Vehicle low-pressure EGR system and condensate water prevention control method

Abstract

The present invention relates to the technical field of vehicle power system control, and in particular to a vehicle low-pressure EGR system and a condensate water prevention control method. The present invention provides a vehicle low-pressure EGR system. By reasonably configuring an EGR cooler, an EGR valve, and a cooling liquid pipe to work in conjunction with each other, the air inflow of low-temperature waste gas and fresh air in a combustion chamber of an engine can be efficiently controlled, thereby increasing a compression ratio of the engine, and reducing fuel consumption of a vehicle.

Description

Vehicle low-pressure EGR system and anti-condensate control method

[0001] Cross-reference to related applications

[0002] The embodiments of the present application are based on and claim priority from Chinese Patent Application No. 202410472085.7 filed on April 19, 2024, the entire contents of which are incorporated herein by reference. TECHNICAL FIELD

[0003] The present application relates to the technical field of vehicle exhaust gas recirculation system control, in particular to a vehicle low-pressure EGR system and an anti-condensate control method. BACKGROUND

[0004] The supercharging technology of internal combustion engines can effectively improve the power density of internal combustion engines, improve the performance and fuel economy of internal combustion engines, and has been widely used in vehicle internal combustion engines in recent years, becoming an important means of internal combustion engine strengthening. At present, most diesel engines and high-performance gasoline engines have adopted supercharging technology. However, with the continuous strengthening of supercharged engines, the load and combustion pressure continue to increase, which will lead to the intensification of engine knock and early combustion tendency, and also lead to the deterioration of NOx emission.

[0005] In order to meet the increasingly stringent emission and fuel economy regulations while continuously improving the performance of the engine, the exhaust gas recirculation (EGR) technology has been increasingly concerned and has gradually become one of the important means to reduce NOx emission, improve thermal efficiency and control combustion process.

[0006] The exhaust gas recirculation system (EGR system for short) is to return part of the exhaust gas in the exhaust pipe to the intake manifold of the engine, and to introduce it into the engine combustion chamber together with fresh air to reduce the in-cylinder combustion temperature and exhaust temperature, increase the compression ratio, and reduce fuel consumption. In order to further reduce fuel consumption, the engine will use a low-pressure EGR system, and the low-pressure EGR system has higher requirements for the reliability design of the engine. The condensate problem caused by the low-pressure EGR technology is a major factor affecting the application of this technology and the reliability of the engine.

[0007] The existing vehicle low-pressure EGR system, in high humidity and low temperature weather, the exhaust gas discharged by the engine has a high temperature, the exhaust gas is combined with fresh air after filtration, and then passes through the intercooler and the throttle valve into the intake manifold. The gas cooled by the intercooler is prone to condensate in a low temperature environment, and the condensate accumulates at the low point, which will cause the condensate to flow into the engine intake port during vehicle acceleration, resulting in engine misfire. SUMMARY

[0008] The technical problems solved by the present application are: in view of the deficiencies of the prior art, a vehicle low-pressure EGR system and a condensate water prevention control method are provided, which can improve the engine compression ratio, reduce the fuel consumption of the vehicle, and effectively prevent condensate water from entering the cylinder to cause engine misfire, and ensure the driving experience of the vehicle.

[0009] To solve the above technical problems, the technical scheme adopted by the present application is:

[0010] One, a vehicle low-pressure EGR system

[0011] The present application provides a vehicle low-pressure EGR system, mainly comprising: an engine exhaust pipe, an exhaust gas cooling circuit and an air filter pipe; one end of the engine exhaust pipe is connected to the air outlet end of the engine 1, and the other end is connected to the exhaust gas cooling circuit, the exhaust gas cooling circuit is provided with an EGR cooler 7 and an EGR valve 8 in sequence, the air outlet end of the EGR valve 8 is connected to the air filter pipe through a mixing valve 9, and is connected to the air inlet end of the engine 1 together;

[0012] The EGR valve 8, the mixing valve 9 and the engine 1 are electrically connected with the low-pressure EGR system controller.

