Exhaust gas recirculation system and control method

Abstract

The present application discloses an exhaust gas recirculation system and control method, which relates to the field of exhaust gas recirculation technology. The system comprises: a main flow path, which includes a supercharger, an intercooler, an engine, and an exhaust turbine in sequence along the direction of airflow; the exhaust gas recirculation system further comprises: an exhaust branch path, which includes the engine's exhaust manifold, an EGR cooler, an EGR valve, a one-way control valve, and the engine's intake manifold in sequence along the direction of airflow; all components of the exhaust gas circulation branch path are arranged closely to the circumference of the engine. The control method comprises the following steps: when the engine requires the exhaust branch path to be opened, the on-board ECU sends an opening signal instruction to the EGR valve, and the EGR valve opens according to the opening signal instruction; the main flow path and the exhaust branch path operate simultaneously, and fresh air and exhaust gas are evenly mixed and then enter the engine cylinder. In the exhaust gas recirculation system and control method of the present application, the EGR valve has a low operating temperature, can effectively prevent backflow, and has a compact structure and occupies little space.

Description

Technical Field

[0001] The present application relates to the field of exhaust gas recirculation technology, and in particular to an exhaust gas recirculation system and a control method. Background Art

[0002] Exhaust Gas Recirculation (EGR) is becoming increasingly common. Specifically, an EGR valve controls a certain amount of exhaust gas through a pipeline, where it is reintroduced into the combustion chamber, mixed with fresh air passing through the intercooler, and then fed into the cylinders for combustion. This effectively reduces NOx and CO2 emissions and is an effective measure for meeting emission standards. However, the increasing demand for exhaust gas standards, the need for after-treatment systems to reduce engine exhaust emissions, and the aging of diesel engines have necessitated an increase in EGR rates.

[0003] In the related art, an exhaust gas recirculation system such as Figure 1 As shown, it includes a Venturi tube a, an EGR valve b, an EGR line c, a mechanical linkage mechanism d, an engine e, an EGR cooler f, and an exhaust manifold g. The combined variable-section Venturi tube a with integrated inner cone adjustment and a mechanical linkage mechanism improves mixing efficiency and can increase the EGR rate. Although this technical solution can increase the EGR rate, it has the following disadvantages:

[0004] 1) EGR valve b is located at the outlet of exhaust manifold 6. Its high operating temperature leads to poor reliability. EGR valve b components are made of high-temperature resistant materials, which is costly. Engine exhaust gas, containing carbon particles, water vapor, sulfides, or chloride ions, passes through the EGR valve b. The accumulation of corrosive substances or carbon particles can easily cause EGR valve b to become stuck or leak, resulting in product failure.

[0005] 2) When the pressure inside the Venturi tube a is greater than the pressure at the outlet of the EGR line c, air will flow back from the Venturi tube a into the EGR line c, affecting the EGR rate and engine performance.

[0006] 3) The combined variable-section Venturi tube a is equipped with a set of mechanical linkage mechanisms d, which has a complex structure, high cost, and is prone to failure, affecting engine performance and having poor reliability. Summary of the Invention

[0007] In response to the defects in the prior art, the purpose of this application is to provide an exhaust gas recirculation system and control method, in which the EGR valve has a low operating temperature, can effectively prevent backflow, has a compact structure and occupies little space.

[0008] To achieve the above objectives, the technical solution adopted is: an exhaust gas recirculation system, which includes a main flow path, and the main flow path includes a supercharger, an intercooler, an engine and an exhaust gas turbine in the direction of air flow; the exhaust gas recirculation system also includes:

[0009] The exhaust gas branch includes the engine's exhaust manifold, EGR cooler, EGR valve, one-way control valve and engine's intake manifold in sequence along the airflow direction; all components of the exhaust gas circulation branch are closely arranged on the circumference of the engine.

[0010] On the basis of the above technical solution, the intercooler and the intake manifold of the engine are connected through the intercooler rear intake pipe, and one end of the exhaust branch is connected to the intercooler rear intake pipe through the EGR mixing device.

[0011] On the basis of the above technical solution, the one-way control valve and the EGR mixing device are connected through the EGR outlet pipe. The EGR mixing device has a sealed tube structure, which is integrated in the outlet end of the EGR outlet pipe and installed in the air intake pipe after the intercooler. The EGR mixing device includes an end pipe structure with several mixing groove-shaped air ports, and the end pipe structure is connected to the EGR outlet pipe.

