EGR device, control method, flow calculation method and diagnosis method

Abstract

The invention relates to an EGR device, a control method, a flow calculation method and a diagnosis method, and relates to the field of engines, and the EGR device is arranged on an EGR gas taking pipe and comprises an EGR valve plate and an EGR valve plate limiting regulator; the inner top wall of the EGR gas taking pipe extends downwards in an inclined mode to form a top protruding part, a rotating shaft is arranged at the bottom of the top protruding part, the EGR valve plate is installed on the top protruding part through the rotating shaft, and the inner bottom wall of the EGR gas taking pipe extends upwards in an inclined mode to form a bottom protruding part towards the EGR valve plate. The EGR valve plate limiting adjuster is located above the EGR valve plate and can abut against the EGR valve plate so as to adjust the distance between the free end of the EGR valve plate and the bottom protruding part, and then gas flow in the EGR gas taking pipe is controlled. Exhaust pulse energy can be fully utilized, EGR flow can be accurately adjusted, different working condition requirements of an engine are met, gas backflow is prevented, and safe and reliable operation is ensured.

Description

Technical Field

[0001] The present invention relates to the field of engines, and in particular to an EGR device and a control method, a flow calculation method, and a diagnosis method. Background Art

[0002] The Exhaust Gas Recirculation (EGR) system is a key engine function. Its core function is to redirect some of the engine's exhaust gas back into the cylinders. This recirculated exhaust gas mixes with fresh air and then participates in the combustion process again. By precisely controlling the amount of recirculated exhaust gas, the engine's combustion environment can be effectively optimized, improving combustion efficiency and ultimately boosting overall engine efficiency.

[0003] However, existing EGR systems have exposed some shortcomings in practical applications. Typically, such systems control the exhaust gas flow by placing a valve in the passage from exhaust gas to fresh air. The valve opening is read and regulated by an electronic control unit. Although the flow of exhaust gas into the intake system can be controlled by adjusting the valve opening, the operating mode of existing EGR systems is relatively simple and difficult to adapt to complex and changing engine operating conditions. In addition, the accuracy of existing technologies in EGR rate calculation and system diagnosis also has room for improvement, which may limit the optimization of the engine combustion process and affect further improvement of engine performance.

[0004] A thorough analysis of the engine's operating cycle reveals that the four strokes of the engine—intake, compression, power, and exhaust—are performed in a cyclical sequence. This means that the exhaust process is not a continuous, stable flow, but rather exhibits distinct pulse characteristics. During this exhaust pulse flow, the pressure of the exhaust system fluctuates significantly in both time and space. Simultaneously, the exhaust gas velocity also exhibits a pulsed pattern of variation as the exhaust pulses change. These exhaust pulse characteristics significantly impact the efficiency and accuracy of the EGR system, and existing EGR systems still need to be enhanced in their ability to cope with these exhaust pulse characteristics to achieve more precise exhaust gas flow control and improved engine performance. Summary of the Invention

[0005] The purpose of the present invention is to provide an EGR device and a control method, a flow calculation method, and a diagnostic method. By optimizing the design and control logic of components such as the EGR valve limit regulator, closing contacts and opening contacts, the exhaust pulse energy can be fully utilized to accurately adjust the EGR flow to meet the different operating conditions of the engine, prevent gas backflow, and ensure safe and reliable operation; at the same time, with the help of precise flow calculation and system diagnosis, the combustion process can be optimized, nitrogen oxide emissions can be reduced, and the engine's environmental performance, fuel economy and power output can be improved, its intelligence level and adaptability can be enhanced, and the scope of application can be broadened, with good market prospects and economic value.

