Hydrogen internal combustion engine EGR system control method, system and device and storage medium

Abstract

The invention relates to a hydrogen internal combustion engine EGR system control method, system and device and a storage medium. A target EGR rate is obtained; the current opening degree of the EGR valve is controlled and adjusted; acquiring current air mass flow, hydrogen mass flow, exhaust gas oxygen concentration and mixed gas oxygen concentration of exhaust gas and fresh air; according to the air mass flow, the hydrogen mass flow, the exhaust gas oxygen concentration and the mixed gas oxygen concentration, the current actual EGR rate is obtained through an oxygen concentration balance method; and comparing the actual EGR rate with the target EGR rate, taking a comparison result as an adjustment basis, returning to adjust the current opening degree of the EGR valve, and obtaining real-time data again until the difference between the current actual EGR rate and the target EGR rate is smaller than a preset threshold value. Compared with the prior art, the method has the advantages of improving the accuracy and stability of EGR rate measurement and calculation of the hydrogen internal combustion engine and the like.

Description

Technical Field

[0001] The present invention relates to the technical field of hydrogen internal combustion engines, and in particular to a method, system, device and storage medium for controlling an EGR system of a hydrogen internal combustion engine. Background Art

[0002] With the continuous increase in demand for traditional energy and the prominence of global warming, the world's major automobile producers have accelerated their deployment and made the development of clean energy vehicles a national strategy. Hydrogen energy is a secondary energy source that is abundant in source, green, low-carbon, and widely used. It is of great significance to building a clean, low-carbon, safe and efficient energy system and achieving the goals of carbon peak and carbon neutrality. Compared with diesel and natural gas, hydrogen has the characteristics of high calorific value, high diffusion coefficient, low ignition energy, and wide ignition limit. It is easy to form a uniform mixture with air, and its working mode is similar to that of natural gas engines, which is conducive to achieving lean combustion and improving the economy of the engine. The higher flame combustion speed makes the engine closer to the ideal thermodynamic cycle, and the higher self-ignition temperature of hydrogen can be used for higher compression ratio combustion, thereby improving the thermal efficiency of the engine. In addition, the combustion products do not contain any carbon-based pollutants, which can truly achieve zero carbon emissions.

[0003] Exhaust gas recirculation (EGR) is an effective way to reduce nitrogen oxide (NOx) emissions and improve the efficiency of hydrogen fuel internal combustion engines. The general principle of EGR to reduce NOx is the change in the reaction kinetics and physical properties of the hydrogen mixture, which will significantly change the basic properties of the flame, including laminar flame speed, adiabatic flame temperature and flame structure, which directly determines the combustion characteristics of the hydrogen internal combustion engine. For hydrocarbon fuels, the EGR rate is generally calculated based on the carbon dioxide concentration. For example, Chinese patent CN114941593A discloses a measuring device and a measuring method for the EGR rate of an internal combustion engine, wherein the device is connected to a carbon dioxide measuring device connected to the intake system of the internal combustion engine, and the carbon dioxide measuring device is used to measure the carbon dioxide content in the gas entering the combustion chamber in the intake system. The carbon dioxide measuring device is connected to the EGR system or exhaust system of the internal combustion engine, and is used to measure the carbon dioxide content of the exhaust gas entering the EGR system after combustion in the combustion chamber, and the carbon dioxide measuring device is responsible for measuring the carbon dioxide content in the air. The carbon dioxide measuring device transmits data to the data acquisition module. Unlike the composition of EGR in traditional internal combustion engines, the main components of EGR in hydrogen internal combustion engines are nitrogen (N2) and water vapor (H2O), and there is no carbon dioxide emission. Therefore, the calculation of EGR rate in hydrogen internal combustion engines is different from that in traditional gasoline and diesel engines. If the EGR rate is directly obtained by the calculation method based on carbon dioxide concentration and used for EGR control, the obtained calculation result will be inaccurate and it will be difficult to achieve stable control. Summary of the invention

[0004] The purpose of the present invention is to provide a hydrogen internal combustion engine EGR system control method, system, device and storage medium in order to overcome the defects of the above-mentioned prior art that the EGR rate measurement results will be inaccurate and difficult to achieve stable control.

