EGR system, control method and vehicle

Abstract

The invention provides an EGR system, a control method and a vehicle. The EGR system comprises an engine module, an electromechanical coupling supercharger module and an electric compressor module. The engine module comprises an engine body, an engine ECU, an air inlet mechanism and an exhaust mechanism. The electric gas compressor module comprises an EGR controller and an electric gas compressor, and the EGR controller is used for adjusting the rotating speed of the electric gas compressor so as to control the EGR flow; the electromechanical coupling supercharger module comprises a gas compressor, a turbine, a two-way motor, a waste gas bypass valve and a storage battery. The two-way motor works in a motor mode or a generator mode according to the working condition of an engine. The electromechanical coupling supercharger module is adopted to achieve energy recovery, so that the power supply requirements of all electrical equipment are met, the situation that the engine efficiency is reduced due to the fact that an electric gas compressor module is additionally arranged is avoided, and the problems that in the prior art, EGR cannot achieve the high EGR rate, global range adjustment, slow dynamic response, low control precision and the like at the same time are solved.

Description

Technical Field

[0001] The present invention relates to the technical field of engine EGR, and in particular to an EGR system, a control method and a vehicle. Background Art

[0002] EGR (Exhaust Gas Recirculation) technology is an emission reduction technology widely used in internal combustion engines. The core principle is to introduce a part of the combustion exhaust gas of the internal combustion engine into the intake circuit and mix it with fresh air to participate in combustion, achieving the effects of reducing combustion temperature, reducing the generation amount of nitrogen oxides and anti-knock.

[0003] With the increasingly strict regulations on vehicle emission reduction, especially the requirement to control nitrogen oxide emissions, the application range of EGR technology and the EGR rate when using EGR technology are gradually increasing. A higher EGR rate requires the system to have higher precision and response speed to meet the needs of different working conditions. However, the existing EGR systems have problems such as complex system, high cost, poor reliability, etc., and may also lead to a decrease in engine thermal efficiency and poor economy. Summary of the Invention

[0004] Embodiments of the present invention provide an EGR system, a control method and a vehicle. The EGR system can overcome the problems existing in the prior art, such as the inability of EGR to simultaneously achieve a high EGR rate, full-range adjustment, slow dynamic response and low control precision, complex system, high cost, poor reliability, etc. Moreover, an electromechanical coupling supercharger module is used to realize energy recovery, so as to meet the power supply requirements of all electrical equipment on the electric compressor module, the electromechanical coupling supercharger module and the engine module, and can avoid the reduction of engine efficiency caused by adding an electric compressor module, which is beneficial to improving the engine thermal efficiency, economy and responsiveness of the engine.

[0005] According to an aspect of the present invention, an EGR system is provided, including an engine module, an electromechanical coupling supercharger module and an electric compressor module. The engine module includes an engine body, an engine ECU, an intake mechanism and an exhaust mechanism. The input end of the electric compressor module is connected to the exhaust mechanism, and the output end of the electric compressor module is connected to the intake mechanism;

[0006] The electric compressor module includes an EGR controller and an electric compressor. The EGR controller is used to adjust the working state of the electric compressor to control the EGR flow rate;

[0007] The electromechanical coupling supercharger module includes a compressor, a turbine, a bidirectional motor, an exhaust gas bypass valve, and a battery. The turbine and the exhaust gas bypass valve are both connected to the exhaust mechanism. The compressor is connected to the turbine through the bidirectional motor. The bidirectional motor is configured to operate in a motor mode or a generator mode according to the engine operating conditions.

[0008] Optionally, the electric compressor, the engine ECU, the control terminal of the bidirectional motor, and the control terminal of the exhaust gas bypass valve are all connected to the EGR controller. The EGR controller determines the engine operating conditions based on the information provided by the engine ECU. When the engine is in an acceleration condition, the EGR controller controls the exhaust gas bypass valve to close and simultaneously controls the bidirectional motor to operate in the motor mode. The bidirectional motor drives the turbine and the compressor to increase their rotational speeds through a rotating shaft to improve economy. When the engine is in a steady-state condition, the EGR controller obtains the SOC of the battery. When the SOC is greater than or equal to a first threshold, the EGR controller controls the opening degree of the exhaust gas bypass valve according to the engine operating condition requirements and controls the bidirectional motor to operate in the generator mode. The bidirectional motor supplies power to the electric compressor. When the SOC is less than the first threshold, the EGR controller closes the exhaust gas bypass valve according to the engine operating condition requirements and controls the bidirectional motor to operate in the generator mode. The bidirectional motor supplies power to the electric compressor and simultaneously charges the battery.

[0009] Optionally, the electric compressor module further includes a drive motor, an electronically controlled three-way valve, a first pressure sensor, a second pressure sensor, a first temperature sensor, and a second temperature sensor.

[0010] The control terminal of the drive motor, the control terminal of the electronically controlled three-way valve, the first pressure sensor, the second pressure sensor, the first temperature sensor, and the second temperature sensor are all connected to the EGR controller. The drive motor is used to drive the electric compressor to operate. The input end of the electric compressor is connected to the exhaust manifold of the exhaust mechanism. The output end of the electric compressor is connected to the input end of the electronically controlled three-way valve. The first output end of the electronically controlled three-way valve is connected to the intake mechanism. The second output end of the electronically controlled three-way valve is connected to the input end of the electric compressor. The first pressure sensor and the first temperature sensor are disposed at the input end of the electric compressor. The second pressure sensor is disposed at the output end of the electric compressor. The second temperature sensor is disposed at the first output end of the electronically controlled three-way valve.

[0011] Optionally, it further includes a first EGR cooler. The electric supercharger module further includes a second EGR cooler, a first coolant flow control valve, and a second coolant flow control valve. The control ends of the first coolant flow control valve and the second coolant flow control valve are both connected to the EGR controller. The input end of the electric supercharger is connected to the exhaust manifold of the exhaust mechanism through the first EGR cooler. The first output end of the electronic three-way valve is connected to the intake mechanism through the second EGR cooler. The second temperature sensor is arranged at the output end of the second EGR cooler. The input end of the first coolant flow control valve is connected to the engine cooling circuit, and the coolant returns to the engine cooling circuit after passing through the first EGR cooler; the input end of the second coolant flow control valve is connected to the engine cooling circuit, and the coolant returns to the engine cooling circuit after passing through the second EGR cooler.

[0012] Optionally, the electric supercharger module further includes a drive motor, a first switching valve, a second switching valve, a first pressure sensor, a second pressure sensor, a first temperature sensor, and a second temperature sensor;

[0013] The control end of the drive motor, the control end of the first switching valve, the control end of the second switching valve, the first pressure sensor, the second pressure sensor, the first temperature sensor, and the second temperature sensor are all connected to the EGR controller. The drive motor is used to drive the electric supercharger to operate. The input end of the electric supercharger is connected to the exhaust manifold of the exhaust mechanism. The input ends of the first switching valve and the second switching valve are both connected to the output end of the electric supercharger. The output end of the first switching valve is connected to the intake mechanism. The output end of the second switching valve is connected to the input end of the electric supercharger. The first pressure sensor and the first temperature sensor are arranged at the input end of the electric supercharger. The second pressure sensor is arranged at the output end of the electric supercharger. The second temperature sensor is arranged at the output end of the first switching valve.

[0014] Optionally, it further includes a first EGR cooler. The electric supercharger module further includes a second EGR cooler, a first coolant flow control valve, and a second coolant flow control valve. The control ends of the first coolant flow control valve and the second coolant flow control valve are both connected to the EGR controller. The input end of the electric supercharger is connected to the exhaust manifold of the exhaust mechanism through the first EGR cooler. The output end of the first switching valve is connected to the intake mechanism through the second EGR cooler. The second temperature sensor is arranged at the output end of the second EGR cooler. The input end of the first coolant flow control valve is connected to the engine cooling circuit, and the coolant returns to the engine cooling circuit after passing through the first EGR cooler. The input end of the second coolant flow control valve is connected to the engine cooling circuit, and the coolant returns to the engine cooling circuit after passing through the second EGR cooler.

