, this method can further determine the specific location of the leak, providing more accurate basis for maintenance and repair. This method not only improves the accuracy of detection, but also helps us to discover and solve potential problems in the exhaust gas recirculation system in a timely manner, ensuring the normal operation of the engine and meeting the emission standards. First, S is used to confirm whether the detection unit in the engine exhaust gas recirculation system is working properly. This step can be used to rule out the possibility that the engine exhaust gas recirculation system failure is caused by an abnormal detection unit. Only when the detection unit is working properly can it provide accurate measurement data. After confirming that the detection unit is working properly, the engine is started and adjusted to a predetermined load condition. Under the predetermined load condition, the exhaust gas recirculation system should be able to function properly. At this time, the deviation between the actual supercharging pressure and the required supercharging pressure needs to be monitored. According to system design, this deviation should be within the allowed range. If the actual supercharging pressure is lower than the required supercharging pressure, and the difference between the two exceeds the predetermined deviation, it indicates that there is a leak in the exhaust gas recirculation system. Therefore, S200 can be used to determine whether there is a leak in the exhaust gas recirculation system. Once a leak is confirmed, S300 can be used to determine the location of the leak. To determine the specific location of the leak, the EGR valve needs to be closed while keeping the supercharger and engine working properly. After the EGR valve is closed, the engine's exhaust gases can no longer recirculate through the exhaust gas recirculation line to the intake air line. Next, the flow rate of the gases in the exhaust gas recirculation line needs to be monitored. If the flow rate of the gases in the exhaust gas recirculation line is zero, i.e., no gases enter the exhaust gas recirculation line through the exhaust port of the exhaust gas recirculation line, it indicates that the intake air has leaked in the intake air line. If there is a backflow in the exhaust gas recirculation line, i.e., gases flow from the exhaust port of the exhaust gas recirculation line to the EGR valve, it indicates that there is no leak in the intake air line, and the leak occurs in the exhaust gas recirculation line.The engine exhaust gas recirculation system leakage detection method provided in the embodiment can determine the leakage position by closing the EGR valve, which can improve the maintenance efficiency and is convenient to operate. Through the method, the maintenance personnel can quickly locate the specific position of the leakage, thereby performing targeted maintenance, avoiding unnecessary disassembly and inspection, and greatly saving time and cost.

[0012] In addition, the engine exhaust gas recirculation system leakage detection method according to the application can further have the following additional technical features:

[0013] In some embodiments of the application, the detection unit is configured to include an intake pressure sensor arranged between the exhaust end of the exhaust gas recirculation pipeline and the intake port of the engine, and the intake pressure sensor is used to measure the intake pressure.

[0014] In some embodiments of the application, the S100 includes:

[0015] In the working condition that the engine is powered on but not started, the supercharger is in a shutdown state, the EGR valve is in a closed state, it is judged whether the intake pressure measured by the intake pressure sensor is equal to the atmospheric pressure, and according to the intake pressure equal to the atmospheric pressure, it is confirmed that the intake pressure sensor works normally.

[0016] In some embodiments of the application, the detection unit is configured to include a differential pressure flowmeter arranged between the exhaust end of the exhaust gas recirculation pipeline and the EGR valve, and the differential pressure flowmeter is used to measure the differential pressure in the exhaust gas recirculation pipeline.

[0017] In some embodiments of the application, the S100 includes: in the working condition that the engine is powered on but not started, the supercharger is in a shutdown state, the EGR valve is in a closed state, it is judged whether the differential pressure measured by the differential pressure flowmeter is zero, and according to the differential pressure being zero, it is confirmed that the differential pressure flowmeter works normally.

[0018] In some embodiments of the application, the S100 includes: in the working condition that the engine is started to idle, the EGR valve is in a closed state, it is judged whether the differential pressure measured by the differential pressure flowmeter is zero, and according to the differential pressure being zero, it is confirmed that the differential pressure flowmeter works normally.

