An exhaust gas recirculation system with an air compressor branch and a control method

Abstract

This application discloses an exhaust gas recirculation (EGR) system and control method including an air compressor branch, relating to the field of exhaust gas recirculation technology. The EGR system includes an EGR control module, an exhaust gas recirculation branch, and an air compressor branch. The exhaust gas recirculation branch, along the airflow direction, sequentially includes an EGR cooler, an EGR valve, and a first check valve. The air compressor branch, along the airflow direction, consists of an air compressor and a second check valve, with the air compressor branch spanning both sides of the first check valve. The outlet of the second check valve is connected between the first check valve and the intake manifold via a pipeline. When the exhaust gas recirculation branch is operating, the air compressor in the air compressor branch draws exhaust gas from the exhaust gas recirculation branch. The EGR control module controls the opening and closing of the EGR valve via an onboard ECU. The exhaust gas recirculation system and control method of this application improve the EGR rate by drawing exhaust gas from the exhaust gas recirculation branch through the air compressor branch, thereby solving the problem of low EGR rate in traditional exhaust gas recirculation systems.

Description

Technical Field

[0001] This application relates to the field of exhaust gas recirculation technology, specifically to an exhaust gas recirculation system and control method including an air compressor branch. Background Technology

[0002] Currently, exhaust gas recirculation (EGR) is being used more and more widely. Specifically, by controlling a certain amount of exhaust gas through the EGR valve, it is reintroduced into the combustion chamber through the pipeline and mixed with fresh air that has passed through the intercooler before being sent into the cylinder for combustion. This reduces the emission of NOx and CO2 gases and is an effective measure to meet emission requirements.

[0003] In related technologies, in traditional exhaust gas recirculation systems, exhaust gas is split into two paths after exiting the engine's exhaust manifold: one path goes through the exhaust gas turbine normally, and the other path returns to the engine's intake manifold through the EGR valve.

[0004] However, traditional exhaust gas recirculation systems have a relatively low EGR rate. With the development of automotive technology, the upgrading of exhaust emission standards, and the demand for original exhaust gas in aftertreatment systems, as well as aging issues, the EGR rate (also known as the proportion of exhaust gas recirculation) needs to be further improved.

[0005] Therefore, those skilled in the art urgently need to design new technical solutions to further improve the EGR rate. Summary of the Invention

[0006] In view of the deficiencies in the existing technology, the purpose of this application is to provide an exhaust gas recirculation system and control method with an air compressor branch, which improves the EGR rate by drawing exhaust gas from the exhaust gas recirculation branch through the air compressor branch, thereby solving the problem of low EGR rate in traditional exhaust gas recirculation systems.

[0007] To achieve the above objectives, the first aspect is the adoption of the following technical solution: an exhaust gas recirculation system including an air compressor branch, comprising a main branch, wherein the main branch, along the airflow direction, consists of a turbocharger, an intercooler, an intake manifold, an engine block, an exhaust manifold, and an exhaust turbine; the exhaust gas recirculation system includes an EGR control module, an exhaust gas recirculation branch disposed between the intake manifold and the exhaust manifold, and an air compressor branch connected in parallel to the exhaust gas recirculation branch; the exhaust gas recirculation branch, along the airflow direction, includes an EGR cooler, an EGR valve, and a first one-way valve, wherein the flow direction of the first one-way valve is from the intake manifold to the exhaust manifold;

[0008] The air compressor branch consists of an air compressor and a second one-way valve in sequence along the airflow direction, with the air compressor branch spanning both sides of the first one-way valve; the flow direction of the second one-way valve is from the air compressor to the intake manifold; the outlet of the second one-way valve is connected between the first one-way valve and the intake manifold via a pipeline; when the exhaust gas recirculation branch is working, the air compressor in the air compressor branch draws exhaust gas from the exhaust gas recirculation branch; the EGR control module controls the opening and closing of the EGR valve through the vehicle ECU.

[0009] Based on the above technical solution, the EGR valve is normally closed; the air compressor is connected between the EGR valve and the first one-way valve through a bypass intake pipe, and a bypass valve is provided on the bypass intake pipe; both the EGR valve and the bypass valve are connected to the vehicle ECU, and the EGR valve and the bypass valve are open or closed at the same time.

[0010] Based on the above technical solution, the EGR control module receives engine speed signal and engine torque signal in real time. When the engine speed is greater than or equal to the first speed threshold and the engine torque is greater than or equal to the first torque threshold, the EGR control module controls the EGR valve and bypass valve to open simultaneously through the vehicle ECU, and the air compressor draws exhaust gas from the exhaust gas recirculation branch.

[0011] Based on the above technical solution, the EGR cooler is in a normally closed state and is connected to the vehicle ECU; the vehicle ECU controls the EGR cooler and the EGR valve to open or close simultaneously.

[0012] Based on the above technical solution, the EGR control module includes a parameter relationship table of speed, torque and the optimal power of the air compressor.