[0012] On the basis of the above technical solution, the exhaust gas recirculation system further includes a pulse conversion device, the pulse conversion device includes an olive-shaped cavity, and the one-way control valve is arranged inside the pulse conversion device.

[0013] On the basis of the above technical solution, a layer of corrosion-resistant sleeve is provided inside the EGR valve.

[0014] Based on the above technical solution, the engine body of the engine is rectangular, the intake manifold is arranged at a corner of the engine body, the exhaust manifold is arranged at a side end face of the engine, and the entire exhaust gas circulation branch is arranged along the side end face of the engine body.

[0015] The present application discloses a control method based on the above-mentioned exhaust gas recirculation system, wherein the EGR valve is in a normally closed state and is connected to an on-board ECU via a signal line. The control method comprises the following steps:

[0016] When the engine needs to open the exhaust branch, the on-board ECU sends an opening signal command to the EGR valve, and the EGR valve opens according to the opening signal command; the main path and the exhaust branch work at the same time, and the exhaust gas enters the intake manifold through the exhaust manifold, EGR cooler, EGR valve and one-way control valve; at the same time, fresh air enters the intake manifold through the supercharger and intercooler, and the fresh air and exhaust gas are evenly mixed and then enter the engine cylinder.

[0017] On the basis of the above technical solution, the intercooler and the intake manifold of the engine are connected through the intercooler rear intake pipe, and one end of the exhaust branch is connected to the intercooler rear intake pipe through the EGR mixing device;

[0018] The fresh air and exhaust gas are uniformly mixed and then enter the cylinder of the engine, comprising:

[0019] Fresh air and exhaust gas are evenly mixed in the EGR mixing device and enter the intake manifold through the intercooler rear intake pipe.

[0020] On the basis of the above technical solution, the one-way control valve and the EGR mixing device are connected through the EGR outlet pipe. The EGR mixing device has a sealed tube structure, which is integrated in the outlet end of the EGR outlet pipe and installed in the air intake pipe after the intercooler. The EGR mixing device includes an end pipe structure with several mixing groove-shaped air ports, and the end pipe structure is connected to the EGR outlet pipe.

[0021] On the basis of the above technical solution, the exhaust gas recirculation system further comprises a pulse conversion device, the pulse conversion device comprises an olive-shaped cavity, and the one-way control valve is arranged inside the pulse conversion device;

[0022] The exhaust gas enters the intake manifold through the exhaust manifold, the EGR cooler, the EGR valve and the one-way control valve, comprising:

[0023] The exhaust gas passes through the one-way control valve after being stabilized by the pulse conversion device.

[0024] The beneficial effects of the technical solution provided by this application include:

[0025] 1. In the exhaust gas recirculation system and control method of the present application, the EGR valve is arranged at the rear end of the EGR cooler in the exhaust gas branch, that is, the EGR valve works at the cold end and the operating temperature of the EGR valve is low. Compared with the existing technical solution in which the EGR valve works at the hot end, it can greatly reduce material costs and has high reliability.

[0026] A one-way control valve is set in the exhaust branch, which can prevent fresh air from flowing back into the exhaust branch and effectively prevent the occurrence of backflow. At the same time, the present application specifically controls the structural size of the EGR cooler, EGR valve and one-way control valve, so that all components of the exhaust gas circulation branch are neatly and tightly arranged in the circumference of the engine without excessively widening the length and width of the engine body. The structure is compact and occupies little space.

[0027] Furthermore, the one-way control valve is arranged at the rear end of the EGR valve. When EGR is required, the EGR valve opens, and the exhaust gas passes through the EGR valve and the one-way control valve in sequence and enters the engine cylinder; when the EGR valve is closed, no exhaust gas passes through and the one-way control valve does not work. The normally closed EGR valve protects the one-way control valve in disguise, thereby increasing the service life of the one-way control valve. The system structure is simple and the reliability is high.

[0028] 2. In the exhaust gas recirculation system and control method of the present application, the EGR mixing device is integrated in the outlet end of the EGR outlet pipe and installed in the intake pipe after the intercooler; the EGR mixing device is provided with an end pipe structure with a plurality of mixing groove-shaped air ports evenly distributed in the circumferential direction. The plurality of mixing groove-shaped air ports can realize uniform mixing of exhaust gas and fresh air, which enters the cylinder of the engine to participate in combustion, can improve the mixing uniformity by more than double, and improve the engine performance.