[0013] Two, a vehicle low-pressure EGR system condensate water prevention control method

[0014] Based on the same inventive concept, the present application also provides a condensate water prevention control method for the above-mentioned low-pressure EGR system, which specifically comprises the following steps:

[0015] S1, according to the engine speed, torque, and ambient temperature and EGR cooler air outlet temperature, the condensate water accumulation is calculated and obtained;

[0016] S2, according to the experimental measurement of condensate water consumption data table, the condensate water consumption under the action of atmospheric flow and manifold negative pressure is obtained;

[0017] S3, according to the difference between the condensate water accumulation and the condensate water consumption, the EGR rate limiting control is executed.

[0018] Compared with the prior art, the present application has the following main advantages:

[0019] 1. The present application provides a vehicle low-pressure EGR system, which can efficiently control the intake amount of low-temperature exhaust gas and fresh air in the engine combustion chamber by reasonably setting the EGR cooler, the EGR valve and the cooling liquid pipeline, thereby improving the engine compression ratio and reducing the fuel consumption of the vehicle;

[0020] 2、The application provides a kind of vehicle low pressure EGR system anti-condensate control method, by obtaining ambient temperature, intake manifold temperature, EGR cooler temperature, simultaneously according to engine operating time and the speed and torque of engine etc., can accurately judge the accumulation degree of condensate, to effectively limit low pressure EGR rate;

[0021] 3、The application is combined by main condensate accumulation calculation method, condensate consumption calculation method and EGR rate limit control method, can effectively prevent condensate from entering cylinder and causing engine misfire, ensure vehicle driving experience. BRIEF DESCRIPTION OF DRAWINGS

[0022] Figure 1 is a kind of vehicle low pressure EGR system overall schematic diagram in the embodiment of the application;

[0023] Figure 2 is the flow chart of the anti-condensate control method in the embodiment of the application.

[0024] In the figure: 1-engine;2-turbine;3-compressor;4-air filter;5-catalyst;6-gasoline particulate trap;7-EGR cooler;8-EGR valve;9-mixing valve;10-throttle;11-temperature sensor;12-pressure difference sensor. Embodiment of the application

[0025] In order to make the purpose, technical scheme and advantages of the application clearer and more apparent, the application will be further described in detail below with reference to the drawings and examples. It should be understood that the specific examples described herein are only used to explain the application and not to limit the application. In addition, the technical features involved in each embodiment of the application described below can be combined with each other as long as they do not conflict with each other.

[0026] It should be noted that according to the needs of implementation, each step / component described in this application can be split into more steps / components, or two or more steps / components or part of the operation of the steps / components can be combined into a new step / component to achieve the purpose of the application.

[0027] In the present application, unless otherwise explicitly specified and limited, the terms "first", "second" are only used for descriptive purposes, and cannot be understood as indicating or implying relative importance or implicitly indicating the number of indicated technical features. Therefore, the features limited by "first", "second" can include at least one of the features explicitly or implicitly. In the description of the application, the meaning of "a plurality of" is at least two, for example, two, three, etc., unless otherwise explicitly specified and limited.

[0028] Embodiment one, the embodiment provides a kind of vehicle low pressure EGR system, as shown in Figure 1, mainly includes: engine exhaust pipe, exhaust cooling loop and air filter pipe;The engine exhaust pipe one end is connected with the air outlet end of engine 1, the other end is connected to exhaust cooling loop, the exhaust cooling loop is equipped with EGR cooler 7 and EGR valve 8 in sequence, the air outlet end of the EGR valve 8 is connected with the air filter pipe by mixing valve 9, and is connected to the air inlet end of the engine 1 in common;

[0029] The EGR valve 8, mixing valve 9 and engine 1 are electrically connected with the low pressure EGR system controller.

[0030] Further, the engine exhaust pipe is sequentially provided with turbine 2, catalytic converter 5 and gasoline particulate trap 6, and the exhaust gas discharged by engine 1 flows through the engine exhaust pipe and then enters the exhaust cooling loop.

[0031] Further, the air outlet end of the EGR cooler 7 is provided with a temperature sensor 11, and a differential pressure sensor 12 is connected between the two ends of the EGR valve 8, and the temperature sensor 11 and the differential pressure sensor 12 are electrically connected with the low pressure EGR system controller.