[0013] Based on the above technical solution, when the EGR valve is open, if the EGR control module detects that the engine speed is less than or equal to the second speed threshold or the engine torque is less than or equal to the second torque threshold, the vehicle ECU controls the EGR valve and the bypass valve to close simultaneously.

[0014] Based on the above technical solution, an air filter is also installed before the turbocharger. The pipeline between the turbocharger and the air filter is connected to the bypass intake pipeline through the air compressor intake pipeline. A solenoid valve is installed on the air compressor intake pipeline. A two-position three-way conversion valve is installed between the air compressor and the second one-way valve. One port of the two-position three-way conversion valve is connected to the air tank through a pipeline. Both the solenoid valve and the two-position three-way conversion valve are connected to the vehicle ECU. The opening and closing states of the solenoid valve and the EGR valve are always opposite. When the EGR valve is closed, the solenoid valve is open, and air passes through the air filter, the air compressor intake pipeline, enters the air compressor, and then enters the air tank.

[0015] Based on the above technical solution, the exhaust gas recirculation system also includes a dryer and a pressure sensor installed in the gas tank. The dryer is installed between the two-position three-way switching valve and the gas tank, and the pressure sensor is connected to the vehicle ECU. When the pressure inside the gas tank reaches a set threshold, the high-pressure gas is discharged into the atmosphere through the unloading port of the dryer. At the same time, the vehicle ECU controls the solenoid valve and the air compressor to shut down.

[0016] Secondly, this application also discloses a control method based on the above-mentioned exhaust gas recirculation system, wherein the EGR valve is normally closed, the air compressor branch is in a non-working state when the EGR valve is closed, and the EGR control module receives engine speed signal and engine torque signal in real time.

[0017] The control method includes the following steps:

[0018] The EGR control module detects that the engine speed is greater than or equal to a first speed threshold and the engine torque is greater than or equal to a first torque threshold. The EGR control module controls the EGR valve to open through the vehicle ECU.

[0019] The EGR control module looks up the table to obtain the optimal power of the air compressor, and the air compressor operates at the optimal power. The air compressor draws exhaust gas from the exhaust gas circulation branch.

[0020] The main branch, the exhaust gas recirculation branch, and the air compressor branch work simultaneously. Exhaust gas enters the intake manifold through the exhaust manifold, EGR cooler, EGR valve, and first one-way valve. The air compressor draws exhaust gas from between the EGR valve and the first one-way valve and circulates it to the intake manifold. At the same time, fresh air enters the intake manifold through the turbocharger and intercooler. After the fresh air and exhaust gas are mixed, they enter the engine body.

[0021] Based on the above technical solution, the EGR valve is normally closed; the air compressor is connected between the EGR valve and the first one-way valve through a bypass intake pipe, and a bypass valve is provided on the bypass intake pipe; both the EGR valve and the bypass valve are connected to the vehicle ECU, and the EGR valve and the bypass valve are open or closed at the same time.

[0022] The EGR control module receives engine speed and engine torque signals in real time. When the engine speed is greater than or equal to the first speed threshold and the engine torque is greater than or equal to the first torque threshold, the EGR control module controls the EGR valve and bypass valve to open simultaneously through the vehicle ECU, and the air compressor draws exhaust gas from the exhaust gas recirculation branch.

[0023] The beneficial effects of the technical solution provided in this application include:

[0024] 1. The exhaust gas recirculation system and control method including an air compressor branch of this application, wherein the air compressor branch and the exhaust gas recirculation branch work simultaneously, the air compressor branch can draw exhaust gas from the exhaust gas recirculation branch, thereby changing the exhaust gas volume ratio of the main branch and the exhaust gas recirculation branch, so that more exhaust gas enters the exhaust gas recirculation branch, thus improving the EGR rate. In actual operation, the suction force can be changed as needed to improve the EGR rate. Compared with the existing system where the exhaust gas volume ratio of the main branch and the exhaust gas recirculation branch is constant and the EGR rate is small, this application can greatly improve the EGR rate and improve energy utilization.

[0025] 2. The exhaust gas recirculation system and control method with an air compressor branch in this application, by setting clear triggering conditions, the exhaust gas recirculation branch does not work under normal circumstances, but is triggered to start working when the engine speed is greater than or equal to a first speed threshold and the engine torque is greater than or equal to a first torque threshold. This enables automated control, effectively improves the EGR rate, and is safe and reliable.

[0026] 3. The exhaust gas recirculation system and control method with air compressor branch of this application specifically sets clear working conditions (first speed threshold and first torque threshold) and disengagement conditions (second speed threshold and second torque threshold) for the exhaust gas recirculation branch of the engine, which can realize automatic control, maximize the improvement of EGR rate and reduce harmful gas emissions.