[0029] 3. In the exhaust gas recirculation system of the present application, the pulse conversion device is used to reduce the air pressure and flow fluctuations so that the airflow tends to a constant pressure and constant flow. The one-way control valve is arranged in the pulse conversion device, which can improve the reliability of the one-way control valve, effectively increase the EGR rate, and thus improve the engine performance.

[0030] 4. In the exhaust gas recirculation system of this application, the EGR valve passage is equipped with a corrosion-resistant sleeve made of stainless steel. Specifically, the EGR valve is made of aluminum alloy. This sleeve solves high-temperature sticking, corrosion, and carbon deposit issues, improving the reliability of the EGR valve and system, reducing the material's temperature resistance requirements, and reducing cost. BRIEF DESCRIPTION OF THE DRAWINGS

[0031] In order to more clearly illustrate the technical solutions in the embodiments of the present application, the following briefly introduces the drawings required for use in the description of the embodiments. Obviously, the drawings described below are only some embodiments of the present application. For ordinary technicians in this field, other drawings can be obtained based on these drawings without any creative work.

[0032] Figure 1 This is a schematic diagram of the exhaust gas recirculation principle of the prior art;

[0033] Figure 2 This is the exhaust gas recirculation principle diagram of this application;

[0034] Figure 3 This is a structural diagram of the exhaust gas recirculation system of this application;

[0035] Figure 4 This is a schematic structural diagram of the pulse conversion device, one-way control valve and one-way control valve seat of the present application;

[0036] Figure 5This is a schematic diagram of the anti-corrosion sleeve structure of the EGR valve of this application;

[0037] Figure 6 This is a structural diagram of the EGR mixing device of this application;

[0038] Figure numerals: 1. Exhaust manifold; 2. EGR intake pipe; 3. EGR cooler; 4. EGR valve; 5. Pulse conversion device; 6. One-way control valve; 8. EGR outlet pipe; 9. EGR mixing device; 12. Intake manifold; 13. Anti-corrosion sleeve; 15. Mixing groove-shaped air port; 16. Engine; 17. Exhaust turbine; 21. Supercharger; 22. Intercooler; 23. Intake pipe after intercooler. DETAILED DESCRIPTION

[0039] In order to make the purpose, technical solutions and advantages of this application more clearly understood, the present invention is further described in detail below with reference to the accompanying drawings and examples. It should be understood that the specific embodiments described herein are only intended to illustrate the present invention and are not intended to limit the present invention. In addition, the technical features involved in the various embodiments of the present invention described below may be combined with each other as long as they do not conflict with each other.

[0040] like Figures 2 to 6 As shown, the present application discloses an embodiment of an exhaust gas recirculation system, which includes a main flow path and an exhaust gas branch path. The main flow path includes a supercharger 21, an intercooler 22, an engine 16, and an exhaust turbine 17. The airflow direction is the supercharger 21, the intercooler 22, the intake manifold 12 of the engine 16, the engine cylinders, the exhaust manifold 1 of the engine 16, and the exhaust turbine 17. The supercharger 21 and the exhaust turbine 17 are linked by a shaft and rotate synchronously. Specifically, the main flow path is a classic engine structure.

[0041] The exhaust gas recirculation system also includes an exhaust branch circuit, which includes the exhaust manifold 1 of engine 16, the EGR cooler 3, the EGR valve 4, the one-way control valve 6, and the intake manifold 12 of engine 16. Airflow flows in this order: exhaust manifold 1, EGR cooler 3, EGR valve 4, one-way control valve 6, and intake manifold 12. The exhaust branch circuit reintroduces exhaust gas from exhaust manifold 1 into the engine cylinders, where it mixes with fresh air from the main circuit and is then delivered for combustion. All components of the exhaust branch circuit are positioned in close proximity to the circumference of engine 16.

[0042] In the exhaust gas branch of the exhaust gas recirculation system of the present application, the EGR valve 4 is arranged at the rear end of the EGR cooler 3, that is, the EGR valve 4 works at the cold end, and the operating temperature of the EGR valve 4 is low. Compared with the existing technical solution in which the EGR valve 4 works at the hot end, the material cost can be greatly reduced and the reliability is high.