[0032] Further, the air filter pipe is provided with an air filter 4, and the filtered air is mixed with the cooled exhaust gas through the mixing valve 9 and then enters the air inlet end of the engine.

[0033] Further, the air inlet end pipe of the engine is provided with a compressor 3 and a throttle valve 10 for controlling the amount of mixed gas entering the engine.

[0034] Further, the EGR cooler and the EGR valve are arranged on the exhaust cooling loop, and the exhaust gas passes through the cooling liquid in the EGR cooler to reduce the temperature to a preset temperature value after passing through the GPF (gasoline particulate trap);

[0035] The low pressure EGR system controller adjusts the opening degree of the EGR valve to control the amount of exhaust gas introduced into the combustion chamber of the engine cylinder, and when the EGR valve is closed, the exhaust gas cooled by the EGR cooler cannot be introduced into the engine combustion chamber; Fresh air passes through the air filter, and the opening degree of the mixing valve is controlled to control the amount of fresh air entering.

[0036] Embodiment two, based on the same inventive concept, the embodiment also provides a kind of low pressure EGR system anti-condensation control method as described above, as shown in Figure 2, including the following control strategies:

[0037] S1, according to engine speed, torque, and ambient temperature and EGR cooler outlet temperature, calculate the condensation accumulation amount;

[0038] S2, obtaining the condensate consumption under the atmospheric flow and the manifold negative pressure according to the experimental measured condensate consumption data table;

[0039] S3, performing the EGR rate limitation control according to the difference between the condensate accumulation and the condensate consumption.

[0040] Further, the condensate accumulation is obtained by the following formula:

[0041] m acc =∑f1(N Eng ， R Eng )·f(T EGRCoolTemp -T AmbentTemp )

[0042] wherein, m acc is the condensate accumulation, T EGRCoolTemp is the EGR cooler outlet temperature, T AmbentTemp is the ambient temperature, N Eng is the engine speed, R Eng is the engine torque load, f1(N Eng ， R Eng ) is the condensate basic accumulation obtained by the table lookup, and f1(T EGRCoolTemp -T AmbentTemp ) is the accumulation coefficient obtained according to the difference between the EGR cooler outlet temperature and the ambient temperature.

[0043] Further, the condensate consumption is obtained by the following formula:

[0044] m consum =∑f2(N Eng ， M Eng )·f (T EGRCoolTemp -T AmbentTemp )

[0045] wherein, m consum is the condensate consumption, T EGRCoolTemp is the EGR cooler outlet temperature, T AmbentTemp is the ambient temperature, N Eng is the engine speed, R Eng is the engine torque load, f2(N Eng ， R Eng ) is the condensate consumption obtained by the table lookup.

[0046] Further, the performing the EGR rate limitation control comprises:

[0047] When the difference between the condensate accumulation and the condensate consumption is less than a preset threshold, the EGR system is allowed to be turned on, otherwise the EGR system is not allowed to be turned on.

[0048] Meanwhile, the EGR rate is adjusted in real time according to the value of m acc -m consum .

[0049] In embodiment three, a condensate control method for a low-pressure EGR system of a vehicle is provided. The low-pressure EGR system of the vehicle produces accumulated condensate under low temperature and high humidity. Under normal conditions, the condensate is consumed by atmospheric flow or negative pressure of the manifold.

[0050] The general opening condition of the EGR is that the ambient temperature is higher than a preset value one (-7℃) and the engine water temperature is greater than a preset value two (60℃). Even if the above conditions are met, there is still a risk of condensate accumulation.

[0051] In this embodiment, the ambient temperature, intake manifold temperature and EGR cooler temperature are obtained, and the degree of condensate is determined according to the engine operating time, engine speed and torque, so as to limit the low-pressure EGR rate. Specifically as follows:

[0052] 1) The condensate accumulation is calculated according to the engine speed, torque, ambient temperature and temperature after the EGR cooler.