[0027] 4. The exhaust gas recirculation system and control method with an air compressor branch in this application not only draws in exhaust gas but also stores high-pressure gas. The pipeline between the booster and the air filter is connected to the bypass intake pipeline through the air compressor intake pipeline. A solenoid valve is installed on the air compressor intake pipeline. The opening and closing states of the solenoid valve and the EGR valve are always opposite, so that the air compressor in the exhaust gas recirculation system can also store high-pressure gas. That is, the exhaust gas recirculation system with an air compressor branch in this application can share the original air compressor for storing high-pressure gas without the need for an additional separate air compressor, thus saving space and greatly reducing costs. Attached Figure Description

[0028] To more clearly illustrate the technical solutions in the embodiments of this application, the accompanying drawings used in the description of the embodiments will be briefly introduced below. Obviously, the accompanying drawings described below are only some embodiments of this application. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0029] Figure 1 This is a schematic diagram illustrating the principle of exhaust gas recirculation disclosed in an embodiment of this application;

[0030] Reference numerals: 1. Air filter; 2. Turbocharger; 3. Intercooler; 4. Intake connection pipe; 5. Intake manifold; 6. Engine block; 7. Exhaust manifold; 8. Exhaust turbine; 9. EGR intake pipe; 10. EGR cooler; 11. EGR valve; 12. First check valve; 13. EGR outlet pipe; 14. Bypass valve; 15. Bypass intake pipe; 16. Air compressor intake pipe; 17. Solenoid valve; 18. Air compressor; 19. Switching valve; 20. Dryer; 21. Air receiver; 22. Air compressor bypass outlet pipe; 23. Second check valve; 24. Pressure sensor; 25. On-board ECU; 26. EGR control module. Detailed Implementation

[0031] To make the objectives, technical solutions, and advantages of this application clearer, the present invention will be further described in detail below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are merely illustrative of the invention and are not intended to limit the invention. Furthermore, the technical features involved in the various embodiments of the present invention described below can be combined with each other as long as they do not conflict with each other.

[0032] The purpose of this application is to provide an exhaust gas recirculation system and control method that includes an air compressor branch. By using an air compressor branch connected in parallel with the exhaust gas recirculation branch, exhaust gas is cleverly extracted to improve the EGR rate, thereby solving the problem of low EGR rate in traditional exhaust gas recirculation systems and further reducing NOx and CO2 emissions.

[0033] like Figure 1 As shown, this application discloses an embodiment of an exhaust gas recirculation system including an air compressor branch. The exhaust gas recirculation system includes a main branch, which, along the airflow direction, consists of a turbocharger 2, an intercooler 3, an intake manifold 5, an engine body 6, an exhaust manifold 7, and an exhaust turbine 8. The turbocharger 2 and the exhaust turbine 8 are linked by a shaft and rotate synchronously. Specifically, the main branch is a classic engine structure, which will not be described in detail in this application.

[0034] The exhaust gas recirculation system includes an EGR control module 26, an exhaust gas recirculation branch, and an air compressor branch. The exhaust gas recirculation branch is located between the intake manifold 5 and the exhaust manifold 7. The air compressor branch is connected in parallel to the exhaust gas recirculation branch, which creates a negative pressure inside the exhaust gas recirculation branch and increases the flow rate of the exhaust gas.

[0035] The exhaust gas recirculation branch includes, in sequence along the airflow direction, an EGR cooler 10, an EGR valve 11, and a first check valve 12. The flow direction of the first check valve 12 is from the intake manifold 5 to the exhaust manifold 7.

[0036] In this application's exhaust gas recirculation branch, the EGR valve 11 is located at the rear end of the EGR cooler 10, meaning the EGR valve 11 operates at the cold end and has a low operating temperature. Compared to existing technologies where the EGR valve 11 operates at the hot end, this design offers higher reliability, effectively protects the EGR valve 11, and extends its service life. A first check valve 12 is also included in the exhaust gas recirculation branch to prevent fresh air from flowing back into the exhaust gas branch, effectively preventing backflow and ensuring safety and reliability.

[0037] Specifically, the air compressor branch consists of air compressor 18 and second check valve 23 sequentially along the airflow direction, with the air compressor branch spanning both sides of the first check valve 12; the flow direction of the second check valve 23 is from air compressor 18 to intake manifold 5. The air inlet of air compressor 18 is connected between EGR valve 11 and first check valve 12 via a pipeline, and the air outlet of second check valve 23 is connected between first check valve 12 and intake manifold 5 via a pipeline. The second check valve 23 prevents exhaust gas from the exhaust gas recirculation branch from flowing back to the air compressor branch.

[0038] When the exhaust gas recirculation (EGR) branch is operating, the air compressor 18 in the air compressor branch draws exhaust gas from the EGR branch, creating a negative pressure state in the EGR branch to increase the EGR rate. Specifically, the EGR rate is the volume of exhaust gas flowing through the EGR branch divided by the volume of exhaust gas exiting the exhaust manifold. The EGR valve 11 is connected to the vehicle ECU 25, which is connected to the EGR control module 26. The EGR control module 26 controls the opening and closing of the EGR valve 11 through the vehicle ECU 25.