[0015] Optionally, the intake mechanism includes an air filter, an intercooler, a throttle valve, a mixer, and an intake manifold. The output end of the air filter is connected to the input end of the supercharger. The output end of the supercharger is connected to the input end of the intercooler. The output end of the intercooler is connected to the first input end of the mixer. The output end of the second EGR cooler is connected to the second input end of the mixer. The output end of the mixer is connected to the intake manifold. The throttle valve is arranged between the intercooler and the mixer.

[0016] The exhaust mechanism includes an exhaust manifold and a post-processor. The first output end of the exhaust manifold is connected to the input end of the electric supercharger. The second output end of the exhaust manifold is connected to the input end of the post-processor through the turbine. The third output end of the exhaust manifold is connected to the input end of the post-processor through the waste gas bypass valve.

[0017] According to another aspect of the present invention, there is provided a control method for an EGR system, which is applicable to the above EGR system. The control method includes:

[0018] Obtain the parameters in the electric supercharger module and the engine operating parameters provided by the engine ECU;

[0019] Determine the operating state of the engine according to the engine operating parameters, and control the bidirectional motor to work in the motor mode or the generator mode according to the operating state of the engine. When the engine is in a non-shutdown state, adjust the operating state of the electric supercharger according to the parameters in the electric supercharger module and the engine operating parameters provided by the engine ECU to control the EGR flow rate.

[0020] Optionally, controlling the bidirectional motor to work in the motor mode or the generator mode according to the operating state of the engine includes:

[0021] When the engine is in the acceleration condition, the EGR controller controls the exhaust gas bypass valve to close, and at the same time controls the bidirectional motor to operate in the motor mode. The bidirectional motor drives the turbine and the compressor to increase the speed through the rotating shaft, so as to improve the economy;

[0022] When the engine is in the steady-state condition, the EGR controller obtains the SOC of the battery. When the SOC is greater than or equal to the first threshold, the EGR controller controls the opening degree of the exhaust gas bypass valve according to the engine condition requirements, and controls the bidirectional motor to operate in the generator mode. The bidirectional motor supplies power to the electric compressor; when the SOC is less than the first threshold, the EGR controller closes the exhaust gas bypass valve according to the engine condition requirements, and controls the bidirectional motor to operate in the generator mode. The bidirectional motor supplies power to the electric compressor and charges the battery at the same time.

[0023] Optionally, the electric compressor module includes a drive motor, a first pressure sensor, a second pressure sensor, a first temperature sensor and a second temperature sensor, and obtains the parameters in the electric compressor module and the engine operation parameters provided by the engine ECU, including:

[0024] Obtain the signals collected by the first pressure sensor, the second pressure sensor, the first temperature sensor, the second temperature sensor, the current speed of the drive motor, and the throttle pedal position, engine speed, intake air flow, intake manifold pressure sensor signal and target EGR flow issued by the engine ECU.

[0025] Optionally, after obtaining the parameters in the electric compressor module and the engine operation parameters provided by the engine ECU, it further includes:

[0026] According to the intake manifold pressure sensor signal, combined with the calibration Map of the flow and pressure loss between the electric compressor and the intake manifold, calculate the target boost pressure of the electric compressor;

[0027] According to the target EGR flow, the pressure of the first pressure sensor, the target boost pressure, the temperature of the first temperature sensor and the gas flow equation of the electric compressor, calculate the target speed of the drive motor, and adjust the current speed of the drive motor to the target speed;

[0028] According to the pressure of the first pressure sensor, the pressure of the second pressure sensor, the temperature of the first temperature sensor and the gas flow equation of the electric compressor, calculate the actual EGR flow.

[0029] Optionally, when the engine is in a non-shutdown state, the operating state of the electric supercharger is adjusted according to the parameters in the electric supercharger module and the engine operating parameters provided by the engine ECU to control the EGR flow rate, including:

[0030] When the engine is in a non-shutdown state, obtain the magnitude of the target EGR flow rate;

[0031] When the target EGR flow rate is 0, control the gas at the output end of the electric supercharger to return to the input end of the electric supercharger, and at the same time control the rotational speed of the drive motor to the idling state and maintain the self-circulation mode of the electric supercharger;

[0032] When the target EGR flow rate is not 0, control the gas at the output end of the electric supercharger to be transmitted to the intake mechanism, compare the actual EGR flow rate with the target EGR flow rate, and when the actual EGR flow rate is equal to the target EGR flow rate, maintain the rotational speed of the drive motor. When the actual EGR flow rate is not equal to the target EGR flow rate, adjust the rotational speed of the drive motor until the actual EGR flow rate is equal to the target EGR flow rate.

[0033] Optionally, the electric supercharger module includes an electronically controlled three-way valve. When the target EGR flow rate is 0, the electronically controlled three-way valve switches to the second channel, so that the gas at the output end of the electric supercharger returns to the input end of the electric supercharger; when the target EGR flow rate is not 0, the electronically controlled three-way valve switches to the first channel, so that the gas at the output end of the electric supercharger is transmitted to the intake mechanism.

[0034] Optionally, the electric supercharger module includes a first switching valve and a second switching valve. When the target EGR flow rate is 0, the first switching valve is closed and the second switching valve is opened, so that the gas at the output end of the electric supercharger returns to the input end of the electric supercharger; when the target EGR flow rate is not 0, the first switching valve is opened and the second switching valve is closed, so that the gas at the output end of the electric supercharger is transmitted to the intake mechanism.

[0035] Optionally, the EGR system further includes a first EGR cooler, and the electric supercharger module further includes a second EGR cooler, a first coolant flow control valve, and a second coolant flow control valve; the control method further includes:

[0036] When the engine is operating or the ambient temperature is higher than the first preset temperature, the EGR controller controls the opening degree of the first coolant flow control valve so that the temperature of the first temperature sensor is greater than the second preset temperature;

[0037] When the temperature of the first temperature sensor is greater than or equal to the second preset temperature, the EGR controller controls to maintain the current opening degree of the first coolant flow control valve; when the temperature of the first temperature sensor is less than the second preset temperature, the EGR controller controls to adjust the opening degree of the first coolant flow control valve until the temperature of the first temperature sensor is greater than or equal to the second preset temperature, and simultaneously controls the second coolant flow control valve to be fully open;

[0038] When the engine is in a shutdown state and the ambient temperature is lower than the first preset temperature, the EGR controller controls the opening degrees of the first coolant flow control valve and the second coolant flow control valve so that the temperature of the first temperature sensor is greater than or equal to the second preset temperature, the temperature of the second temperature sensor is greater than or equal to the third preset temperature, and after maintaining operation for a preset time, the engine shuts down;

[0039] When the temperature of the first temperature sensor is greater than or equal to the second preset temperature and the temperature of the second temperature sensor is greater than or equal to the third preset temperature, the EGR controller controls to maintain the current opening degrees of the first coolant flow control valve and the second coolant flow control valve; when the temperature of the first temperature sensor is less than the second preset temperature and the temperature of the second temperature sensor is less than the third preset temperature, the EGR controller controls to adjust the opening degrees of the first coolant flow control valve and the second coolant flow control valve until the temperature of the first temperature sensor is greater than or equal to the second preset temperature and the temperature of the second temperature sensor is greater than or equal to the third preset temperature;

[0040] Wherein, the second preset temperature is greater than the third preset temperature, and the third preset temperature is greater than the first preset temperature.

[0041] According to another aspect of the present invention, a vehicle is provided, including the above EGR system.

