A calibration method, calibration module, and readable storage medium for enhancing passive regeneration of particulate traps.

Abstract

This application relates to a calibration method for passive regeneration of a DPF (48) in an exhaust aftertreatment system, the system comprising a tightly coupled aftertreatment system (20) having a first SCR (24) and an underground aftertreatment system (40) including the DPF (48) and a second SCR (44) located downstream of the DPF (48), the method comprising: based on the concentration ratio (R0) of NO2 and particulate matter in exhaust gas upstream of the DPF (48) NO2 / Soot ), the level of smoke and dust inside DPF(48) (L S ), upstream exhaust temperature of DPF(48) (T) 48UP The first step (S1) is to determine the calibration factor (F) by consulting a calibration factor table or curve; the calibration factor (F) is then applied to the first urea metering injection quantity (M) to be injected into the upstream exhaust gas of the first SCR (24). 25ini Thus, the first urea calibration injection quantity (M) is obtained. 25cor The second step (S2) of the calibration process. This application also relates to a calibration module including a processor and a memory storing executable instructions, and a readable storage medium storing executable instructions that, when executed, cause the machine to perform the above calibration method.

Description

Technical Field

[0001] This application relates to the field of vehicle exhaust aftertreatment, and more specifically to a calibration method for the passive regeneration of a particulate filter (DPF) in an enhanced exhaust aftertreatment system (ATS). This application also relates to a calibration module for performing this method and a readable storage medium. Background Technology

[0002] To meet increasingly stringent vehicle emission requirements worldwide, various exhaust aftertreatment systems have been developed to reduce NOx emissions from vehicles, especially diesel vehicles, into the atmosphere. X And the amount of particulate matter.

[0003] In order to minimize NO emissions into the atmosphere X The exhaust aftertreatment system may include a cryogenic or close-coupled aftertreatment system (Close Coupled ATS or cc-ATS) and an underground aftertreatment system (Under Floor ATS or uf-ATS), with the cc-ATS located upstream of the uf-ATS. Exhaust from the engine first enters the cc-ATS, where it is reduced and the NO in the exhaust is eliminated by the first selective catalytic reduction unit (SCR) within it. X Part of the content. Of which NO... X The reduced NO content in the exhaust gas then enters the uf-ATS, where the second SCR reduces and eliminates the remaining NO in the exhaust gas. X Another or second part of the content. The exhaust gas after exiting the uf-ATS is directly released into the atmospheric environment, at which point the residual NO in the exhaust gas... X The content needs to meet a specific content threshold corresponding to a specific emission requirement.

[0004] In addition to a second SCR, the uf-ATS also includes a DPF for capturing and removing at least some or all of the particles in the exhaust. It is well known that to ensure the particulate filter's ability or efficiency in adsorbing or capturing particles, the DPF needs to remove accumulated particles through regeneration. Active regeneration of the DPF requires the injection of fuel into the exhaust, where particulate combustion occurs with the assistance of the fuel.

[0005] Currently, the amount of reducing agent urea injected into the first and second SCRs is typically based on the NO in the exhaust gas entering the cc-ATS and uf-ATS, respectively. X The content was determined without considering DPF regeneration. The aim is to enhance passive DPF regeneration to reduce the need for active regeneration. Summary of the Invention

[0006] The purpose of this application is to enhance or promote the passive regeneration of the DPF in order to reduce the need for active regeneration and save fuel.

[0007] According to a first aspect of this application, a calibration method for passive regeneration of a DPF in an exhaust aftertreatment system is provided, wherein the exhaust aftertreatment system includes a tightly coupled aftertreatment system having a first SCR and an underground aftertreatment system including the DPF and a second SCR located downstream of the DPF, the method comprising the following steps:

[0008] The first step is to determine the calibration factor by consulting a calibration factor table or curve based on the NO2 to particulate matter concentration ratio in the exhaust gas upstream of the DPF, the particulate matter level inside the DPF, and the exhaust gas temperature upstream of the DPF.