[0043] A one-way control valve 6 is provided in the exhaust branch, which can prevent fresh air from flowing back into the exhaust branch and effectively prevent the occurrence of backflow. At the same time, the present application specifically controls the structural size of the EGR cooler 3, the EGR valve 4 and the one-way control valve 6, so that all components of the exhaust gas circulation branch are neatly and tightly arranged in the circumference of the engine 16 without excessively widening the length and width of the engine body. The structure is compact and occupies little space.

[0044] Furthermore, the one-way control valve 6 is arranged at the rear end of the EGR valve 4. When EGR is required, the EGR valve 4 opens, and the exhaust gas passes through the EGR valve 4 and the one-way control valve 6 in sequence and enters the engine cylinder; when the EGR valve 4 is closed, no exhaust gas passes through, and the one-way control valve 6 does not work. The normally closed EGR valve 4 protects the one-way control valve 6 in disguise, thereby increasing the service life of the one-way control valve 6. The system structure is simple and the reliability is high.

[0045] Specifically, the exhaust manifold 1 is communicated with the EGR cooler 3 through the EGR intake pipe 2 .

[0046] like Figure 2 As shown, in one embodiment, the exhaust gas recirculation system further includes an exhaust gas branch, which includes the exhaust manifold 1 of the engine 16, the EGR cooler 3, the EGR valve 4, the one-way control valve 6, and the intake manifold 12 of the engine 16. The airflow direction is exhaust manifold 1, EGR cooler 3, EGR valve 4, one-way control valve 6, and intake manifold 12. Based on the above technical solution, the intercooler 22 and the intake manifold 12 of the engine 16 are connected by an intercooler post-intake pipe 23. One end of the exhaust gas branch is connected to the intercooler post-intake pipe 23 through the EGR mixing device 9. Specifically, the exhaust gas and fresh air are fully mixed in the EGR mixing device 9 before entering the intake manifold 12.

[0047] Specifically, the diameter of the EGR mixing device 9 is larger than the diameter of the EGR outlet pipe 8, and the EGR outlet pipe 8 is inserted into the EGR mixing device 9. The EGR mixing device 9 can achieve uniform mixing of exhaust gas and fresh air, thereby improving engine performance.

[0048] Furthermore, on the basis of the above technical solution, the one-way control valve 6 and the EGR mixing device 9 are connected through the EGR outlet pipe 8. The EGR mixing device 9 is a sealed pipe structure. The EGR mixing device 9 is integrated at the outlet end of the EGR outlet pipe 8 (see FIG. Figure 6 ), the EGR mixing device 9 is installed in the air intake pipe 23 after the intercooler, that is, the fresh air passes through the EGR mixing device 9 when flowing through.

[0049] The EGR mixing device 9 includes an end pipe structure with several mixing slot-shaped air ports 15, which are connected to the EGR outlet pipe 8. Specifically, the end pipe structure is perpendicular to the axis of the intercooler rear intake pipe 23. Exhaust gas flows into the EGR mixing device 9 through the mixing slot-shaped air ports 15, and fresh air flows through the EGR mixing device 9, thoroughly mixing the exhaust gas and fresh air.

[0050] In the exhaust gas recirculation system of the present application, the EGR mixing device 9 is integrated at the outlet end of the EGR outlet pipe 8 and installed in the intercooler rear intake pipe 23; the EGR mixing device 9 is provided with an end pipe structure with a plurality of mixing groove-shaped air ports 15 uniformly distributed in the circumferential direction. The plurality of mixing groove-shaped air ports 15 can realize uniform mixing of exhaust gas and fresh air, which enters the cylinder of the engine to participate in combustion, can improve the mixing uniformity by more than double, and improve the engine performance.

[0051] like Figure 4 As shown, in one embodiment, the exhaust gas recirculation system further includes a pulse conversion device 5 , the pulse conversion device 5 includes an olive-shaped cavity, and the one-way control valve 6 is disposed in the olive-shaped cavity of the pulse conversion device 5 .

[0052] In the exhaust gas recirculation system of the present application, the pulse conversion device 5 is used to reduce the air pressure and flow fluctuations so that the airflow tends to a constant pressure and constant flow. The one-way control valve 6 is arranged in the pulse conversion device 5, which can improve the reliability of the one-way control valve 6 and effectively improve the EGR rate.

[0053] Preferably, the one-way control valve 6 is a diaphragm valve, which is sensitive and can work normally without a large pressure difference.

[0054] The exhaust gas recirculation system of the present application, through the one-way control valve 6 and the pulse conversion device 5, ensures that exhaust gas can flow stably into the intercooler rear intake pipe 23. After being mixed by the EGR mixing device 9, it flows into the engine intake manifold. The one-way control valve 6 prevents backflow and can effectively increase the EGR rate, thereby improving engine performance.