[0042] The EGR system provided by the embodiment of the present invention includes an engine module, an electromechanical coupling supercharger module, and an electric compressor module. The engine module includes an engine body, an engine ECU, an intake mechanism, and an exhaust mechanism. The input end of the electric compressor module is connected to the exhaust mechanism, and the output end of the electric compressor module is connected to the intake mechanism. The electric compressor module introduces a part of the exhaust gas discharged from the exhaust mechanism into the intake mechanism to achieve EGR. The electric compressor module includes an EGR controller and an electric compressor. The EGR controller adjusts the working state of the electric compressor according to the parameters in the electric compressor module and the engine operation parameters provided by the engine ECU to control the EGR flow rate. The electromechanical coupling supercharger module includes a compressor, a turbine, a bidirectional motor, an exhaust gas bypass valve, and a battery. Both the turbine and the exhaust gas bypass valve are connected to the exhaust mechanism. The compressor is connected to the turbine through the bidirectional motor. The bidirectional motor is used to operate in the motor mode or the generator mode according to the engine working conditions. In the motor mode, the battery is used to supply power to the electric compressor, and the bidirectional motor drives the turbine and the compressor to increase the rotational speed through the rotating shaft to improve the economy. In the generator mode, the bidirectional motor supplies power to the electric compressor to drive the electric compressor to work, and can also charge the battery when the SOC of the battery is low. Compared with the prior art, the EGR system provided by the embodiment of the present invention uses the electromechanical coupling supercharger module to achieve energy recovery, thereby meeting the power supply requirements of all electrical equipment on the electric compressor module, the electromechanical coupling supercharger module, and the engine module, avoiding the reduction of the engine efficiency caused by adding the electric compressor module, and at the same time improving the responsiveness. It is beneficial to improve the engine thermal efficiency, the economy and the responsiveness of the engine. Moreover, it simplifies the layout of the EGR system, which is beneficial to reducing the system cost. By using the electric compressor module, the automatic calculation and precise control of the EGR flow rate are realized. Compared with the low-pressure EGR system, the venturi tube, the one-way valve, and the electric EGR valve are cancelled, and the structure of the patent solution is simpler, which is beneficial to reducing the system cost. By using the electric compressor, the independent control of the EGR flow rate can be realized, decoupling the EGR flow rate from the intake control, which is beneficial to achieving high EGR rate control under all Map working conditions of the engine. Compared with the traditional natural gas engine, in order to take into account all working conditions of the engine and avoid the problems of insufficient EGR rate and high knock risk in common working conditions, methods such as reducing the EGR rate, using a low-performance supercharger, and throttle throttling are adopted. By using this solution, a high-efficiency supercharger can be matched to increase the intake pressure, which is beneficial to improving the economy, power performance, and reliability of the engine.

[0043] It should be understood that the content described in this part is not intended to identify the key or important features of the embodiments of the present invention, nor is it used to limit the scope of the present invention. Other features of the present invention will become easily understood through the following description. Description of the Drawings

[0044] To more clearly illustrate the technical solutions in this embodiment, the following will briefly introduce the accompanying drawings required in the description of the embodiment. Obviously, the accompanying drawings in the following description are only some embodiments of the present invention. For those of ordinary skill in the art, without creative efforts, other accompanying drawings can be obtained based on these drawings.

[0045] Figure 1 It is a schematic structural diagram of an EGR system provided by an embodiment of the present invention;

[0046] Figure 2 It is a schematic structural diagram of another EGR system provided by an embodiment of the present invention;

[0047] Figure 3 It is a schematic flowchart of a control method for an EGR system provided by an embodiment of the present invention;

[0048] Figure 4 It is a schematic flowchart of another control method for EGR provided by an embodiment of the present invention. Detailed implementation manners

[0049] To enable those skilled in the art of this technology to better understand this solution, the following will clearly and completely describe the technical solutions in the embodiments of the present invention in conjunction with the accompanying drawings in the embodiments of the present invention. Obviously, the described embodiments are only some of the embodiments of the present invention, rather than all of them. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative efforts shall fall within the scope of protection of the present invention.

[0050] It should be noted that the terms "first", "second", etc. in the specification and claims of the present invention and the above accompanying drawings are used to distinguish similar objects, and do not necessarily need to be used to describe a specific order or sequence. It should be understood that such data can be interchanged under appropriate circumstances so that the embodiments of the present invention described here can be implemented in an order other than those illustrated or described here. In addition, the terms "including" and "having" and any variations thereof are intended to cover non-exclusive inclusion. For example, a process, method, system, product or device that includes a series of steps or units does not necessarily have to be limited to those clearly listed steps or units, but may include other steps or units not clearly listed or inherent to these processes, methods, products or devices.

[0051] Figure 1 It is a schematic structural diagram of an EGR system provided by an embodiment of the present invention, referring to Figure 1, the EGR system includes an engine module 20, an electromechanical coupling supercharger module 30, and an electric compressor module 4. The engine module 20 includes an engine body 1, an engine ECU 13, an intake mechanism, and an exhaust mechanism. The intake mechanism includes an intake manifold 12, and the exhaust mechanism includes an exhaust manifold 2. The input end of the electric compressor module 4 is connected to the exhaust mechanism (an output end of the exhaust manifold 2), and the output end of the electric compressor module 4 is connected to the intake mechanism (an input end of the intake manifold 12). The electric compressor module 4 includes an EGR controller 401 and an electric compressor 407. The EGR controller 401 is used to adjust the working state of the electric compressor 407 to control the EGR flow rate. The electromechanical coupling supercharger module 30 includes a compressor 8, a turbine 5, a bidirectional motor 412, an exhaust gas bypass valve 413, and a storage battery 14. The turbine 5 and the exhaust gas bypass valve 413 are both connected to the exhaust mechanism. The compressor 8 is connected to the turbine 5 through the bidirectional motor 412. The bidirectional motor 412 is used to operate in the motor mode or the generator mode according to the engine operating conditions.

[0052] Among them, the engine module 20 in the EGR system can be a natural gas engine. Fresh air enters the engine body 1 from the intake mechanism. The engine body 1 is used to burn natural gas to do work and discharge exhaust gas from the exhaust mechanism. The engine body 1 includes a plurality of cylinders. Figure 1 It is schematically shown in [the figure] that the engine body 1 includes 6 cylinders, which is not a limitation of the present invention. The engine ECU 13, that is, the Electronic Control Unit, can also be called the "vehicle computer" and is the most important part determining the performance of the whole vehicle. As one of the core components of modern automotive electronics, there may be multiple ECUs in a vehicle, each managing different functions; and there is information exchange between each ECU. Although the control system on the whole vehicle is becoming more and more complex, it still must have the most basic structure - a microprocessor (CPU), a memory (ROM, RAM), an input / output interface (I / O), an analog-to-digital converter (AD), and large-scale integrated circuits such as shaping and driving. The engine ECU 13 is used to control the engine operation and collect various operation parameters during the engine operation. The electric compressor 407 is arranged in the electric compressor module 4 to achieve the EGR function. The EGR controller 401 adjusts the electric compressor 407 to output different pressures according to the parameters in the electric compressor module 4 and the engine operation parameters provided by the engine ECU 13, thereby controlling the EGR flow rate. The specific control method can refer to the following embodiments.

[0053] In the electromechanical coupling supercharger module 30, the exhaust gas passes through the exhaust manifold 2 and is divided into three paths. One path enters the electric compressor 407 to achieve EGR, one path enters the turbine 5 to achieve turbocharging, and one path enters the exhaust gas bypass valve 413 and is discharged. The turbine 5 drives the compressor 8 to rotate through a rotating shaft, and a bidirectional motor 412 is installed on the rotating shaft. The EGR controller 401 controls the bidirectional motor 412 and the exhaust gas bypass valve 413. Optionally, the control ends of the electric compressor 407, the engine ECU 13, the bidirectional motor 412, and the exhaust gas bypass valve 413 are all connected to the EGR controller 401. The EGR controller 401 judges the engine working condition according to the information provided by the engine ECU 13. When the engine is in the acceleration working condition, the EGR controller 401 controls the exhaust gas bypass valve 413 to close, and at the same time controls the bidirectional motor 412 to work in the motor mode. The bidirectional motor 412 drives the turbine 5 and the compressor 8 to increase the speed through the rotating shaft to improve the economy; when the engine is in the steady-state working condition, the EGR controller 401 obtains the SOC of the battery 14. When the SOC is greater than or equal to the first threshold, the EGR controller 401 controls the opening of the exhaust gas bypass valve 413 according to the engine working condition requirements and controls the bidirectional motor 412 to work in the generator mode. The bidirectional motor 412 supplies power to the electric compressor 407; when the SOC is less than the first threshold, the EGR controller 401 closes the exhaust gas bypass valve 413 according to the engine working condition requirements and controls the bidirectional motor 412 to work in the generator mode. The bidirectional motor 412 supplies power to the electric compressor 407 and charges the battery 14 at the same time.