[0006] In order to achieve the above-mentioned purpose, the technical solution of the present invention provides an EGR device, which is arranged in an EGR air intake pipe, including an EGR valve plate and an EGR valve plate limit adjuster; the inner top wall of the EGR air intake pipe is provided with a top bulge extending obliquely downward, and the bottom of the top bulge is provided with a rotating shaft, and the EGR valve plate is installed on the top bulge through the rotating shaft, and the inner bottom wall of the EGR air intake pipe is provided with a bottom bulge extending obliquely upward toward the EGR valve plate; the EGR valve plate limit adjuster is located above the EGR valve plate, and it can abut the EGR valve plate to adjust the distance between the free end of the EGR valve plate and the bottom bulge, thereby controlling the gas flow in the EGR air intake pipe.

[0007] Preferably, the EGR valve plate limit adjuster is located in the EGR air intake pipe from the top convex portion to the bottom convex portion, and is located above the EGR valve plate. It can rotate around its own middle part, and its outer surface is smooth and one side convex outward. The convex part can drive the EGR valve plate downward to rotate during rotation, thereby controlling the maximum opening position of the EGR valve plate and adjusting the EGR flow.

[0008] Preferably, an EGR valve closing contact is provided on the top of the bottom convex portion, and the top of the EGR valve closing contact can abut against the EGR valve plate to prevent the EGR valve plate from continuing to rotate downward, and the EGR valve closing contact can output a low-level signal by being electrically connected to the engine controller to feedback the closing state of the EGR valve plate.

[0009] Preferably, the free end of the EGR valve plate is located between the EGR valve plate limit regulator and the EGR valve plate closing contact.

[0010] Preferably, an EGR valve plate opening contact is provided on the outer surface of the EGR valve plate limit regulator, which is located in the segment of the EGR valve plate that is close to the EGR valve plate from the protrusion. It can output a high-level signal by being electrically connected to the engine controller to feedback the opening state of the EGR valve plate, and a sensor is provided inside the EGR valve plate limit regulator to feedback the opening degree to the engine controller.

[0011] The technical solution of the present invention provides a control method for an EGR device. When the engine needs to increase the EGR flow, the EGR valve limit regulator is rotated so that the EGR valve is allowed to open to a larger position, allowing more pulsed airflow to pass into the downstream; when the EGR flow needs to be reduced, the EGR valve limit regulator is rotated so that the EGR valve is only allowed to open to a smaller position, reducing the pulsed airflow, until the EGR valve is pressed into the closed position.

[0012] The technical solution of the present invention provides a flow calculation method for an EGR device, comprising the following steps:

[0013] Circuits are respectively provided on the EGR valve plate, the EGR valve plate limit regulator, the EGR valve plate closing contact, and the EGR valve plate opening contact parts, so that the engine controller reads the parts status;

[0014] A position sensor is provided on the EGR valve limit regulator to read the opening size;

[0015] A switch signal is set on the EGR valve plate so that the controller reads the voltage signal, wherein the open contact is high level and the closed contact is low level;

[0016] The controller processes the above signal, obtains the opening duration and flow cross-sectional area of the EGR valve plate, and calculates the EGR flow rate in combination with the pressure and temperature before and after the EGR pipeline read.

[0017] Preferably, the method comprises the following steps:

[0018] According to the EGR valve limit regulator opening signal, the flow channel cross-sectional area Amax of the EGR valve when the valve is in the maximum open state at the current opening is obtained;

[0019] According to the EGR valve switch signal, the closing time T0, the opening process time T1, the maximum opening position time T2, and the closing process time T3 are obtained;

[0020] The opening and closing of the EGR valve is simplified to a process of uniform cross-sectional area change, that is, the cross-sectional area uniformly increases from 0 to Amax within T1, and uniformly decreases from Amax to 0 within T3;

[0021] Based on this, the cross-sectional area at each moment is determined;

[0022] Combining parameters such as EGR valve inlet pressure, outlet pressure, and inlet temperature, the Bernoulli equation and continuity equation are used to calculate the instantaneous EGR flow rate.

[0023] The instantaneous flow rate is integrated within an opening and closing cycle and divided by the cycle, and the engine EGR rate is obtained by combining it with the fresh air flow rate.