[0009] The second step involves applying the calibration factor to the first urea metering injection quantity to be injected into the upstream exhaust gas of the first SCR, thereby obtaining the first urea calibration injection quantity;

[0010] The third step is to obtain the efficiency of the tightly coupled aftertreatment system or the NOx content in the upstream exhaust gas of the underground aftertreatment system based on the first urea calibration injection amount.

[0011] The fourth step is to determine the second urea metering injection quantity in the upstream exhaust of the second SCR to be injected into the underground aftertreatment system based on the efficiency or the NOx content in the upstream exhaust of the underground aftertreatment system and the allowable NOx content threshold corresponding to a specific emission requirement.

[0012] The fifth step is to determine whether the final NOx content in the exhaust gas discharged from the underground after-treatment system is within the permissible NOx content threshold.

[0013] The sixth termination step when the final NOx content is less than or equal to the permissible NOx content threshold.

[0014] According to a second aspect of this application, a calibration module is provided, comprising:

[0015] Processor; and

[0016] A memory storing executable instructions, which, when executed, cause the processor to perform the calibration method described above.

[0017] According to a third aspect of this application, a readable storage medium is provided having executable instructions stored thereon, which, when executed, cause a machine to perform the above-described calibration method.

[0018] As described above, according to this application, by reducing the first urea injection quantity, the selective reduction catalytic device of the closely coupled aftertreatment system can reduce or remove NO. X The amount of NO in the exhaust gas is reduced, thus reducing the amount of NO entering the underground after-treatment system.X The increased fuel consumption facilitates the passive regeneration of the particulate filter, which in turn reduces the number of necessary active regeneration cycles or lengthens the active regeneration interval of the particulate filter, thereby reducing the amount of fuel required for auxiliary active regeneration and achieving fuel savings. Attached Figure Description

[0019] The above and other features and advantages of this application can be appreciated from the detailed description given below with reference to the accompanying drawings.

[0020] Figure 1 This is a simplified schematic block diagram of the vehicle exhaust aftertreatment system of this application;

[0021] Figure 2 This is a flowchart of a calibration method for passive regeneration of a particulate trap in an underground after-treatment system for enhancing a vehicle after-treatment system, according to an embodiment of this application.

[0022] Figure 3 Schematic illustration Figure 2 The schematic diagram of the calibration algorithm for the calibration method;

[0023] Figure 4a and 4b These are examples of the first and second sub-calibration factor tables, respectively.

[0024] Figure 5 The illustration shows the process of execution. Figure 2 A simplified diagram of the calibration module for the method. Detailed Implementation

[0025] The principles of the present invention will now be described in detail with reference to the embodiments shown in the figures. Those skilled in the art should understand that these embodiments are merely exemplary and do not constitute any limitation on the present invention.

[0026] This application relates to an exhaust aftertreatment system including a cryogenic or close-coupled aftertreatment system (cc-ATS) 20 and an underground aftertreatment system (uf-ATS) 40.

[0027] Figure 1A schematic simplified block diagram of an exhaust aftertreatment system according to an embodiment of this application is shown. The figure shows a vehicle engine 10, from which exhaust gas flows in an exhaust pipe 15 along a flow direction D. The exhaust aftertreatment system described above is disposed on the exhaust pipe 15. In this document, the direction of exhaust gas flow from the engine 10 in the exhaust pipe 15 is indicated by D (solid arrow), and the terms "upstream" and "downstream" as used herein are relative to the flow direction D of the exhaust gas in the exhaust pipe 15. For example, in the exhaust aftertreatment system of this application, if the first component is disposed upstream of the second component or the second component is disposed downstream of the first component, it means that the exhaust gas from the engine 10 first enters the first component and then enters the second component. Furthermore, those skilled in the art should understand that the terms "comprising" or "including" have an open-ended meaning, indicating that in addition to the objects following the term, other unlisted objects may be included.