[0054] Among them, when the engine is in the acceleration condition, the engine needs to output greater power. At this time, a higher intake pressure is required from the supercharger. At this time, the EGR controller 401 controls the waste gas bypass valve 413 to close, so that more waste gas passes through the turbine 5 to increase the rotational speed of the turbine 5. At the same time, it controls the bidirectional motor 412 to work as a motor, and drives the turbine 5 and the compressor 8 to quickly increase their rotational speeds through the rotating shaft, so as to improve the economy and thus enhance the engine responsiveness. At this time, in addition to supplying power to the EGR controller 401, the engine ECU 13 and other electrical devices on the engine, the storage battery 14 also supplies power to the electric compressor 407. The storage battery 14 can also provide the battery state signals to the EGR controller, including: state of charge (SOC), voltage, current and temperature. When the engine is operating in the steady-state condition, the EGR controller 401 judges the SOC of the storage battery 14. When the SOC is greater than or equal to the first threshold value, where the first threshold value can be set according to actual requirements, such as 95%, 90%, etc., when the SOC is greater than or equal to the first threshold value, it can be determined that the storage battery 14 does not need to be charged. At this time, the EGR controller 401 controls the opening degree of the waste gas bypass valve 413 according to the engine condition requirements, and controls the bidirectional motor 412 to work as a generator to supply power to the electric compressor 407 and drive the electric compressor 407 to work to provide the EGR flow required by the EGR system; when the SOC is less than the first threshold value, the EGR controller 401 closes the waste gas bypass valve 413 according to the engine condition requirements, and controls the bidirectional motor 412 to work as a generator to supply power to the electric compressor 407 and drive the electric compressor 407 to work to provide the EGR flow required by the EGR system, and simultaneously charges the storage battery 14.

[0055] Compared with the prior art, the EGR system provided by the embodiments of the present invention uses an electromechanical coupling supercharger module to achieve energy recovery, thereby meeting the power supply requirements of all electrical equipment on the electric compressor module, the electromechanical coupling supercharger module, and the engine module. It can avoid the reduction of engine efficiency caused by adding an electric compressor module, and at the same time improve the responsiveness. It is beneficial to improve the engine thermal efficiency, economy and responsiveness. Moreover, it simplifies the layout of the EGR system, which is beneficial to reducing the system cost. By using an electric compressor module, automatic calculation and precise control of the EGR flow are realized. Compared with the low-pressure EGR system, the venturi tube, check valve, and electric EGR valve are eliminated. The structure of this patent solution is simpler, which is beneficial to reducing the system cost. Using an electric compressor can achieve independent control of the EGR flow, decouple the EGR flow from the intake control, and is beneficial to achieving high EGR rate control under all Map operating conditions of the engine. Compared with traditional natural gas engines, in order to take into account all operating conditions of the engine and avoid problems such as insufficient EGR rate and high knocking risk in common operating conditions, methods such as reducing the EGR rate, using a low-performance supercharger, and throttle throttling are adopted. With this solution, a high-efficiency supercharger can be matched to increase the intake pressure, which is beneficial to improving the economy, power performance, responsiveness and reliability of the engine.

[0056] Continue to refer to Figure 1 , optionally, the electric compressor module 4 further includes a drive motor 406, an electronically controlled three-way valve 408, a first pressure sensor 404, a second pressure sensor 405, a first temperature sensor 403, and a second temperature sensor 410; the control end of the drive motor 406, the control end of the electronically controlled three-way valve 408, the first pressure sensor 404, the second pressure sensor 405, the first temperature sensor 403, and the second temperature sensor 410 are all connected to the EGR controller 401. The drive motor 406 is used to drive the electric compressor 407 to operate. The input end of the electric compressor 407 is connected to the exhaust manifold 2 of the exhaust mechanism, the output end of the electric compressor 407 is connected to the input end of the electronically controlled three-way valve 408, the first output end of the electronically controlled three-way valve 408 is connected to the intake mechanism, the second output end of the electronically controlled three-way valve 408 is connected to the input end of the electric compressor 407, the first pressure sensor 404 and the first temperature sensor 403 are arranged at the input end of the electric compressor 407, the second pressure sensor 405 is arranged at the output end of the electric compressor 407, and the second temperature sensor 410 is arranged at the first output end of the electronically controlled three-way valve 408.

[0057] Among them, the first pressure sensor 404 is used to measure the pressure at the input end of the electric compressor 407 and transmit it to the EGR controller 401. The second pressure sensor 405 is used to measure the pressure at the output end of the electric compressor 407 and transmit it to the EGR controller 401. The first temperature sensor 403 is used to measure the temperature at the input end of the electric compressor 407 (the exhaust gas temperature before EGR) and transmit it to the EGR controller 401. The second temperature sensor 410 is used to measure the temperature at the first output end of the electronically controlled three-way valve 408 (the temperature of the gas entering the intake mechanism during EGR) and transmit it to the EGR controller 401. The drive motor 406 can be a high-speed DC motor, which has the functions of a motor (maintaining or accelerating the speed) and a generator (decelerating). Adjusting the speed of the drive motor 406 can adjust the pressure at the output end of the electric compressor 407, realizing the pressure adjustment of the electric compressor module 4. The electronically controlled three-way valve 408 includes an input end and two output ends. The input end is connected to the output end of the electric compressor 407. The first output end is connected to the intake mechanism, and the second output end is connected to the input end of the electric compressor 407, thus forming two channels. When EGR is required, the gas output by the electric compressor 407 is transmitted to the intake mechanism through the electronically controlled three-way valve 408. When EGR is not required, the gas output by the electric compressor 407 returns to the input end of the electric compressor 407 through the electronically controlled three-way valve 408.

[0058] Continue to refer to Figure 1 , optionally, the EGR system further includes a first EGR cooler 3. The electric compressor module 4 further includes a second EGR cooler 409, a first coolant flow control valve 402, and a second coolant flow control valve 411. The control ends of the first coolant flow control valve 402 and the second coolant flow control valve 411 are both connected to the EGR controller 401. The input end of the electric compressor 407 is connected to the exhaust manifold 2 of the exhaust mechanism through the first EGR cooler 401. The first output end of the electronically controlled three-way valve 408 is connected to the intake mechanism through the second EGR cooler 409. The second temperature sensor 410 is arranged at the output end of the second EGR cooler 409. The input end of the first coolant flow control valve 402 is connected to the engine cooling circuit, and the coolant returns to the engine cooling circuit after passing through the first EGR cooler 3; the input end of the second coolant flow control valve 411 is connected to the engine cooling circuit, and the coolant returns to the engine cooling circuit after passing through the second EGR cooler 409.

[0059] Among them, the first EGR cooler 3 is used to control the temperature of the exhaust gas input into the electric supercharger 407. The first EGR cooler 3 is connected to the engine's cooling circuit through the first coolant flow control valve 402. When the opening degree of the first coolant flow control valve 402 changes, the coolant flow rate through the first EGR cooler 3 is different, and different cooling capabilities of the first EGR cooler 3 can be adjusted. The second EGR cooler 409 is used to adjust the temperature of the gas entering the intake mechanism through EGR. The second EGR cooler 409 is connected to the engine's cooling circuit through the second coolant flow control valve 411. When the opening degree of the second coolant flow control valve 411 changes, the coolant flow rate through the second EGR cooler 409 is different, and different cooling capabilities of the second EGR cooler 409 can be adjusted. The opening degrees of the first coolant flow control valve 402 and the second coolant flow control valve 411 are controlled by the EGR controller 401.

[0060] The EGR system provided by the embodiment of the present invention adopts an electric supercharger module, which is beneficial to improving the reliability, EGR responsiveness and control accuracy of the electric supercharger assembly. By using an electronically controlled three-way valve to switch the air flow channel and a high-speed DC motor with the functions of a motor and a generator, it can ensure that the drive motor does not stop during the operation of the engine, thus solving the reliability problem caused by the repeated start and stop of the electric supercharger and the problem of low EGR responsiveness speed. In addition, precise control of the temperature of the EGR circuit is achieved through the first coolant flow control valve and the second coolant flow control valve, so that the gas in the EGR circuit is always at an appropriate temperature, which is beneficial to improving the reliability and economy of the system.