[0024] The technical solution of the present invention provides a diagnostic method for an EGR device, comprising the following contents:

[0025] When the EGR valve limit regulator is in the closed state and the engine controller reads the EGR valve high level, the feedback limit regulator position is unreasonable fault;

[0026] Under certain speed and load, when the EGR valve limit regulator is open and the engine controller continuously reads the EGR valve high level, the feedback valve is stuck in the open position fault;

[0027] At a certain speed and load, when the EGR valve limit regulator is open and the engine controller continuously reads the EGR valve low level, the feedback valve is stuck in the closed position fault.

[0028] The present invention has the following beneficial technical effects:

[0029] By rationally designing components such as the EGR valve limiter, the EGR valve closing and opening contacts, and other components, this invention fully utilizes exhaust pulse energy and precisely controls EGR flow to meet the needs of varying engine operating conditions. Furthermore, the device is compact, easy to manufacture and install, and effectively reduces combustion temperatures, nitrogen oxide emissions, and enhances the engine's environmental performance without significantly increasing engine manufacturing costs.

[0030] The EGR flow calculation method proposed in this invention combines multiple parameters, such as the EGR valve on / off signal, the limit regulator opening signal, and the pressure and temperature before and after the EGR line. By simplifying the calculation model and utilizing the Bernoulli equation and the continuity equation, it can accurately measure the EGR flow, providing reliable data support for engine combustion control and emission optimization. Furthermore, the EGR system diagnostic method proposed in this invention can promptly and accurately diagnose common EGR system faults, such as improper EGR valve limit regulator position and EGR valve stuck, ensuring stable engine operation, reducing downtime, and increasing engine service life.

[0031] The EGR device and control method, flow calculation method, and system diagnostic method of the present invention work together to optimize the engine's combustion process, improve fuel economy and power output, enhance the engine's adaptability to varying operating conditions, and broaden its application range. Furthermore, the present invention enhances the engine's intelligence level, enabling it to better adapt to the development trend of intelligent and connected modern vehicles, and has promising market application prospects and economic value. BRIEF DESCRIPTION OF THE DRAWINGS

[0032] Figure 1A schematic diagram of the EGR valve plate closed state in an EGR device and control method, flow calculation method, and diagnosis method of the present invention;

[0033] Figure 2 A schematic diagram of the EGR valve opening state in an EGR device and control method, flow calculation method, and diagnosis method of the present invention;

[0034] Figure 3 This is a schematic diagram of electrical signal connections in an EGR device and control method, flow calculation method, and diagnostic method of the present invention;

[0035] Figure 4 A schematic diagram of exhaust pulses, EGR valve switches, and EGR valve signals in an EGR device and control method, flow calculation method, and diagnosis method of the present invention;

[0036] Figure 5 This is a flow chart of EGR flow calculation in an EGR device and control method, flow calculation method, and diagnosis method of the present invention;

[0037] Figure 6 The present invention provides an EGR device and control method, flow calculation method, and EGR device diagnostic process in the diagnostic method. Figure 1 ;

[0038] Figure 7 The present invention provides an EGR device and control method, flow calculation method, and EGR device diagnostic process in the diagnostic method. Figure 2 ;

[0039] Figure 8 The present invention provides an EGR device and control method, flow calculation method, and EGR device diagnostic process in the diagnostic method. Figure 3 .

[0040] Figure numerals: 1. EGR air intake pipe; 2. EGR valve plate; 3. EGR valve plate limit regulator; 4. EGR valve plate opening contact; 5. EGR valve plate closing contact; 6. EGR valve plate limit regulator opening signal; 7. rotating shaft; 8. top convex part; 9. bottom convex part. DETAILED DESCRIPTION

[0041] The following will clearly and completely describe the technical solutions in the embodiments of the present invention in conjunction with the accompanying drawings. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. All other embodiments obtained by ordinary technicians in this field based on the embodiments of the present invention without making any creative efforts shall fall within the scope of protection of the present invention.

