EGR exhaust gas flow control system and method and engine

Abstract

The invention relates to the technical field of exhaust gas recirculation of engines, in particular to an EGR exhaust gas flow control system and method and an engine. The EGR waste gas flow control system comprises an EGR channel and a control device, an inlet of the EGR channel is used for being communicated with an exhaust manifold, an outlet of the EGR channel is used for being communicated with an intake manifold, an EGR valve assembly is arranged in the EGR channel and comprises a first EGR valve and a second EGR valve, the valve diameter of the first EGR valve is smaller than that of the second EGR valve, and the valve diameter of the first EGR valve is smaller than that of the second EGR valve. The control device is electrically connected with the first EGR valve and the second EGR valve. According to the EGR exhaust gas flow control system in the embodiment, the control device automatically adjusts the opening values of the two EGR valves by monitoring the operation parameters of the engine in real time, and it is ensured that the actual EGR rate conforms to the preset target EGR rate. In this way, even under the condition that the working condition of the engine changes rapidly, accurate control over the exhaust gas flow can be kept.

Description

Technical Field

[0001] The present invention relates to the technical field of exhaust gas recirculation of an engine, and in particular to a control system and a control method for an EGR exhaust gas flow rate and an engine. Background Art

[0002] In modern internal combustion engines, exhaust gas recirculation (EGR) systems are widely used to reduce nitrogen oxide (NOx) emissions and meet increasingly stringent emission regulations. The EGR system reintroduces a portion of the exhaust gas into the engine's intake system and mixes it with fresh air, thereby reducing combustion temperatures and reducing the generation of NOx. However, under different engine operating conditions, the flow demand for EGR exhaust gas varies, which places high demands on the control accuracy of the EGR system.

[0003] In the prior art, in order to take into account the EGR flow requirements under various operating conditions, a single large-caliber EGR valve is usually used. Although this design can provide sufficient exhaust gas circulation when the flow demand is high, under low flow demand conditions, the larger valve plate is difficult to accurately control the EGR flow at a small opening value, resulting in unstable EGR flow control and large EGR rate deviation, which ultimately affects the emission consistency of the engine. In addition, the traditional EGR system has a slow response speed and cannot adapt to the rapid changes in engine operating conditions in a timely manner, further exacerbating the difficulty of emission control. Summary of the invention

[0004] The purpose of the present invention is to at least solve the problem that the EGR valve flow control is inaccurate, which leads to a large error in the EGR rate control. This purpose is achieved by the following technical solutions:

[0005] A first aspect of the present invention provides a control system for EGR exhaust gas flow, comprising:

[0006] An EGR passage, wherein an inlet of the EGR passage is used to communicate with an exhaust manifold, and an outlet of the EGR passage is used to communicate with an intake manifold, wherein a first EGR valve and a second EGR valve are arranged in parallel in the EGR passage, and a valve diameter of the first EGR valve is smaller than a valve diameter of the second EGR valve;

[0007] A control device is electrically connected to the first EGR valve and the second EGR valve respectively.

[0008] According to the control system of EGR exhaust gas flow of the present invention, under the low load or small flow demand working condition of the engine, the control device mainly controls the opening value of the first EGR valve. Since the first EGR valve has a smaller valve plate, more accurate exhaust gas flow regulation can be achieved under low flow conditions. When the engine is under high load or large flow demand working conditions, the control device can open the second EGR valve. The valve plate of the second EGR valve is larger, which is suitable for handling a larger flow of exhaust gas. At the same time, in some cases, the two EGR valves can work simultaneously to provide a larger flow or more flexible flow control. The control device automatically adjusts the opening values ​​of the two EGR valves by real-time monitoring of engine operating parameters (such as engine load or speed) to ensure that the actual EGR rate is consistent with the preset target EGR rate. In this way, even when the engine working conditions change rapidly, the accurate control of the exhaust gas flow can be maintained. This embodiment significantly improves the control accuracy of the EGR flow by setting two EGR valves of different sizes in the EGR channel and selecting an appropriate valve for control according to demand, especially under low flow conditions, which can effectively reduce flow fluctuations and reduce control errors. At the same time, precise EGR flow control allows the EGR rate to be stabilized near the set value, reducing the emission inconsistency caused by EGR rate deviation. Especially in the context of meeting strict emission regulations, this technical effect is crucial to improving the consistency of engine emissions. In addition, the control device can quickly adjust the opening value of the two EGR valves according to different engine operating conditions, ensuring that the exhaust gas flow responds to the engine load changes in a timely manner, improving the dynamic response capability of the EGR system, and thus improving the overall engine operating efficiency and emission control performance.