[0061] Figure 2 is a schematic structural diagram of another EGR system provided by the embodiment of the present invention. Refer to Figure 2, the EGR system includes an engine module 20, an electromechanical coupling supercharger module 30, and an electric compressor module 4. The engine module 20 includes an engine body 1, an engine ECU 13, an intake mechanism, and an exhaust mechanism. The intake mechanism includes an intake manifold 12, and the exhaust mechanism includes an exhaust manifold 2. The input end of the electric compressor module 4 is connected to the exhaust mechanism (an output end of the exhaust manifold 2), and the output end of the electric compressor module 4 is connected to the intake mechanism (an input end of the intake manifold 12); the electric compressor module 4 includes an EGR controller 401 and an electric compressor 407. Both the electric compressor 407 and the engine ECU 13 are connected to the EGR controller 401. The electromechanical coupling supercharger module 30 includes a compressor 8, a turbine 5, a bidirectional motor 412, an exhaust gas bypass valve 413, and a storage battery 14. Optionally, the electric compressor module 4 further includes a drive motor 406, a first switching valve 414, a second switching valve 415, a first pressure sensor 404, a second pressure sensor 405, a first temperature sensor 403, and a second temperature sensor 410; the control end of the drive motor 406, the control end of the first switching valve 414, the control end of the second switching valve 415, the first pressure sensor 404, the second pressure sensor 405, the first temperature sensor 403, and the second temperature sensor 410 are all connected to the EGR controller 401. The drive motor 406 is used to drive the electric compressor 407 to operate. The input end of the electric compressor 407 is connected to the exhaust manifold 2 of the exhaust mechanism. The input ends of the first switching valve 414 and the second switching valve 415 are both connected to the output end of the electric compressor 407. The output end of the first switching valve 414 is connected to the intake mechanism. The output end of the second switching valve 405 is connected to the input end of the electric compressor 407. The first pressure sensor 404 and the first temperature sensor 403 are arranged at the input end of the electric compressor 407. The second pressure sensor 405 is arranged at the output end of the electric compressor 407. The second temperature sensor 410 is arranged at the output end of the first switching valve 414.

[0062] Among them, Figure 2 The difference between the shown embodiment and Figure 1 the shown embodiment is that the electronically controlled three-way valve 408 is replaced by a first switching valve 414 and a second switching valve 415, and the other structures are the same. The same parts as the foregoing embodiments will not be described in detail here. When EGR is required, the EGR controller 401 controls the first switching valve 414 to open and the second switching valve 415 to close. The gas output by the electric compressor 407 is transmitted to the intake mechanism through the first switching valve 414. When EGR is not required, the EGR controller 401 controls the first switching valve 414 to close and the second switching valve 415 to open. The gas output by the electric compressor 407 returns to the input end of the electric compressor 407 through the second switching valve 415.

[0063] Continue to refer toFigure 2 , optionally, the EGR system further includes a first EGR cooler 3, and the electric supercharger module 4 further includes a second EGR cooler 409, a first coolant flow control valve 402, and a second coolant flow control valve 411. The control ends of the first coolant flow control valve 402 and the second coolant flow control valve 411 are both connected to the EGR controller 401. The input end of the electric supercharger 407 is connected to the exhaust manifold 2 of the exhaust mechanism through the first EGR cooler 3. The output end of the first switching valve 414 is connected to the intake mechanism through the second EGR cooler 409. The second temperature sensor 410 is disposed at the output end of the second EGR cooler 409. The input end of the first coolant flow control valve 402 is connected to the engine cooling circuit, and the coolant returns to the engine cooling circuit after passing through the first EGR cooler 3; the input end of the second coolant flow control valve 411 is connected to the engine cooling circuit, and the coolant returns to the engine cooling circuit after passing through the second EGR cooler 409.

[0064] Continue to refer to Figure 1 or Figure 2 , optionally, the intake mechanism includes an air filter 7, an intercooler 9, a throttle valve 10, a mixer 11, and an intake manifold 12. The output end of the air filter 7 is connected to the input end of the supercharger 8. The output end of the supercharger 8 is connected to the input end of the intercooler 9. The output end of the intercooler 9 is connected to the first input end of the mixer 11. The output end of the second EGR cooler 409 is connected to the second input end of the mixer 11. The output end of the mixer 11 is connected to the intake manifold 12. The throttle valve 10 is disposed between the intercooler 9 and the mixer 11; the exhaust mechanism includes an exhaust manifold 2 and a post-processor 6. The first output end of the exhaust manifold 2 is connected to the input end of the electric supercharger 407. The second output end of the exhaust manifold 2 is connected to the input end of the post-processor 6 through the turbine 5. The third output end of the exhaust manifold 2 is connected to the input end of the post-processor 6 through the waste gas bypass valve 413.

[0065] Among them, the air filter 7 is used to filter the outside air sucked by the engine to prevent impurities in the air from damaging the engine cylinders. The intercooler 9 is used to cool the supercharged gas. The throttle valve 10 is used to adjust the intake air flow. The mixer 11 mixes the air sucked by the engine from the outside and the gas in the EGR and transmits it to the intake manifold 12. The exhaust manifold 2 is provided with three channels. The first channel is connected to the electric supercharger 407 through the first EGR cooler 3 and is used to supply exhaust gas to the EGR circuit. The second channel is connected to the turbine 5. The exhaust gas drives the turbine 5 to rotate, and the exhaust gas passes through the exhaust port of the turbine 5 and is connected to the post-processor 6. The third channel is connected to the post-processor 6 through the waste gas bypass valve 413. The post-processor 6 may include structures such as an oxidation catalyst, a particulate trap, and a selective catalytic reduction device, and can be designed according to actual situations during specific implementation.

[0066] Based on the EGR system provided in the above embodiments, an embodiment of the present invention further provides a control method for an EGR system. Figure 3 As shown in the flowchart of a control method for an EGR system provided by an embodiment of the present invention, which is applicable to the EGR system provided in the above embodiments, refer to Figure 3 , the control method includes:

[0067] S110. Obtain the parameters in the electric supercharger module and the engine operating parameters provided by the engine ECU.

[0068] Among them, the parameters in the electric supercharger module are the parameters inside the module during the operation of the electric supercharger module, which may include the pressure and temperature at the input end of the electric supercharger, the pressure and temperature at the output end of the electric supercharger, etc. The engine operating parameters may include the throttle pedal position, the engine speed, the intake air flow rate, the intake air pressure, etc.

[0069] S120. Determine the operating state of the engine according to the engine operating parameters, control the bidirectional motor to operate in the motor mode or the generator mode according to the operating state of the engine. When the engine is in a non-shutdown state, adjust the operating state of the electric supercharger according to the parameters in the electric supercharger module and the engine operating parameters provided by the engine ECU to control the EGR flow rate.

[0070] Among them, optionally, controlling the bidirectional motor to operate in the motor mode or the generator mode according to the operating state of the engine includes:

[0071] When the engine is in an acceleration condition, the EGR controller controls the exhaust gas bypass valve to close, and at the same time controls the bidirectional motor to operate in the motor mode. The bidirectional motor drives the turbine and the compressor to increase the speed through the rotating shaft to improve the economy.

[0072] When the engine is in a steady-state condition, the EGR controller obtains the SOC of the battery. When the SOC is greater than or equal to the first threshold, the EGR controller controls the opening of the exhaust gas bypass valve according to the engine condition requirements and controls the bidirectional motor to operate in the generator mode. The bidirectional motor supplies power to the electric supercharger. When the SOC is less than the first threshold, the EGR controller closes the exhaust gas bypass valve according to the engine condition requirements, controls the bidirectional motor to operate in the generator mode, the bidirectional motor supplies power to the electric supercharger, and at the same time charges the battery.

[0073] The working mode of the bidirectional motor can refer to the foregoing embodiments and will not be elaborated here.

[0074] When the engine is not in the shutdown state, the engine runs normally, and the EGR demand of the engine is judged according to the parameters in the electric compressor module and the engine operation parameters provided by the engine ECU. When the required EGR rate is relatively high, the compression ratio of the electric compressor is controlled to be relatively large. When the required EGR rate is relatively low, the compression ratio of the electric compressor is controlled to be relatively small. When EGR is not required, the electric compressor is controlled to self-circulate, and the output gas returns to the input end.

