Exhaust gas recirculation device with self-cleaning function and self-cleaning method

Abstract

The invention relates to an exhaust gas recirculation device with a self-cleaning function. The exhaust gas recirculation device comprises an engine control module, an EGR valve, an EGR cooler, an EGR after-cooling temperature sensor, an EGR cooler water inlet pipe, an EGR cooler water outlet pipe and an electronic throttle valve. The engine control module is connected with the electronic throttle valve through a wire. The EGR valve is connected with the EGR cooler through a bolt; the EGR after-cooling temperature sensor is mounted on an outlet pipeline of the EGR cooler; the electronic throttle valve is connected in series between the EGR cooler and the EGR cooler water inlet pipe; and the EGR cooler water outlet pipe is connected with the EGR cooler. The invention further relates to a self-cleaning method of the exhaust gas recirculation device with the self-cleaning function. The efficiency of the EGR cooler in the operation process of the engine is improved; and the time cost and the labor cost are saved.

Description

Technical Field

[0001] The present invention relates to the technical field of engine exhaust gas recirculation systems, and particularly to an exhaust gas recirculation device with a self-cleaning function and a self-cleaning method. Background Art

[0002] With the tightening of emission regulations, most vehicles need to add an exhaust gas recirculation system to meet the requirements of emission regulations. As the engine runs for a longer time, carbon deposits will form on the cooler of the exhaust gas recirculation, increasing the resistance of the exhaust gas recirculation and reducing the efficiency of the exhaust gas recirculation and the cooling efficiency. After running for a period of time, it is necessary to manually remove it for cleaning the cooler, wasting a large amount of labor and material costs.

[0003] The defects of the prior art are as follows:

[0004] 1. As the engine runs for a longer time, carbon deposits will form on the cooler of the exhaust gas recirculation, increasing the resistance of the exhaust gas recirculation, thereby reducing the efficiency of the exhaust gas recirculation and the cooling efficiency.

[0005] 2. Since the cooler needs to be manually removed for cleaning after the system runs for a period of time, a large amount of labor and material costs are wasted. Summary of the Invention

[0006] The present invention aims at the above problems and provides an exhaust gas recirculation device with a self-cleaning function and a self-cleaning method, aiming to improve the efficiency of the EGR cooler during the operation of the engine; save time costs and labor costs.

[0007] To solve the above problems, the technical solution provided by the present invention is as follows:

[0008] An exhaust gas recirculation device with a self-cleaning function includes an engine control module, an EGR valve, an EGR cooler, an EGR post-cooling temperature sensor, an EGR cooler inlet pipe, an EGR cooler outlet pipe, and an electronic throttle valve, wherein:

[0009] The engine control module is connected to the electronic throttle valve through a wire; the EGR valve is connected to the EGR cooler through a bolt; the EGR post-cooling temperature sensor is installed on the outlet pipeline of the EGR cooler; the electronic throttle valve is connected in series between the EGR cooler and the EGR cooler inlet pipe; the EGR cooler outlet pipe is connected to the EGR cooler.

[0010] Preferably, the fins inside the EGR cooler are coated with a noble metal material by electroplating process.

[0011] A self-cleaning method for the exhaust gas recirculation device using the above self-cleaning function includes the following steps:

[0012] S100. Calculate the exhaust manifold temperature through an artificially preset internal engine logic algorithm, expressed by the following formula:

[0013] T out = T in + Δt

[0014] Δt = (θ 1 + α × θ 2 + P in × θ 3 + R × θ 2 ) ÷ μ

[0015] Where: T out is used to represent the exhaust manifold temperature; T in is used to represent the intake ambient temperature; Δt is used to represent the temperature difference; θ 1 is used to represent the exhaust temperature estimation constant; α is used to represent the advance angle; θ 2 is used to represent the advance angle estimation constant in the exhaust temperature; P in is used to represent the intake pressure; θ 3 is used to represent the intake pressure estimation constant in the exhaust temperature; R is used to represent the engine speed; μ is used to represent the air-fuel ratio;