[0053] m acc =∑f1(N Eng ， R Eng )·f(T EGRCoolTemp -T AmbentTemp ) ①

[0054] Wherein, m acc is the condensate accumulation, T EGRCoolTemp is the temperature after the EGR cooler, T AmbentTemp is the ambient temperature, N Eng is the engine speed, R Eng is the engine load, f1(N Eng ， R Eng ) is the condensate accumulation obtained by table lookup, and f1(T EGRCoolTemp -T AmbentTemp ) is the accumulation coefficient obtained according to the difference between the temperature after the EGR cooler and the ambient temperature.

[0055] 2) Since the accumulated water is consumed under the action of atmospheric flow or manifold negative pressure, the condensate consumption calculation formula is as follows in the consumption area of high speed and high torque or low speed and low torque:

[0056] mconsum =∑f2(N Eng ， M Eng )·f (T EGRCoolTemp -T AmbentTemp ) ②

[0057] Wherein, m consum is the condensate consumption, T EGRCoolTemp is the temperature after EGR cooler, T AmbentTemp is the ambient temperature, N Eng is the engine speed, R Eng is the engine load, f2(N Eng ， R Eng ) is the condensate consumption obtained by looking up table.

[0058] 3) According to the difference between m acc -m consum , one of the conditions for starting EGR is judged, if m acc -m consum is less than a certain value, EGR is allowed to start, and the limit value r EGRLim of EGR rate is shown in formula ③, otherwise EGR is not allowed to start.

[0059] r EGRLim= f （ T Manifold ） ③

[0060] Example four, based on the same inventive concept, the embodiment also provides a vehicle with manual and automatic combination, the vehicle is provided with the low pressure EGR system as described above.

[0061] Further, the part not described in detail in the application is the same as the prior art or realized by the prior art.

[0062] Summarized above:

[0063] 1、 the vehicle low pressure EGR system is proposed, the EGR cooler, the EGR valve and the cooling liquid pipeline are reasonably arranged, the intake amount of low-temperature exhaust gas and fresh air in the engine combustion chamber can be efficiently controlled, and then the engine compression ratio is improved, and the fuel consumption of the vehicle is reduced;

[0064] 2、 the vehicle low pressure EGR system anti-condensate control method is proposed, the ambient temperature, the intake manifold temperature and the EGR cooler temperature are obtained, and according to the engine running time, the engine speed and the torque and other conditions, the accumulation degree of condensate can be accurately judged, so that the low pressure EGR rate is effectively limited;

[0065] 3、The application can effectively prevent condensed water from entering the cylinder to cause engine misfire and ensure vehicle driving experience by combining the main condensed water accumulation calculation method, the condensed water consumption calculation method and the EGR rate limit control method.

[0066] Those skilled in the art will appreciate that embodiments of the application can be supplied as methods, systems, or computer program products. Accordingly, the application can be embodied in the form of an entirely hardware embodiment, an entirely software embodiment, or an embodiment combining software and hardware aspects. Furthermore, the application can be embodied in the form of a computer program product on one or more computer readable storage media (including, but not limited to, disk memory, CD-ROMs, optical storage media, etc.) having computer usable program code embodied thereon.

[0067] The present application is described with reference to the flowchart and / or block diagram illustrations of the methods, apparatus (systems), and computer program products according to embodiments of the application. It will be understood that each block of the flowchart and / or block diagrams, and combinations of blocks in the flowchart and / or block diagrams, can be implemented by computer program instructions. These computer program instructions can be provided to a processor of a general purpose computer, special purpose computer, embedded processor, or other programmable data processing apparatus to produce a machine, such that the instructions, which execute via the processor of the computer or other programmable data processing apparatus, create means for implementing the functions specified in the flowchart and / or block diagram block or blocks.

[0068] These computer program instructions can also be stored in a computer readable memory that can direct a computer or other programmable data processing apparatus to function in a particular manner, such that the instructions stored in the computer readable memory produce an article of manufacture including instructions which implement the function specified in the flowchart and / or block diagram block or blocks.

[0069] These computer program instructions can also be loaded onto a computer or other programmable data processing apparatus to cause a series of operational steps to be performed on the computer or other programmable apparatus to produce a computer implemented process such that the instructions which execute on the computer or other programmable apparatus provide steps for implementing the functions specified in the flowchart and / or block diagram block or blocks.