[0009] In addition, the control system of the EGR exhaust gas flow rate according to the present invention may also have the following additional technical features:

[0010] In some embodiments of the present invention, the first EGR valve includes a first EGR valve plate having a first diameter, the second EGR valve includes a second EGR valve plate having a second diameter, and a ratio of the first diameter to the second diameter is 2:3.

[0011] A second aspect of the present invention provides a method for controlling the EGR exhaust gas flow rate, which is implemented according to the above-mentioned control system for the EGR exhaust gas flow rate, and comprises the following steps:

[0012] Get EGR rate and total intake volume;

[0013] Calculating an EGR demand according to the EGR rate and the total intake air volume;

[0014] According to the EGR demand being within a preset range, the first EGR valve and the second EGR valve are controlled respectively.

[0015] In some embodiments of the present invention, the steps of respectively controlling the first EGR valve and the second EGR valve according to the EGR demand being within a preset range include:

[0016] The EGR demand is less than or equal to a first threshold, and the first EGR valve is controlled to be opened and the second EGR valve is controlled to be closed;

[0017] The opening value of the first EGR valve is adjusted according to the EGR demand.

[0018] In some embodiments of the present invention, the steps of respectively controlling the first EGR valve and the second EGR valve according to the EGR demand being within a preset range include:

[0019] The EGR demand is greater than a first threshold and less than or equal to a second threshold, controlling the first EGR valve to close and the second EGR valve to open;

[0020] The opening value of the second EGR valve is adjusted according to the EGR demand.

[0021] In some embodiments of the present invention, according to the EGR demand being within a preset range, the steps of respectively controlling the first EGR valve and the second EGR valve include:

[0022] The EGR demand is greater than a second threshold, controlling the first EGR valve to open and the second EGR valve to open;

[0023] The opening value of the first EGR valve and the opening value of the second EGR valve are adjusted according to the EGR demand.

[0024] In some embodiments of the present invention, the step of obtaining the EGR rate includes:

[0025] Obtaining the operating conditions of the engine;

[0026] A preset EGR rate mapping table is searched according to the operating conditions.

[0027] In some embodiments of the present invention, the step of obtaining the total intake air amount is to obtain a value of a mass air flow sensor in the intake manifold.

[0028] In some embodiments of the present invention, according to the EGR rate and the total intake air volume, the formula for calculating the EGR demand is:

[0029] A third aspect of the present invention provides an engine, comprising the above-mentioned EGR exhaust gas flow control system. BRIEF DESCRIPTION OF THE DRAWINGS

[0030] Various other advantages and benefits will become apparent to those of ordinary skill in the art by reading the detailed description of the preferred embodiments below. The accompanying drawings are only for the purpose of illustrating the preferred embodiments and are not to be considered as limiting the present invention. Moreover, the same reference numerals are used throughout the accompanying drawings to represent the same components. In the accompanying drawings:

[0031] Figure 1 The structure diagram of the control system of the EGR exhaust gas flow rate according to the embodiment of the present invention is schematically shown;

[0032] Figure 2 for Figure 1 A cross-sectional view of the first embodiment taken along plane AA;

[0033] Figure 3 for Figure 1 A cross-sectional view of the first embodiment taken along plane AA;

[0034] Figure 4 A flow chart schematically shows a method for controlling the EGR exhaust gas flow rate according to an embodiment of the present invention;

[0035] Figure 5 A circuit control diagram of a method for controlling an EGR exhaust gas flow rate according to an embodiment of the present invention is schematically shown;

[0036] Figure 6 This is the universal diagram of EGR rate.

[0037] The reference numerals are as follows:

[0038] 100. Engine;

[0039] 101. Exhaust manifold; 102. Intake manifold; 10. Cylinder; 20. EGR valve assembly; 201. EGR channel; 21. First EGR valve; 22. Second EGR valve; 23. EGR cooler; 30. Turbine; 40. After-processor; 50. Air filter; 60. Compressor; 70. Intercooler; 80. Throttle valve. DETAILED DESCRIPTION

[0040] The exemplary embodiments of the present disclosure will be described in more detail below with reference to the accompanying drawings. Although the exemplary embodiments of the present disclosure are shown in the accompanying drawings, it should be understood that the present disclosure can be implemented in various forms and should not be limited by the embodiments described herein. On the contrary, these embodiments are provided in order to enable a more thorough understanding of the present disclosure and to fully convey the scope of the present disclosure to those skilled in the art.