[0075] The control method of the EGR system provided by the embodiment of the present invention uses an electromechanical coupling supercharger module to realize energy recovery, thereby meeting the power supply requirements of all electrical equipment on the electric compressor module, the electromechanical coupling supercharger module, and the engine module, and can avoid the reduction of engine efficiency caused by adding an electric compressor module. It is beneficial to improve the engine thermal efficiency and enhance the economy and responsiveness of the engine. Using an electric compressor can realize independent control of the EGR flow rate, decouple the EGR flow rate from the intake control, and is beneficial to realizing high EGR rate control under all Map working conditions of the engine. Compared with traditional natural gas engines, in order to take into account all working conditions of the engine and avoid problems such as insufficient EGR rate and high knocking risk in common working conditions, methods such as reducing the EGR rate, using a low-performance supercharger, and throttle throttling are adopted. By adopting this solution, a high-efficiency supercharger can be matched to increase the intake pressure, which is beneficial to improving the economy, power performance, responsiveness, and reliability of the engine.

[0076] Optionally, referring to Figure 1 or Figure 2 , the electric compressor module 4 includes a drive motor 406, a first pressure sensor 404, a second pressure sensor 405, a first temperature sensor 403, and a second temperature sensor 410. Obtaining the parameters in the electric compressor module and the engine operation parameters provided by the engine ECU includes:

[0077] Obtaining the signals collected by the first pressure sensor, the second pressure sensor, the first temperature sensor, the second temperature sensor, the current speed of the drive motor, and the throttle pedal position, engine speed, intake air flow, intake manifold pressure sensor signal P1, and target EGR flow rate Q issued by the engine ECU 目标 .

[0078] Among them, the first pressure sensor 404 is used to measure the pressure at the input end of the electric compressor 407, the second pressure sensor 405 is used to measure the pressure at the output end of the electric compressor 407, the first temperature sensor 403 is used to measure the temperature at the input end of the electric compressor 407 (the exhaust gas temperature before EGR), the second temperature sensor 410 is used to measure the temperature at the output end of the electric compressor 407 (the temperature of the gas entering the intake mechanism after EGR), and the target EGR flow rate Q 目标 can be pre-calibrated according to the specific engine model.

[0079] Figure 4 Schematic diagram of another EGR control method provided by an embodiment of the present invention, refer to Figure 4 , the control method includes:

[0080] S210. Obtain the parameters in the electric supercharger module and the engine operating parameters provided by the engine ECU.

[0081] Among them, the parameters in the electric supercharger module include the signals collected by the first pressure sensor, the second pressure sensor, the first temperature sensor, the second temperature sensor, the current speed of the drive motor, the throttle pedal position, the engine speed, the intake air flow rate, the intake manifold pressure sensor signal P1 and the target EGR flow rate Q provided by the engine ECU 目标 .

[0082] S220. According to the intake manifold pressure sensor signal, calculate the target boost pressure of the electric supercharger in combination with the calibration Map of the flow rate and pressure loss between the electric supercharger and the intake manifold.

[0083] Among them, the calibration Map of the flow rate and pressure loss between the electric supercharger and the intake manifold can be pre-calibrated using an engine test bench, and the target boost pressure P2 can be obtained by looking up the Map according to the foregoing parameters.

[0084] S230. Calculate the target speed of the drive motor according to the target EGR flow rate, the pressure of the first pressure sensor, the target boost pressure, the temperature of the first temperature sensor, and the gas flow equation of the gas flowing through the electric supercharger, and adjust the current speed of the drive motor to the target speed.

[0085] According to the target EGR flow rate Q 目标 , the pressure P3 of the first pressure sensor, the target boost pressure P2, and the temperature T of the first temperature sensor in , combined with the gas flow equation Q = f(p3, p2, n, T in )(the gas flow rate is a function related to pressure, speed, and temperature, and the specific expression can be calibrated according to the actual situation), the target speed n of the drive motor can be calculated, and the current speed of the drive motor can be adjusted to the target speed.

[0086] S240. Calculate the actual EGR flow rate according to the pressure of the first pressure sensor, the pressure of the second pressure sensor, the temperature of the first temperature sensor, and the gas flow equation of the gas flowing through the electric supercharger.

[0087] It can be understood that since there may be deviations during actual operation, it is necessary to further calculate the actual EGR flow rate Q according to the pressure of the first pressure sensor, the pressure of the second pressure sensor, the temperature of the first temperature sensor, and the gas flow equation of the gas flowing through the electric supercharger实际 。

[0088] S250. When the engine is in a non-shutdown state, obtain the magnitude of the target EGR flow rate.

[0089] S261. When the target EGR flow rate is 0, control the gas at the output end of the electric compressor to return to the input end of the electric compressor, and at the same time control the rotational speed of the drive motor to the idling state and maintain the self-circulation mode of the electric compressor.

[0090] Among them, when the target EGR flow rate Q 目标 = 0, it indicates that the working condition at this time does not require EGR. At this time, control the gas at the output end of the electric compressor to return to the input end of the electric compressor. By maintaining the self-circulation mode of the electric compressor, the repeated start and stop of the electric compressor can be avoided, and the system reliability can be improved.

[0091] S262. When the target EGR flow rate is not 0, control the gas at the output end of the electric compressor to be transmitted to the intake mechanism, compare the actual EGR flow rate with the target EGR flow rate. When the actual EGR flow rate is equal to the target EGR flow rate, maintain the rotational speed of the drive motor. When the actual EGR flow rate is not equal to the target EGR flow rate, adjust the rotational speed of the drive motor until the actual EGR flow rate is equal to the target EGR flow rate.

[0092] Among them, when the target EGR flow rate Q 目标 ≠ 0, it indicates that the working condition at this time requires EGR. Control the gas at the output end of the electric compressor to be transmitted to the intake mechanism, and compare the actual EGR flow rate Q 实际 with the target EGR flow rate Q 实际 , when Q 实际 = Q 目标 , maintain the rotational speed of the drive motor. When Q 实际 ≠ Q 目标 , adjust the rotational speed of the drive motor until Q 实际 = Q 目标 .

[0093] In an embodiment, referring to Figure 1 , optionally, the electric compressor module 4 includes an electronically controlled three-way valve 408. When the target EGR flow rate is 0, the electronically controlled three-way valve 408 switches to the second channel, so that the gas at the output end of the electric compressor 407 returns to the input end of the electric compressor 407; when the target EGR flow rate is not 0, the electronically controlled three-way valve 408 switches to the first channel, so that the gas at the output end of the electric compressor 407 is transmitted to the intake mechanism.

[0094] In another embodiment, referring to Figure 2Optionally, the electric compressor module 4 includes a first switching valve 414 and a second switching valve 415. When the target EGR flow rate is 0, the first switching valve 414 is closed and the second switching valve 415 is opened, so that the gas at the output end of the electric compressor 407 returns to the input end of the electric compressor 407; when the target EGR flow rate is not 0, the first switching valve 414 is opened and the second switching valve 415 is closed, so that the gas at the output end of the electric compressor 407 is transmitted to the intake mechanism.

[0095] This embodiment uses an electronically controlled three-way valve or two switching valves to switch the air flow channel, and a high-speed DC motor with motor and generator functions as a driving motor, which can ensure that the motor never stops during engine operation, thereby solving the reliability problem caused by repeated starting and stopping of the electric compressor, and the problem of low EGR responsiveness speed.

[0096] refer to Figure 1 or Figure 2 Optionally, the EGR system further includes a first EGR cooler 3, and the electric compressor module 4 further includes a second EGR cooler 409, a first coolant flow control valve 402, and a second coolant flow control valve 411; the EGR system control method provided by the embodiment of the present invention further includes:

[0097] When the engine is running or the ambient temperature is higher than the first preset temperature, the EGR controller controls the opening of the first coolant flow control valve so that the temperature of the first temperature sensor is greater than the second preset temperature. The EGR controller controls the second coolant flow control valve to be fully opened so that the second EGR cooler operates at maximum cooling capacity.