[0042] This invention provides an engine EGR device and control method, flow calculation method, and system diagnostic method, designed to fully utilize exhaust pulse energy and accurately calculate EGR flow. The EGR device is installed in an EGR air intake pipe 1 and includes an EGR valve plate 2, an EGR valve limit adjuster 3, an EGR valve closing contact 5, and an EGR valve opening contact 4. The EGR air intake pipe 1 is located within the engine compartment, connected to the engine exhaust pipe at one end and the intake pipe at the other. It guides some exhaust gas from the exhaust pipe to the intake pipe, achieving exhaust gas recirculation, lowering combustion temperatures, and reducing nitrogen oxide emissions.

[0043] A top protrusion 8 extends diagonally downward from the inner top wall of the EGR intake pipe 1. A pivot shaft 7 is located at the bottom of the protrusion 8. The EGR valve disc 2 is mounted on the protrusion 8 via the pivot shaft 7 and can rotate about the protrusion 7. The free end of the EGR valve disc 2 is positioned between the EGR valve disc limit adjuster 3 and the EGR valve disc closing contact 5, thereby controlling the flow of exhaust gas. A bottom protrusion 9 extends diagonally upward toward the EGR valve disc 2 from the inner bottom wall of the EGR intake pipe 1. The EGR valve disc closing contact 5 is located at the top of the protrusion 9. The top of the EGR valve disc closing contact 5 abuts the EGR valve disc 2 and prevents further downward rotation. Furthermore, the EGR valve disc closing contact 5 is electrically connected to the engine controller to output a low-level signal. When the EGR valve disc 2 is closed, the valve disc contacts the EGR valve disc closing contact 5, forming a low-level signal loop that provides feedback to the engine controller regarding the closed state of the EGR valve disc 2.

[0044] The EGR valve plate limiter 3 is located at the top of the section from the top protrusion 8 to the bottom protrusion 9 within the EGR intake pipe 1, near the EGR valve plate 2. The EGR valve plate limiter 3 is rotatable about its center. Its outer surface is smooth, with a slight outward protrusion on one side. This protrusion drives the EGR valve plate 2 downward as the EGR valve plate limiter 3 rotates, thereby controlling the maximum opening position of the EGR valve plate 2, adjusting the opening range of the EGR valve plate 2, and thus regulating the EGR flow rate. An EGR valve plate opening contact 4 is provided on the outer surface of the EGR valve plate limiter 3. This contact 4 is located near the EGR valve plate 2, extending from the protrusion. This contact 4 is electrically connected to the engine controller to output a high-level signal. When the EGR valve plate 2 is open, the valve plate contacts the EGR valve plate opening contact 4, forming a high-level signal circuit that provides feedback to the engine controller regarding the opening status of the EGR valve plate 2. In addition, a sensor is provided inside the EGR valve limit regulator 3 to feed back the opening degree to the engine controller.

[0045] According to the different working requirements of the engine, the working status of the EGR device is as follows:

[0046] In the free state, the EGR valve plate 2 relies on its own elasticity and gravity to press against the EGR valve plate closing contact 5, preventing the exhaust gas from flowing. Figure 1 At this time, the EGR device is in the closed state, which is suitable for engine shutdown or operating conditions where EGR is not required. Even if there is an exhaust pulse exerting force to push the EGR valve plate 2, the EGR valve plate 2 can still be closed due to the limitation of the EGR valve plate limit regulator 3.

[0047] When the engine operating conditions require a certain amount of EGR, such as Figure 2 As shown, the EGR valve plate limiter 3 is opened to a certain degree. When the engine exhaust pulse reaches the EGR valve plate 2, the exhaust gas exerts force on the EGR valve plate 2, pushing the valve plate open rapidly to the position permitted by the EGR valve plate limiter 3. There, it presses against the EGR valve plate opening contact 4, allowing exhaust gas to pass. As exhaust pressure decreases, the EGR valve plate 2 automatically rebounds and closes. Because the required EGR flow rate varies under different engine operating conditions, the engine controller can adjust the opening of the EGR valve plate limiter 3 to increase the EGR flow entering the engine.

