A method for regenerating a particulate filter and an engine aftertreatment system

Abstract

This application provides a particulate filter regeneration method and an engine aftertreatment system. The regeneration method includes: obtaining the flow resistance value of the particulate filter; if the flow resistance value is equal to or equal to a first preset value, passive regeneration is performed; if the flow resistance value is less than the first preset value, active regeneration is performed; and if the flow resistance value is less than a second preset value, regeneration is terminated. Therefore, this regeneration method regenerates the particulate filter based on the flow resistance value. Compared with existing technologies, this avoids the problem of continued regeneration even after carbon deposit removal is completed due to insufficient carbon load or regeneration time. It also avoids the situation where the particulate filter is overloaded and unable to regenerate, thus exhibiting high regeneration reliability. Furthermore, this regeneration method includes active or passive regeneration based on the flow resistance value of the particulate filter, allowing the method to select an appropriate regeneration mode according to the carbon load of the particulate filter, ensuring regeneration efficiency.

Description

Technical Field

[0001] This application relates to the field of exhaust gas treatment technology, and in particular to a particulate filter regeneration method and a post-treatment system. Background Technology

[0002] Particulate matter is one of the main pollutants in diesel engine exhaust emissions. Currently, the most effective aftertreatment device for reducing diesel engine particulate matter emissions is the Diesel Particulate Filter (DPF). However, after a certain period of particulate matter capture, the DPF needs to be cleaned to remove the carbon particles accumulated on it.

[0003] To avoid the need to remove the DPF from a service station every time carbon particulate matter is cleaned, thus reducing the frequency of DPF removal and lowering the time and economic costs of DPF cleaning, as well as preventing damage to the clamps at the DPF due to frequent disassembly and potential sealing issues, DPF regeneration has become the mainstream method for DPF cleaning. Therefore, how to reliably perform DPF regeneration has become a key concern for those skilled in the art. Summary of the Invention

[0004] In view of this, this application provides a method for regenerating a particle trap, the scheme of which is as follows:

[0005] A particulate filter regeneration method is provided for regenerating a particulate filter in an engine aftertreatment system, the aftertreatment system further including an exhaust gas delivery pipe, the particulate filter being located within the exhaust gas delivery pipe, the regeneration method comprising:

[0006] Obtain the flow resistance value of the particle trap;

[0007] If the flow resistance value of the particle trap is greater than or equal to a first preset value, the post-processing system is controlled to passively regenerate the particle trap.

[0008] If the flow resistance value of the particle trap is less than the first preset value, the post-processing system is controlled to actively regenerate the particle trap;

[0009] During the passive and active regeneration of the particle trap, the flow resistance value of the particle trap is monitored. When the flow resistance value of the particle trap is less than a second preset value, the regeneration of the particle trap is terminated.

[0010] Wherein, the first preset value is greater than the second preset value.

[0011] Optionally, obtaining the flow resistance value of the particle trap includes:

[0012] The calculated pressure difference generated by the exhaust gas passing through the particulate filter is obtained;

[0013] The measured pressure difference generated by the exhaust gas passing through the particulate filter is obtained.

[0014] If the difference between the calculated pressure difference and the measured pressure difference is less than a third preset value, the flow resistance value of the particle trap is obtained by using Kalman filtering and the calculated pressure difference.

[0015] Optionally, the aftertreatment system further includes an oxidation catalyst located within the exhaust gas delivery duct, wherein the oxidation catalyst and the particulate filter are arranged sequentially along the exhaust gas transmission direction; active regeneration of the particulate filter includes:

[0016] The post-processing system is heated to actively regenerate the particle trap;

[0017] Heating the post-processing system includes:

[0018] The temperature at a first location in the exhaust gas delivery pipe is monitored. The first location is located below the oxidizing catalyst. The first location and the oxidizing catalyst are arranged sequentially along the exhaust gas delivery direction, and the first location is located between the oxidizing catalyst and the particulate filter.

[0019] The first fuel injection quantity is obtained based on the temperature at the first location and the target temperature at the first location;

[0020] The engine injector is used to perform secondary fuel injection, and the amount of secondary fuel injection is set to the first amount of fuel injection, until the temperature at the first position rises to the target temperature at the first position;

[0021] The secondary fuel injection is performed after the injector injects the required amount of fuel for the engine, and the first fuel injection amount varies with the temperature at the first location until the temperature at the first location rises to the target temperature at the first location.

[0022] Optionally, active regeneration of the particle trap further includes:

[0023] The temperature at the second location of the exhaust gas delivery pipeline is monitored, and the particulate filter and the second location are arranged sequentially along the exhaust gas transmission direction;

[0024] If the temperature at the second position is greater than the target temperature at the first position, a second fuel injection quantity is obtained based on the temperature at the second position and the target temperature at the second position.

[0025] The amount of fuel injected during the secondary fuel injection is set to the second amount of fuel injected until the temperature at the second position reaches the target temperature at the second position.

[0026] Wherein, the target temperature at the second position is greater than the target temperature at the first position, and the second fuel injection quantity changes with the temperature at the second position until the temperature at the second position is the target temperature at the second position.

[0027] Optionally, active regeneration of the particle trap further includes:

[0028] During the active regeneration of the particulate filter, the rate of change of the flow resistance value of the particulate filter is obtained;

[0029] If the rate of change of the flow resistance value is greater than the fourth preset value, the amount of fuel injected during the secondary fuel injection is reduced.

[0030] Optionally, heating the post-processing system further includes:

[0031] Before heating the aftertreatment system, the intake air volume of the engine is adjusted until the temperature at the third position of the exhaust gas delivery pipe is the target temperature at the third position; the third position is located above the oxidation catalyst, and the third position and the oxidation catalyst are arranged sequentially along the exhaust gas transmission direction;

[0032] The target temperature at the first location is greater than the target temperature at the third location.