[0016] S200. Read the temperature after EGR cooling through the temperature sensor after EGR cooling;

[0017] S300. According to the preset calibration parameters of the EGR cooler, calculate the current EGR cooler efficiency through the current exhaust manifold temperature of the engine and the temperature after EGR cooling, expressed by the following formula:

[0018]

[0019] Where: E is used to represent the EGR cooler efficiency; is used to represent the cooler inlet temperature; is used to represent the cooler outlet temperature; is used to represent the inlet water temperature;

[0020] S400. Determine whether the current EGR cooler efficiency reaches the artificially preset EGR cooler self-cleaning start condition, and then perform the following operations according to the judgment result:

[0021] If the current EGR cooler efficiency reaches the EGR cooler self-cleaning start condition, it is determined that the EGR cooler self-cleaning is required, and then the EGR cooler self-cleaning process is executed;

[0022] If the current efficiency of the EGR cooler does not reach the self-cleaning start condition of the EGR cooler, it is determined that the self-cleaning of the EGR cooler is not required, and the engine runs normally.

[0023] Preferably, the self-cleaning start condition of the EGR cooler is that the current efficiency of the EGR cooler is lower than 80% and lasts for 10 minutes.

[0024] Preferably, the self-cleaning process of the EGR cooler includes the following steps:

[0025] Sa100. Control the EGR valve to be in the fully open position;

[0026] Sa200. By controlling the electronic valve, reduce the water flow rate into the EGR cooler, so that the gas temperature in the EGR cooler gradually rises until it reaches above the ignition temperature of the noble metal chemical reaction;

[0027] Sa300. Through the engine control module, control the engine to perform post-injection of diesel, so that the post-injected diesel enters the EGR cooler, and under the catalytic action of the noble metal material on the fins in the EGR cooler, the diesel burns in the EGR cooler, thereby increasing the temperature in the EGR cooler;

[0028] Sa400. According to the self-cleaning characteristics of the EGR cooler, set the standard duration for each self-cleaning;

[0029] Sa500. After the self-cleaning is completed, control the engine control module to detect the efficiency of the EGR cooler of the EGR cooler, and then perform the following operations according to the detection results:

[0030] If the current efficiency of the EGR cooler meets the determination condition of successful self-cleaning preset manually, it is determined that the self-cleaning is successful;

[0031] If the current efficiency of the EGR cooler meets the determination condition of failed self-cleaning preset manually, it is determined that the self-cleaning fails, and then the self-cleaning process of the EGR cooler is executed again.

[0032] Preferably, in step Sa300, in order to prevent the temperature in the EGR cooler from rising rapidly, which may cause damage to the EGR cooler, a gradient temperature control sub-process is set; the gradient temperature control sub-process includes the following steps:

[0033] Sb100. Control the engine to perform post-injection of diesel through the engine control module, thereby controlling the EGR cooler to reach a first gradient temperature control range preset manually within a first temperature control time threshold preset manually, and stabilizing within the first gradient temperature control range until the duration reaches a first temperature control stabilization duration preset manually, so that the temperature inside the EGR cooler is evenly distributed;

[0034] Sb200. Control to increase the diesel injection amount, thereby controlling the EGR cooler to reach a second gradient temperature control range preset manually within a second temperature control time threshold preset manually, and stabilizing within the second gradient temperature control range until the duration reaches a second temperature control stabilization duration preset manually;

[0035] Sb300. Control to increase the diesel injection amount, thereby controlling the EGR cooler to reach a third gradient temperature control range preset manually within a third temperature control time threshold preset manually, and control the diesel injection amount to keep the inside of the EGR cooler continuously within the third gradient temperature control range.

[0036] Preferably, during the execution of the gradient temperature control sub-process, the engine control module compares the reading value of the EGR cooled temperature sensor with the first gradient temperature control range, the second gradient temperature control range, and the third gradient temperature control range, and adjusts the post-injection fuel injection amount in real time, so that the temperature inside the EGR cooler is within a controllable range.

[0037] Preferably, the ignition temperature of the noble metal chemical reaction in step Sa200 is 280 °C.