[0070] Those skilled in the art will readily appreciate that the above described embodiments of the application are merely intended to be illustrative and not limiting of the application. Any modification, equivalent substitution and improvement, etc. made within the spirit and principle of the application should be included in the protection scope of the application.

Claims

1. A low pressure EGR system for a vehicle, comprising an engine exhaust pipe, an exhaust cooling loop and an air filter pipe; one end of the engine exhaust pipe is connected to an exhaust end of an engine, and the other end is connected to the exhaust cooling loop, the exhaust cooling loop is provided with an EGR cooler and an EGR valve in sequence, an exhaust end of the EGR valve is connected to the air filter pipe through a mixing valve, and the exhaust end of the air filter pipe is connected to an air intake end of the engine; the EGR valve, the mixing valve and the engine are electrically connected to a low pressure EGR system controller.

2. A vehicle low pressure EGR system according to claim 1 wherein, A turbine (2), a catalytic converter (5) and a gasoline particulate filter (6) are provided in sequence on the engine exhaust pipe, and exhaust gas discharged from the engine (1) flows through the engine exhaust pipe and then enters the exhaust cooling loop.

3. The vehicle low pressure EGR system of claim 1, wherein, A temperature sensor (11) is provided at an exhaust end of the EGR cooler (7), and a differential pressure sensor (12) is connected between two ends of the EGR valve (8), and the temperature sensor (11) and the differential pressure sensor (12) are electrically connected to the low pressure EGR system controller.

4. The vehicle low pressure EGR system of claim 1, wherein, An air filter (4) is provided on the air filter pipe, filtered air is mixed with cooled exhaust gas through the mixing valve (9) and then enters the air intake end of the engine.

5. A vehicle low pressure EGR system as claimed in claim 4 wherein, A compressor (3) and a throttle valve (10) are provided on the air intake end pipe of the engine, for controlling the amount of mixed gas entering the engine.

6. A control method for preventing condensate water based on the low pressure EGR system according to any one of claims 1 to 5, applied to an electronic device of a vehicle, comprising: calculating a condensate water accumulation amount according to engine speed, torque, and ambient temperature and EGR cooler exhaust end temperature; obtaining condensate water consumption under the action of atmospheric flow and manifold negative pressure according to an experimentally measured condensate water consumption data table; performing EGR rate limiting control according to the difference between the condensate water accumulation amount and the condensate water consumption.

7. The anti-condensation control method according to claim 6, wherein The condensate water accumulation amount is obtained by the following formula: m acc =∑f1(N Eng ， R Eng )·f(T EGRCoolTemp -T AmbentTemp ) wherein m acc is the condensed water accumulation, T EGRCoolTemp is the EGR cooler outlet temperature, T AmbentTemp is the ambient temperature, N Eng is the engine speed, R Eng is the engine torque load, f1(N Eng ， R Eng ) is the condensed water base accumulation obtained from a table, f1(T EGRCoolTemp -T AmbentTemp is the accumulation coefficient obtained from the difference between the EGR cooler outlet temperature and the ambient temperature.

8. The anti-condensation control method according to claim 7, wherein The condensate water consumption is obtained by the following formula: m consum =∑f2(N Eng ， M Eng )·f (T EGRCoolTemp -T AmbentTemp ) where m consum is the condenser water consumption, T EGRCoolTemp is the EGR cooler outlet temperature, T AmbentTemp is the ambient temperature, N Eng is the engine speed, R Eng is the engine torque load, f2(N Eng ， R Eng is the condenser water consumption from a look-up table.

9. The anti-condensation control method according to claim 8, wherein The EGR rate limiting control comprises: when the difference between the condensate water accumulation amount and the condensate water consumption is less than a preset threshold, the EGR system is allowed to be turned on, otherwise the EGR system is not allowed to be turned on. The EGR rate is adjusted in real time according to the value of m acc -m consum at the time.

10. A vehicle with a manual and automatic transmission, comprising the low pressure EGR system according to any one of claims 1 to 5.

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