[0005] The purpose of the present invention can be achieved by the following technical solutions:

[0006] According to a first aspect of the present invention, a method for controlling an EGR system of a hydrogen internal combustion engine is provided, comprising the following steps: S1, obtaining a target EGR rate; S2, controlling and adjusting the current opening of the EGR valve; S3, obtaining the current air mass flow, hydrogen mass flow, exhaust gas oxygen concentration, and a mixed gas oxygen concentration of exhaust gas and fresh air; S4, obtaining the current actual EGR rate using an oxygen concentration balance method based on the air mass flow, the hydrogen mass flow, the exhaust gas oxygen concentration, and the mixed gas oxygen concentration; S5, comparing the actual EGR rate with the target EGR rate, and returning the comparison result as a basis for adjustment to S2 for continued execution until the difference between the current actual EGR rate and the target EGR rate is less than a preset threshold.

[0007] As a preferred technical solution, the current actual EGR rate is obtained by using the oxygen concentration balance method, which specifically includes: calculating the oxygen concentration difference according to the exhaust gas oxygen concentration, the mixed gas oxygen concentration and the pre-acquired fresh air oxygen concentration; calculating the exhaust gas mass flow rate according to the oxygen concentration difference, the air mass flow rate, the pre-acquired air molecular weight and the exhaust gas molecular weight; calculating the actual EGR rate according to the exhaust gas mass flow rate, the air mass flow rate and the hydrogen mass flow rate.

[0008] As a preferred technical solution, the oxygen concentration difference is expressed as:

[0009]

[0010] In the formula, Δy O2 is the oxygen concentration difference, y O2-air is the oxygen concentration of fresh air, y O2-mix is the oxygen concentration of the mixed gas, y O2-EGR is the exhaust gas oxygen concentration;

[0011] The exhaust gas mass flow rate is expressed as:

[0012]

[0013] In the formula, m EGR is the exhaust gas mass flow rate, m air is the air mass flow rate, M EGR is the molecular weight of the exhaust gas, M air is the molecular weight of air;

[0014] The actual EGR rate is expressed as:

[0015]

[0016] In the formula, R EGR is the actual EGR rate, m H2 is the hydrogen mass flow rate.

[0017] As a preferred technical solution, the calculation expression of the exhaust gas molecular weight is:

[0018]

[0019] Where λ is the excess air coefficient.

[0020] As a preferred technical solution, in S2, the current opening of the EGR valve is controlled and adjusted by utilizing the PID feedback control principle and the received real-time comparison result.

[0021] As a preferred technical solution, the air mass flow is obtained using an intake air flow meter, the hydrogen mass flow is obtained using a hydrogen flow meter, the exhaust gas oxygen concentration is obtained using an exhaust gas oxygen concentration sensor, and the mixed gas oxygen concentration is obtained using a mixed gas oxygen concentration sensor.

[0022] According to a second aspect of the present invention, a control system for an EGR system of a hydrogen internal combustion engine is provided, comprising a target EGR rate acquisition module, a control module, a real-time data acquisition module, an EGR rate calculation module and a result comparison module; the target EGR rate acquisition module is used to acquire the target EGR rate; the control module is used to control and adjust the current opening of the EGR valve; the real-time data acquisition module is used to acquire the current air mass flow, hydrogen mass flow, exhaust gas oxygen concentration and the mixed gas oxygen concentration of exhaust gas and fresh air; the EGR rate calculation module is used to acquire the current actual EGR rate according to the air mass flow, the hydrogen mass flow, the exhaust gas oxygen concentration and the mixed gas oxygen concentration by using the oxygen concentration balance method; the result comparison module is used to compare the actual EGR rate with the target EGR rate, and return the comparison result as the adjustment basis to the control module for continued execution until the difference between the current actual EGR rate and the target EGR rate is less than a preset threshold.

[0023] As a preferred technical solution, the EGR rate calculation module includes an oxygen concentration difference calculation unit, an exhaust gas mass flow calculation unit and an actual EGR rate calculation unit; the oxygen concentration difference calculation unit is used to calculate the oxygen concentration difference according to the exhaust gas oxygen concentration, the mixed gas oxygen concentration and the pre-acquired fresh air oxygen concentration; the exhaust gas mass flow calculation unit is used to calculate the exhaust gas mass flow according to the oxygen concentration difference, the air mass flow, the pre-acquired air molecular weight and the exhaust gas molecular weight; the actual EGR rate calculation unit is used to calculate the actual EGR rate according to the exhaust gas mass flow, the air mass flow and the hydrogen mass flow.