[0048] In addition, in the engine EGR pipeline, when the pressure downstream of the EGR valve plate 2 is higher than the upstream pressure, regardless of the state of the EGR valve plate limit regulator 3, the pressure downstream of the EGR valve plate 2 will press the EGR valve plate 2 against the EGR valve plate closing contact 5, which can prevent gas backflow.

[0049] The present invention also provides an EGR control method. When the engine needs to increase EGR flow, the EGR valve plate limiter 3 is rotated to allow the EGR valve plate 2 to open further, thereby allowing more pulsed airflow to enter the downstream through the EGR valve plate 2. Conversely, when the engine needs to decrease EGR flow, the EGR valve plate limiter 3 is rotated to allow the EGR valve plate 2 to open only to a smaller position, reducing the pulsed airflow to enter the downstream through the EGR valve plate 2, until the EGR valve plate limiter 3 presses the EGR valve plate 2 into the closed position.

[0050] In addition, the present invention also proposes a method for calculating EGR flow, which includes the following steps:

[0051] Circuits are set on the EGR valve plate 2, EGR valve plate limit regulator 3, EGR valve plate closing contact 5, and EGR valve plate opening contact 4 parts respectively, so that the engine controller can read the status of the above parts, such as Figure 3 As shown;

[0052] A position sensor is provided on the EGR valve limit regulator 3, and the engine controller can read the opening size of the EGR valve limit regulator 3;

[0053] A switch signal is set on the EGR valve plate 2 so that the engine controller can read the voltage signal on the EGR valve plate 2, wherein the EGR valve plate opening contact 4 is connected to a high level and the EGR valve plate closing contact 5 is connected to a low level; when the EGR valve plate 2 and the EGR valve plate opening contact 4 are connected, the engine controller reads a high-level signal from the EGR valve plate 2; when the EGR valve plate 2 and the EGR valve plate closing contact 5 are connected, the engine controller reads a low-level signal from the EGR valve plate 2;

[0054] By processing the above signals, the engine controller can obtain the opening duration and flow cross-sectional area of the EGR valve plate 2, and can calculate the EGR flow rate by combining the pressure and temperature before and after the EGR pipeline read by the engine controller.

[0055] like Figure 4 As shown in the figure, when the engine is running and the EGR valve limiter 3 is open, the EGR valve 2 opens and closes in accordance with the exhaust pressure pulse cycle. The EGR valve switch signal also switches between high and low levels as it contacts the open and close contacts. Combined with the crankshaft angle or time signal, the engine controller can obtain the duration of the EGR valve 2's closing, opening, and opening and closing moments. For ease of description, the EGR valve 2 closing time within one opening and closing cycle, i.e., the low-level duration, is defined as T0. The interval between the low and high levels is defined as T1. The high-level duration is defined as T2. The interval between the high and low levels is defined as T3.

[0056] The specific calculation process is as follows Figure 5 As shown, for each opening of the EGR valve limit regulator 3, there is a corresponding cross-sectional area of the EGR flow channel when the EGR valve 2 is in the maximum open state. It includes the following contents:

[0057] When calculating the EGR flow rate, first, according to the EGR valve limit regulator opening signal 6, the cross-sectional area Amax of the EGR flow channel when the EGR valve plate 2 is in the maximum open state at the current opening is obtained;

[0058] According to the EGR valve plate switch signal, the closing time T0, opening process time T1, maximum opening position time T2 and closing process time T3 of the EGR valve plate 2 are obtained;

[0059] The opening and closing of EGR valve plate 2 can be simplified as a process of uniformly changing cross-sectional area A. That is, during time T1, the cross-sectional area of the EGR flow channel increases uniformly from 0 to Amax; during time T3, the cross-sectional area of the EGR flow channel decreases uniformly from Amax to 0. That is, during stage T0, A = 0; during stage T1, A = t / T1*Amax; during stage T2, A = Amax; and during stage T3, A = (1-t / T1)*Amax. Thus, within a single opening and closing cycle of EGR valve plate 2, the cross-sectional area of the EGR flow channel is determined at each moment.