[0019] In some embodiments of the present application, a hose is arranged on the exhaust gas recirculation pipeline, the differential pressure flow meter comprises an inlet section, the exhaust gas recirculation pipeline comprises a communication pipeline, one end of the hose is sleeved on the inlet section, the other end of the hose is sleeved on the communication pipeline, the inlet section and the communication pipeline are sealingly connected through the hose, and in S100, it is determined that the hose is damaged according to the gas backflow occurring in the exhaust gas recirculation pipeline.

[0020] In some embodiments of the present application, the preset load working condition is that the engine operates at 70% of the rated speed, and the load rate exceeds 30%.

[0021] In some embodiments of the present application, the preset deviation value is 15 kPa to 25 kPa.

[0022] In the present application, an engine exhaust gas recirculation system leak detection system is also provided. The engine exhaust gas recirculation system comprises an engine, a supercharger, an intake pipeline and an exhaust gas recirculation pipeline. The exhaust end of the intake pipeline is in communication with the air inlet of the engine. The intake end of the exhaust gas recirculation pipeline is in communication with the exhaust port of the engine. The exhaust end of the exhaust gas recirculation pipeline is in communication with the intake pipeline. An EGR valve is arranged on the exhaust gas recirculation pipeline. The supercharger is in communication with the intake pipeline for increasing the intake pressure. Based on the above-mentioned engine exhaust gas recirculation system leak detection method, the engine exhaust gas recirculation system leak detection system comprises:

[0023] The detection unit is arranged on the intake pipeline and the exhaust gas recirculation pipeline;

[0024] A controller is electrically connected with the engine, the supercharger, the EGR valve and the detection unit. The controller is used for controlling the operation of the engine, the supercharger, the EGR valve and the detection unit based on the detection result of the detection unit. BRIEF DESCRIPTION OF DRAWINGS

[0025] Various other advantages and benefits will become apparent to those of ordinary skill in the art upon reading the following detailed description of the preferred embodiments. The accompanying drawings are included to provide a better understanding of the preferred embodiments, and are not to be considered as limiting of the application. Moreover, in the drawings, like reference numerals refer to similar components throughout the several views. In the drawings:

[0026] Figure 1 A flow chart of the engine exhaust gas recirculation system leak detection method according to the embodiments of the present application is schematically shown;

[0027] Figure 2A working principle diagram of an engine exhaust gas recirculation system according to an embodiment of the present application is schematically shown.

[0028] Reference numerals in the drawings represent the following:

[0029] 10: hose, 100: engine, 101: intake line, 102: exhaust gas recirculation line, 102a: communication line, 103: exhaust line, 200: EGR valve, 300: intake pressure sensor, 400: differential pressure flowmeter, 500: EGR cooler, 600: air cleaner, 700: intake flowmeter, 800: supercharger, 810: air compressor, 820: turbine, 830: rotation shaft, 900: intercooler, 1000: intake throttle valve, 1100: controller. DETAILED DESCRIPTION

[0030] Example embodiments of the present disclosure will be described more fully hereinafter with reference to the accompanying drawings; however, these embodiments are not intended to limit the scope of the present disclosure, as claimed. Rather, the present disclosure is intended to cover all modifications, equivalents, and alternatives falling within the scope of the present disclosure. Like numbers refer to like elements throughout the description of the figures.

[0031] It is to be understood that the terminology used herein is for the purpose of describing particular example embodiments only and is not intended to be limiting. As used herein, the singular forms "a", "an" and "the" are intended to include the plural forms as well, unless the context clearly indicates otherwise. The terms "comprises", "comprising", "includes", "including" and "has" are inclusive and therefore specify the presence of stated features, steps, operations, elements, and / or components, but do not preclude the presence or addition of one or more other features, steps, operations, elements, components, and / or groups thereof. The method steps, processes, and operations described herein are not to be construed as necessarily requiring their performance in the particular order in which they are described, unless specifically identified as an order dependent step. It is also to be understood that additional or alternative steps can be employed.

[0032] Although the terms first, second, third, and the like can be used herein to describe various elements, components, regions, layers and / or sections, these elements, components, regions, layers and / or sections should not be limited by these terms. These terms can be only used to distinguish one element, component, region, layer or section from another region, layer or section. Terms such as "first", "second", and other numerical terms when used herein do not imply a sequence or order unless clearly indicated by the context. Thus, a first element, component, region, layer or section discussed below could be termed a second element, component, region, layer or section without departing from the teachings of the example embodiments.