[0055] like Figure 5 As shown, in one embodiment, an anti-corrosion sleeve 13 is disposed within the EGR valve 4. In the exhaust gas recirculation system of this application, the EGR valve 4 passageway is provided with an anti-corrosion sleeve 13 made of stainless steel. Specifically, the EGR valve 4 is made of aluminum alloy. This anti-corrosion sleeve 13 solves high-temperature sticking, corrosion, and carbon deposit issues, improving the reliability of the EGR valve and system while reducing material temperature resistance requirements and achieving low cost.

[0056] like Figure 3As shown, in one embodiment, the engine body of the engine 16 is rectangular, the intake manifold 12 is arranged at a corner of the engine body, the exhaust manifold 1 is arranged at a side end surface of the engine, and the entire exhaust branch is arranged along the side end surface of the engine body.

[0057] Specifically, the EGR cooler 3, EGR valve 4, one-way control valve 6 and EGR outlet pipe 8 of the exhaust branch are arranged on a long side end face and a short side end face, neatly expanding the length and width of the engine body, that is, the expansion dimension of the engine body in the length direction is basically equal to the expansion dimension in the width direction.

[0058] This application also discloses a control method for the above-mentioned exhaust gas recirculation system, wherein EGR valve 4 is normally closed and is opened only when the exhaust gas branch needs to be opened. EGR valve 4 is connected to an onboard ECU via a signal line, and the onboard ECU can control the opening or closing of EGR valve 4 and its opening degree can be controlled between 0% and 100%.

[0059] The control method includes the following steps:

[0060] When the engine 16 requires the exhaust branch to open, this can be done manually or when set conditions are met. When the exhaust branch is opened, the onboard ECU sends an opening signal to the EGR valve 4, which then opens to the set opening according to the opening signal. The main flow and exhaust branch operate simultaneously, with exhaust gas entering the intake manifold 12 through the exhaust manifold 1, EGR cooler 3, EGR valve 4, and one-way control valve 6. Simultaneously, fresh air enters the intake manifold 12 through the supercharger 21 and intercooler 22. Fresh air and exhaust gas are evenly mixed in the intake manifold 12 before entering the engine cylinders.

[0061] When the engine 16 does not require the exhaust branch to be opened, the EGR valve 4 remains normally closed.

[0062] In the control method of the present application, the EGR valve 4 is arranged at the rear end of the EGR cooler 3 in the exhaust branch of the exhaust gas recirculation system, that is, the EGR valve 4 works at the cold end, and the operating temperature of the EGR valve 4 is low. Compared with the existing technical solution in which the EGR valve 4 works at the hot end, the material cost can be greatly reduced and the reliability is high.

[0063] A one-way control valve 6 is provided in the exhaust branch, which can prevent fresh air from flowing back into the exhaust branch and effectively prevent the occurrence of backflow. At the same time, the present application specifically controls the structural size of the EGR cooler 3, the EGR valve 4 and the one-way control valve 6, so that all components of the exhaust gas circulation branch are neatly and tightly arranged in the circumference of the engine 16 without excessively widening the length and width of the engine body. The structure is compact and occupies little space.

[0064] At the same time, the one-way control valve 6 is arranged at the rear end of the EGR valve 4. When EGR is required, the EGR valve 4 opens, and the exhaust gas passes through the EGR valve 4 and the one-way control valve 6 in sequence and enters the engine cylinder; when the EGR valve 4 is closed, no exhaust gas passes through, and the one-way control valve 6 does not work. The normally closed EGR valve 4 protects the one-way control valve 6 in disguise, thereby increasing the service life of the one-way control valve 6. The system structure is simple and the reliability is high.

[0065] Regarding control methods, such as Figure 2 As shown, in one embodiment, the intercooler 22 and the intake manifold 12 of the engine 16 are connected via an intercooler rear intake pipe 23, and one end of the exhaust branch is connected to the intercooler rear intake pipe 23 via an EGR mixing device 9. Specifically, the exhaust gas and fresh air are fully mixed in the EGR mixing device 9 before entering the intake manifold 12.

[0066] Specifically, the diameter of the EGR mixing device 9 is larger than the diameter of the EGR outlet pipe 8, and the EGR outlet pipe 8 is inserted into the EGR mixing device 9. The EGR mixing device 9 can achieve uniform mixing of exhaust gas and fresh air, thereby improving engine performance.