[0028] like Figure 1 As shown, the exhaust aftertreatment system of this application includes a cc-ATS 20 with a first selective catalytic reduction (SCR) device 24 and a uf-ATS 40 with a second selective catalytic reduction (SCR) device 44. The lower-temperature exhaust gas generated during the initial start-up of the engine 10 is mainly treated by the cc-ATS 20, while the higher-temperature exhaust gas generated during normal engine operation is mainly treated by the uf-ATS 40. However, under normal circumstances, the cc-ATS 20 and uf-ATS 40 operate simultaneously; the exhaust gas from the engine 10 first enters the cc-ATS 20 and undergoes partial NO removal via its first SCR 24. X The NOx from the cc-ATS 20 is reduced, and then the exhaust gas with some NOx reduced enters the uf-ATS 40 and is further reduced by its second SCR 44. Finally, the exhaust gas from the uf-ATS 40 is directly released into the atmosphere.

[0029] like Figure 1As shown, in addition to the first SCR 24, the cc-ATS 20 may also include a first oxidation catalyst (DOC) 22 located upstream of the first SCR 24 and a first ammonia slip catalyst (ASC) 26 located downstream of the first SCR 24. In addition to the second SCR 44, the uf-ATS 40 may also include a second oxidation catalyst (DOC) 42 and a diesel particulate filter (DPF) 48 located upstream of the second SCR 44, and a second ammonia slip catalyst (ASC) 46 located downstream of the second SCR 44. The first DOC 22 and the second DOC 42 are respectively configured to convert carbon monoxide (CO), hydrocarbons (HC), and nitrogen monoxide (NO) in the flowing exhaust gas into harmless water (H2O), carbon dioxide (CO2), and nitrogen dioxide (NO2) through oxidation reactions. The first ASC 26 and the second ASC 46 are respectively located downstream of the first SCR 24 and the second SCR 44, and are used to reduce the ammonia (NH3) leaking from the exhaust gas downstream of the SCR through catalytic oxidation. The DPF 48 of the uf-ATS 40 is located between the second DOC 42 and the second SCR 44, and is used to adsorb and remove particles in the exhaust gas flowing through it.

[0030] exist Figure 1 The aftertreatment system also includes injecting a reducing agent, such as urea, upstream of the first SCR 24 of the cc-ATS 20 to react with NO in the exhaust gas. X A chemical reaction occurs in the first SCR 24 to remove NO. X The first urea metering and injection device 25, and the upstream of the second SCR 44 of the uf-ATS 40, inject a reducing agent to react with NO in the exhaust gas. X A chemical reaction occurs in the second SCR44 to remove NO. X The second urea metering and injection device 45. The first urea metering and injection device 25 and the second urea metering and injection device 45 may be or include metering valves.

[0031] although Figure 1 As not shown, but those skilled in the art will understand, the exhaust aftertreatment system of this application also includes one or more sensors for measurement purposes, such as, but not limited to, one or more temperature sensors for measuring the exhaust temperature at one or more locations in the exhaust pipe 15, and sensors for measuring the NO in the exhaust at one or more locations in the exhaust pipe 15. X Concentration of one or more NO X Concentration sensors, etc. In one embodiment, the exhaust aftertreatment system may include measuring the temperature and NO concentration of exhaust gas as it exits the engine 10. X Temperature sensor for concentration and NO XConcentration sensor; temperature and NO concentration of exhaust gas emitted from cc-ATS 20 X Temperature sensor for concentration and NO X Concentration sensor; and NO as a final emission of exhaust gas from the aftertreatment system of this application into the atmosphere, i.e., from uf-ATS 40. X NOx concentration sensor. Of course, as needed, sensors can also be set up to measure the temperature, O2 concentration or NOx concentration, ammonia concentration, particulate matter, etc. of exhaust gas entering any component (first DOC 22, first SCR 24, first ASC 26, second DOC 24, second SCR 44, second ASC 46, DPF 48, etc.) and exiting any component.