[0039] The exhaust gas recirculation system of this application, which includes an air compressor branch, operates simultaneously with the exhaust gas recirculation branch. The air compressor branch can draw exhaust gas from the exhaust gas recirculation branch, thereby changing the exhaust gas volume ratio between the main branch and the exhaust gas recirculation branch. This results in more exhaust gas entering the exhaust gas recirculation branch, improving the EGR rate. In practical operation, the suction force can be adjusted as needed to further improve the EGR rate. Compared to existing systems where the exhaust gas volume ratio between the main branch and the exhaust gas recirculation branch remains constant and the EGR rate is relatively low, this application significantly improves the EGR rate.

[0040] In one embodiment, the EGR valve 11 is normally closed. The air compressor 18 is connected between the EGR valve 11 and the first one-way valve 12 via a bypass intake line 15, and a bypass valve 14 is provided on the bypass intake line 15. Both the EGR valve 11 and the bypass valve 14 are connected to the vehicle ECU 25, and the EGR valve 11 and the bypass valve 14 are either open or closed simultaneously, that is, the bypass valve 14 is only opened when the exhaust gas recirculation branch is working.

[0041] The exhaust gas recirculation system containing the air compressor branch of this application has a bypass valve 14 installed on the bypass intake pipe 15, which not only disconnects the air compressor branch, but also isolates the air compressor 18 from the exhaust gas recirculation branch when the exhaust gas recirculation branch is not working, so that the air compressor 18 can be used for other purposes.

[0042] In one embodiment, the EGR control module 26 receives engine speed signal and engine torque signal in real time. When the engine speed is greater than or equal to the first speed threshold and the engine torque is greater than or equal to the first torque threshold, the EGR control module 26 controls the EGR valve 11 and the bypass valve 14 to open simultaneously through the vehicle ECU 25, and the air compressor 18 draws exhaust gas from the exhaust gas recirculation branch.

[0043] Furthermore, the EGR valve 11 and bypass valve 14 are opened to perform EGR circulation. They can be opened automatically or directly controlled by inputting commands through the EGR control module 26.

[0044] Specifically, the air compressor 18 is connected to the vehicle ECU. After the bypass valve 14 is opened, the vehicle ECU controls the air compressor 18 to operate at the optimal power, which corresponds to the maximum EGR rate under the current state.

[0045] The exhaust gas recirculation system with an air compressor branch in this application, by setting clear triggering conditions, allows the exhaust gas recirculation branch to work when it is normally inactive. When the engine speed is greater than or equal to a first speed threshold and the engine torque is greater than or equal to a first torque threshold, the exhaust gas recirculation branch is triggered to start working, which can achieve automated control, effectively improve the EGR rate, and is safe and reliable.

[0046] In one embodiment, the EGR cooler 10 is normally closed and is connected to the vehicle ECU 25. The vehicle ECU 25 controls the EGR cooler 10 and the EGR valve 11 to open or close simultaneously. The function of the EGR cooler 10 is solely to allow the EGR valve 11 to operate at the cold end, providing the EGR valve with a superior working environment and thus improving its efficiency.

[0047] In one embodiment, the EGR control module 26 includes a parameter relationship table of speed, torque and optimal power of the air compressor 18.

[0048] Furthermore, the EGR control module 26 includes a parameter relationship table of speed, torque and optimal power of the air compressor 18. The table was established in advance through a large number of experiments. When the exhaust gas recirculation branch is working, the EGR control module 26 can directly look up the table to control the air compressor 18, thereby maximizing the EGR rate.

[0049] In one embodiment, when the EGR valve 11 is open, if the EGR control module 26 detects that the engine speed is less than or equal to the second speed threshold or the engine torque is less than or equal to the second torque threshold, the vehicle ECU controls the EGR valve 11 and the bypass valve 14 to close simultaneously, and exhaust gas recirculation is no longer performed.

[0050] The exhaust gas recirculation system with an air compressor branch in this application has specifically set clear operating conditions (first speed threshold and first torque threshold) and exit conditions (second speed threshold and second torque threshold) for the exhaust gas recirculation branch of the engine, which can realize automatic control, maximize the improvement of EGR rate, and reduce harmful gas emissions.

[0051] In one embodiment, an air filter 1 is provided before the turbocharger 2, and the pipeline between the turbocharger 2 and the air filter 1 is connected to the bypass intake pipeline 15 through the air compressor intake pipeline 16. A solenoid valve 17 is provided on the air compressor intake pipeline 16.