[0067] Among them, fresh air and exhaust gas are evenly mixed and then enter the cylinder of the engine, including:

[0068] Fresh air and exhaust gas are evenly mixed in the EGR mixing device 9 and enter the intake manifold 12 through the intercooler rear intake pipe 23, so that the fresh air and exhaust gas are mixed more evenly.

[0069] Regarding the control method, further, the one-way control valve 6 and the EGR mixing device 9 are connected through the EGR outlet pipe 8, the EGR mixing device 9 is a sealed pipe structure, and the EGR mixing device 9 is integrated at the outlet end of the EGR outlet pipe 8 (see Figure 6 ), the EGR mixing device 9 is installed in the air intake pipe 23 after the intercooler, that is, the fresh air passes through the EGR mixing device 9 when it flows through. Specifically, Figure 6 (a) is a schematic diagram of the EGR outlet pipe 8 and the EGR mixing device 9. Figure 6 (b) is a schematic diagram of an end pipe structure having a plurality of mixing groove-shaped gas ports 15 .

[0070] The EGR mixing device 9 includes an end pipe structure with several mixing slot-shaped air ports 15, which are connected to the EGR outlet pipe 8. Specifically, the end pipe structure is perpendicular to the axis of the intercooler rear intake pipe 23. Exhaust gas flows into the EGR mixing device 9 through the mixing slot-shaped air ports 15, and fresh air flows through the EGR mixing device 9, thoroughly mixing the exhaust gas and fresh air.

[0071] In the control method of the present application, the EGR mixing device 9 is integrated at the outlet end of the EGR outlet pipe 8 and installed in the intercooler rear intake pipe 23; the EGR mixing device 9 is provided with an end pipe structure with a plurality of mixing groove-shaped air ports 15 uniformly distributed in the circumferential direction. The plurality of mixing groove-shaped air ports 15 can realize uniform mixing of exhaust gas and fresh air, which enters the cylinder of the engine to participate in combustion, can improve the mixing uniformity by more than double, and improve the engine performance.

[0072] Regarding control methods, such as Figure 4 As shown, in one embodiment, the exhaust gas recirculation system further includes a pulse conversion device 5 , the pulse conversion device 5 includes an olive-shaped cavity, and the one-way control valve 6 is disposed in the olive-shaped cavity of the pulse conversion device 5 .

[0073] In the control method of the present application, the pulse conversion device 5 is used to reduce the air pressure and flow fluctuations so that the airflow tends to a constant pressure and constant flow. The one-way control valve 6 is arranged in the pulse conversion device 5, which can improve the reliability of the one-way control valve 6 and effectively improve the EGR rate.

[0074] Preferably, the one-way control valve 6 is a diaphragm valve, which is sensitive and can work normally without a large pressure difference.

[0075] The exhaust gas enters the intake manifold 12 through the exhaust manifold 1, the EGR cooler 3, the EGR valve 4 and the one-way control valve 6, including:

[0076] The exhaust gas passes through the one-way control valve 6 after being stabilized in pressure and flow by the pulse conversion device 5.

[0077] The control method of the present application, through the one-way control valve 6 and the pulse conversion device 5, ensures that exhaust gas can flow stably into the intercooler rear intake pipe 23. After being mixed by the EGR mixing device 9, it flows into the engine intake manifold. The one-way control valve 6 prevents backflow and can effectively increase the EGR rate, thereby improving engine performance.

[0078] Regarding control methods, such as Figure 5 As shown, in one embodiment, an anti-corrosion sleeve 13 is disposed within the EGR valve 4. In the control method of this application, the EGR valve 4 passageway is provided with an anti-corrosion sleeve 13 made of stainless steel. Specifically, the EGR valve 4 is made of aluminum alloy. This anti-corrosion sleeve 13 solves high-temperature sticking, corrosion, and carbon deposit issues, improving the reliability of the EGR valve and system while reducing material temperature resistance requirements and achieving low cost.

[0079] Regarding control methods, such as Figure 3As shown, in one embodiment, the engine body of the engine 16 is rectangular, the intake manifold 12 is arranged at a corner of the engine body, the exhaust manifold 1 is arranged at a side end surface of the engine, and the entire exhaust branch is arranged along the side end surface of the engine body.