[0098] When the temperature of the first temperature sensor is greater than or equal to the second preset temperature, the EGR controller controls to maintain the current opening of the first coolant flow control valve; when the temperature of the first temperature sensor is less than the second preset temperature, the EGR controller controls to adjust the opening of the first coolant flow control valve until the temperature of the first temperature sensor is greater than or equal to the second preset temperature, and at the same time controls the second coolant flow control valve to be fully opened, and the second EGR cooler works at its maximum cooling capacity to reduce the temperature of the cooled EGR gas as much as possible, thereby fully improving the thermal efficiency of the engine.

[0099] When the engine is in a shutdown state and the ambient temperature is lower than a first preset temperature, the EGR controller controls the opening of the first coolant flow control valve and the second coolant flow control valve so that the temperature of the first temperature sensor is greater than or equal to the second preset temperature, the temperature of the second temperature sensor is greater than or equal to the third preset temperature, and the engine is shut down after maintaining operation for a preset time to prevent water vapor in the EGR gas from condensing into water and freezing at low temperatures, thereby causing system failure. The preset time can be calibrated according to actual conditions, and the embodiments of the present invention are not limited to this.

[0100] When the temperature sensed by the first temperature sensor is greater than or equal to the second preset temperature and the temperature sensed by the second temperature sensor is greater than or equal to the third preset temperature, the EGR controller controls to maintain the current opening degrees of the first coolant flow control valve and the second coolant flow control valve; when the temperature of the first temperature sensor is less than the second preset temperature and the temperature of the second temperature sensor is less than the third preset temperature, the EGR controller controls to adjust the opening degrees of the first coolant flow control valve and the second coolant flow control valve until the temperature of the first temperature sensor is greater than or equal to the second preset temperature and the temperature of the second temperature sensor is greater than or equal to the third preset temperature.

[0101] Wherein, the second preset temperature is greater than the third preset temperature, and the third preset temperature is greater than the first preset temperature. Their specific values can be calibrated according to actual situations, and the embodiments of the present invention do not limit this.

[0102] The technical solution of the embodiments of the present invention realizes precise control of the temperature of the EGR circuit through the first coolant flow control valve and the second coolant flow control valve, so that the gas in the EGR circuit is always at an appropriate temperature, which is beneficial to improving the reliability and economy of the system.

[0103] The embodiments of the present invention also provide a vehicle, including the EGR system provided in the above embodiments, where the vehicle includes but is not limited to passenger vehicles, commercial vehicles, industrial vehicles, agricultural machinery, etc.

[0104] Since the vehicle provided in the embodiments of the present invention includes the EGR system provided in the above embodiments and has the same or corresponding technical effects as the EGR system, it will not be elaborated here.

[0105] It should be understood that the various forms of the processes shown above can be used, and steps can be reordered, added or deleted. For example, the steps described in the present invention can be executed in parallel, sequentially or in different orders, as long as the desired results of the technical solution of the present invention can be achieved, and this is not limited herein.

[0106] The above specific embodiments do not constitute a limitation to the protection scope of the present invention. Those skilled in the art should understand that various modifications, combinations, sub - combinations and substitutions can be made according to design requirements and other factors. Any modifications, equivalent substitutions and improvements made within the spirit and principles of the present invention shall be included within the protection scope of the present invention.

Claims

1. An EGR system, characterized in that, It includes an engine module, an electromechanical coupling supercharger module and an electric compressor module. The engine module includes an engine body, an engine ECU, an intake mechanism and an exhaust mechanism. The input end of the electric compressor module is connected to the exhaust mechanism, and the output end of the electric compressor module is connected to the intake mechanism; The electric compressor module includes an EGR controller and an electric compressor. The EGR controller is used to adjust the working state of the electric compressor to control the EGR flow rate; The electromechanical coupling supercharger module includes a compressor, a turbine, a bidirectional motor, an exhaust gas bypass valve and a storage battery. The turbine and the exhaust gas bypass valve are both connected to the exhaust mechanism. The compressor is connected to the turbine through the bidirectional motor. The bidirectional motor is used to operate in the motor mode or the generator mode according to the engine working conditions.

2. The EGR system according to claim 1, characterized in that, The control ends of the electric compressor, the engine ECU, the bidirectional motor and the exhaust gas bypass valve are all connected to the EGR controller. The EGR controller judges the engine working conditions according to the information provided by the engine ECU. When the engine is in the acceleration working condition, the EGR controller controls the exhaust gas bypass valve to close, and at the same time controls the bidirectional motor to work in the motor mode. The bidirectional motor drives the turbine and the compressor to increase the speed through the rotating shaft to improve the economy; when the engine is in the steady-state working condition, the EGR controller obtains the SOC of the storage battery. When the SOC is greater than or equal to the first threshold, the EGR controller controls the opening of the exhaust gas bypass valve according to the engine working condition requirements and controls the bidirectional motor to work in the generator mode. The bidirectional motor supplies power to the electric compressor; when the SOC is less than the first threshold, the EGR controller closes the exhaust gas bypass valve according to the engine working condition requirements and controls the bidirectional motor to work in the generator mode. The bidirectional motor supplies power to the electric compressor and charges the storage battery at the same time.

3. The EGR system according to claim 1, characterized in that, The electric compressor module further includes a drive motor, an electronically controlled three-way valve, a first pressure sensor, a second pressure sensor, a first temperature sensor and a second temperature sensor; The control end of the drive motor, the control end of the electronically controlled three-way valve, the first pressure sensor, the second pressure sensor, the first temperature sensor and the second temperature sensor are all connected to the EGR controller. The drive motor is used to drive the electric compressor to operate. The input end of the electric compressor is connected to the exhaust manifold of the exhaust mechanism. The output end of the electric compressor is connected to the input end of the electronically controlled three-way valve. The first output end of the electronically controlled three-way valve is connected to the intake mechanism. The second output end of the electronically controlled three-way valve is connected to the input end of the electric compressor. The first pressure sensor and the first temperature sensor are arranged at the input end of the electric compressor. The second pressure sensor is arranged at the output end of the electric compressor. The second temperature sensor is arranged at the first output end of the electronically controlled three-way valve.

4. The EGR system according to claim 3, characterized in that, It further includes a first EGR cooler. The electric supercharger module further includes a second EGR cooler, a first coolant flow control valve, and a second coolant flow control valve. The control ends of the first coolant flow control valve and the second coolant flow control valve are both connected to the EGR controller. The input end of the electric supercharger is connected to the exhaust manifold of the exhaust mechanism through the first EGR cooler. The first output end of the electronic three-way valve is connected to the intake mechanism through the second EGR cooler. The second temperature sensor is arranged at the output end of the second EGR cooler. The input end of the first coolant flow control valve is connected to the engine cooling circuit, and the coolant returns to the engine cooling circuit after passing through the first EGR cooler; the input end of the second coolant flow control valve is connected to the engine cooling circuit, and the coolant returns to the engine cooling circuit after passing through the second EGR cooler.

5. The EGR system according to claim 1, characterized in that, The electric supercharger module further includes a drive motor, a first switching valve, a second switching valve, a first pressure sensor, a second pressure sensor, a first temperature sensor, and a second temperature sensor; The control end of the drive motor, the control end of the first switching valve, the control end of the second switching valve, the first pressure sensor, the second pressure sensor, the first temperature sensor, and the second temperature sensor are all connected to the EGR controller. The drive motor is used to drive the electric supercharger to operate. The input end of the electric supercharger is connected to the exhaust manifold of the exhaust mechanism. The input ends of the first switching valve and the second switching valve are both connected to the output end of the electric supercharger. The output end of the first switching valve is connected to the intake mechanism. The output end of the second switching valve is connected to the input end of the electric supercharger. The first pressure sensor and the first temperature sensor are arranged at the input end of the electric supercharger. The second pressure sensor is arranged at the output end of the electric supercharger. The second temperature sensor is arranged at the output end of the first switching valve.