[0033] Optionally, the regeneration method further includes:

[0034] If the flow resistance value of the particulate filter is less than the first preset value, the operating condition of the engine is obtained;

[0035] If the engine's operating conditions meet the active regeneration operating conditions, the particulate filter will be actively regenerated.

[0036] If the engine's operating conditions do not meet the active regeneration conditions, the particulate filter will be passively regenerated, or the regeneration of the particulate filter will be terminated.

[0037] An engine aftertreatment system includes: a particulate filter and an exhaust gas delivery pipe, the particulate filter being located within the exhaust gas delivery pipe, and further includes:

[0038] A first calculation unit is used to obtain the flow resistance value of the particle trap.

[0039] If the flow resistance value of the particulate trap is greater than or equal to a first preset value, the first control unit controls the post-processing system to passively regenerate the particulate trap; if the flow resistance value of the particulate trap is less than the first preset value, the control unit also controls the post-processing system to actively regenerate the particulate trap.

[0040] The monitoring unit is used to monitor the flow resistance value of the particle trap during passive regeneration and the passive regeneration process. When the flow resistance value of the particle trap is less than a second preset value, the control unit is also used to terminate the regeneration of the particle trap.

[0041] Wherein, the first preset value is greater than the second preset value.

[0042] Optionally, the post-processing system further includes:

[0043] An oxidation catalyst is located inside the exhaust gas delivery pipe, and the oxidation catalyst and the particulate filter are arranged sequentially along the exhaust gas transmission direction.

[0044] A first temperature sensor is used to monitor the temperature at a first location in the exhaust gas delivery pipe. The oxidation catalyst and the first location are arranged sequentially along the exhaust gas transmission direction, and the first location is located between the oxidation catalyst and the particulate filter.

[0045] The second calculation unit is used to obtain the first fuel injection quantity based on the temperature at the first location and the target temperature at the first location;

[0046] The control unit is also used to control the engine injector to perform secondary fuel injection and set the amount of secondary fuel injection to the first amount of fuel injection until the temperature at the first position rises to the target temperature at the first position, so as to heat up the aftertreatment system.

[0047] The secondary fuel injection is performed after the injector injects the required amount of fuel for the engine, and the first fuel injection amount varies with the temperature at the first location until the temperature at the first location rises to the target temperature at the first location.

[0048] Optionally, the post-processing system further includes:

[0049] The second temperature sensor is used to monitor the temperature at a second location on the exhaust gas delivery pipe. The second location is located below the particulate filter, and the particulate filter and the second location are arranged sequentially along the exhaust gas transmission direction.

[0050] If the temperature at the second position is greater than the target temperature at the first position, the second calculation unit is further configured to obtain a second fuel injection quantity based on the temperature at the second position and the target temperature at the second position.

[0051] The control unit is also used to set the amount of fuel injected during the secondary fuel injection to the second amount of fuel injection until the temperature at the second position is the target temperature at the second position.

[0052] Wherein, the target temperature at the second position is greater than the target temperature at the first position, and the second fuel injection quantity changes with the temperature at the second position until the temperature at the second position is the target temperature at the second position.

[0053] Compared with the prior art, the beneficial effects of the technical solution of this application are as follows:

[0054] This application provides a particulate filter regeneration method and an engine aftertreatment system. The regeneration method includes: obtaining the flow resistance value of the particulate filter; if the flow resistance value is equal to or equal to a first preset value, passively regenerating the particulate filter; if the flow resistance value is less than the first preset value, actively regenerating the particulate filter; and if the flow resistance value is less than a second preset value, ending the regeneration. Therefore, this regeneration method regenerates the particulate filter based on its flow resistance value, and determines that the particulate filter has completed regeneration when its flow resistance value is less than the second preset value. Compared to existing technologies, this avoids the problem of continued regeneration even after carbon deposit removal is complete due to insufficient model carbon load or insufficient regeneration time. Furthermore, this regeneration method controls regeneration based on the flow resistance value of the particulate filter, rather than calculating the model carbon load, thus avoiding the situation where the particulate filter is overloaded and unable to regenerate, further ensuring regeneration reliability.

[0055] In addition, the regeneration method also includes active or passive regeneration based on the flow resistance value of the particulate filter, so that the regeneration method can select the appropriate regeneration method according to the carbon loading of the particulate filter and ensure regeneration efficiency. Attached Figure Description

[0056] To more clearly illustrate the technical solutions in the embodiments of this application or related technologies, the drawings used in the description of the embodiments or prior art will be briefly introduced below. Obviously, the drawings described below are only embodiments of this application. For those skilled in the art, other drawings can be obtained based on the provided drawings without creative effort.

[0057] The structures, proportions, sizes, etc., shown in the accompanying drawings are only for the purpose of assisting those skilled in the art in understanding and reading the content disclosed in the specification, and are not intended to limit the implementation conditions of this application. Therefore, they have no substantial technical significance. Any modifications to the structure, changes in the proportions, or adjustments to the size should still fall within the scope of the technical content disclosed in this application, provided that they do not affect the effects and purposes that this application can produce.

[0058] Figure 1 A flowchart of a particle trap regeneration method provided in this application;

[0059] Figure 2 A flowchart of a specific embodiment provided in this application;

[0060] Figure 3 A flowchart of another specific embodiment provided for this application. Detailed Implementation

[0061] The embodiments of this application will now be clearly and completely described with reference to the accompanying drawings. Obviously, the described embodiments are merely one area of ​​this application, and not all of the embodiments. All other embodiments obtained by those skilled in the art based on the embodiments of this application without creative effort are within the scope of protection of this application.

[0062] To make the above-mentioned objectives, features and advantages of this application more apparent and understandable, the application will be further described in detail below with reference to the accompanying drawings and specific embodiments.