[0041] It should be understood that the terms used herein are only for the purpose of describing specific example embodiments and are not intended to be limiting. Unless the context clearly indicates otherwise, the singular forms "one", "an" and "said" as used herein may also be meant to include plural forms. The terms "include", "comprise", "contain", and "have" are inclusive, and therefore specify the existence of stated features, steps, operations, elements and / or parts, but do not exclude the existence or addition of one or more other features, steps, operations, elements, parts, and / or combinations thereof. The method steps, processes, and operations described herein are not interpreted as necessarily requiring them to be performed in the specific order described or illustrated, unless the execution order is clearly indicated. It should also be understood that additional or alternative steps may be used.

[0042] Although the terms first, second, third, etc. can be used in the text to describe multiple elements, components, regions, layers and / or sections, these elements, components, regions, layers and / or sections should not be limited by these terms. These terms can only be used to distinguish an element, component, region, layer or section from another region, layer or section. Unless the context clearly indicates, terms such as "first", "second" and other numerical terms do not imply order or sequence when used in the text. Therefore, the first element, component, region, layer or section discussed below can be referred to as the second element, component, region, layer or section without departing from the teaching of the example embodiments.

[0043] For ease of description, spatial relative terms may be used herein to describe the relationship of one element or feature relative to another element or feature as shown in the figure, such as "inside", "outside", "inner side", "outer side", "below", "below", "above", "above", etc. Such spatial relative terms are intended to include different orientations of the device in use or operation in addition to the orientation depicted in the figure. For example, if the device in the figure is turned over, then the elements described as "below other elements or features" or "below other elements or features" will subsequently be oriented as "above other elements or features" or "above other elements or features". Therefore, the example term "below..." can include both above and below orientations.

[0044] like Figure 1As shown, according to an embodiment of the present invention, a control system for EGR exhaust gas flow is proposed, including an EGR channel 201 and a control device, the inlet of the EGR channel 201 is used to be connected to the exhaust manifold 101, and the outlet of the EGR channel 201 is used to be connected to the intake manifold 102, an EGR valve assembly 20 is provided in the EGR channel 201, the EGR valve assembly 20 includes a first EGR valve 21 and a second EGR valve 22, the valve diameter of the first EGR valve 21 is smaller than the valve diameter of the second EGR valve 22, and the control device is electrically connected to the first EGR valve 21 and the second EGR valve 22, respectively.

[0045] According to the control system of the EGR exhaust gas flow rate of the present embodiment, under the low load or small flow demand condition of the engine 100, the control device mainly controls the opening value of the first EGR valve 21. Since the first EGR valve 21 has a smaller valve plate, more accurate exhaust gas flow regulation can be achieved under low flow conditions. When the engine 100 is under high load or large flow demand conditions, the control device can open the second EGR valve 22. The valve plate of the second EGR valve 22 is larger and suitable for handling a larger flow of exhaust gas. At the same time, in some cases, the two EGR valves can work simultaneously to provide a larger flow or more flexible flow control. The control device automatically adjusts the opening values ​​of the two EGR valves by real-time monitoring of the operating parameters of the engine 100 (such as the load or speed of the engine 100) to ensure that the actual EGR rate is consistent with the preset target EGR rate. In this way, even when the operating conditions of the engine 100 change rapidly, the accurate control of the exhaust gas flow rate can be maintained. This embodiment significantly improves the control accuracy of the EGR flow rate by setting two EGR valves of different sizes in the EGR channel 201 and selecting appropriate valves for control according to demand, especially under low flow conditions, which can effectively reduce flow fluctuations and control errors. At the same time, precise EGR flow control allows the EGR rate to be stabilized near the set value, reducing the emission inconsistency problem caused by EGR rate deviation. Especially in the context of meeting strict emission regulations, this technical effect is crucial to improving the emission consistency of the engine 100. In addition, the control device can quickly adjust the opening values ​​of the two EGR valves according to different operating conditions of the engine 100, ensuring that the exhaust gas flow rate responds to the load changes of the engine 100 in a timely manner, improving the dynamic response capability of the EGR system, and thereby improving the overall operating efficiency and emission control performance of the engine 100.

[0046] It is understandable that the EGR valve assembly 20 also includes an EGR cooler 23. The EGR cooler 23 is installed in the EGR passage 201, and the EGR cooler 23 is located between the EGR valve and the intake manifold 102. That is to say, after the exhaust gas has its flow rate adjusted by the two EGR valves, it enters the EGR cooler 23 for cooling and finally enters the intake manifold 102. The EGR cooler 23 cools the adjusted exhaust gas by coolant to reduce the temperature of the exhaust gas, so as to reduce the impact of high-temperature exhaust gas on the intake system. Placing the EGR cooler 23 after the two EGR valves helps to cool the exhaust gas whose flow rate has been precisely adjusted. This means that regardless of the opening value of the EGR valve, the adjusted exhaust gas can maintain a lower and stable temperature before entering the intake manifold 102.