[0038] Preferably, the determination condition for successful self-cleaning in step Sa500 is that the current EGR cooler efficiency is greater than 95%; the determination condition for failed self-cleaning is that the current EGR cooler efficiency is lower than 80% and the duration reaches 30 min.

[0039] Preferably, when the device executes the EGR cooler self-cleaning process three times continuously and the current EGR cooler efficiency is still lower than 80%, it is determined that the EGR cooler fails, and the device displays a fault code to remind that manual intervention is required.

[0040] Compared with the prior art, the present invention has the following advantages:

[0041] 1. Since the present invention realizes the function of automatic carbon cleaning of the EGR cooler, the efficiency of the EGR cooler during the operation of the engine is ensured.

[0042] 2. Since the present invention can achieve the purpose of automatic carbon cleaning of the EGR cooler without manual intervention, a large amount of time cost and labor cost are saved. BRIEF DESCRIPTION OF THE DRAWINGS

[0043] Figure 1 Schematic diagram of the EGR cooler coating for a specific embodiment of the present invention;

[0044] Figure 2 Schematic diagram of the exhaust gas recirculation structure for a specific embodiment of the present invention;

[0045] Figure 3 Schematic diagram of the self - cleaning logic for a specific embodiment of the present invention.

[0046] Wherein: 1. Engine control module, 2. EGR valve, 3. EGR cooler, 4. Temperature sensor after EGR cooling, 5. Inlet pipe of EGR cooler, 6. Outlet pipe of EGR cooler, 7. Electronic throttle valve DETAILED DESCRIPTION OF THE EMBODIMENTS

[0047] The present invention will be further clarified below in conjunction with specific embodiments. It should be understood that these embodiments are only used to illustrate the present invention and not to limit the scope of the present invention. After reading the present invention, various equivalent modifications made by those skilled in the art fall within the scope defined by the appended claims of this application.

[0048] As Figure 1 、 2 shown, an exhaust gas recirculation device with a self - cleaning function includes an engine control module 1, an EGR valve 2, an EGR cooler 3, a temperature sensor 4 after EGR cooling, an inlet pipe 5 of the EGR cooler, an outlet pipe 6 of the EGR cooler, and an electronic throttle valve 7. Wherein:

[0049] The engine control module 1 is connected to the electronic throttle valve 7 through a wire; the EGR valve 2 is connected to the EGR cooler 3 by bolts; the temperature sensor 4 after EGR cooling is installed on the outlet pipeline of the EGR cooler 3; the electronic throttle valve 7 is connected in series between the EGR cooler 3 and the inlet pipe 5 of the EGR cooler; the outlet pipe 6 of the EGR cooler is connected to the EGR cooler 3.

[0050] It should be noted that the fins inside the EGR cooler 3 are coated with a precious metal material by electroplating process.

[0051] As Figure 3 shown, a self - cleaning method for an exhaust gas recirculation device using the self - cleaning function includes the following steps:

[0052] S100. Calculate the exhaust manifold temperature through the engine internal logic algorithm preset manually, expressed by formulas 1 and 2:

[0053] T out = T in +Δt (1)

[0054] Δt = (θ 1 + α × θ 2 + P in × θ 3 + R × θ 2 ) ÷ μ (2)

[0055] Where: T out is used to represent the exhaust manifold temperature; T in is used to represent the intake ambient temperature; Δt is used to represent the temperature difference; θ 1 is used to represent the exhaust temperature estimation constant; α is used to represent the advance angle; θ 2 is used to represent the advance angle estimation constant in the exhaust temperature; xin is used to represent the intake pressure; θ 3 is used to represent the intake pressure estimation constant in the exhaust temperature; R is used to represent the engine speed; μ is used to represent the air-fuel ratio.

[0056] S200. Read the temperature after EGR cooling through the temperature sensor 4 for EGR cooling.