[0063] As described in the background section, improving the reliability of DPF regeneration has become a challenge for those skilled in the art.

[0064] Existing DPF regeneration methods rely on model carbon loading and regeneration time, primarily depending on the model carbon loading obtained from calculations. This leads to continued high-temperature regeneration even after DPF carbon removal is complete, accelerating the aging of the post-treatment system and resulting in poor economic efficiency because the model carbon loading or regeneration time has not reached the limit. Furthermore, to minimize DPF overheating, the aforementioned DPF regeneration methods leave a margin in the calibrated regeneration time, which affects regeneration efficiency.

[0065] In addition, when the carbon loading exceeds the limit of the model carbon loading, that is, when the DPF is overloaded, the calculated model carbon loading is no longer accurate, and therefore carbon removal cannot be performed under the condition of DPF overload.

[0066] Based on this, embodiments of this application provide a method for regenerating a particulate filter (DPF) in an engine aftertreatment system to regenerate the particulate filter and remove carbon from it. The aftertreatment system further includes an exhaust gas delivery pipe, and the particulate filter is located within the exhaust gas delivery pipe. Figure 1 As shown, Figure 1 A flowchart of a particulate filter regeneration method provided in this application is included, the regeneration method comprising:

[0067] S1: Obtain the flow resistance value of the particle trap.

[0068] S2: If the flow resistance value of the particle trap is greater than or equal to the first preset value, control the post-processing system to passively regenerate the particle trap; that is, if the flow resistance value of the particle trap is not greater than the first preset value, control the post-processing system to passively regenerate the particle trap.

[0069] S3: If the flow resistance value of the particle collector is less than the first preset value, control the post-processing system to actively regenerate the particle collector. It should be noted that the regeneration temperature of passive regeneration is lower than that of active regeneration. The regeneration temperature requirement for passive regeneration is approximately between 350℃ and 450℃, while the regeneration temperature requirement for active regeneration is approximately between 450℃ and 600℃.

[0070] S4: During the passive and active regeneration of the particulate filter, the flow resistance value of the particulate filter is monitored. When the flow resistance value of the particulate filter is less than the second preset value, the regeneration of the particulate filter is ended, and the carbon removal of the particulate filter is completed.

[0071] Wherein, the first preset value is greater than the second preset value. This application does not limit the specific values ​​of the first and second preset values, but depends on the specific circumstances.

[0072] It should be noted that the flow resistance of the particulate filter represents the resistance encountered by exhaust gas as it passes through the filter. When the amount of carbon deposits on the particulate filter is large, the resistance is also large; conversely, when the amount of carbon deposits is small, the resistance is small. Therefore, the flow resistance value of the particulate filter is related to its carbon load, and thus the carbon deposit situation can be characterized by the flow resistance. Specifically, a larger flow resistance value indicates a larger amount of carbon deposits, and vice versa. Based on this, the regeneration method provided in this application obtains the flow resistance value of the particulate filter, and the completion of regeneration can be determined based on this value. Specifically, when the flow resistance value is less than a second preset value, it indicates that the resistance encountered by the exhaust gas as it passes through the particulate filter is small, thus indicating that carbon removal has been completed. In other words, the regeneration of the particulate filter is complete, and regeneration can be stopped.

[0073] As described above, the regeneration method provided in this application regenerates the particulate filter based on its flow resistance value, and determines that the particulate filter has completed regeneration when its flow resistance value is less than a second preset value. Therefore, compared to existing technologies, the regeneration method provided in this application controls regeneration by using the flow resistance value of the particulate filter, rather than controlling the regeneration process by the model carbon load and regeneration time. This avoids the problem of continued regeneration even after carbon deposition has been eliminated due to insufficient model carbon load and regeneration time, thus exhibiting higher regeneration reliability. Furthermore, the regeneration method provided in this application controls regeneration by using the flow resistance value of the particulate filter, rather than by calculating the model carbon load, which also avoids the situation where the particulate filter is overloaded and unable to regenerate, further ensuring regeneration reliability.

[0074] In addition, it is known that the flow resistance value of a particulate filter can reflect the carbon loading. The regeneration method provided in this application also includes active or passive regeneration based on the flow resistance value of the particulate filter. That is, the regeneration method can select an appropriate regeneration mode according to the carbon loading of the particulate filter. Specifically, when the flow resistance value is greater than or equal to a first preset value, i.e., the carbon loading is large, passive regeneration is performed. When the flow resistance value is less than a second preset value, i.e., the carbon loading is small, active regeneration is performed to ensure regeneration efficiency.

[0075] Based on the above embodiments, in one embodiment of this application, for step S1, obtaining the flow resistance value of the particle trap includes:

[0076] The calculated pressure difference Δp1 generated by the exhaust gas passing through the particulate filter is obtained. Obtaining the calculated pressure difference Δp1 includes: constructing a physical model of the particulate filter pressure difference based on its filtration mechanism; using this physical model to calculate the pressure difference across the particulate filter; and thus obtaining the calculated pressure difference Δp1 generated by the exhaust gas passing through the particulate filter. The calculation formula is as follows:

[0077] Δp1=Δp cont&exp +Δp inlet +Δp wall +Δp soot +Δp outlet

[0078]

[0079]

[0080]

[0081]

[0082]

[0083] Where, Δp cont&exp Δp is the pressure drop caused by the exhaust gas flowing into and out of the filter. inlet and Δp outlet These represent the pressure drops Δp and Δp caused by the exhaust gas flowing through the inlet and outlet channels, respectively. wall Δp is the pressure drop generated by the exhaust gas passing through the filter wall. soot The pressure drop generated by the exhaust gas passing through the particulate matter layer on the filter wall is μ, the gas flow dynamic viscosity coefficient of the exhaust gas is μ, and the gas volume flow rate (m³) of the exhaust gas passing through the particulate matter trap is Q. 3 / s, V is the volume of the carrier, ω s denoted as , where 'a' is the wall thickness of the small hole (mm), 'a' is the side length of the small hole on the end face of the filter body (mm), and 'k' is the thickness of the small hole. wall k represents the permeability of the filter wall. soot ρ is the permeability of the granular layer; ω is the thickness of the cake layer on the filter wall (mm), F is the coefficient of friction, L is the pore length (mm), and ρ is the density of the granular layer. g Let ξ be the gas density of the exhaust gas, ξ be the contraction / expansion inertial loss coefficient, and D be the diameter of the carrier. Therefore, based on the above formula, the calculated pressure difference Δp1 can be obtained from the real-time state of the exhaust gas passing through the particulate filter.