[0024] According to a third aspect of the present invention, there is provided a hydrogen internal combustion engine EGR system control device, comprising a memory, a processor, and a program stored in the memory, wherein the processor implements the method described when executing the program.

[0025] According to a fourth aspect of the present invention, there is provided a storage medium having a program stored thereon, wherein the program implements the method described above when executed.

[0026] Compared with the prior art, the present invention has the following beneficial effects:

[0027] 1. The present invention proposes an oxygen concentration balance method to calculate the actual EGR rate of a hydrogen internal combustion engine in real time. The oxygen concentration balance method is implemented based on air mass flow, hydrogen mass flow, exhaust gas oxygen concentration, and mixed gas oxygen concentration of exhaust gas and fresh air. The main components of the hydrogen internal combustion engine EGR are fully utilized to complete the calculation, and there is no need to use carbon dioxide content to participate in the calculation. The accuracy of the hydrogen internal combustion engine EGR rate calculation can be effectively improved, thereby achieving the stability of the hydrogen internal combustion engine EGR system control;

[0028] 2. The present invention can realize online closed-loop control based on the PID principle through the target EGR rate input by the computer and the actual EGR rate result calculated, which can effectively improve the stability of the constant EGR rate working condition when the hydrogen internal combustion engine is running. BRIEF DESCRIPTION OF THE DRAWINGS

[0029] Figure 1 A schematic flow chart of the method provided by the present invention;

[0030] Figure 2 Schematic diagram of measuring point positions in an embodiment of the present invention;

[0031] Figure 3 A schematic diagram of the structure of a device is provided in an embodiment of the present invention;

[0032] Among them: 301, target EGR rate acquisition module; 302, control module; 303, real-time data acquisition module; 304, EGR rate calculation module; 305, result comparison module. DETAILED DESCRIPTION

[0033] The present invention is described in detail below in conjunction with the accompanying drawings and specific embodiments. This embodiment is implemented based on the technical solution of the present invention, and provides a detailed implementation method and specific operation process, but the protection scope of the present invention is not limited to the following embodiments.

[0034] Example

[0035] like Figure 1 As shown, this embodiment provides a method for controlling an EGR system of a hydrogen internal combustion engine, the method comprising the following steps:

[0036] Step S1, obtaining a target EGR rate;

[0037] Step S2, controlling and adjusting the current opening of the EGR valve;

[0038] Step S3, obtaining the current air mass flow rate, hydrogen mass flow rate, exhaust gas oxygen concentration, and mixed gas oxygen concentration of exhaust gas and fresh air;

[0039] Step S4, obtaining the current actual EGR rate by using an oxygen concentration balance method according to the air mass flow rate, the hydrogen mass flow rate, the exhaust gas oxygen concentration and the mixed gas oxygen concentration;

[0040] Step S5, compare the actual EGR rate with the target EGR rate, and use the comparison result as the adjustment basis to return to step S2 and continue to execute until the difference between the current actual EGR rate and the target EGR rate is less than a preset threshold.

[0041] In step S3, the air mass flow is obtained by the intake air flow meter, the hydrogen mass flow is obtained by the hydrogen flow meter, the exhaust gas oxygen concentration is obtained by the exhaust gas oxygen concentration sensor, and the mixed gas oxygen concentration is obtained by the mixed gas oxygen concentration sensor. In this embodiment, the intake air flow meter, the mixed gas oxygen concentration sensor, and the exhaust gas oxygen concentration sensor are respectively placed at measuring point 1, measuring point 2, and measuring point 3 in the hydrogen internal combustion engine EGR system. The positions of the measuring points are as follows: Figure 2 As shown, in addition, a hydrogen flow meter is placed in the intake manifold to measure the hydrogen flow rate.