[0057] S300. According to the preset calibration parameters of the EGR cooler 3, calculate the current EGR cooler efficiency through the current exhaust manifold temperature of the engine and the temperature after EGR cooling, expressed by Equation 3:

[0058]

[0059] Where: E is used to represent the EGR cooler efficiency; is used to represent the inlet temperature of the cooler; is used to represent the outlet temperature of the cooler; is used to represent the inlet water temperature.

[0060] S400. Judge whether the current EGR cooler efficiency reaches the self-cleaning start condition of the EGR cooler preset manually, and then perform the following operations according to the judgment result:

[0061] If the current EGR cooler efficiency reaches the self-cleaning start condition of the EGR cooler, it is determined that the EGR cooler 3 needs to be self-cleaned, and then the EGR cooler self-cleaning process is executed.

[0062] If the current EGR cooler efficiency does not reach the self-cleaning start condition of the EGR cooler, it is determined that the EGR cooler 3 does not need to be self-cleaned, and the engine runs normally.

[0063] In this specific embodiment, the self-cleaning start condition of the EGR cooler is that the current EGR cooler efficiency is lower than 80% and lasts for 10 minutes.

[0064] In this specific embodiment, counting starts when the efficiency of the EGR cooler is lower than 80%, with 1 count accumulated per second. When the count reaches 10 minutes, it is determined that the EGR cooler 3 needs to perform self-cleaning. If during the process, the efficiency of the EGR cooler is higher than 85%, the counter is cleared, and counting starts again until the efficiency of the EGR cooler is lower than 80% again. When the count reaches 600, it is determined at this time that the efficiency of the EGR cooler is lower than the normal value and self-cleaning is required.

[0065] It should be noted that the self-cleaning process of the EGR cooler includes the following steps:

[0066] Sa100. Control the EGR valve 2 to be in the fully open position. The EGR valve 2 is fully open by the engine control module 1 to make the opening of the EGR valve 2 reach the maximum, so that the post-injected diesel can enter the EGR cooler 3.

[0067] Sa200. Reduce the water flow rate into the EGR cooler 3 by controlling the electronic valve 7, so that the gas temperature in the EGR cooler 3 gradually rises until it reaches above the ignition temperature of the noble metal chemical reaction. Closing the inlet water pipe of the EGR cooler 3 prevents the engine cooling water from cooling the EGR cooler 3, causing the internal gas temperature of the EGR cooler 3 to rise and reach the ignition temperature of diesel.

[0068] Sa300. Control the engine to perform post-injection of diesel through the engine control module 1, so that the post-injected diesel enters the EGR cooler 3, and the diesel burns in the EGR cooler 3 under the catalytic action of the noble metal material on the fins in the EGR cooler 3, thereby increasing the temperature in the EGR cooler 3.

[0069] Sa400. According to the self-cleaning characteristics of the EGR cooler 3, the noble metal component on the surface of the EGR cooler 3 chemically reacts with the inlet gas of the EGR cooler 3, HC + O 2 generates H 2 O and CO 2 , C + O 2 generates CO 2 , thereby cleaning the ash in the EGR cooler 3 and setting the standard duration for each self-cleaning.

[0070] Sa500. After self-cleaning is completed, control the engine control module 1 to detect the EGR cooler efficiency of the EGR cooler 3, and then perform the following operations according to the detection results:

[0071] If the current EGR cooler efficiency meets the determination conditions for successful self-cleaning preset manually, it is determined that the self-cleaning is successful.

[0072] If the current EGR cooler efficiency meets the determination condition for self-cleaning failure preset manually, it is determined that the self-cleaning fails, and then the EGR cooler self-cleaning process is executed again.

[0073] In this specific embodiment, the ignition temperature of the noble metal chemical reaction in step Sa200 is 280 °C.

[0074] In this specific embodiment, to protect the EGR motor and prevent the peak current of the EGR valve controller from being too large and burning out the motor, the engine control module 1 controls the opening of the EGR valve 2 to reach 80%, so that even if there is an instantaneous overshoot, the EGR motor will not be burned out.

[0075] In this specific embodiment, the engine control module 1 closes the water inlet pipe of the EGR cooler 3, and controls the electronic valve of the EGR cooler 3 through the engine control module 1 to gradually reduce the opening by 10% until it is fully closed. This step prevents the closing of the water inlet pipe of the EGR cooler 3 from causing too much impact on the engine water pump.