[0084] The measured pressure difference Δp2 generated by the exhaust gas passing through the particulate filter is obtained.

[0085] If the difference between the calculated pressure difference Δp1 and the measured pressure difference Δp2 is less than a third preset value, the flow resistance calculation value B of the particle trap is obtained by using Kalman filtering and the calculated pressure difference Δp1.

[0086] Specifically, the calculated flow resistance value B of the particle trap is obtained using Kalman filtering and the calculated pressure difference Δp1, including:

[0087] The pressure difference-volume flow rate relationship for a particulate filter is as follows:

[0088]

[0089] In this relationship, the pressure difference is the calculated pressure difference Δp1. ρ is the gas volumetric flow rate when the exhaust gas passes through the particulate filter, μ is the gas dynamic viscosity coefficient of the exhaust gas, ρ is the gas density of the exhaust gas, A and C are calculation coefficients, and B is the calculated flow resistance value.

[0090] The general formula for Kalman filtering is as follows:

[0091] X(k|k-1)=A1X(k-1|k-1)+B1U(k)

[0092] P(k|k-1)=A1P(k-1|k-1)A1 T +Q1

[0093] X(k|k)=X(k|k-1)+K(k)[Z(k)-HX(k|k-1)]

[0094]

[0095] P(k|k)=[IK(k)H]P(k|k-1)

[0096] The pressure difference-volume flow rate relationship formula for the above particulate filter was fitted using Kalman filtering to obtain the following:

[0097] X = [ABC] T

[0098] Where A is the identity matrix and B is the zero matrix and represents the calculated flow resistance value. It should be noted that, besides using Kalman filtering to fit the pressure difference-volume flow rate relationship formula for the particulate filter, other methods such as least multiplication can also be used to fit the pressure difference-volume flow rate relationship formula to obtain the flow resistance value.

[0099] Specifically, in this embodiment, the regeneration method obtains the flow resistance value of the particle trap by using Kalman filtering and calculating the pressure difference Δp1. Furthermore, the difference between the calculated pressure difference Δp1 and the measured pressure difference Δp2 is less than a third preset value, thereby ensuring that the flow resistance value of the particle trap is obtained using... If the difference between the calculated pressure difference Δp1 and the measured pressure difference Δp2 is less than the third preset value, it can be considered that the calculated pressure difference Δp1 based on the flow resistance value is the same as the measured pressure difference Δp2 obtained using the pressure difference sensor. This indicates that the obtained flow resistance value conforms to the PV characteristics of the particulate filter, thus ensuring the accuracy of the particulate filter's flow resistance value. This, in turn, helps ensure the accuracy of regeneration using the particulate filter's flow resistance value, thereby guaranteeing the reliability of this regeneration method. Furthermore, since the calculated pressure difference Δp1 is known to be obtained based on the real-time state of the exhaust gas passing through the particulate filter, the flow resistance value obtained based on this calculated pressure difference Δp1 will also change according to the real-time state of the exhaust gas passing through the particulate filter. Therefore, this flow resistance value can reflect the carbon loading of the particulate filter in real time, further helping to ensure the accuracy of regeneration using the particulate filter's flow resistance value, thus guaranteeing the reliability of this regeneration method.

[0100] It should be noted that the above flow resistance value can also be calculated using other methods such as least multiplication, depending on the specific circumstances.

[0101] In one embodiment of this application, the aftertreatment system further includes an oxidizing catalyst located within the exhaust gas delivery duct. The oxidizing catalyst and the particulate filter are arranged sequentially along the exhaust gas delivery direction within the exhaust gas delivery duct, that is, the oxidizing catalyst is positioned above the particulate filter within the exhaust gas delivery duct. Based on this, step S3, actively regenerating the particulate filter, includes:

[0102] The post-processing system is heated to meet the temperature requirements for active regeneration, so as to actively regenerate the particle collector.

[0103] Heating the post-processing system includes:

[0104] The temperature at a first location in the exhaust gas delivery duct is monitored. This first location is situated below the oxidizing catalyst. Specifically, within the exhaust gas delivery duct, the first location and the oxidizing catalyst are arranged sequentially along the exhaust gas transmission direction, with the first location located between the oxidizing catalyst and the particulate filter. In other words, the temperature at the first location is the temperature following the oxidizing catalyst, and the target temperature at the first location is the target temperature following the oxidizing catalyst.

[0105] The first fuel injection quantity is obtained based on the temperature at the first location and the target temperature at the first location, specifically based on the difference between the temperature at the first location and the target temperature at the first location.

[0106] The engine injector is used to perform secondary fuel injection, and the amount of secondary fuel injection is set to the first amount of fuel injection, until the temperature at the first position rises to the target temperature at the first position.

[0107] The secondary fuel injection occurs after the injector has injected the required amount of fuel for the engine, and the first injection amount varies with the temperature at the first location until the temperature at the first location reaches the target temperature. It should be noted that during engine operation, the injector injects the required amount of fuel according to a set time. The aforementioned secondary fuel injection, occurring after the injector has injected the required amount of fuel, specifically refers to a delayed injection after the injector has injected the required amount of fuel at the set time, to increase the amount of fuel in the exhaust gas.