[0052] A two-position three-way switching valve 19 is installed between the air compressor 18 and the second one-way valve 23. One port of the two-position three-way switching valve 19 is connected to the air tank 21 via a pipeline. Specifically, the three ports of the two-position three-way switching valve 19 are respectively connected to the air compressor 18, the air tank 21, and the second one-way valve 23. Both the solenoid valve 17 and the two-position three-way switching valve 19 are connected to the vehicle ECU 25, and the vehicle ECU 25 controls the opening and closing of the solenoid valve 17 to control the connection direction of the two-position three-way switching valve 19.

[0053] The opening and closing states of solenoid valve 17 and EGR valve 11 are always opposite. That is, when the exhaust gas recirculation branch is working, solenoid valve 17 remains closed and the air compressor plays the role of drawing exhaust gas. When the exhaust gas recirculation branch is not working, solenoid valve 17 is open and the air compressor 18 plays the role of filling the air tank 21 with air. The high-pressure air in the air tank 21 is used by the braking system.

[0054] When EGR valve 11 is closed, solenoid valve 17 is opened, and air passes through air filter 1, air compressor intake line 16, enters air compressor 18, and then enters air tank 21 for use by the braking system.

[0055] In the exhaust gas recirculation system with an air compressor branch of this application, the air compressor 18 not only serves to draw in exhaust gas but also to store high-pressure gas. The pipeline between the booster 2 and the air filter 1 is connected to the bypass intake pipeline 15 through the air compressor intake pipeline 16. A solenoid valve 17 is installed on the air compressor intake pipeline 16. The opening and closing states of the solenoid valve 17 and the EGR valve 11 are always opposite, so that the air compressor 18 of the exhaust gas recirculation system can also serve to store high-pressure gas. That is, the exhaust gas recirculation system with an air compressor branch of this application can share the original air compressor 18 for storing high-pressure gas without the need to set up an additional air compressor 18 separately, without occupying extra space, which greatly saves costs.

[0056] In one embodiment, the exhaust gas recirculation system further includes a dryer 20 and a pressure sensor 24 disposed on a gas storage tank 21. The dryer 20 is disposed between a two-position three-way switching valve 19 and a gas storage tank 21, and the pressure sensor 24 is connected to an on-board ECU 25.

[0057] When the pressure in the air tank 21 reaches the set threshold, the high-pressure gas is discharged into the atmosphere through the unloading port of the dryer 20 and no longer enters the air tank 21; at the same time, the vehicle ECU 25 controls the solenoid valve 17 and the air compressor 18 to close. Specifically, the air compressor 18 is electrically connected to the vehicle ECU 25 and is controlled by the vehicle ECU 25 to open, close and adjust its power.

[0058] In one embodiment, the output port of the intercooler 3 is connected to the intake manifold 5 via the intake connection pipe 4, and the first one-way valve 12 is connected to the intake connection pipe 4 via the EGR outlet pipe 13. That is, the intake connection pipe 4 and the EGR outlet pipe 13 first cross and converge before connecting to the intake manifold 5. The two-position three-way switching valve 19 is connected to the EGR outlet pipe 13 via the air compressor bypass outlet pipe 22, and the second one-way valve 23 is installed on the air compressor bypass outlet pipe 22.

[0059] This application also discloses a control method based on the above-mentioned exhaust gas recirculation system, wherein the EGR valve 11 is normally closed, the air compressor branch is in a non-working state when the EGR valve 11 is closed, and the EGR control module 26 receives the engine speed signal and the engine torque signal in real time.

[0060] The control method includes the following steps:

[0061] When the EGR control module 26 detects that the engine speed is greater than or equal to the first speed threshold and the engine torque is greater than or equal to the first torque threshold, the exhaust gas recirculation loop is triggered to open, and the EGR control module 26 controls the EGR valve 11 to open through the vehicle ECU.

[0062] The EGR control module 26 looks up the table to obtain the optimal power of the air compressor 18. The vehicle ECU controls the air compressor 18 to operate at the optimal power. The air compressor 18 draws exhaust gas from the exhaust gas recirculation branch. The optimal power of the air compressor 18 corresponds to the maximum EGR rate of the current state.

[0063] The main branch, the exhaust gas recirculation branch, and the air compressor branch work simultaneously. Exhaust gas enters the intake manifold 5 through the exhaust manifold 7, EGR cooler 10, EGR valve 11, and first one-way valve 12. The air compressor 18 draws exhaust gas from between the EGR valve 11 and the first one-way valve 12 and circulates it to the intake manifold 5. At the same time, fresh air enters the intake manifold 5 through the turbocharger 2 and intercooler 3. The fresh air and exhaust gas are mixed and then enter the engine body.

[0064] The exhaust gas recirculation system control method of this application involves the exhaust gas recirculation branch working when the EGR control module 26 detects that the engine speed is greater than or equal to a first speed threshold and the engine torque is greater than or equal to a first torque threshold. The EGR control module 26 looks up the table to obtain the optimal power of the air compressor 18, and the on-board ECU controls the air compressor 18 to operate at the optimal power, which can maximize the EGR rate.