[0042] Each flow meter and sensor sends the measured real-time data to the ECU (Electronic Control Unit). Each step of the above method can be executed by the ECU control unit. The specific execution process is as follows:

[0043] (1) Input the target EGR rate;

[0044] (2) The ECU control unit receives the target EGR rate and opens the EGR valve to a certain initial opening;

[0045] (3) The ECU control unit collects the current air mass flow m air , Hydrogen mass flow rate m H2 , exhaust gas oxygen concentration y O2-EGR , the oxygen concentration of the mixture of exhaust gas and fresh air O2-mix ;

[0046] (4) Calculate the oxygen concentration difference Δy according to the following formula O2 :

[0047]

[0048] In the formula, y O2-air Fresh air oxygen concentration: 21%;

[0049] (5) Calculate the exhaust gas mass flow rate m according to the following formula EGR :

[0050]

[0051] Where M air Molecular weight of air: 29; M EGR is the molecular weight of the exhaust gas, calculated according to the following formula:

[0052]

[0053] In the formula, λ is the excess air coefficient, expressed as:

[0054]

[0055] (6) Calculate the current actual EGR rate R EGR :

[0056]

[0057] (7) The ECU control unit feeds back the real-time collected data information and calculation results to the computer for real-time display, and compares the calculated actual EGR rate result with the target EGR rate. Specifically, the ECU control unit adjusts the opening of the heat exchange valve and the EGR valve based on the comparison results using the PID principle, and then feeds back the EGR rate results for comparison, and then adjusts them based on the results; this cycle repeats until the current calculated EGR rate result basically matches the target.

[0058] A hydrogen internal combustion engine EGR system control method proposed in this embodiment calculates the EGR rate based on oxygen concentration. Specifically, the EGR rate is calculated by measuring air mass flow, hydrogen mass flow, exhaust gas oxygen concentration and mixed gas oxygen concentration. This method can solve the problem of low calculation accuracy of the EGR rate of the hydrogen internal combustion engine and form a closed-loop control of the EGR rate.

[0059] Furthermore, if Figure 3 As shown, this embodiment also provides a hydrogen internal combustion engine EGR system control system, which includes a target EGR rate acquisition module 301, a control module 302, a real-time data acquisition module 303, an EGR rate calculation module 304 and a result comparison module 305. Among them, the target EGR rate acquisition module 301 acquires the target EGR rate; the control module 302 is used to control and adjust the current opening of the EGR valve; the real-time data acquisition module 303 is used to acquire the current air mass flow, hydrogen mass flow, exhaust gas oxygen concentration and the mixed gas oxygen concentration of exhaust gas and fresh air; the EGR rate calculation module 304 is used to obtain the current actual EGR rate by using the oxygen concentration balance method according to the air mass flow, hydrogen mass flow, exhaust gas oxygen concentration and mixed gas oxygen concentration; the result comparison module 305 is used to compare the actual EGR rate with the target EGR rate, and return the comparison result as the adjustment basis to the control module 302 for continued execution until the difference between the current actual EGR rate and the target EGR rate is less than the preset threshold. Optionally, the EGR rate calculation module 304 also includes an oxygen concentration difference calculation unit, an exhaust gas mass flow calculation unit and an actual EGR rate calculation unit. Among them, the oxygen concentration difference calculation unit is used to calculate the oxygen concentration difference according to the exhaust gas oxygen concentration, the mixed gas oxygen concentration and the pre-acquired fresh air oxygen concentration; the exhaust gas mass flow calculation unit is used to calculate the exhaust gas mass flow according to the oxygen concentration difference, the air mass flow, the pre-acquired air molecular weight and the exhaust gas molecular weight; the actual EGR rate calculation unit is used to calculate the actual EGR rate according to the exhaust gas mass flow, the air mass flow and the hydrogen mass flow. The specific operation process of each module and unit in the system is basically consistent with the execution process of each step of the aforementioned method, and will not be repeated here.