[0108] Because the active regeneration of the particulate filter involves high temperatures, the aftertreatment system needs to be heated during active regeneration. Therefore, in this embodiment, the regeneration method includes increasing the amount of fuel in the exhaust gas through secondary injection, i.e., delayed injection, so that the exhaust gas carries a certain amount of fuel. The fuel in the exhaust gas undergoes oxidation and exothermic reactions in the oxidation catalyst, thereby heating the aftertreatment system to meet the temperature requirements for active regeneration, thus enabling the aftertreatment system to actively regenerate the particulate filter.

[0109] Furthermore, when this regeneration method heats up the aftertreatment system, it also includes controlling the first injection quantity during secondary injection based on the difference between the post-catalyst temperature and the target temperature. In other words, the amount of fuel in the exhaust gas is controlled according to the difference between the post-catalyst temperature and the target temperature. The heat generated by the oxidation of fuel in the catalyst then controls the temperature of the aftertreatment system, thereby controlling the regeneration temperature. Simultaneously, in this regeneration method, the first injection quantity changes with the post-catalyst temperature until it reaches the target temperature. Therefore, this regeneration method uses the post-catalyst temperature as the control target, performing closed-loop control of the first injection quantity during secondary injection to stabilize the post-catalyst temperature at the target temperature as much as possible. Since the aftertreatment system is heated by the oxidation of fuel in the exhaust gas in the oxidizing catalyst, the temperature after the oxidizing catalyst also represents the temperature of the aftertreatment system after heating. Therefore, stabilizing the temperature after the oxidizing catalyst at the target temperature means stabilizing the temperature of the aftertreatment system after heating at the target temperature, thereby achieving temperature stability of the aftertreatment system. This avoids the impact of large temperature fluctuations on regeneration efficiency during the regeneration process, ensuring the efficiency of active regeneration and thus guaranteeing the regeneration efficiency of this regeneration method.

[0110] Optionally, in one embodiment of this application, the target temperature at the first position, i.e., the target temperature after the oxidizing catalyst, is around 500°C, which satisfies the temperature requirements for active regeneration while avoiding excessively high temperatures at the start of active regeneration. However, this application does not limit the specific value of the aforementioned target temperature at the first position; it depends on the specific circumstances.

[0111] As regeneration proceeds, the oxidation of carbon deposits in the particulate filter releases heat, which also causes the post-treatment system to heat up. The impact of this heat release on the post-treatment system temperature can be monitored by checking the post-particulate filter temperature. When the post-particulate filter temperature exceeds the target temperature of the oxidation catalyst, it indicates that the heat release from the carbon deposits has increased the temperature of the post-treatment system. Since temperature control is very strict during regeneration, the regeneration temperature should be a suitable temperature, neither too high nor too low. Based on this, in one embodiment of this application, the active regeneration of the particulate filter further includes:

[0112] During active regeneration, the temperature at the second position of the exhaust gas delivery pipe is monitored. The second position is located below the particulate filter, meaning that the particulate filter and the second position are arranged sequentially along the exhaust gas transmission direction. Therefore, the temperature at the second position of the exhaust gas delivery pipe is the downstream temperature of the particulate filter, and the target temperature at the second position is the target temperature of the downstream temperature of the particulate filter.

[0113] If the temperature at the second position is greater than the target temperature at the first position, meaning the carbon deposits release heat and raise the temperature of the aftertreatment system, then the temperature of the aftertreatment system, i.e., the regeneration temperature, should be the temperature after the particulate filter. The second injection quantity is obtained based on the temperature at the second position and the target temperature at the second position; specifically, the second injection quantity is obtained based on the difference between the temperature at the second position and the target temperature at the second position.

[0114] The amount of fuel injected during the secondary fuel injection is set to the second amount of fuel injected until the temperature at the second position reaches the target temperature at the second position.

[0115] Wherein, the target temperature at the second position is greater than the target temperature at the first position, and the second fuel injection quantity changes with the temperature at the second position until the temperature at the second position is the target temperature at the second position.

[0116] As described above, if the exothermic reaction of carbon deposits causes the aftertreatment system to heat up, this regeneration method determines the second fuel injection quantity based on the post-temperature of the particulate filter and its target temperature. This second fuel injection quantity changes with the post-temperature of the particulate filter until the post-temperature of the particulate filter reaches the target temperature. Therefore, when the exothermic reaction of carbon deposits causes the aftertreatment system to heat up, this regeneration method uses the post-temperature of the particulate filter as the control target and performs closed-loop control to stabilize the post-temperature of the particulate filter at its target temperature. This, in turn, stabilizes the temperature of the aftertreatment system at the target temperature, thus stabilizing the regeneration temperature at the target temperature of the particulate filter. This ensures that even if the exothermic reaction of carbon deposits causes the aftertreatment system to heat up, the temperature of the aftertreatment system can be stabilized at a suitable temperature by controlling the amount of fuel injected in the second fuel injection. This prevents the regeneration temperature from rising due to the exothermic reaction of carbon deposits, which could lead to overheating of the particulate filter and damage or even destruction of the particulate filter, thus guaranteeing the reliability of the regeneration method.

[0117] Furthermore, when the exothermic reaction of carbon deposits causes the aftertreatment system to heat up, this regeneration method uses the temperature after the particulate filter as the control target to achieve temperature control during regeneration. This ensures accurate temperature control, maintaining the regeneration temperature at a suitable level to guarantee regeneration efficiency. It also prevents the particulate filter from overheating during regeneration, ensuring regeneration reliability. It should be noted that during active regeneration, the temperature of the exhaust gas after passing through the particulate filter will be the same as the regeneration temperature; therefore, the temperature after the particulate filter can accurately characterize the regeneration temperature.