[0047] Specifically, the control system of the EGR exhaust gas flow rate of the present embodiment is applied to an engine 100, wherein the engine 100 includes a cylinder 10, and the exhaust port of the cylinder 10 is directly connected to the exhaust manifold 101. The exhaust manifold 101 is used to collect the exhaust gas from each cylinder 10. The exhaust manifold 101 collects the exhaust gas from the exhaust port of the cylinder 10 and guides it to the inlet of the EGR channel 201. At the same time, the exhaust manifold 101 is also connected in sequence by the turbine 30 and the after-processor 40. The exhaust manifold 101 plays the role of guiding the exhaust gas to the EGR system and the exhaust system to ensure that the exhaust gas flows according to the designed path. The inlet of the EGR channel 201 is connected to the exhaust manifold 101, and part of the exhaust gas enters the EGR channel 201 from the exhaust manifold 101. The outlet of the EGR channel 201 is connected to the intake manifold 102, and the controlled exhaust gas enters the intake system for recirculation. A first EGR valve 21 and a second EGR valve 22 are arranged in parallel in the EGR passage 201 for precisely adjusting the exhaust gas flow rate entering the intake system. The turbine 30 is arranged in the direction from the inlet to the outlet of the exhaust manifold 101, and is located after the inlet of the EGR passage 201. Most of the exhaust gas in the exhaust manifold 101 will pass through the turbine 30 before entering the EGR passage 201 to drive the turbine part of the supercharger, increase the intake pressure, and improve the intake efficiency of the engine 100. The post-processor 40 is located after the turbine 30 and continues along the flow direction of the exhaust manifold 101. The post-processor 40 includes a diesel oxidation catalyst (DOC), a diesel particulate filter (DPF), and a selective catalytic reduction (SCR) device, etc., which are used to treat harmful substances in the remaining exhaust gas.

[0048] Specifically, the outlet of the intake manifold 102 is directly connected to the intake port of the cylinder 10 of the engine 100 to provide the cylinder 10 with a mixed gas. On the intake manifold 102 between the throttle valve 80 and the cylinder 10, the outlet of the EGR passage 201 is connected thereto for introducing the controlled and cooled exhaust gas. The air filter 50 is arranged at the inlet of the intake system for filtering the air entering the engine 100, removing dust and impurities, and ensuring the cleanliness of the air. The compressor 60 is located after the air filter 50 for compressing the intake air to increase the density and pressure of the air. The intercooler 70 is installed after the compressor 60 for cooling the compressed high-temperature air, reducing its temperature, and increasing the density of the air. The throttle valve 80 is arranged between the intercooler 70 and the intake manifold 102 for adjusting the air flow entering the cylinder 10. The inlet of the EGR passage 201 is connected to the exhaust manifold 101, and the outlet is connected to the intake manifold 102. The precisely controlled and cooled exhaust gas enters the intake manifold 102 between the throttle valve 80 and the cylinder 10, and is mixed with fresh air before entering the cylinder 10. The connection point between the EGR passage 201 and the intake manifold 102 is located between the throttle valve 80 and the cylinder 10, so that the exhaust gas can be fully mixed with the compressed and cooled air before entering the cylinder 10. Since the exhaust gas flow is precisely controlled, this mixing helps to optimize the combustion process and reduce the emission of nitrogen oxides.

[0049] In the first embodiment, the first EGR valve 21 includes a first EGR valve 21 plate with a first diameter, and the second EGR valve 22 includes a second EGR valve 22 plate with a second diameter, and the ratio of the first diameter to the second diameter is 2:3. The first diameter of the first EGR valve 21 is relatively small (a ratio of 2), which is suitable for fine control under low flow conditions. The smaller valve plate diameter enables the valve to more accurately adjust the exhaust gas flow entering the intake system under a small opening value, thereby improving the control accuracy, especially under low load or idling conditions with high EGR rate requirements. The second diameter of the second EGR valve 22 is relatively large (a ratio of 3), which can provide a larger flow cross-sectional area under high flow demand, reduce flow resistance, and ensure that the exhaust gas can quickly and fully enter the intake system under high load conditions. This design ensures that the EGR system can still operate efficiently when a large flow demand is required, without insufficient flow or response delay due to the small valve plate diameter. Setting the ratio of the first diameter to the second diameter to 2:3 means that the first EGR valve 21 can accurately control a small flow, while the second EGR valve 22 is suitable for controlling a larger flow. This hierarchical control enables the entire EGR system to cover EGR demands from the lowest to the highest, avoiding the problem of control failure or reduced accuracy of a single valve under extreme operating conditions.