[0060] Further, the present embodiment also provides a hydrogen internal combustion engine EGR system control device, including a memory, a processor, and a program stored in the memory, and the processor implements one or more steps of the aforementioned method when executing the program. The device processor includes a central processing unit (CPU), which can perform various appropriate actions and processes according to computer program instructions stored in a read-only memory (ROM) or computer program instructions loaded from a storage unit to a random access memory (RAM). In the RAM, various programs and data required for the operation of the device can also be stored. The CPU, ROM, and RAM are connected to each other through a bus. The input / output (I / O) interface is also connected to the bus. Multiple components in the device are connected to the I / O interface, including: input units, such as keyboards, mice, etc.; output units, such as various types of displays, speakers, etc.; storage units, such as disks, optical disks, etc.; and communication units, such as network cards, modems, wireless communication transceivers, etc. The communication unit allows the device to exchange information / data with other devices through computer networks such as the Internet and / or various telecommunication networks. The processing unit performs the various methods and processes described above, such as one or more steps of the aforementioned method. For example, in some embodiments, one or more steps of the foregoing method may be implemented as a computer software program, which is tangibly contained in a machine-readable medium, such as a storage unit. In some embodiments, part or all of the computer program may be loaded and / or installed on the device via a ROM and / or a communication unit. When the computer program is loaded into the RAM and executed by the CPU, one or more steps of the foregoing method may be executed. Alternatively, in other embodiments, the CPU may be configured to execute one or more steps of the foregoing method in any other appropriate manner (e.g., by means of firmware). The functions described above may be performed at least in part by one or more hardware logic components. For example, without limitation, exemplary types of hardware logic components that may be used include: field programmable gate arrays (FPGAs), application specific integrated circuits (ASICs), application specific standard products (ASSPs), system on chip (SOCs), complex programmable logic devices (CPLDs), and the like.

[0061] Further, the present embodiment also provides a storage medium on which a program is stored, and when the program is executed, one or more steps of the aforementioned method are implemented. The device processor includes a central processing unit (CPU), which can perform various appropriate actions and processes according to computer program instructions stored in a read-only memory (ROM) or computer program instructions loaded from a storage unit into a random access memory (RAM). In the RAM, various programs and data required for the operation of the device can also be stored. The CPU, ROM, and RAM are connected to each other through a bus. The input / output (I / O) interface is also connected to the bus. Multiple components in the device are connected to the I / O interface, including: input units, such as keyboards, mice, etc.; output units, such as various types of displays, speakers, etc.; storage units, such as disks, optical disks, etc.; and communication units, such as network cards, modems, wireless communication transceivers, etc. The communication unit allows the device to exchange information / data with other devices through computer networks such as the Internet and / or various telecommunication networks. The processing unit performs the various methods and processes described above, such as one or more steps of the aforementioned method. For example, in some embodiments, one or more steps of the foregoing method may be implemented as a computer software program, which is tangibly contained in a machine-readable medium, such as a storage unit. In some embodiments, part or all of the computer program may be loaded and / or installed on the device via a ROM and / or a communication unit. When the computer program is loaded into the RAM and executed by the CPU, one or more steps of the foregoing method may be executed. Alternatively, in other embodiments, the CPU may be configured to execute one or more steps of the foregoing method in any other appropriate manner (e.g., by means of firmware). The functions described above may be performed at least in part by one or more hardware logic components. For example, without limitation, exemplary types of hardware logic components that may be used include: field programmable gate arrays (FPGAs), application specific integrated circuits (ASICs), application specific standard products (ASSPs), system on chip (SOCs), complex programmable logic devices (CPLDs), and the like.

[0062] The preferred specific embodiments of the present invention are described in detail above. It should be understood that a person skilled in the art can make many modifications and changes based on the concept of the present invention without creative work. Therefore, any technical solution that can be obtained by a person skilled in the art through logical analysis, reasoning or limited experiments based on the concept of the present invention on the basis of the prior art should be within the scope of protection determined by the claims.

Claims

1. A method for controlling an EGR system of a hydrogen internal combustion engine, characterized in that: The following steps are involved: S1, obtaining the target EGR rate; S2, controlling and adjusting the current opening of the EGR valve; S3, obtaining the current air mass flow rate, hydrogen mass flow rate, exhaust gas oxygen concentration, and mixed gas oxygen concentration of exhaust gas and fresh air; S4, obtaining a current actual EGR rate by using an oxygen concentration balance method according to the air mass flow rate, the hydrogen mass flow rate, the exhaust gas oxygen concentration and the mixed gas oxygen concentration; S5, comparing the actual EGR rate with the target EGR rate, and returning the comparison result as an adjustment basis to S2 to continue execution until the difference between the current actual EGR rate and the target EGR rate is less than a preset threshold.