[0080] Specifically, the EGR cooler 3, EGR valve 4, one-way control valve 6 and EGR outlet pipe 8 of the exhaust branch are arranged on a long side end face and a short side end face, neatly expanding the length and width of the engine body, that is, the expansion dimension of the engine body in the length direction is basically equal to the expansion dimension in the width direction.

[0081] In the exhaust gas recirculation system and control method of the present application, in the exhaust gas branch, the EGR valve 4 is arranged at the rear end of the EGR cooler 3, that is, the EGR valve 4 works at the cold end, and the operating temperature of the EGR valve 4 is low. Compared with the existing technical solution in which the EGR valve 4 works at the hot end, the material cost can be greatly reduced and the reliability is high.

[0082] A one-way control valve 6 is provided in the exhaust branch, which can prevent fresh air from flowing back into the exhaust branch and effectively prevent the occurrence of backflow. At the same time, the present application specifically controls the structural size of the EGR cooler 3, the EGR valve 4 and the one-way control valve 6, so that all components of the exhaust gas circulation branch are neatly and tightly arranged in the circumference of the engine 16 without excessively widening the length and width of the engine body. The structure is compact and occupies little space.

[0083] Furthermore, the one-way control valve 6 is arranged at the rear end of the EGR valve 4. When EGR is required, the EGR valve 4 opens, and the exhaust gas passes through the EGR valve 4 and the one-way control valve 6 in sequence and enters the engine cylinder; when the EGR valve 4 is closed, no exhaust gas passes through, and the one-way control valve 6 does not work. The normally closed EGR valve 4 protects the one-way control valve 6 in disguise, thereby increasing the service life of the one-way control valve 6. The system structure is simple and the reliability is high.

[0084] In the exhaust gas recirculation system and control method of the present application, the EGR mixing device 9 is integrated in the outlet end of the EGR outlet pipe 8 and installed in the intercooler rear intake pipe 23; the EGR mixing device 9 is provided with an end pipe structure with a plurality of mixing groove-shaped air ports 15 uniformly distributed in the circumferential direction. The plurality of mixing groove-shaped air ports 15 can realize uniform mixing of exhaust gas and fresh air, which enters the cylinder of the engine to participate in combustion, can improve the mixing uniformity by more than double, and improve the engine performance.

[0085] In the exhaust gas recirculation system of the present application, the pulse conversion device 5 is used to reduce the air pressure and flow fluctuations so that the airflow tends to a constant pressure and constant flow. The one-way control valve 6 is arranged in the pulse conversion device 5, which can improve the reliability of the one-way control valve 6, effectively increase the EGR rate, and thus improve the engine performance.

[0086] In the exhaust gas recirculation system of this application, the EGR valve 4 is equipped with a corrosion-resistant sleeve 13 made of stainless steel. Specifically, the EGR valve 4 is made of aluminum alloy. This sleeve 13 solves the problems of high-temperature sticking, corrosion, and carbon deposits, improving the reliability of the EGR valve and system, reducing the material's temperature resistance requirements, and reducing cost.

[0087] In the description of this application, it should be noted that the terms "upper" and "lower" and the like indicate orientations or positional relationships based on the orientations or positional relationships shown in the accompanying drawings, and are only for the convenience of describing this application and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore cannot be understood as a limitation on this application. Unless otherwise clearly specified and limited, the terms "installed", "connected", and "connected" should be understood in a broad sense, for example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be a direct connection, or an indirect connection through an intermediate medium, or it can be internal communication between two elements. For those of ordinary skill in the art, the specific meanings of the above terms in this application can be understood according to the specific circumstances.

[0088] It should be noted that, in this application, relational terms such as "first" and "second" are used only to distinguish one entity or operation from another entity or operation, and do not necessarily require or imply any actual relationship or order between these entities or operations. Moreover, the terms "include", "comprise" or any other variants thereof are intended to cover non-exclusive inclusion, so that a process, method, article or device comprising a series of elements includes not only those elements, but also other elements not explicitly listed, or also includes elements inherent to such process, method, article or device. In the absence of further restrictions, an element defined by the sentence "comprising a ..." does not exclude the presence of other identical elements in the process, method, article or device comprising the element.

[0089] The foregoing is merely a list of specific embodiments of the present application, intended to enable those skilled in the art to understand and implement the present application. Various modifications to these embodiments will be readily apparent to those skilled in the art, and the general principles defined herein may be implemented in other embodiments without departing from the spirit or scope of the present application. Therefore, the present application is not limited to the embodiments shown herein, but is intended to conform to the broadest scope consistent with the principles and novel features of the present application.