[0065] Regarding the control method of the exhaust gas recirculation system, in one embodiment, the EGR valve 11 is normally closed, and the air compressor 18 is connected between the EGR valve 11 and the first one-way valve 12 through a bypass intake line 15, and a bypass valve 14 is provided on the bypass intake line 15. Both the EGR valve 11 and the bypass valve 14 are connected to the vehicle ECU 25, and the EGR valve 11 and the bypass valve 14 are either open or closed simultaneously, that is, the bypass valve 14 is only opened when the exhaust gas recirculation branch is working.

[0066] The control method of this application uses a bypass valve 14 installed on the bypass intake pipe 15, which not only disconnects the air compressor branch, but also isolates the air compressor 18 from the exhaust gas recirculation branch when the exhaust gas recirculation branch is not working, so that the air compressor 18 can be used for other purposes.

[0067] Regarding the control method of the exhaust gas recirculation system, in one embodiment, the EGR control module 26 receives the engine speed signal and the engine torque signal in real time. When the engine speed is greater than or equal to the first speed threshold and the engine torque is greater than or equal to the first torque threshold, the EGR control module 26 controls the EGR valve 11 and the bypass valve 14 to open simultaneously through the vehicle ECU 25, and the air compressor 18 draws the exhaust gas from the exhaust gas recirculation branch.

[0068] Furthermore, the EGR valve 11 and bypass valve 14 are opened to perform EGR circulation. They can be opened automatically or directly controlled by inputting commands through the EGR control module 26.

[0069] Specifically, the air compressor 18 is connected to the vehicle ECU. After the bypass valve 14 is opened, the vehicle ECU controls the air compressor 18 to operate at the optimal power, which corresponds to the maximum EGR rate under the current state.

[0070] The control method of this application, by setting clear triggering conditions, ensures that the exhaust gas recirculation branch does not work under normal circumstances, but is triggered to start working when the engine speed is greater than or equal to a first speed threshold and the engine torque is greater than or equal to a first torque threshold. This enables automated control, effectively improves the EGR rate, and is safe and reliable.

[0071] Regarding the control method of the exhaust gas recirculation system, in one embodiment, the EGR cooler 10 is in a normally closed state and is connected to the vehicle ECU 25; the vehicle ECU 25 controls the EGR cooler 10 and the EGR valve 11 to open or close simultaneously. The function of the EGR cooler 10 is solely to allow the EGR valve 11 to operate at the cold end, providing the EGR valve with an excellent working environment, thereby improving the efficiency of the EGR valve.

[0072] Regarding the control method of the exhaust gas recirculation system, in one embodiment, the EGR control module 26 includes a parameter relationship table of speed, torque and optimal power of the air compressor 18.

[0073] Furthermore, the EGR control module 26 includes a parameter relationship table of speed, torque and optimal power of the air compressor 18. The table was established in advance through a large number of experiments. When the exhaust gas recirculation branch is working, the EGR control module 26 can directly look up the table to control the air compressor 18, thereby maximizing the EGR rate.

[0074] Regarding the control method of the exhaust gas recirculation system, in one embodiment, when the EGR valve 11 is open, if the EGR control module 26 detects that the engine speed is less than or equal to the second speed threshold or the engine torque is less than or equal to the second torque threshold, the on-board ECU controls the EGR valve 11 and the bypass valve 14 to close simultaneously, and exhaust gas recirculation is no longer performed.

[0075] The exhaust gas recirculation system with an air compressor branch in this application has specifically set clear operating conditions (first speed threshold and first torque threshold) and exit conditions (second speed threshold and second torque threshold) for the exhaust gas recirculation branch of the engine, which can realize automatic control, maximize the improvement of EGR rate, and reduce harmful gas emissions.

[0076] Regarding the control method of the exhaust gas recirculation system, in one embodiment, an air filter 1 is also provided before the turbocharger 2, and the pipeline between the turbocharger 2 and the air filter 1 is connected to the bypass intake pipeline 15 through the air compressor intake pipeline 16. A solenoid valve 17 is provided on the air compressor intake pipeline 16.

[0077] A two-position three-way switching valve 19 is installed between the air compressor 18 and the second one-way valve 23. One port of the two-position three-way switching valve 19 is connected to the air tank 21 via a pipeline. Specifically, the three ports of the two-position three-way switching valve 19 are respectively connected to the air compressor 18, the air tank 21, and the second one-way valve 23. Both the solenoid valve 17 and the two-position three-way switching valve 19 are connected to the vehicle ECU 25, and the vehicle ECU 25 controls the opening and closing of the solenoid valve 17 to control the connection direction of the two-position three-way switching valve 19.

[0078] The opening and closing states of solenoid valve 17 and EGR valve 11 are always opposite. That is, when the exhaust gas recirculation branch is working, solenoid valve 17 remains closed and the air compressor plays the role of drawing exhaust gas. When the exhaust gas recirculation branch is not working, solenoid valve 17 is open and the air compressor 18 plays the role of filling the air tank 21 with air. The high-pressure air in the air tank 21 is used by the braking system.