[0076] It should be further noted that the engine control module 1 controls the injector to perform multiple injections, so that the later-injected diesel directly reaches the EGR cooler 3 after passing through the exhaust pipe and the EGR valve 2, and does not burn in the engine cylinder and the exhaust pipe.

[0077] In this specific embodiment, the engine controls the injector to inject at -165 degrees before top dead center. At this time, the engine exhaust valve is open, and the diesel will reach the EGR cooler 3 along with the engine exhaust movement.

[0078] It should be further noted that in step Sa300, in order to prevent the temperature in the EGR cooler 3 from rising rapidly, which may cause damage to the EGR cooler 3, a gradient temperature control sub-process is set; the gradient temperature control sub-process includes the following steps:

[0079] Sb100. Control the engine to perform post-injection of diesel through the engine control module 1, so as to control the EGR cooler 3 to reach the manually preset first gradient temperature control interval within the manually preset first temperature control time threshold, and stabilize within the first gradient temperature control interval until the duration reaches the manually preset first temperature control stable duration, so that the temperature in the EGR cooler 3 is evenly distributed.

[0080] Sb200. Control to increase the diesel injection amount, so as to control the EGR cooler 3 to reach the manually preset second gradient temperature control interval within the manually preset second temperature control time threshold, and stabilize within the second gradient temperature control interval until the duration reaches the manually preset second temperature control stable duration.

[0081] Sb300 controls to increase the diesel injection amount, thereby controlling the EGR cooler 3 to reach the manually preset third temperature control gradient range within the manually preset third temperature control time threshold, and controlling the diesel injection amount to keep the temperature inside the EGR cooler 3 within the third temperature control gradient range continuously.

[0082] In this specific embodiment, the first temperature control time threshold is 2 min; the first temperature control gradient range is 350 ± 20 °C; the first temperature control stable duration is 3 min; the second temperature control time threshold is 2 min; the second temperature control gradient range is 450 ± 20 °C; the second temperature control stable duration is 3 min; the third temperature control time threshold is 3 min; the third temperature control gradient range is 550 ± 50 °C.

[0083] It should be further noted that during the execution of the gradient temperature control sub - process, the engine control module 1 compares the reading value of the EGR post - cooling temperature sensor 4 with the first, second, and third temperature control gradient ranges, and adjusts the post - injection fuel injection amount in real - time to keep the temperature inside the EGR cooler 3 within a controllable range.

[0084] It should be further noted that at different temperatures, the self - cleaning ability characteristics of the EGR cooler 3 are different. The higher the temperature, the stronger the self - cleaning ability of the EGR cooler 3; when the temperature exceeds 650, the EGR cooler 3 has a risk of cracking.

[0085] It should be further noted that the gas temperature inside the EGR cooler 3 is set to 550 ± 50 °C. Within this temperature range, the EGR cooler 3 has strong self - cleaning ability and will not be damaged. According to the self - cleaning characteristics of the EGR cooler 3, the carbon deposits inside the EGR cooler 3 can be completely removed within 30 min.

[0086] It should be further noted that the determination condition for successful self - cleaning in step Sa500 is that the current EGR cooler efficiency is greater than 95%; the determination condition for failed self - cleaning is that the current EGR cooler efficiency is lower than 80% and the duration reaches 30 min.

[0087] It should be noted that when the device executes the EGR cooler self - cleaning process three times continuously and the current EGR cooler efficiency is still lower than 80%, it is determined that the EGR cooler 3 fails, and the device displays a fault code to remind that manual intervention is required.

[0088] In the foregoing detailed description, various features are combined in a single embodiment to simplify the present disclosure. This method of disclosure should not be interpreted as reflecting an intention that the embodiments of the claimed subject matter require more features than those stated in each claim. On the contrary, as reflected in the appended claims, the present invention lies in a state with fewer features than all the features of the disclosed single embodiment. Accordingly, the appended claims are hereby expressly incorporated into the detailed description, where each claim stands alone as a separate preferred embodiment of the present invention.