[0033] For the sake of description, spatial relative terms can be used herein for the purpose of describing one element or feature's relationship to another element or feature as illustrated in the figures. Such relative terms include, for example, "internal," "external," "lateral," "medial," "under," "below," "above," "on," and the like. These spatially relative terms are intended to encompass different orientations of the device in use or operation in addition to the orientation depicted in the figures. For example, if a device is inverted, then an element described as "below" or "beneath" another element or feature would be oriented "above" or "over" the other element or feature. Thus, the example term "below" can encompass both an orientation of above and below. The devices can be otherwise oriented (rotated 90 degrees or at other orientations) and the spatially relative descriptors used herein interpreted accordingly.

[0034] Figure 1 A flow chart of a method for detecting leakage of an engine exhaust gas recirculation system according to an embodiment of the present application is schematically shown. Figure 2 A working principle diagram of an engine exhaust gas recirculation system according to an embodiment of the present application is schematically shown. As shown in Figure 1 And 2 A method for detecting leakage of an engine exhaust gas recirculation system is provided by the present application. The present embodiment takes the engine exhaust gas recirculation system shown in Figure 1 A method for detecting leakage of an engine exhaust gas recirculation system is provided by the present application. The present embodiment takes the engine exhaust gas recirculation system shown in

[0035] S100, confirming whether a detection unit in the engine exhaust gas recirculation system is working normally;

[0036] S200, according to the detection unit in the engine exhaust gas recirculation system working normally, and according to the engine 100 being in a working condition of a preset load, making the supercharger 800 in a working state, and making the EGR valve 200 in an open state, judging the relationship between an actual supercharging pressure of the engine 100 and a required supercharging pressure of the engine 100;

[0037] S300, according to the actual supercharging pressure is lower than the required supercharging pressure and the difference between the actual supercharging pressure and the required supercharging pressure is greater than the preset deviation value, closing the EGR valve 200, according to the flow of gas in the exhaust gas recirculation pipeline 102 is zero, it is determined that the air leakage occurs in the intake pipeline 101; according to the gas backflow in the exhaust gas recirculation pipeline 102, it is determined that the air leakage occurs in the exhaust gas recirculation pipeline 102.

[0038] In the case that the exhaust gas recirculation system of the engine 100 can operate normally, start the engine 100 and adjust it to a preset load condition. In this process, the supercharger 800 starts to work, so that the intake pressure in the intake pipeline 101 is significantly improved. At this time, the ERG valve is in the open state, and the exhaust gas discharged by the engine 100 can smoothly flow from the intake port to the exhaust port of the exhaust gas recirculation pipeline 102, that is, the gas can flow back from the exhaust port of the engine 100 to the intake pipeline 101, and then back to the cylinder of the engine 100, so as to achieve the purpose of exhaust gas recirculation. The air leakage detection method of the engine exhaust gas recirculation system proposed in this embodiment can accurately determine the relationship between the actual supercharging pressure of the engine 100 and the required supercharging pressure of the engine 100 to determine whether air leakage occurs in the engine exhaust gas recirculation system. In addition, through this method, we can further determine the specific location of air leakage, so as to provide more accurate basis for maintenance and repair. This method not only improves the accuracy of detection, but also helps us to discover and solve the potential problems in the exhaust gas recirculation system in time, to ensure the normal operation of the engine 100 and the satisfaction of emission standards.

[0039] Firstly, it is necessary to confirm whether the detection unit in the engine exhaust gas recirculation system can work normally through S100. This step can be used to exclude the possibility that the engine exhaust gas recirculation system failure is caused by abnormal detection unit. Only when it is ensured that the detection unit can work normally, can the detection unit provide accurate measurement data.