[0060] According to the current EGR valve inlet pressure, outlet pressure, inlet temperature, EGR flow channel cross-sectional area and other parameters, the instantaneous EGR flow rate at the current moment is calculated using the Bernoulli equation and the continuity equation.

[0061] The EGR flow calculated in the above process fluctuates significantly, making it difficult to control. Therefore, averaging is necessary. To obtain steady-state EGR flow, the instantaneous EGR flow is integrated over the opening and closing cycle of EGR valve 2. This is then divided by the cycle (T0 + T1 + T2 + T3), and combined with the fresh air flow to obtain the engine EGR rate.

[0062] The engine EGR system proposed in this invention incorporates the pressure changes of exhaust pulses in the EGR line into its calculations, as well as the valve opening and closing times, enabling more accurate EGR flow calculations. By reading the on / off signals from EGR valve 2, the engine's EGR system can be diagnosed with precision across each cylinder's combustion cycle, enabling timely and accurate detection of EGR and exhaust anomalies.

[0063] Finally, the present invention also provides an EGR system diagnostic method, according to the characteristics of the engine exhaust pulse airflow and the operating conditions of different speeds and loads, such as Figure 6 As shown, it includes the following:

[0064] When the EGR valve limit regulator 3 is in the closed state and the engine controller reads the EGR valve 2 high level, it feedbacks that the EGR valve limit regulator 3 position is unreasonable;

[0065] Under appropriate engine speed and load, when EGR valve limit regulator 3 is in the open state and the engine controller continuously reads EGR valve 2 high level, feedback is that EGR valve 2 is stuck in the open position fault;

[0066] Under appropriate engine speed and load, when the EGR valve limit regulator 3 is in the open state and the engine controller continuously reads the low level of the EGR valve 2, it feedbacks that the EGR valve 2 is stuck in the closed position fault.

[0067] Finally, it should be noted that the above is only a preferred embodiment of the present invention and is not intended to limit the present invention. Although the present invention has been described in detail with reference to the aforementioned embodiments, those skilled in the art can still modify the technical solutions described in the aforementioned embodiments or make equivalent substitutions for some of the technical features therein. Any modifications, equivalent substitutions, improvements, etc. made within the spirit and principles of the present invention should be included in the scope of protection of the present invention.

Claims

1. An EGR device, characterized in that: The invention is provided on an EGR air intake pipe (1), and comprises an EGR valve plate (2) and an EGR valve plate limit regulator (3); a top convex portion (8) is extended obliquely downward from the inner top wall of the EGR air intake pipe (1), a rotating shaft (7) is provided at the bottom of the top convex portion (8), the EGR valve plate (2) is mounted on the top convex portion (8) via the rotating shaft (7), and a bottom convex portion (9) is extended obliquely upward toward the EGR valve plate (2) from the inner bottom wall of the EGR air intake pipe (1); the EGR valve plate limit regulator (3) is located above the EGR valve plate (2), and can abut against the EGR valve plate (2) to adjust the distance between the free end of the EGR valve plate (2) and the bottom convex portion (9), thereby controlling the gas flow in the EGR air intake pipe (1).

2. The EGR device according to claim 1, characterized in that: The EGR valve plate limit regulator (3) is located in the EGR air intake pipe (1) from the top convex portion (8) to the bottom convex portion (9), and is located above the EGR valve plate (2). It can rotate around its own middle part, and its outer surface is smooth and one side convex outward. The convex portion can drive the EGR valve plate (2) to rotate downward during rotation, thereby controlling the maximum opening position of the EGR valve plate (2) and adjusting the EGR flow rate.