[0089] The above-described disclosed embodiments are described to enable any person skilled in the art to make or use the present invention. For those skilled in the art, various modifications of these embodiments are obvious, and the general principles defined herein can also be applied to other embodiments without departing from the spirit and scope of the present disclosure. Therefore, the present disclosure is not limited to the embodiments given herein, but is consistent with the broadest scope of the principles and novel features disclosed in this application.

[0090] The foregoing description includes examples of one or more embodiments. Of course, it is impossible to describe all possible combinations of components or methods for the purpose of describing the above embodiments, but those of ordinary skill in the art should recognize that each embodiment can be further combined and arranged. Therefore, the embodiments described herein are intended to cover all such changes, modifications, and variations that fall within the scope of the appended claims. In addition, with respect to the term "comprising" used in the specification or claims, this term is covered in a manner similar to the term "including", as explained when "including" is used as a transitional word in the claims. In addition, any use of the term "or" in the specification or claims of the claims is to mean "non-exclusive or".

[0091] The specific embodiments described above further elaborate on the purpose, technical solutions, and beneficial effects of the present invention. It should be understood that the above description is only the specific embodiments of the present invention and is not used to limit the protection scope of the present invention. Any modifications, equivalent replacements, improvements, etc. made within the spirit and principles of the present invention shall be included within the protection scope of the present invention.

Claims

1. An exhaust gas recirculation device with a self-cleaning function, characterized in that: The invention comprises an engine control module (1), an EGR valve (2), an EGR cooler (3), an EGR cooling post-temperature sensor (4), an EGR cooler water inlet pipe (5), an EGR cooler water outlet pipe (6), and an electronic throttle valve (7), wherein: The engine control module (1) is connected to the electronic throttle valve (7) via a wire; the EGR valve (2) is connected to the EGR cooler (3) via bolts; the EGR post-cooling temperature sensor (4) is installed on the outlet pipeline of the EGR cooler (3); the electronic throttle valve (7) is connected in series between the EGR cooler (3) and the EGR cooler water inlet pipe (5); and the EGR cooler water outlet pipe (6) is connected to the EGR cooler (3).

2. The exhaust gas recirculation device with self-cleaning function according to claim 1, characterized in that: The fins inside the EGR cooler (3) are coated with precious metal material through an electroplating process.

3. A self-cleaning method for an exhaust gas recirculation device utilizing the self-cleaning function of claim 2, characterized in that: The following steps are involved: S100. Calculate the exhaust manifold temperature by using a manually preset engine internal logic algorithm, as expressed by the following formula: T out =T in +Δt Δt=(θ1+α×θ2+P in ×θ3+R×θ2)÷μ Where: T out Used to characterize the exhaust manifold temperature; T in It is used to characterize the intake ambient temperature; Δt is used to characterize the temperature difference; θ1 is used to characterize the exhaust temperature estimation constant; α is used to characterize the advance angle; θ2 is used to characterize the advance angle estimation constant in the exhaust temperature; P in Used to characterize the intake pressure; θ3 is used to characterize the intake pressure estimation constant in the exhaust temperature; R is used to characterize the engine speed; μ is used to characterize the air-fuel ratio; S200. Reading the EGR cooling temperature through the EGR cooling temperature sensor (4); S300. According to the preset calibration parameters of the EGR cooler (3), the current EGR cooler efficiency is calculated by the current exhaust manifold temperature of the engine and the EGR cooling temperature, which is expressed as follows: Wherein: E is used to characterize the efficiency of the EGR cooler; Used to characterize the cooler inlet temperature; Used to characterize the cooler outlet temperature; Used to characterize the inlet water temperature; S400. Determine whether the current EGR cooler efficiency reaches the manually preset EGR cooler self-cleaning start condition, and then perform the following operations according to the determination result: If the current efficiency of the EGR cooler reaches the EGR cooler self-cleaning start condition, it is determined that the EGR cooler (3) needs to be self-cleaned, and then the EGR cooler self-cleaning process is executed; If the current efficiency of the EGR cooler does not reach the EGR cooler self-cleaning start condition, it is determined that the EGR cooler (3) does not need to be self-cleaned, and the engine operates normally.