[0040] After confirming that the detection unit is working normally, start the engine 100 and adjust it to a preset load condition. Under the preset load condition, the exhaust gas recirculation system should be able to operate normally. At this time, attention should be paid to the deviation value between the actual supercharging pressure and the required supercharging pressure. According to the system design, this deviation value should be within the allowable range. If the actual supercharging pressure is lower than the required supercharging pressure, and the difference between them exceeds the preset deviation value, it indicates that there is air leakage in the exhaust gas recirculation system. Therefore, it can be judged through S200 whether there is air leakage in the exhaust gas recirculation system. Once it is confirmed that there is air leakage, the location of air leakage can be further determined through S300.

[0041] In order to determine the specific location of the air leakage, the EGR valve 200 needs to be closed, but at the same time, the supercharger 800 and the engine 100 need to be kept normal. After the EGR valve 200 is closed, the gas discharged by the engine 100 can no longer flow back into the intake pipe 101 through the exhaust gas recirculation pipe 102. Next, the flow rate of the gas in the exhaust gas recirculation pipe 102 needs to be monitored. If the flow rate of the gas in the exhaust gas recirculation pipe 102 is zero, that is, the gas does not enter the exhaust gas recirculation pipe 102 through the gas outlet end of the exhaust gas recirculation pipe 102, it indicates that the intake air has leaked in the intake pipe 101. If the exhaust gas recirculation pipe 102 has backflow, that is, the gas flows from the gas outlet end of the exhaust gas recirculation pipe 102 to the direction of the EGR valve 200, it indicates that there is no air leakage in the intake pipe 101, and the air leakage occurs in the exhaust gas recirculation pipe 102.

[0042] The air leakage detection method of the engine exhaust gas recirculation system provided in the embodiment can determine the location of the air leakage by closing the EGR valve 200. This method not only helps to improve the efficiency of the later maintenance, but also is very convenient to operate. Through this method, the maintenance personnel can quickly locate the specific location of the air leakage, so as to carry out targeted maintenance, avoid unnecessary disassembly and inspection, and greatly save time and cost.

[0043] Further, the controller 1100 is used to control the operation of the engine 100, the supercharger 800, the EGR valve 200 and the detection unit. The controller 1100 is used to receive signals from each device and process these signals, generate control instructions according to the received signals and preset control rules, and control each device. The connection between the controller 1100 and each device and the control mode of the controller 1100 to each device are mature technical means, and will not be described in detail here.

[0044] Further, the exhaust port of the engine 100 is communicated with an exhaust pipe 103. The gas inlet end of the exhaust gas recirculation pipe 102 is communicated with the exhaust pipe 103. When the engine 100 is in a preset load working condition and the exhaust gas recirculation system is normally operated, the EGR valve 200 will be opened. At this time, part of the gas discharged by the engine 100 will flow back into the engine 100 through the exhaust gas recirculation pipe 102, so as to reduce the emission and improve the combustion efficiency. And the other part of the gas will continue to be discharged to the external environment through the exhaust pipe 103. Such a design not only helps to reduce the emission of harmful gases, but also improves the overall performance and fuel efficiency of the engine.

[0045] Optionally, the supercharger 800 is a turbocharger. A turbocharger is an air compression device whose main function is to increase the intake pressure of the engine 100, thereby increasing the power and efficiency of the engine 100. The turbocharger 800 includes two main parts: an air compressor 810 and a turbine 820, which are connected by a shaft 830 to ensure their coordinated work. The air compressor 810 is arranged on the intake pipe 101 and is located upstream of the exhaust gas recirculation pipe 102, ensuring that the air compressor 810 can effectively suck in external air and compress it. The turbine 820 is arranged on the exhaust pipe 103 and is located downstream of the intake end of the exhaust gas recirculation pipe 102. The function of the turbine 820 is to use the heat and pressure in the exhaust gas emitted by the engine 100 to drive the rotation of the turbine blades. When the engine 100 is running, the exhaust gas will be discharged through the exhaust pipe 103 and enter the turbine 820. The turbine 820 uses the energy of these exhaust gases to make the turbine blades rotate at high speed. The turbine 820 is connected to the air compressor 810 through the shaft 830, so when the turbine 820 rotates, the shaft 830 will also rotate, thereby driving the air compressor 810 to rotate. The air compressor 810 inhales external air during rotation and compresses it through the compressor mechanism, thereby significantly increasing the intake pressure. This design not only improves the intake efficiency of the engine 100, but also optimizes the combustion process, so that the engine 100 can output higher power with lower fuel consumption. The high-efficiency working mode of the turbocharger significantly improves the overall performance of the engine 100, and also provides better power performance and fuel economy for the vehicle.