[0079] When EGR valve 11 is closed, solenoid valve 17 is opened, and air passes through air filter 1, air compressor intake line 16, enters air compressor 18, and then enters air tank 21 for use by the braking system.

[0080] In the control method of this application, the air compressor 18 not only plays the role of sucking up exhaust gas, but also plays the role of storing high-pressure gas. The pipeline between the booster 2 and the air filter 1 is connected to the bypass intake pipeline 15 through the air compressor intake pipeline 16. A solenoid valve 17 is installed on the air compressor intake pipeline 16. The opening and closing states of the solenoid valve 17 and the EGR valve 11 are always opposite, so that the air compressor 18 of the exhaust gas recirculation system can also play the role of storing high-pressure gas. That is, the exhaust gas recirculation system with air compressor branch of this application can share the original air compressor 18 for storing high-pressure gas, without the need to set up an additional air compressor 18 separately, without occupying additional space, which greatly saves costs.

[0081] Regarding the control method of the exhaust gas recirculation system, in one embodiment, the exhaust gas recirculation system further includes a dryer 20 and a pressure sensor 24 disposed on a gas storage tank 21. The dryer 20 is disposed between a two-position three-way switching valve 19 and a gas storage tank 21, and the pressure sensor 24 is connected to an on-board ECU 25.

[0082] When the pressure in the air tank 21 reaches the set threshold, the high-pressure gas is discharged into the atmosphere through the unloading port of the dryer 20 and no longer enters the air tank 21; at the same time, the vehicle ECU 25 controls the solenoid valve 17 and the air compressor 18 to close. Specifically, the air compressor 18 is electrically connected to the vehicle ECU 25 and is controlled by the vehicle ECU 25 to open, close and adjust its power.

[0083] In the description of this application, it should be noted that the terms "upper," "lower," etc., indicating the orientation or positional relationship are based on the orientation or positional relationship 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, or be constructed and operated in a specific orientation, and therefore should not be construed as a limitation of this application. Unless otherwise expressly specified and limited, the terms "installed," "connected," and "linked" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral connection; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium; they can refer to the internal communication between two elements. For those skilled in the art, the specific meaning of the above terms in this application can be understood according to the specific circumstances.

[0084] It should be noted that in this application, relational terms such as "first" and "second" are used merely to distinguish one entity or operation from another, and do not necessarily require or imply any such actual relationship or order between these entities or operations. Furthermore, the terms "comprising," "including," or any other variations thereof are intended to cover non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements includes not only those elements but also other elements not expressly listed, or elements inherent to such a process, method, article, or apparatus. Without further limitations, an element defined by the phrase "comprising one..." does not exclude the presence of other identical elements in the process, method, article, or apparatus that includes said element.

[0085] The above description is merely a specific embodiment of this application, enabling those skilled in the art to understand or implement this 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 this application. Therefore, this application is not to be limited to the embodiments shown herein, but is to be accorded the widest scope consistent with the principles and novel features claimed herein.

Claims

1. An exhaust gas recirculation system including an air compressor branch, comprising a main branch, wherein the main branch comprises, in sequence along the airflow direction, a turbocharger (2), an intercooler (3), an intake manifold (5), an engine body (6), an exhaust manifold (7), and an exhaust gas turbine (8), characterized in that: The exhaust gas recirculation system includes an EGR control module (26), an exhaust gas recirculation branch located between the intake manifold (5) and the exhaust manifold (7), and an air compressor branch connected in parallel to the exhaust gas recirculation branch; the exhaust gas recirculation branch includes an EGR cooler (10), an EGR valve (11), and a first check valve (12) in sequence along the airflow direction, and the flow direction of the first check valve (12) is from the intake manifold (5) to the exhaust manifold (7); The air compressor branch consists of an air compressor (18) and a second check valve (23) in sequence along the airflow direction, and the air compressor branch spans both sides of the first check valve (12); the flow direction of the second check valve (23) is from the air compressor (18) to the intake manifold (5); the outlet of the second check valve (23) is connected between the first check valve (12) and the intake manifold (5) through a pipeline; when the exhaust gas recirculation branch is working, the air compressor (18) of the air compressor branch draws the exhaust gas from the exhaust gas recirculation branch; the EGR control module (26) controls the opening and closing of the EGR valve (11) through the vehicle ECU (25); The EGR valve (11) is normally closed; the air compressor (18) is connected between the EGR valve (11) and the first check valve (12) through a bypass intake pipe (15), and a bypass valve (14) is provided on the bypass intake pipe (15); the EGR valve (11) and the bypass valve (14) are both connected to the vehicle ECU (25), and the EGR valve (11) and the bypass valve (14) are either open or closed at the same time; A two-position three-way switching valve (19) is provided between the air compressor (18) and the second one-way valve (23). Two of the ports of the two-position three-way switching valve (19) are respectively connected to the air compressor (18) and the second one-way valve (23). An air filter (1) is also provided before the booster (2). The pipeline between the booster (2) and the air filter (1) is connected to the bypass intake pipeline (15) through the air compressor intake pipeline (16). A solenoid valve (17) is provided on the air compressor intake pipeline (16). The opening and closing states of the solenoid valve (17) and the EGR valve (11) are always opposite.