4. The self-cleaning method according to claim 3, characterized in that: The EGR cooler self-cleaning start condition is that the current efficiency of the EGR cooler is lower than 80% and lasts for 10 minutes.

5. The self-cleaning method according to claim 3, characterized in that: The EGR cooler self-cleaning process comprises the following steps: Sa100. Control the EGR valve (2) to be in a fully open position; Sa200. By controlling the electronic valve (7) to reduce the water flow into the EGR cooler (3), the gas temperature in the EGR cooler (3) is gradually increased until it reaches above the ignition temperature of the chemical reaction of the precious metal; Sa300. Controlling the engine to perform post-injection of diesel through the engine control module (1), so that the post-injected diesel enters the EGR cooler (3), and the diesel is burned in the EGR cooler (3) under the catalytic action of the precious metal material on the fins in the EGR cooler (3), thereby increasing the temperature in the EGR cooler (3); Sa400. According to the self-cleaning characteristics of the EGR cooler (3), set the standard duration of each self-cleaning; Sa500. After the self-cleaning is completed, the engine control module (1) is controlled to detect the EGR cooler efficiency of the EGR cooler (3), and then the following operations are performed according to the detection result: If the current efficiency of the EGR cooler meets the manually preset determination condition for successful self-cleaning, it is determined that the self-cleaning is successful; If the current EGR cooler efficiency meets the manually preset self-cleaning failure determination condition, it is determined that the self-cleaning has failed, and then the EGR cooler self-cleaning process is re-executed.

6. The self-cleaning method according to claim 5, characterized in that: In step Sa300, in order to prevent the temperature in the EGR cooler (3) from rising rapidly and thus causing damage to the EGR cooler (3), a gradient temperature control sub-process is provided; the gradient temperature control sub-process comprises the following steps: Sb100. The engine is controlled by the engine control module (1) to perform post-injection of diesel, thereby controlling the EGR cooler (3) to reach a first manually preset gradient temperature control interval within a first manually preset temperature control time threshold, and to stabilize within the first gradient temperature control interval until the duration reaches a first manually preset temperature control stabilization duration, so that the temperature in the EGR cooler (3) is evenly distributed; Sb200. Control to increase the diesel injection amount, thereby controlling the EGR cooler (3) to reach the manually preset second gradient temperature control interval within the manually preset second temperature control time threshold, and stabilize within the second gradient temperature control interval until the duration reaches the manually preset second temperature control stabilization duration; Sb300. Control to increase the diesel injection amount, thereby controlling the EGR cooler (3) to reach a manually preset third gradient temperature control interval within a manually preset third temperature control time threshold, and controlling the diesel injection amount so that the EGR cooler (3) continues to remain within the third gradient temperature control interval.

7. The self-cleaning method according to claim 6, characterized in that: During the execution of the gradient temperature control sub-process, the engine control module (1) compares the reading of the EGR cooling post-temperature sensor (4) with the first gradient temperature control interval, the second gradient temperature control interval, and the third gradient temperature control interval, and adjusts the post-injection fuel injection amount in real time to keep the temperature in the EGR cooler (3) within a controllable range.

8. The self-cleaning method according to claim 3, characterized in that: The ignition temperature of the noble metal chemical reaction in step Sa200 is 280°C.

9. The self-cleaning method according to claim 5, characterized in that: The condition for determining whether the self-cleaning is successful in step Sa500 is that the current EGR cooler efficiency is greater than 95%; the condition for determining whether the self-cleaning fails is that the current EGR cooler efficiency is less than 80% and lasts for 30 minutes.

10. The self-cleaning method according to claim 9, characterized in that: When the device performs the EGR cooler self-cleaning process three times in succession and the current EGR cooler efficiency is still lower than 80%, the EGR cooler (3) is judged to be failed, and the device displays a fault code to remind that manual intervention is required.

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