[0050] In the second embodiment, the EGR valve assembly 20 is separated by a partition, and the area ratio of the two sides is about 4:9.

[0051] like Figure 4 and Figure 5 As shown, the present invention also provides a method for controlling the EGR exhaust gas flow rate, which is implemented according to the above-mentioned control system of the EGR exhaust gas flow rate, and comprises the following steps:

[0052] Get EGR rate and total intake air volume;

[0053] The EGR requirement is calculated based on the EGR rate and the total intake air volume;

[0054] According to the EGR demand being within a preset range, the first EGR valve 21 and the second EGR valve 22 are controlled respectively.

[0055] According to the control method of the EGR exhaust gas flow of the present embodiment, the control method can realize accurate regulation of the exhaust gas flow by calculating the EGR demand and accurately controlling the EGR valve based on a preset range, especially under small flow demand, the use of the first EGR valve 21 significantly improves the control accuracy and reduces the error. Accurate EGR control helps to maintain a stable EGR rate, ensuring that the engine 100 can achieve the expected emission level under different working conditions, and avoid the problem of excessive emissions caused by unstable EGR flow control. At the same time, by acquiring the engine 100 working condition data in real time and calculating the EGR demand in real time, the method can quickly respond to changes in the operating state of the engine 100, ensuring the optimal performance of the EGR system under different working conditions. This efficient response capability improves the adaptability of the engine 100 under dynamic conditions.

[0056] In some embodiments, the steps of controlling the first EGR valve 21 and the second EGR valve 22 respectively according to the EGR demand within a preset range include the step of controlling the first EGR valve 21 to open and the second EGR valve 22 to close when the EGR demand is less than or equal to a first threshold, and adjusting the opening value of the first EGR valve 21 according to the EGR demand. Among them, a first threshold of the EGR demand is preset to distinguish between low flow and medium and high flow demands. When the EGR demand is less than or equal to the first threshold, the system only controls the first EGR valve 21 to open. Since the valve plate of the first EGR valve 21 is small, its opening value can be accurately adjusted to meet the small flow demand. At the same time, the system controls the second EGR valve 22 to remain closed to prevent unnecessary large flow of exhaust gas from entering the intake system. Finally, according to the actual EGR demand, the opening value of the first EGR valve 21 is accurately adjusted to ensure that the exhaust gas flow entering the intake system matches the demand. By controlling the first EGR valve 21 alone when the EGR demand is small, the system can achieve fine flow regulation. Since the valve plate of the first EGR valve 21 is relatively small, its opening value can be controlled very accurately, which reduces the fluctuation of the EGR flow rate and improves the control accuracy of the EGR rate, especially under low load conditions.

[0057] In some embodiments, the step of controlling the first EGR valve 21 and the second EGR valve 22 respectively according to the EGR demand within the preset range further includes: when the EGR demand is greater than the first threshold and less than or equal to the second threshold, controlling the first EGR valve 21 to close and the second EGR valve 22 to open, and adjusting the opening value of the second EGR valve 22 according to the EGR demand. Wherein, a second threshold of the EGR demand is preset to distinguish between medium flow demand and large flow demand. When the EGR demand is greater than the first threshold and less than or equal to the second threshold, the system closes the first EGR valve 21. The system opens the second EGR valve 22 and adjusts its opening value according to the actual EGR demand. Since the second EGR valve 22 has a larger diameter, this setting enables it to cope with medium flow demand and ensure the stability and accuracy of the flow. By closing the first EGR valve 21 under medium flow demand and adjusting the opening value of the second EGR valve 22, the system can more stably control the EGR amount within the medium flow range. The larger diameter of the second EGR valve 22 enables it to provide smooth and accurate flow regulation within this range, reducing the fluctuation of the EGR rate. At the same time, through clear threshold settings, the system can quickly switch control modes under different flow requirements, reducing errors and delays in the flow regulation process. This not only improves the control accuracy of the EGR system, but also enhances the reliability of the system, especially under rapidly changing engine 100 operating conditions.