[0118] The flow resistance of a particulate filter is known to characterize its carbon loading; therefore, the rate of change in flow resistance can characterize the rate of carbon removal. However, the rate of carbon removal is also a key concern during particulate filter regeneration. Therefore, in the active regeneration process of the particulate filter, step S3 includes:

[0119] During the active regeneration of the particulate trap, the rate of change of flow resistance of the particulate trap is obtained.

[0120] If the flow resistance change rate is greater than the fourth preset value, the amount of fuel injected for the second fuel injection will be adjusted.

[0121] Specifically, when the flow resistance change rate exceeds the fourth preset value, it indicates a rapid carbon removal rate, which generates high heat. Therefore, to prevent the particulate filter from overheating due to excessively rapid carbon removal, when the flow resistance change rate exceeds the fourth preset value (i.e., exceeds a certain limit), the fuel injection quantity during secondary fuel injection is reduced to decrease the amount of fuel in the exhaust gas. This reduces the temperature of the aftertreatment system and the particulate filter, thus preventing overheating and ensuring reliable regeneration.

[0122] It should be noted that in this embodiment, when the rate of change of flow resistance is greater than a certain limit, reducing the amount of fuel injected during the second injection can be either reducing the first amount of fuel injected during the second injection or reducing the second amount of fuel injected during the second injection, depending on the change of flow resistance value.

[0123] Regarding the heating of the post-processing system, in one embodiment of this application, heating the post-processing system further includes:

[0124] Before heating the aftertreatment system, the engine's intake air volume is adjusted until the temperature at the third position in the exhaust gas delivery pipe reaches the target temperature for that third position. This third position is located above the oxidizing catalyst, and the third position and the oxidizing catalyst are arranged sequentially along the exhaust gas transmission direction. In other words, the temperature at the third position is the temperature before the oxidizing catalyst. The target temperature at the first position is greater than the target temperature at the third position.

[0125] It should be noted that the oxidation catalyst can only work when it reaches a certain temperature. Therefore, this regeneration method also includes adjusting the engine's intake air volume to raise the temperature of the oxidation catalyst to meet its operating temperature for subsequent heating processes.

[0126] It should be noted that active regeneration of the particulate filter requires the engine to meet certain conditions, namely, the engine's operating conditions must meet certain requirements, such as engine speed, which depends on the actual situation. If the engine's operating conditions do not meet the active regeneration conditions, active regeneration cannot be performed even if the flow resistance value of the particulate filter is less than a first preset value. Therefore, in one embodiment of this application, the regeneration method further includes:

[0127] If the flow resistance value of the particulate filter is less than the first preset value, the operating condition of the engine is obtained.

[0128] If the engine's operating conditions meet the active regeneration requirements, the particulate filter will be actively regenerated.

[0129] If the engine's operating conditions do not meet the active regeneration conditions, the particulate filter will be passively regenerated, or the regeneration of the particulate filter will be terminated.

[0130] The following is a detailed description of a particle trap regeneration method provided in this application through a specific embodiment, which takes an example where the flow resistance value at the start of regeneration is greater than or equal to a first preset value. The flowchart of this specific embodiment is as follows: Figure 2 As shown: The flow resistance value of the particulate filter DPF is calculated. Passive regeneration is performed based on the flow resistance value of the particulate filter DPF. During passive regeneration, the change in flow resistance value is monitored. When the flow resistance value of the particulate filter DPF drops below a first preset value, active regeneration is performed. Simultaneously, the change in flow resistance value is monitored during active regeneration. Regeneration ends when the flow resistance value drops below a second preset value. For example... Figure 3 As shown, active regeneration includes: monitoring the pre-temperature of the oxidized catalyst DOC, adjusting the engine intake air volume based on the pre-temperature of the oxidized catalyst DOC and its target temperature until the pre-temperature of the oxidized catalyst DOC reaches the target temperature, then monitoring the post-temperature of the oxidized catalyst DOC, adjusting the injection quantity of secondary fuel injection based on the monitored post-temperature of the oxidized catalyst DOC and its target temperature until the post-temperature of the oxidized catalyst DOC rises to the target temperature of the post-temperature of the oxidized catalyst DOC, and when the post-temperature of the particulate filter DPF is greater than the target temperature of the post-temperature of the oxidized catalyst DOC as regeneration progresses, adjusting the injection quantity of secondary fuel injection based on the post-temperature of the particulate filter DPF and its target temperature until the post-temperature of the particulate filter DPF rises to the target temperature of the post-temperature of the particulate filter DPF.

[0131] Accordingly, this application also provides an engine aftertreatment system, in which the regeneration method described in any of the above embodiments is applied. The aftertreatment system includes: a particulate filter and an exhaust gas delivery pipe, wherein the particulate filter is located within the exhaust gas delivery pipe. The aftertreatment system further includes:

[0132] The first calculation unit obtains the flow resistance value of the particle trap.

[0133] If the flow resistance value of the particulate trap is greater than or equal to a first preset value, the first control unit controls the post-processing system to passively regenerate the particulate trap; if the flow resistance value of the particulate trap is less than the first preset value, the control unit also controls the post-processing system to actively regenerate the particulate trap.

[0134] The monitoring unit is used to monitor the flow resistance value of the particle trap during passive regeneration and the passive regeneration process. When the flow resistance value of the particle trap is less than a second preset value, the control unit is also used to terminate the regeneration of the particle trap.

[0135] Wherein, the first preset value is greater than the second preset value.