[0046] Optionally, an air filter 600 is arranged upstream of the air compressor 810 to filter the air entering the engine 100, preventing dust, particulate matter and other impurities from entering the engine 100, thereby protecting the engine 100 from wear and damage. An air flow meter 700 is arranged between the air filter 600 and the air compressor 810, which is used to measure the intake amount of the engine 100, and the intake amount information is converted into an electrical signal input to the ECU (Electronic Control Unit) through the connection of the circuit, so that the ECU determines the fuel injection amount and ignition time.

[0047] Optionally, a intercooler 900 is arranged between the air compressor 810 and the outlet end of the exhaust gas recirculation pipeline 102, which is used to reduce the temperature of the pressurized high-temperature gas, so as to reduce the thermal load of the engine 100, improve the intake efficiency, thereby increasing the power of the engine 100, and preventing engine 100 from being damaged by knocking, etc. An intake throttle valve 1000 is arranged between the intercooler 900 and the outlet end of the exhaust gas recirculation pipeline 102, which is used to control the intake speed of the engine 100, thereby realizing the control of the movement speed of the engine 100.

[0048] Further, an EGR cooler 500 is arranged on the exhaust gas recirculation pipeline 102, and the EGR cooler 500 is arranged between the differential pressure flowmeter 400 and the EGR valve 200. The EGR cooler 500 is a high-efficiency water-cooled heat exchanger, and its main function is to further reduce the temperature of the exhaust gas participating in recirculation. In this way, the EGR cooler 500 can effectively reduce the highest combustion peak temperature that may occur during the combustion process, thereby improving the overall performance and fuel efficiency of the engine.

[0049] Further, the detection unit is configured to include an intake pressure sensor 300 arranged between the outlet end of the exhaust gas recirculation pipeline 102 and the intake port of the engine 100, and the intake pressure sensor 300 is used to measure the intake pressure, so as to ensure that the engine 100 can work normally and maintain a stable operating state, and at the same time improve the performance and fuel efficiency of the engine 100. The detection unit is configured to include a differential pressure flowmeter 400 arranged between the outlet end of the exhaust gas recirculation pipeline 102 and the EGR valve 200, and the differential pressure flowmeter 400 is used to measure the pressure difference in the exhaust gas recirculation pipeline 102. The differential pressure flowmeter 400 can measure whether the gas backflow occurs in the exhaust gas recirculation pipeline 102, that is, according to the negative value of the differential pressure flowmeter 400, it can be determined that the gas backflow occurs in the exhaust gas recirculation pipeline 102. By ensuring that the detection unit can provide correct measurement data, it can be excluded that the engine exhaust gas recirculation system failure is caused by abnormal detection unit.

[0050] Further, S100 includes: when the engine 100 is powered on but not started, the supercharger 800 is in a shutdown state, the EGR valve 200 is in a closed state, and it is judged whether the intake pressure measured by the intake pressure sensor 300 is equal to the atmospheric pressure. According to the intake pressure equal to the atmospheric pressure, it is confirmed that the intake pressure sensor 300 works normally. Understandably, when the engine 100 is powered on but not started, the pressure in the system is basically the same as the atmospheric pressure of the external environment, and the pressure value measured by the intake pressure sensor 300 is the standard atmospheric pressure, which indicates that the intake pressure sensor 300 is normal.

[0051] Further, S100 comprises: in the working condition that the engine 100 is powered on but not started, the supercharger 800 is in the stop state, the EGR valve 200 is in the closed state, and it is judged whether the differential pressure measured by the differential pressure flowmeter 400 is zero. According to the zero differential pressure, it is confirmed that the differential pressure flowmeter 400 is normal. Understandably, when the engine 100 is powered on but not started, the pressure in the exhaust gas recirculation pipeline 102 is basically the same as the atmospheric pressure of the external environment, and the differential pressure measured by the differential pressure flowmeter 400 is zero, which indicates that the differential pressure flowmeter 400 is normal.