[0058] In some embodiments, the step of controlling the first EGR valve 21 and the second EGR valve 22 respectively according to the EGR demand within the preset range further includes, when the EGR demand is greater than the second threshold, controlling the first EGR valve 21 to open and the second EGR valve 22 to open, and adjusting the opening value of the first EGR valve 21 and the second EGR valve 22 according to the EGR demand. When the EGR demand exceeds the second threshold, the system opens the first EGR valve 21 and the second EGR valve 22 at the same time. The system adjusts the opening values ​​of the first EGR valve 21 and the second EGR valve 22 according to the actual EGR demand to achieve accurate large flow control. This linkage control strategy ensures that the system can provide a smooth and sufficient amount of exhaust gas recirculation even under the maximum flow demand. In the case of a large EGR demand, by adjusting the opening values ​​of the first EGR valve 21 and the second EGR valve 22 at the same time, the system can respond to the large flow demand more flexibly. This linkage control ensures the stability of the exhaust flow, and the EGR rate can be accurately controlled even under the maximum load.

[0059] It is understood that the step of obtaining the EGR rate includes obtaining the operating condition of the engine 100 and searching the preset EGR rate mapping table according to the operating condition. Specifically, first, through sensors and the engine 100 control unit (i.e., ECU), the key operating parameters of the engine 100 are monitored in real time, such as the two key parameters of the engine 100 speed (RPM) and load (Load), and of course, parameters such as intake pressure (MAP), intake air temperature (IAT), and throttle opening value (TPS) can also be referred to. These parameters directly reflect the current operating state of the engine 100. According to the obtained operating parameters, the current operating condition of the engine 100 is determined. For example, by combining the speed and load, it can be determined whether the engine 100 is in idle, partial load or high load conditions. Secondly, during the development stage of the engine 100, engineers will preset an EGR rate mapping table based on experimental data and emission requirements. The mapping table records the target EGR rate values ​​under different operating conditions, usually expressed in a two-dimensional table form, with the horizontal axis being the engine 100 speed and the vertical axis being the engine 100 load, and the value in the table being the target EGR rate. According to the current working condition of the engine 100, the corresponding EGR rate is searched in the mapping table. The search process can be a direct search or an interpolation calculation to obtain the target EGR rate value closest to the current working condition. Finally, the obtained target EGR rate is used to guide the subsequent EGR valve control. In actual application, the target value of the EGR rate is transmitted to the control device through the ECU, and the control device adjusts the opening value of the first EGR valve 21 and / or the second EGR valve 22 according to this target value to achieve the desired exhaust gas recirculation ratio. During actual operation, the system may continuously monitor the actual EGR rate and compare it with the target EGR rate. If a deviation occurs, the control device will further adjust the opening value of the EGR valve to correct the actual EGR rate to ensure that the system is stable near the preset value. By obtaining the operating condition of the engine 100 in real time and searching the preset EGR rate mapping table, this embodiment can provide the most suitable EGR rate target for different working conditions. This dynamic adjustment ensures the precise control of the EGR rate under different working conditions, thereby optimizing the combustion process of the engine 100.

[0060] Specifically, the step of the control device correcting the actual EGR rate includes, first, monitoring the actual EGR rate in the exhaust system in real time through sensors (such as oxygen sensors, NOx sensors or EGR flow sensors) on the engine 100. The oxygen sensor can detect the oxygen content in the exhaust gas, thereby indirectly reflecting the proportion of exhaust gas recirculation; the NOx sensor is used to directly measure the concentration of nitrogen oxides and provide feedback on combustion efficiency and emissions. The data collected by the sensor is transmitted to the engine 100 control unit (ECU), and is processed and filtered to eliminate noise and interference to ensure the accuracy of the data. Secondly, the ECU calculates the actual EGR rate under the current working condition based on the signal provided by the sensor. The actual EGR rate refers to the proportion of exhaust gas recirculation in the exhaust system under specific working conditions, which is compared with the target EGR rate to evaluate the operating state of the system. The target EGR rate is provided by a preset EGR rate mapping table and is searched in real time according to the current engine 100 working condition. The actual EGR rate calculated in real time is compared with the target EGR rate to calculate the error between the two. The error is usually expressed as a percentage difference or an absolute value difference. Then, the system sets an allowable error range, that is, an error tolerance. If the error between the actual EGR rate and the target EGR rate is within the tolerance range, the system considers that the EGR control is normal and no adjustment is required. If the error exceeds the tolerance range, the system determines that correction is required to make the actual EGR rate as close to the target EGR rate as possible. Finally, according to the size and direction of the error, the ECU adjusts the opening value of the EGR valve through the control signal. If the error is positive (the actual EGR rate is higher than the target EGR rate), it means that the amount of exhaust gas entering the intake system is too much. The system will reduce the opening value of the EGR valve assembly 20 and reduce the exhaust gas flow. If the error is negative (the actual EGR rate is lower than the target EGR rate), it means that the amount of exhaust gas is insufficient. The system will increase the opening value of the EGR valve assembly 20 and increase the exhaust gas flow. Through real-time monitoring and feedback correction, the system can maintain a high consistency between the actual EGR rate and the target EGR rate under various operating conditions, reduce control errors, and ensure the stability of the combustion process.