[0136] As described above, when regenerating the particulate filter, this post-processing system can regenerate it based on the filter's flow resistance value. Regeneration is considered complete when the flow resistance value is less than a second preset value. Therefore, this post-processing system avoids the problem of continuous regeneration due to insufficient carbon loading or insufficient regeneration time, exhibiting high regeneration reliability. Furthermore, it avoids overloading the particulate filter, further ensuring regeneration reliability.

[0137] In addition, the post-processing system also includes the ability to select between active and passive regeneration based on the flow resistance value. In other words, the appropriate regeneration method can be selected according to the carbon load of the particulate filter. Specifically, when the flow resistance value is greater than or equal to the first preset value, i.e., the carbon load is large, passive regeneration is performed, and when the flow resistance value is less than the second preset value, i.e., the carbon load is small, active regeneration is performed to ensure regeneration efficiency.

[0138] Based on the above embodiments, in one embodiment of this application, the post-processing system further includes:

[0139] An oxidizing catalyst is located inside the exhaust gas delivery pipe, and the oxidizing catalyst and the particulate filter are arranged sequentially along the exhaust gas transmission direction.

[0140] A first temperature sensor is used to monitor the temperature at a first location in the exhaust gas delivery pipe. The first location is located below the oxidizing catalyst. The oxidizing catalyst and the first location are arranged sequentially along the exhaust gas transmission direction, and the first location is located between the oxidizing catalyst and the particulate filter.

[0141] The second calculation unit is used to obtain the first fuel injection quantity based on the temperature at the first location and the target temperature at the first location.

[0142] The control unit is also used to control the engine injector to perform secondary fuel injection and set the amount of secondary fuel injection to a first amount of fuel injection until the temperature at the first position rises to the target temperature at the first position, so as to heat up the aftertreatment system.

[0143] The secondary fuel injection is performed after the injector injects the required amount of fuel for the engine, and the first fuel injection amount varies with the temperature at the first location until the temperature at the first location rises to the target temperature at the first location.

[0144] Based on the above embodiments, in one embodiment of this application, the post-processing system further includes:

[0145] The second temperature sensor is used to monitor the temperature at a second location in the exhaust gas delivery pipe. The second location is located below the particulate filter, and the particulate filter and the second location are arranged sequentially along the exhaust gas transmission direction.

[0146] If the temperature at the second position is greater than the target temperature at the first position, the second calculation unit is further configured to obtain a second fuel injection quantity based on the temperature at the second position and the target temperature at the second position.

[0147] The control unit is also configured to set the injection quantity of the secondary injection to the second injection quantity until the temperature at the second position is the target temperature at the second position.

[0148] Wherein, the target temperature at the second position is greater than the target temperature at the first position, and the second fuel injection quantity changes with the temperature at the second position until the temperature at the second position is the target temperature at the second position.

[0149] In summary, this application provides a particulate filter regeneration method and an engine aftertreatment system. The regeneration method includes: obtaining the flow resistance value of the particulate filter; if the flow resistance value is equal to or equal to a first preset value, passively regenerating the particulate filter; if the flow resistance value is less than the first preset value, actively regenerating the particulate filter; and if the flow resistance value is less than a second preset value, ending the regeneration. Therefore, this regeneration method regenerates the particulate filter based on its flow resistance value, and determines that the particulate filter has completed regeneration when its flow resistance value is less than the second preset value. Compared to existing technologies, this avoids the problem of continued regeneration even after carbon deposit removal due to insufficient model carbon load or regeneration time, and also avoids the situation where the particulate filter is overloaded and unable to regenerate, thus exhibiting high regeneration reliability.

[0150] In addition, the regeneration method also includes active or passive regeneration based on the flow resistance value of the particulate filter, so that the regeneration method can select the appropriate regeneration method according to the carbon loading of the particulate filter and ensure regeneration efficiency.

[0151] The various embodiments in this specification are described in a progressive, parallel, or combined manner. Each embodiment focuses on its differences from other embodiments, and similar or identical areas between embodiments can be referred to interchangeably. For the apparatuses disclosed in the embodiments, since they correspond to the methods disclosed in the embodiments, the descriptions are relatively simple, and relevant details can be found in the description of the method area.

[0152] It should be noted that, in the description of this application, the terms "upper," "lower," "top," "bottom," "inner," and "outer," etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings, and are only for the convenience of describing this application and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation, and therefore should not be construed as a limitation of this application. When a component is considered to be "connected" to another component, it can be directly connected to the other component or there may be a component centrally located at the same time.

[0153] It should also be noted that, in this document, relational terms such as "first" and "second" are used merely to distinguish one entity or operation from another, and do not necessarily require or imply any such actual relationship or order between these entities or operations. Furthermore, the terms "comprising," "including," or any other variations thereof are intended to cover non-exclusive inclusion, such that an article or apparatus comprising a list of elements includes not only those elements but also other elements not expressly listed, or elements inherent to such an article or apparatus. Without further limitations, an element defined by the phrase "comprising one..." does not exclude the presence of other identical elements in the article or apparatus that includes the aforementioned element.

[0154] The above description of the disclosed embodiments enables those skilled in the art to make or use this application. Various modifications to these embodiments will be readily apparent to those skilled in the art, and the general principles defined herein may be implemented in other embodiments without departing from the spirit or scope of this application. Therefore, this application is not to be limited to the embodiments shown herein, but is to be accorded the widest scope consistent with the principles and novel features disclosed herein.