[0052] Further, S100 comprises: in the working condition that the engine 100 is started to idle, the EGR valve 200 is in the closed state, and it is determined that the differential pressure measured by the differential pressure flowmeter 400 is zero. In the idle working condition, the engine 100 runs without external load, the intake air amount is low, and the combustion condition is poor. At this time, the EGR valve 200 is usually in the closed state. In the idle working condition, the intake air pressure measured by the intake air pressure sensor 300 is slightly higher than the atmospheric pressure, but the differential pressure is small, and the differential pressure measured by the differential pressure flowmeter 400 is still zero. By changing the working condition, it is verified again whether the intake air pressure sensor 300 and the differential pressure flowmeter 400 are normal.

[0053] Further, the exhaust gas recirculation pipeline 102 is provided with a rubber tube 10, the differential pressure flowmeter 400 comprises an inlet section, the exhaust gas recirculation pipeline 102 comprises a communication pipeline 102a, one end of the rubber tube 10 is sleeved on the inlet section, the other end of the rubber tube 10 is sleeved on the communication pipeline 102a, and the inlet section and the communication pipeline 102a are sealingly connected through the rubber tube 10. In S300, according to the gas backflow occurring in the exhaust gas recirculation pipeline 102, it is determined that the rubber tube 10 is damaged. Understandably, according to the reading of the differential pressure flowmeter 400, it can be judged whether the gas backflow occurs in the exhaust gas recirculation pipeline 102. When the reading of the differential pressure flowmeter 400 is negative, it can be determined that the gas backflow occurs in the exhaust gas recirculation pipeline 102. The main material of the rubber tube 10 is synthetic rubber, which has good damping effect. By connecting the differential pressure flowmeter 400 and the pipeline through the rubber tube 10, the damage of the differential pressure flowmeter 400 caused by the vibration of the engine 100 can be reduced. In addition, the rubber tube 10 also has good wear resistance, corrosion resistance and high temperature resistance. However, although the rubber tube 10 has high temperature resistance, and the gas entering the exhaust gas recirculation pipeline 102 is cooled by the EGR cooler 500, the cooled exhaust gas still has high temperature and pressure. After a long time of work, the rubber tube 10 is still inevitably prone to damage. Other parts of the exhaust gas recirculation pipeline 102 usually use cast fixing parts. Therefore, when the exhaust gas recirculation pipeline 102 leaks, it can be basically determined that the gas leakage occurs in the rubber tube 10.

[0054] In some embodiments, the differential pressure flow meter 400 is a venturi flow meter. The venturi flow meter has significant advantages in the field of fluid measurement. Its structural features make it possible to avoid the problems of sharp edge abrasion and fouling similar to orifice throttling devices during use, and at the same time, it can effectively adjust (straighten) the velocity distribution gradient and various non-axisymmetric velocity distributions that may exist in the fluid in the pre-throttling pipe, thereby achieving high precision and high stability of flow measurement. This feature makes the venturi flow meter widely used in the exhaust gas recirculation system.

[0055] Further, the EGR valve 200 controls the amount of recirculated exhaust gas according to the operating conditions to reduce emission pollution. When the engine 100 is at idle speed, low speed and small load, or cold state operation, or when the engine 100 needs high power performance in full load state, the EGR valve 200 does not work. When the engine 100 enters the warm-up stage and the speed exceeds the idle speed, the EGR valve 200 starts to work. In the working condition from the start of the engine 100 to the preset load, the EGR valve 200 is in working condition, but in order to detect the location of the air leakage, the operation of actively closing the EGR valve 200 is needed. Alternatively, the working condition of the preset load is that the engine 100 operates at 70% of the rated speed, and the load rate exceeds 30%. This means that the engine 100 is in a medium speed operating state and a medium load working state. In this case, the supercharger 800 starts to work, so that the intake air pressure is significantly improved. At the same time, the EGR valve 200 is also opened, so that a part of the exhaust gas flows into the intake air pipeline 101 through the exhaust gas recirculation pipeline 102. In other embodiments, the speed of the engine 100 can be 65%, 75% or 80% of the rated speed, and the load rate can be 35%, 40% or 45%, etc., which is selected according to the performance of the engine 100, which can ensure that the supercharger 800 operates and the EGR valve 200 is opened.