[0061] It is understood that the step of obtaining the total intake air volume is to obtain the value of the mass air flow sensor in the intake manifold 102. The mass air flow sensor (MAF) is usually installed at the entrance of the intake manifold 102, close to the position between the air filter and the compressor 60. The MAF sensor provides accurate intake air volume data by measuring the mass of air flowing through it. When the engine 100 is running, the MAF sensor measures the mass air flow entering the intake manifold 102 in real time. The sensor transmits the air mass flow data to the ECU in the form of an electrical signal. After receiving the signal from the MAF sensor, the ECU performs signal processing and filtering to remove noise and unnecessary fluctuations to ensure the accuracy and stability of the data. If necessary, the ECU can integrate the time according to the instantaneous air flow and calculate the cumulative intake volume (i.e., the total intake volume) within a certain period of time. The total intake volume obtained is input into the EGR control model together with other engine 100 operating condition data to calculate the required EGR flow and target EGR rate. The mass air flow sensor can accurately measure the mass air flow entering the engine 100 and provide real-time and accurate data. This accuracy is crucial for subsequent EGR flow control and ensures precise control of the system under various operating conditions.

[0062] It can be understood that the formula for calculating the EGR demand based on the EGR rate and the total intake volume is:

[0063]

[0064] In a specific embodiment, the first threshold is set to 50 kg / h, and the second threshold is set to 100 kg / h.

[0065] Example 1

[0066] Under the operating condition of the current speed of 2000 rpm and torque of 180 N·m, if Figure 6 As shown, the current EGR flow is 69.6 kg / h, and the EGR demand is greater than the first threshold and less than the second threshold. According to the control method, the first EGR valve 21 is fully closed at this time, and only the second EGR valve 22 is used to control the flow of the EGR valve. The opening value of the second EGR valve 22 is obtained by finding the second EGR valve 22 opening value setting MAP, and the acquisition method is still to find and obtain the parameters according to the current engine 100 operating condition of 2000 revolutions, that is, 180 N·m of torque. As shown in the figure below, the second EGR valve 22 opening value is found and output, and the opening value can be obtained as 25% through interpolation.

[0067] Example 2

[0068] Assuming that the current operating condition of the engine 100 is a speed of 1500 rpm and a torque of 120 N·m, through the EGR demand calculation model, we get the current EGR flow rate of 40 kg / h. This flow value is less than the first threshold value (50 kg / h). At this time, according to the control method, only the first EGR valve 21 is operated, and the second EGR valve 22 remains closed. MAP is set by looking up the opening value of the first EGR valve 21, and the search is performed according to the parameters of the current operating condition of the engine 100, which is a speed of 1500 rpm and a torque of 120 N·m. Assume that the opening value of the first EGR valve 21 found is set to 15%. The first EGR valve 21 operates at an opening value of 15%, ensuring accurate small-flow EGR control to meet the operating requirements of the engine 100 while maintaining a low emission level.

[0069] Example 3

[0070] Assuming that the current operating condition of the engine 100 is a speed of 2500 rpm and a torque of 250 N·m, through the EGR demand calculation model, we get the current EGR flow rate of 120 kg / h. This flow value is greater than the second threshold (100 kg / h). In this case, both the first EGR valve 21 and the second EGR valve 22 need to be opened to meet the high EGR flow demand. At this time, the first EGR valve 21 is fully open, and the opening of the second EGR valve 22 is set by finding the opening value of the two EGR valves in parallel to set the MAP, and the search is performed according to the parameters of the current operating condition of the engine 100, which is a speed of 2500 rpm and a torque of 250 N·m. The opening of the second EGR valve 22 is 30%. The first EGR valve 21 and the second EGR valve 22 work simultaneously with an opening of 100% and 30% respectively, ensuring that sufficient exhaust gas flow is provided to support the emission control requirements and combustion stability under high load operation.

[0071] It should be noted that the EGR flow rate, the first EGR valve 21 and the second EGR valve 22 obtained according to the operating conditions of the engine 100 are all example parameters of a certain engine 100 .