3. The EGR device according to claim 2, characterized in that: An EGR valve closing contact (5) is provided at the top of the bottom convex portion (9); the top of the EGR valve closing contact (5) can abut against the EGR valve (2) to prevent the EGR valve (2) from continuing to rotate downward; and the EGR valve closing contact (5) can output a low-level signal by being electrically connected to an engine controller to provide feedback on the closing state of the EGR valve (2).

4. The EGR device according to claim 3, characterized in that: The free end of the EGR valve plate (2) is located between the EGR valve plate limit regulator (3) and the EGR valve plate closing contact (5).

5. The EGR device according to claim 4, characterized in that: An EGR valve plate opening contact (4) is provided on the outer surface of the EGR valve plate limit regulator (3), which is located in a segment of the EGR valve plate limit regulator (3) close to the EGR valve plate (2) from the protrusion. The contact can output a high-level signal by being electrically connected to the engine controller to feed back the opening state of the EGR valve plate (2). A sensor is also provided inside the EGR valve plate limit regulator (3) to feed back the opening degree to the engine controller.

6. A control method for an EGR device according to any one of claims 1 to 5, characterized in that: When the engine needs to increase the EGR flow, the EGR valve plate limit regulator (3) is rotated so that the EGR valve plate (2) is allowed to open to a larger position, allowing more pulse airflow to pass into the downstream; when the EGR flow needs to be reduced, the EGR valve plate limit regulator (3) is rotated so that the EGR valve plate (2) is only allowed to open to a smaller position, reducing the pulse airflow, until the EGR valve plate (2) is pressed tightly in the closed position.

7. A flow calculation method for an EGR device according to any one of claims 1 to 5, characterized in that: The following steps are involved: Circuits are respectively provided on the EGR valve plate (2), the EGR valve plate limit regulator (3), the EGR valve plate closing contact (5), and the EGR valve plate opening contact (4), so that the engine controller reads the states of the parts; A position sensor is provided on the EGR valve limit regulator (3) to read the opening size; A switch signal is set on the EGR valve plate (2) so that a controller reads a voltage signal, wherein an open contact is connected to a high level and a closed contact is connected to a low level; The controller processes the above signal, obtains the opening duration and flow cross-sectional area of the EGR valve plate (2), and calculates the EGR flow rate in combination with the pressure and temperature before and after the EGR pipeline read.

8. The flow calculation method of an EGR device according to claim 7, characterized in that: The following steps are involved: According to the EGR valve plate limit regulator opening signal (6), the flow channel cross-sectional area Amax when the EGR valve plate (2) is in the maximum opening state at the current opening is obtained; According to the EGR valve switch signal, the closing time T0, the opening process time T1, the maximum opening position time T2, and the closing process time T3 are obtained; The opening and closing of the EGR valve plate (2) is simplified to a process of uniform change of cross-sectional area, that is, the cross-sectional area uniformly increases from 0 to Amax within time T1, and uniformly decreases from Amax to 0 within time T3; Based on this, the cross-sectional area at each moment is determined; Combining parameters such as EGR valve inlet pressure, outlet pressure, and inlet temperature, the Bernoulli equation and continuity equation are used to calculate the instantaneous EGR flow rate. The instantaneous flow rate is integrated within an opening and closing cycle and divided by the cycle, and the engine EGR rate is obtained by combining it with the fresh air flow rate.

9. A diagnostic method for an EGR device according to any one of claims 1 to 5, characterized in that: Includes the following: When the EGR valve plate limit regulator (3) is in a closed state and the engine controller reads a high level of the EGR valve plate (2), a fault of an unreasonable position of the feedback limit regulator is generated; Under certain speed and load, when the EGR valve plate limit regulator (3) is open and the engine controller continuously reads the EGR valve plate (2) as a high level, the feedback valve plate is stuck in the open position and fails; At a certain speed and load, when the EGR valve plate limit regulator (3) is opened and the engine controller continuously reads a low level of the EGR valve plate (2), the feedback valve plate is stuck in the closed position and fails.

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