2. An exhaust gas recirculation system with an air compressor branch according to claim 1, characterized in that: The EGR control module (26) receives engine speed signal and engine torque signal in real time. When the engine speed is greater than or equal to the first speed threshold and the engine torque is greater than or equal to the first torque threshold, the EGR control module (26) controls the EGR valve (11) and bypass valve (14) to open simultaneously through the vehicle ECU (25), and the air compressor (18) draws exhaust gas from the exhaust gas circulation branch.

3. An exhaust gas recirculation system with an air compressor branch according to claim 1, characterized in that: The EGR cooler (10) is normally closed and is connected to the vehicle ECU (25). The vehicle ECU (25) controls the EGR cooler (10) and the EGR valve (11) to open or close simultaneously.

4. An exhaust gas recirculation system with an air compressor branch according to claim 1, characterized in that: The EGR control module (26) contains a parameter relationship table of speed, torque and optimal power of the air compressor (18).

5. An exhaust gas recirculation system with an air compressor branch according to claim 2, characterized in that, When the EGR valve (11) is open, when the EGR control module (26) detects that the engine speed is less than or equal to the second speed threshold or the engine torque is less than or equal to the second torque threshold, the vehicle ECU controls the EGR valve (11) and the bypass valve (14) to close simultaneously.

6. The exhaust gas recirculation system including an air compressor branch as described in claim 1, characterized in that: One port of the two-position three-way switching valve (19) is connected to the air tank (21) via a pipeline; both the solenoid valve (17) and the two-position three-way switching valve (19) are connected to the vehicle ECU (25); when the EGR valve (11) is closed, the solenoid valve (17) is opened, and air passes through the air filter (1), the air compressor intake pipeline (16), enters the air compressor (18), and then enters the air tank (21).

7. The exhaust gas recirculation system including an air compressor branch as described in claim 6, characterized in that: The exhaust gas recirculation system also includes a dryer (20) and a pressure sensor (24) installed in the gas storage tank (21). The dryer (20) is located between the two-position three-way switching valve (19) and the gas storage tank (21), and the pressure sensor (24) is connected to the vehicle ECU (25). When the pressure inside the gas storage tank (21) reaches a set threshold, the high-pressure gas is discharged into the atmosphere through the unloading hole of the dryer (20). At the same time, the vehicle ECU (25) controls the solenoid valve (17) and the air compressor (18) to close.

8. A control method based on the waste gas recirculation system of claim 1, characterized in that, The EGR valve (11) is normally closed, the air compressor branch is in a non-working state when the EGR valve (11) is closed, and the EGR control module (26) receives engine speed signal and engine torque signal in real time. The control method includes the following steps: The EGR control module (26) detects that the engine speed is greater than or equal to the first speed threshold and the engine torque is greater than or equal to the first torque threshold. The EGR control module (26) controls the EGR valve (11) to open through the vehicle ECU. The EGR control module (26) looks up the table to obtain the optimal power of the air compressor (18), and the air compressor (18) operates at the optimal power. The air compressor (18) draws the exhaust gas from the exhaust gas circulation branch. The main branch, the exhaust gas recirculation branch, and the air compressor branch work simultaneously. Exhaust gas enters the intake manifold (5) through the exhaust manifold (7), the EGR cooler (10), the EGR valve (11), and the first check valve (12). The air compressor (18) draws exhaust gas from between the EGR valve (11) and the first check valve (12) and circulates it to the intake manifold (5). At the same time, fresh air enters the intake manifold (5) through the turbocharger (2) and the intercooler (3). After the fresh air and exhaust gas are mixed, they enter the engine body.

9. The control method as described in claim 8, characterized in that: The EGR valve (11) is normally closed; the air compressor (18) is connected between the EGR valve (11) and the first check valve (12) through a bypass intake pipe (15), and a bypass valve (14) is provided on the bypass intake pipe (15); the EGR valve (11) and the bypass valve (14) are both connected to the vehicle ECU (25), and the EGR valve (11) and the bypass valve (14) are either open or closed at the same time; The EGR control module (26) receives engine speed signal and engine torque signal in real time. When the engine speed is greater than or equal to the first speed threshold and the engine torque is greater than or equal to the first torque threshold, the EGR control module (26) controls the EGR valve (11) and bypass valve (14) to open simultaneously through the vehicle ECU (25), and the air compressor (18) draws exhaust gas from the exhaust gas circulation branch.

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