Claims

1. A method for regenerating a particulate filter, characterized in that, A method for regenerating a particulate filter in an engine aftertreatment system, the aftertreatment system further including an exhaust gas delivery duct, wherein the particulate filter is located within the exhaust gas delivery duct, the regeneration method comprising: Obtain the flow resistance value of the particle trap; If the flow resistance value of the particle trap is greater than or equal to a first preset value, the post-processing system is controlled to passively regenerate the particle trap. If the flow resistance value of the particle trap is less than the first preset value, the post-processing system is controlled to actively regenerate the particle trap; During the passive and active regeneration of the particle trap, the flow resistance value of the particle trap is monitored. When the flow resistance value of the particle trap is less than a second preset value, the regeneration of the particle trap is terminated. Wherein, the first preset value is greater than the second preset value; The aftertreatment system further includes an oxidation catalyst located within the exhaust gas delivery duct, the oxidation catalyst and the particulate filter being arranged sequentially along the exhaust gas transmission direction; active regeneration of the particulate filter includes: The post-processing system is heated to actively regenerate the particle trap; Heating the post-processing system includes: Monitor the temperature at a first location in the exhaust gas delivery pipeline, the first location being between the oxidizing catalyst and the particulate filter; The first fuel injection quantity is obtained based on the temperature at the first location and the target temperature at the first location; The engine injector is used to perform secondary fuel injection, and the amount of secondary fuel injection is set to the first amount of fuel injection, until the temperature at the first position rises to the target temperature at the first position; The secondary fuel injection is performed after the injector injects the required amount of fuel for the engine, and the first fuel injection amount varies with the temperature at the first location until the temperature at the first location rises to the target temperature at the first location. The temperature at the second location of the exhaust gas delivery pipeline is monitored, and the particulate filter and the second location are arranged sequentially along the exhaust gas transmission direction; If the temperature at the second position is greater than the target temperature at the first position, a second fuel injection quantity is obtained based on the temperature at the second position and the target temperature at the second position. Set the amount of fuel injected for the second injection to the second amount of fuel injected until the temperature at the second position is the target temperature at the second position; Wherein, the target temperature at the second position is greater than the target temperature at the first position, and the second fuel injection quantity changes with the temperature at the second position until the temperature at the second position is the target temperature at the second position; The active regeneration of the particulate filter further includes: adjusting the intake air volume of the engine before heating the aftertreatment system until the temperature at the third position of the exhaust gas delivery pipe is the target temperature at the third position; the third position and the oxidation catalyst are arranged sequentially along the exhaust gas transmission direction. The target temperature at the first location is greater than the target temperature at the third location.

2. The particulate filter regeneration method according to claim 1, characterized in that, Obtaining the flow resistance value of the particle trap includes: The calculated pressure difference generated by the exhaust gas passing through the particulate filter is obtained; The measured pressure difference generated by the exhaust gas passing through the particulate filter is obtained. If the difference between the calculated pressure difference and the measured pressure difference is less than a third preset value, the flow resistance value of the particle trap is obtained by using Kalman filtering and the calculated pressure difference.

3. The particulate filter regeneration method according to claim 1, characterized in that, Active regeneration of the particle trap also includes: During the active regeneration of the particulate filter, the rate of change of the flow resistance value of the particulate filter is obtained; If the rate of change of the flow resistance value is greater than the fourth preset value, the amount of fuel injected for secondary fuel injection is reduced.

4. The particulate filter regeneration method according to claim 1, characterized in that, The regeneration method also includes: If the flow resistance value of the particulate filter is less than the first preset value, the operating condition of the engine is obtained; If the engine's operating conditions meet the active regeneration operating conditions, the particulate filter will be actively regenerated. If the engine's operating conditions do not meet the active regeneration conditions, the particulate filter will be passively regenerated, or the regeneration of the particulate filter will be terminated.

5. An engine aftertreatment system for performing the method according to any one of claims 1-4, characterized in that, include: A particulate filter and an exhaust gas delivery pipeline, wherein the particulate filter is located within the exhaust gas delivery pipeline, and further includes: A first calculation unit is used to obtain the flow resistance value of the particle trap. If the flow resistance value of the particulate filter is greater than or equal to a first preset value, the control unit controls the post-processing system to passively regenerate the particulate filter; if the flow resistance value of the particulate filter is less than the first preset value, the control unit also controls the post-processing system to actively regenerate the particulate filter. The monitoring unit is used to monitor the flow resistance value of the particle trap during passive and active regeneration of the particle trap. When the flow resistance value of the particle trap is less than a second preset value, the control unit is also used to terminate the regeneration of the particle trap. Wherein, the first preset value is greater than the second preset value.

6. The engine aftertreatment system according to claim 5, characterized in that, The post-processing system also includes: An oxidation catalyst is located inside the exhaust gas delivery pipe, and the oxidation catalyst and the particulate filter are arranged sequentially along the exhaust gas transmission direction. A first temperature sensor is used to monitor the temperature at a first location in the exhaust gas delivery pipe, the first location being located between the oxidation catalyst and the particulate filter. The second calculation unit is used to obtain the first fuel injection quantity based on the temperature at the first location and the target temperature at the first location; The control unit is also used to control the engine injector to perform secondary fuel injection and set the amount of secondary fuel injection to the first amount of fuel injection until the temperature at the first position rises to the target temperature at the first position, so as to heat up the aftertreatment system. The secondary fuel injection is performed after the injector injects the required amount of fuel for the engine, and the first fuel injection amount varies with the temperature at the first location until the temperature at the first location rises to the target temperature at the first location.

7. The engine aftertreatment system according to claim 6, characterized in that, The post-processing system also includes: The second temperature sensor is used to monitor the temperature at a second location on the exhaust gas delivery pipe. The particulate filter and the second location are arranged sequentially along the exhaust gas transmission direction. If the temperature at the second position is greater than the target temperature at the first position, the second calculation unit is further configured to obtain a second fuel injection quantity based on the temperature at the second position and the target temperature at the second position. The control unit is also used to set the amount of fuel injected for secondary fuel injection to the second amount of fuel injection until the temperature at the second position is the target temperature at the second position; Wherein, the target temperature at the second position is greater than the target temperature at the first position, and the second fuel injection quantity changes with the temperature at the second position until the temperature at the second position is the target temperature at the second position.

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