[0056] Further, the preset deviation value is 15-25 kPa. The consistency of the required boost pressure and the actual boost pressure of the engine 100 is a key factor to ensure the normal operation and performance of the engine 100. During the operation of the engine 100, if the actual boost pressure can accurately meet the required boost pressure of the engine 100, it means that the supercharging system of the engine 100 is working normally and can provide sufficient pressure to support the efficient operation of the engine 100. In actual operation, the actual boost pressure can be obtained by the intake air pressure measured by the intake air pressure sensor 300 and the opening degree of the intake air throttle valve 1000, and then the actual boost pressure and the required boost pressure are compared. If the actual boost pressure deviates from the required boost pressure by more than a certain limit, it means that there is air leakage in the system. For example, the preset deviation value can be 15 kPa, 20 kPa or 25 kPa, etc., which is determined according to the performance of the engine 100 and the actual working condition. The calculation of the actual boost pressure by the intake air pressure and the opening degree of the intake air throttle valve 1000 is a conventional technical means in the art, which will not be described in detail here.

[0057] Referring to Figure 2 The present application also provides an air leakage detection system for an engine exhaust gas recirculation system. The engine exhaust gas recirculation system comprises an engine 100, a supercharger 800, an intake air pipeline 101 and an exhaust gas recirculation pipeline 102. The outlet of the intake air pipeline 101 is connected to the air inlet of the engine 100, the inlet of the exhaust gas recirculation pipeline 102 is connected to the exhaust outlet of the engine 100, the outlet of the exhaust gas recirculation pipeline 102 is connected to the intake air pipeline 101, and the exhaust gas recirculation pipeline 102 is provided with an EGR valve 200. The supercharger 800 is connected to the intake air pipeline 101 to increase the intake air pressure. Based on the above-mentioned air leakage detection method for the engine exhaust gas recirculation system, the air leakage detection system for the engine exhaust gas recirculation system comprises a detection unit and a controller 1100. The intake air pipeline 101 and the exhaust gas recirculation pipeline 102 are both provided with the detection unit; the engine 100, the supercharger 800, the EGR valve 200 and the detection unit are electrically connected to the controller 1100, and the controller 1100 is used to control the operation of the engine 100, the supercharger 800, the EGR valve 200 and the detection unit based on the detection results of the detection unit. The connection between the controller 1100 and each device and the control mode of the controller 1100 to each device are mature technical means in the art, which will not be described in detail here.

[0058] The above is only a preferred specific embodiment of the present application, but the protection scope of the present application is not limited thereto. Any changes or replacements within the technical scope disclosed by the present application can be easily thought of by those skilled in the art, which should be covered within the protection scope of the present application. Therefore, the protection scope of the present application should be subject to the protection scope of the claims.

Claims

1. A blow-by gas detection method for an engine exhaust gas recirculation system, the engine exhaust gas recirculation system comprising an engine (100), a supercharger (800), an intake pipe (101), and an exhaust gas recirculation pipe (102), an outlet end of the intake pipe (101) being in communication with an air intake port of the engine (100), an inlet end of the exhaust gas recirculation pipe (102) being in communication with an exhaust port of the engine (100), an outlet end of the exhaust gas recirculation pipe (102) being in communication with the intake pipe (101), the exhaust gas recirculation pipe (102) being provided with an EGR valve (200), the supercharger (800) being in communication with the intake pipe (101) for increasing intake air pressure, characterized in that, The method for detecting leakage of the engine EGR system comprises the following steps: S100: confirming whether the detection unit in the engine EGR system is working normally; S200: according to the working of the detection unit in the engine EGR system and the engine (100) being in a preset load condition, the supercharger (800) is in a working state, the EGR valve (200) is in an open state, and the relationship between the actual supercharging pressure of the engine (100) and the required supercharging pressure of the engine (100) is determined; S300: according to the actual supercharging pressure being lower than the required supercharging pressure and the difference between the actual supercharging pressure and the required supercharging pressure being greater than a preset deviation value, the EGR valve (200) is closed, the gas flow in the EGR pipeline (102) is zero, it is determined that leakage occurs in the intake pipeline (101), and gas backflow occurs in the EGR pipeline (102), it is determined that leakage occurs in the EGR pipeline (102).