[0072] In some embodiments, the EGR valve assembly 20 may include more than two EGR valves, and the valve caliber of each EGR valve is different, and the control method of the EGR exhaust gas flow rate is also changed accordingly according to the number of EGR valves. Specifically, in the EGR exhaust gas flow rate control method of the present invention, if the EGR valve assembly 20 includes more than two EGR valves, and the valve caliber of each EGR valve is different, the control strategy can be more refined to adapt to more diverse working conditions and provide more accurate flow control. This configuration can greatly enhance the flexibility and accuracy of the system. For example, the system includes three or more EGR valves, such as a first EGR valve, a second EGR valve, a third EGR valve, etc., and the valve caliber of each valve is different, and they are arranged from small to large to adapt to the flow demand from low to high. According to the flow characteristics of each EGR valve, multiple flow thresholds are set, such as a first threshold, a second threshold, a third threshold, etc., and each threshold corresponds to starting a corresponding EGR valve. According to the actual EGR demand, the system controls the valves through the following logic: when the EGR demand is less than the first threshold, only the first EGR valve is opened; when the EGR demand is between the first and second thresholds, the first EGR valve is closed and the second EGR valve is opened; when the EGR demand is between the second and third thresholds, the second EGR valve is closed and the third EGR valve is opened; when the EGR demand is greater than the third threshold, the third EGR valve and all the above EGR valves are opened. The multi-valve configuration allows the system to adjust the EGR flow more finely, providing a wider adjustment range and higher control accuracy.

[0073] The present embodiment further provides an engine 100, comprising the above-mentioned EGR exhaust gas flow control system.

[0074] The above is only a preferred specific embodiment of the present invention, but the protection scope of the present invention is not limited thereto. Any changes or substitutions that can be easily thought of by a person skilled in the art within the technical scope disclosed by the present invention should be included in the protection scope of the present invention. Therefore, the protection scope of the present invention shall be subject to the protection scope of the claims.

Claims

1. A control system for EGR exhaust gas flow, characterized in that: include: An EGR passage, wherein an inlet of the EGR passage is used to communicate with an exhaust manifold, and an outlet of the EGR passage is used to communicate with an intake manifold, wherein a first EGR valve and a second EGR valve are arranged in parallel in the EGR passage, and a valve diameter of the first EGR valve is smaller than a valve diameter of the second EGR valve; A control device is electrically connected to the first EGR valve and the second EGR valve respectively.

2. The EGR exhaust gas flow control system according to claim 1, characterized in that: The first EGR valve includes a first EGR valve plate having a first diameter, and the second EGR valve includes a second EGR valve plate having a second diameter, and a ratio of the first diameter to the second diameter is 2:

3.

3. A method for controlling EGR exhaust gas flow, characterized in that: The control system for the EGR exhaust gas flow rate according to claim 1 or 2 is implemented, comprising the following steps: Get EGR rate and total intake volume; Calculating an EGR demand according to the EGR rate and the total intake air volume; According to the EGR demand being within a preset range, the first EGR valve and the second EGR valve are controlled respectively.

4. The method for controlling the EGR exhaust gas flow rate according to claim 3, characterized in that: According to the EGR demand being within a preset range, the steps of respectively controlling the first EGR valve and the second EGR valve include: The EGR demand is less than or equal to a first threshold, and the first EGR valve is controlled to be opened and the second EGR valve is controlled to be closed; The opening value of the first EGR valve is adjusted according to the EGR demand.

5. The method for controlling the EGR exhaust gas flow rate according to claim 4, characterized in that: According to the EGR demand being within a preset range, the step of controlling the first EGR valve and the second EGR valve respectively further includes: The EGR demand is greater than the first threshold and less than or equal to a second threshold, controlling the first EGR valve to close and the second EGR valve to open; The opening value of the second EGR valve is adjusted according to the EGR demand.

6. The method for controlling the EGR exhaust gas flow rate according to claim 5, characterized in that: According to the EGR demand being within a preset range, the step of controlling the first EGR valve and the second EGR valve separately further comprises: The EGR demand is greater than the second threshold, controlling the first EGR valve to open and the second EGR valve to open; The opening value of the first EGR valve and the opening value of the second EGR valve are adjusted according to the EGR demand.

7. The method for controlling the EGR exhaust gas flow rate according to claim 3, characterized in that: The steps to obtain the EGR rate include: Obtaining the operating conditions of the engine; A preset EGR rate mapping table is searched according to the operating conditions.

8. The method for controlling the EGR exhaust gas flow rate according to claim 3, characterized in that: The step of obtaining the total intake air volume is to obtain the value of the mass air flow sensor in the intake manifold.

9. The method for controlling the EGR exhaust gas flow rate according to claim 3, characterized in that: According to the EGR rate and the total intake air volume, the formula for calculating the EGR demand is:

10. An engine, characterized in that: A control system comprising the EGR exhaust gas flow rate according to claim 1 or 2.

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