2. The hydrogen internal combustion engine EGR system control method according to claim 1, characterized in that: The oxygen concentration balance method is used to obtain the current actual EGR rate, including: Calculating an oxygen concentration difference according to the exhaust gas oxygen concentration, the mixed gas oxygen concentration, and a pre-acquired fresh air oxygen concentration; Calculating the exhaust gas mass flow rate according to the oxygen concentration difference, the air mass flow rate, the pre-acquired air molecular weight and the exhaust gas molecular weight; An actual EGR rate is calculated according to the exhaust gas mass flow rate, the air mass flow rate, and the hydrogen mass flow rate.

3. The hydrogen internal combustion engine EGR system control method according to claim 2, characterized in that: The oxygen concentration difference is expressed as: In the formula, Δy O2 is the oxygen concentration difference, y O2-air is the oxygen concentration of fresh air, y O2-mix is the oxygen concentration of the mixed gas, y O2-EGR is the exhaust gas oxygen concentration; The exhaust gas mass flow rate is expressed as: In the formula, m EGR is the exhaust gas mass flow rate, m air is the air mass flow rate, M EGR is the molecular weight of the exhaust gas, M air is the molecular weight of air; The actual EGR rate is expressed as: In the formula, R EGR is the actual EGR rate, m H2 is the hydrogen mass flow rate.

4. The hydrogen internal combustion engine EGR system control method according to claim 3, characterized in that: The calculation expression of the exhaust gas molecular weight is: Where λ is the excess air coefficient.

5. The hydrogen internal combustion engine EGR system control method according to claim 1, characterized in that: In S2, the current opening of the EGR valve is controlled and adjusted by utilizing the PID feedback control principle and the received real-time comparison result.

6. The hydrogen internal combustion engine EGR system control method according to claim 1, characterized in that: The air mass flow is obtained by using an intake air flow meter, the hydrogen mass flow is obtained by using a hydrogen flow meter, the exhaust gas oxygen concentration is obtained by using an exhaust gas oxygen concentration sensor, and the mixed gas oxygen concentration is obtained by using a mixed gas oxygen concentration sensor.

7. A hydrogen internal combustion engine EGR system control system, characterized in that: It includes a target EGR rate acquisition module, a control module, a real-time data acquisition module, an EGR rate calculation module and a result comparison module; The target EGR rate acquisition module is used to acquire the target EGR rate; The control module is used to control and adjust the current opening of the EGR valve; The real-time data acquisition module is used to obtain the current air mass flow, hydrogen mass flow, exhaust gas oxygen concentration and mixed gas oxygen concentration of exhaust gas and fresh air; The EGR rate calculation module is used to obtain the current actual EGR rate by using the oxygen concentration balance method according to the air mass flow, the hydrogen mass flow, the exhaust gas oxygen concentration and the mixed gas oxygen concentration; The result comparison module is used to compare the actual EGR rate with the target EGR rate, and return the comparison result as an adjustment basis to the control module for continued execution until the difference between the current actual EGR rate and the target EGR rate is less than a preset threshold.

8. The hydrogen internal combustion engine EGR system control system according to claim 7, characterized in that: The EGR rate calculation module includes an oxygen concentration difference calculation unit, an exhaust gas mass flow calculation unit and an actual EGR rate calculation unit; The oxygen concentration difference calculation unit is used to calculate the oxygen concentration difference according to the exhaust gas oxygen concentration, the mixed gas oxygen concentration and the pre-acquired fresh air oxygen concentration; The exhaust gas mass flow calculation unit is used to calculate the exhaust gas mass flow according to the oxygen concentration difference, the air mass flow, the pre-acquired air molecular weight and the exhaust gas molecular weight; The actual EGR rate calculation unit is used to calculate the actual EGR rate according to the exhaust gas mass flow rate, the air mass flow rate and the hydrogen mass flow rate.

9. A hydrogen internal combustion engine EGR system control device, comprising a memory, a processor, and a program stored in the memory, characterized in that: When the processor executes the program, the method according to any one of claims 1 to 6 is implemented.

10. A storage medium having a program stored thereon, characterized in that: When the program is executed, the method according to any one of claims 1 to 6 is implemented.

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