Claims

1. An exhaust gas recirculation system comprising a main flow path, wherein the main flow path sequentially comprises a supercharger (21), an intercooler (22), an engine (16) and an exhaust gas turbine (17) along the air flow direction; characterized in that: The exhaust gas recirculation system further comprises: An exhaust gas branch, which includes an exhaust manifold (1) of an engine (16), an EGR cooler (3), an EGR valve (4), a one-way control valve (6), and an intake manifold (12) of the engine (16) in sequence along the airflow direction; all components of the exhaust gas circulation branch are closely arranged in the circumference of the engine (16); The exhaust gas recirculation system further comprises a pulse conversion device (5), the pulse conversion device (5) comprises an olive-shaped cavity, and the one-way control valve (6) is arranged inside the pulse conversion device (5); the one-way control valve (6) is a diaphragm valve; The engine body of the engine (16) is rectangular, the intake manifold (12) is arranged at a corner of the engine body, the exhaust manifold (1) is arranged at a side end face of the engine, and the entire exhaust gas circulation branch is arranged along the side end face of the engine body; the EGR cooler (3), the EGR valve (4) and the one-way control valve (6) control the size of the structure and are neatly and closely arranged in the circumference of the engine (16).

2. The exhaust gas recirculation system according to claim 1, characterized in that: The intercooler (22) and the intake manifold (12) of the engine (16) are connected via an intercooler rear intake pipe (23), and one end of the exhaust branch is connected to the intercooler rear intake pipe (23) via an EGR mixing device (9).

3. The exhaust gas recirculation system according to claim 2, characterized in that: The one-way control valve (6) and the EGR mixing device (9) are connected via the EGR outlet pipe (8). The EGR mixing device (9) is a sealed tube structure, which is integrated at the outlet end of the EGR outlet pipe (8) and installed in the intercooler rear intake pipe (23). The EGR mixing device (9) includes an end pipe structure having a plurality of mixing groove-shaped air ports (15), and the end pipe structure is connected to the EGR outlet pipe (8).

4. An exhaust gas recirculation system according to any one of claims 1 to 3, characterized in that: A layer of corrosion-resistant sleeve (13) is provided inside the EGR valve (4).

5. A control method for the exhaust gas recirculation system according to claim 1, characterized in that: The EGR valve (4) is in a normally closed state, and the EGR valve (4) is connected to the vehicle-mounted ECU via a signal line. The control method comprises the following steps: When the engine (16) requires opening the exhaust branch, the vehicle ECU sends an opening signal instruction to the EGR valve (4), and the EGR valve (4) opens according to the opening signal instruction; the main flow and the exhaust branch work simultaneously, and the exhaust gas enters the intake manifold (12) through the exhaust manifold (1), the EGR cooler (3), the EGR valve (4) and the one-way control valve (6); at the same time, fresh air enters the intake manifold (12) through the supercharger (21) and the intercooler (22), and the fresh air and the exhaust gas are evenly mixed and then enter the cylinder of the engine.

6. The control method according to claim 5, wherein: The intercooler (22) and the intake manifold (12) of the engine (16) are connected via an intercooler rear intake pipe (23), and one end of the exhaust branch is connected to the intercooler rear intake pipe (23) via an EGR mixing device (9); The fresh air and exhaust gas are uniformly mixed and then enter the cylinder of the engine, comprising: Fresh air and exhaust gas are uniformly mixed in the EGR mixing device (9) and enter the intake manifold (12) through the intercooler rear intake pipe (23).

7. The control method according to claim 6, wherein: The one-way control valve (6) and the EGR mixing device (9) are connected via the EGR outlet pipe (8). The EGR mixing device (9) is a sealed tube structure, which is integrated at the outlet end of the EGR outlet pipe (8) and installed in the intercooler rear intake pipe (23). The EGR mixing device (9) includes an end pipe structure having a plurality of mixing groove-shaped air ports (15), and the end pipe structure is connected to the EGR outlet pipe (8).

8. The control method according to claim 5, wherein: The exhaust gas enters the intake manifold (12) through the exhaust manifold (1), the EGR cooler (3), the EGR valve (4) and the one-way control valve (6), comprising: The exhaust gas passes through the pulse conversion device (5) to stabilize the pressure and flow, and then passes through the one-way control valve (6).

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