6. The EGR system according to claim 5, characterized in that, It further includes a first EGR cooler. The electric supercharger module further includes a second EGR cooler, a first coolant flow control valve, and a second coolant flow control valve. The control ends of the first coolant flow control valve and the second coolant flow control valve are both connected to the EGR controller. The input end of the electric supercharger is connected to the exhaust manifold of the exhaust mechanism through the first EGR cooler. The output end of the first switching valve is connected to the intake mechanism through the second EGR cooler. The second temperature sensor is arranged at the output end of the second EGR cooler. The input end of the first coolant flow control valve is connected to the engine cooling circuit, and the coolant returns to the engine cooling circuit after passing through the first EGR cooler; the input end of the second coolant flow control valve is connected to the engine cooling circuit, and the coolant returns to the engine cooling circuit after passing through the second EGR cooler.

7. The EGR system according to claim 4 or 6, characterized in that, The intake mechanism includes an air filter, an intercooler, a throttle valve, a mixer, and an intake manifold. The output end of the air filter is connected to the input end of the compressor. The output end of the compressor is connected to the input end of the intercooler. The output end of the intercooler is connected to the first input end of the mixer. The output end of the second EGR cooler is connected to the second input end of the mixer. The output end of the mixer is connected to the intake manifold. The throttle valve is arranged between the intercooler and the mixer. The exhaust mechanism includes an exhaust manifold and a post-processor. The first output end of the exhaust manifold is connected to the input end of the electric compressor. The second output end of the exhaust manifold is connected to the input end of the post-processor through the turbine. The third output end of the exhaust manifold is connected to the input end of the post-processor through the exhaust gas bypass valve.

8. A control method for an EGR system, characterized in that, Applicable to the EGR system according to any one of claims 1 to 7, the control method includes: Obtain the parameters in the electric compressor module and the engine operation parameters provided by the engine ECU. Determine the operation state of the engine according to the engine operation parameters, control the bidirectional motor to work in the motor mode or the generator mode according to the operation state of the engine. When the engine is in a non-shutdown state, adjust the working state of the electric compressor according to the parameters in the electric compressor module and the engine operation parameters provided by the engine ECU to control the EGR flow rate.

9. The control method of the EGR system according to claim 8, characterized in that, Controlling the bidirectional motor to work in the motor mode or the generator mode according to the operation state of the engine includes: When the engine is in an acceleration condition, the EGR controller controls the exhaust gas bypass valve to close, and at the same time controls the bidirectional motor to work in the motor mode. The bidirectional motor drives the turbine and the compressor to increase the speed through the rotating shaft to improve the economy. When the engine is in a steady-state condition, the EGR controller obtains the SOC of the battery. When the SOC is greater than or equal to the first threshold, the EGR controller controls the opening degree of the exhaust gas bypass valve according to the engine condition requirements, and controls the bidirectional motor to work in the generator mode. The bidirectional motor supplies power to the electric compressor. When the SOC is less than the first threshold, the EGR controller closes the exhaust gas bypass valve according to the engine condition requirements, and controls the bidirectional motor to work in the generator mode. The bidirectional motor supplies power to the electric compressor and charges the battery at the same time.

10. The control method of the EGR system according to claim 8, characterized in that, The electric compressor module includes a drive motor, a first pressure sensor, a second pressure sensor, a first temperature sensor, and a second temperature sensor. Obtaining the parameters in the electric compressor module and the engine operation parameters provided by the engine ECU includes: Obtain the signals collected by the first pressure sensor, the second pressure sensor, the first temperature sensor, the second temperature sensor, the current speed of the drive motor, and the throttle pedal position, engine speed, intake air flow, intake manifold pressure sensor signal, and target EGR flow rate issued by the engine ECU.

11. The control method of the EGR system according to claim 10, characterized in that, After obtaining the parameters in the electric supercharger module and the engine operating parameters provided by the engine ECU, it further includes: According to the intake manifold pressure sensor signal, combined with the calibration Map of the flow rate and pressure loss of the pipeline between the electric supercharger and the intake manifold, calculate the target boost pressure of the electric supercharger; According to the target EGR flow rate, the pressure of the first pressure sensor, the target boost pressure, the temperature of the first temperature sensor, and the gas flow equation of the gas flowing through the electric supercharger, calculate the target speed of the drive motor, and adjust the current speed of the drive motor to the target speed; According to the pressure of the first pressure sensor, the pressure of the second pressure sensor, the temperature of the first temperature sensor, and the gas flow equation of the gas flowing through the electric supercharger, calculate the actual EGR flow rate.

12. The control method of the EGR system according to claim 11, characterized in that, When the engine is in a non-shutdown state, adjust the working state of the electric supercharger according to the parameters in the electric supercharger module and the engine operating parameters provided by the engine ECU to control the EGR flow rate, including: When the engine is in a non-shutdown state, obtain the magnitude of the target EGR flow rate; When the target EGR flow rate is 0, control the gas at the output end of the electric supercharger to return to the input end of the electric supercharger, and at the same time control the speed of the drive motor to the idling state, and maintain the self-circulation mode of the electric supercharger; When the target EGR flow rate is not 0, control the gas at the output end of the electric supercharger to be transmitted to the intake mechanism, compare the actual EGR flow rate with the target EGR flow rate. When the actual EGR flow rate is equal to the target EGR flow rate, keep the speed of the drive motor. When the actual EGR flow rate is not equal to the target EGR flow rate, adjust the speed of the drive motor until the actual EGR flow rate is equal to the target EGR flow rate.

13. The control method of the EGR system according to claim 12, characterized in that, The electric supercharger module includes an electronically controlled three-way valve. When the target EGR flow rate is 0, the electronically controlled three-way valve switches to the second channel, so that the gas at the output end of the electric supercharger returns to the input end of the electric supercharger; when the target EGR flow rate is not 0, the electronically controlled three-way valve switches to the first channel, so that the gas at the output end of the electric supercharger is transmitted to the intake mechanism.

14. The control method of the EGR system according to claim 12, characterized in that, The electric supercharger module includes a first switching valve and a second switching valve. When the target EGR flow rate is 0, the first switching valve is closed and the second switching valve is opened, so that the gas at the output end of the electric supercharger returns to the input end of the electric supercharger; when the target EGR flow rate is not 0, the first switching valve is opened and the second switching valve is closed, so that the gas at the output end of the electric supercharger is transmitted to the intake mechanism.

15. The control method of the EGR system according to claim 10, characterized in that, The EGR system further includes a first EGR cooler, and the electric supercharger module further includes a second EGR cooler, a first coolant flow control valve, and a second coolant flow control valve; the control method further includes: When the engine is operating or the ambient temperature is higher than the first preset temperature, the EGR controller controls the opening degree of the first coolant flow control valve so that the temperature of the first temperature sensor is greater than the second preset temperature; When the temperature of the first temperature sensor is greater than or equal to the second preset temperature, the EGR controller controls to maintain the current opening degree of the first coolant flow control valve; when the temperature of the first temperature sensor is less than the second preset temperature, the EGR controller controls to adjust the opening degree of the first coolant flow control valve until the temperature of the first temperature sensor is greater than or equal to the second preset temperature, and at the same time controls the second coolant flow control valve to be fully open; When the engine is in a shutdown state and the ambient temperature is lower than the first preset temperature, the EGR controller controls the opening degrees of the first coolant flow control valve and the second coolant flow control valve so that the temperature of the first temperature sensor is greater than or equal to the second preset temperature, and the temperature of the second temperature sensor is greater than or equal to the third preset temperature, and shuts down after running for a preset time; When the temperature of the first temperature sensor is greater than or equal to the second preset temperature and the temperature of the second temperature sensor is greater than or equal to the third preset temperature, the EGR controller controls to maintain the current opening degrees of the first coolant flow control valve and the second coolant flow control valve; when the temperature of the first temperature sensor is less than the second preset temperature and the temperature of the second temperature sensor is less than the third preset temperature, the EGR controller controls to adjust the opening degrees of the first coolant flow control valve and the second coolant flow control valve until the temperature of the first temperature sensor is greater than or equal to the second preset temperature and the temperature of the second temperature sensor is greater than or equal to the third preset temperature; Wherein, the second preset temperature is greater than the third preset temperature, and the third preset temperature is greater than the first preset temperature.

16. A vehicle, characterized in that, Including the EGR system according to any one of claims 1 to 7.

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