2. The method of claim 1, wherein, The detection unit is configured to comprise an intake pressure sensor (300) arranged between the gas outlet end of the EGR pipeline (102) and the air inlet of the engine (100), and the intake pressure sensor (300) is used to measure the intake pressure.

3. The method of claim 2, wherein, The S100 comprises: In the condition that the engine (100) is powered on but not started, the supercharger (800) is in a shutdown state, the EGR valve (200) is in a closed state, it is determined whether the intake pressure measured by the intake pressure sensor (300) is equal to the atmospheric pressure, and according to the intake pressure being equal to the atmospheric pressure, it is confirmed that the intake pressure sensor (300) is working normally.

4. The method of claim 1, wherein, The detection unit is configured to comprise a differential pressure flowmeter (400) arranged between the gas outlet end of the EGR pipeline (102) and the EGR valve (200), and the differential pressure flowmeter (400) is used to measure the pressure difference in the EGR pipeline (102).

5. The method of claim 4, wherein, The S100 comprises: in the condition that the engine (100) is powered on but not started, the supercharger (800) is in a shutdown state, the EGR valve (200) is in a closed state, it is determined whether the pressure difference measured by the differential pressure flowmeter (400) is zero, and according to the pressure difference being zero, it is confirmed that the differential pressure flowmeter (400) is working normally.

6. The method of claim 4, wherein, The S100 comprises: in the condition that the engine (100) is started to idle, the EGR valve (200) is in a closed state, it is determined whether the pressure difference measured by the differential pressure flowmeter (400) is zero, and according to the pressure difference being zero, it is confirmed that the differential pressure flowmeter (400) is working normally.

7. The method of claim 4, wherein, The waste gas recirculation pipeline (102) is provided with a hose (10), the differential pressure flowmeter (400) comprises an inlet section, the waste gas recirculation pipeline (102) comprises a communication pipeline (102a), one end of the hose (10) is sleeved on the inlet section, the other end of the hose (10) is sleeved on the communication pipeline (102a), and the inlet section and the communication pipeline (102a) are sealingly connected through the hose (10). In S300, it is determined that the hose (10) is damaged according to the gas backflow occurring in the waste gas recirculation pipeline (102).

8. The method of claim 1, wherein, The preset load working condition is that the engine (100) operates at 70% of the rated speed and the load rate exceeds 30%.

9. The method of claim 1, wherein, The preset deviation value is 15kPa-25kPa.

10. An engine exhaust gas recirculation system blow-by detection system, the engine exhaust gas recirculation system comprising an engine (100), a supercharger (800), an intake pipe (101) and an exhaust gas recirculation pipe (102), an outlet end of the intake pipe (101) and an air intake port of the engine (100) being in communication, an inlet end of the exhaust gas recirculation pipe (102) and an exhaust port of the engine (100) being in communication, an outlet end of the exhaust gas recirculation pipe (102) and the intake pipe (101) being in communication, the exhaust gas recirculation pipe (102) being provided with an EGR valve (200), the supercharger (800) and the intake pipe (101) being in communication for increasing intake air pressure, characterized in that, The engine waste gas recirculation system leakage detection method according to any one of claims 1-9, wherein the engine waste gas recirculation system leakage detection system comprises: The detection unit is arranged on the intake pipeline (101) and the waste gas recirculation pipeline (102); A controller (1100) is electrically connected with the engine (100), the supercharger (800), the EGR valve (200) and the detection unit, and is used for controlling the operation of the engine (100), the supercharger (800), the EGR valve (200) and the detection unit based on the detection result of the detection unit.

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