[0032] This application considers the impact of NOx content in exhaust gas on the passive regeneration of DPF 48 and provides a novel calibration method to enhance the passive regeneration of DPF 48 in uf-ATS 40 and thus reduce the active regeneration process by altering the amount of urea in the exhaust gas upstream of the first SCR 24 of cc-ATS 20 injected by the first urea metering and injection device 25. Specifically, this application assigns a calibration factor F to the urea injection quantity determined by the first urea metering and injection device 25. Figure 2 A flowchart of the calibration method is shown. Figure 3 A schematic diagram illustrating the calibration algorithm of the calibration method of this application is shown below. Figure 2 and 3 This application describes a calibration method for passive regeneration of DPF 48 for enhancing uf-ATS 40.

[0033] The calibration method of this application mainly includes step S1 of determining the calibration factor F and applying the calibration factor F to the first urea metering injection volume M. 25ini Step S2 involves correcting it. Here, the first urea metering injection quantity M... 25ini The NO in the upstream exhaust of the cc-ATS 20 can be determined based on the following: X Content N 20UP The upstream exhaust temperature T of the first SCR 24 24UP ; and other parameters including the exhaust volume FL discharged from engine 10. In this document, upstream exhaust of a component refers to the exhaust entering the component; downstream exhaust of a component refers to the exhaust exiting the component.

[0034] Step S1, which determines the calibration factor F, is based on the ratio R of NO2 and particulate matter in the exhaust gas upstream of DPF 48. NO2 / Soot The dust level inside DPF 48 (L) S The upstream exhaust temperature T of DPF 48 48UPObtained by consulting calibration tables or calibration curves.

[0035] Among them, the dust level L in the DPF S This refers to the amount of soot accumulated within the DPF. First, based on engine speed and the amount of fuel injected into the engine, the total soot level or amount emitted by the engine is obtained by consulting a calibration table or curve; then, based on the engine's displacement (FL) and the upstream exhaust temperature (T) of the second DOC 42... 42UP The first soot consumed by the passive regeneration of DPF 48 is obtained by looking up calibration tables or curves for these parameters; based on the O2 concentration in the upstream exhaust of DPF 48, engine displacement FL, and upstream exhaust temperature T of DPF 48. 48UP The amount of second soot consumed by the active regeneration of DPF 48 is obtained by looking up the calibration table or curve for the parameters. Then, the amount of first and second soot consumed by DPF 48 is subtracted from the total soot level or amount to obtain the soot level L inside DPF 48. S .

[0036] The calibration table or calibration curve is obtained by recording and summarizing the experiments and compiling the calibration factor table or curve.

[0037] As mentioned above, the calibration factor F is based on R. NO2 / Soot L S 、 and T 48UP With the three parameters determined, the calibration table or calibration curve can be a three-dimensional table or curve based on the above three parameters.

[0038] Optionally, for easier illustration and operation, a two-dimensional table format can be used. That is, a first factor F1 is obtained based on two of the three parameters mentioned above, and a second factor F2 is obtained based on two different parameters. Then, a calibration factor F is obtained using the first factor F1 and the second factor F2; for example, the calibration factor F is equal to the product of the first factor F1 and the second factor F2. Since both the first factor F1 and the second factor F2 are within the range of 0 and 1, the calibration factor F is a value that is neither less than 0 nor greater than 1.

[0039] like Figure 4a and 4b The smoke level L within DPF 48 is shown separately. S And the exhaust temperature T upstream of DPF 48 48UP An exemplary first sub-calibration factor table for the calibrated first factor F1, and based on the above R... NO2 / Soot And the exhaust temperature T upstream of DPF 48 48UP An exemplary second sub-calibration factor table for the calibrated second factor F2. For example, when the dust level L within DPF 48... SThe exhaust temperature T upstream of 20g, DPF 48 48UP At 300℃, the first factor F1 is 0.14; when R NO2 / Soot The exhaust temperature T upstream of DPF48 is 50. 48UP At 300℃, the second factor F2 is 0.07, and the calibration factor F is 0.0098.

[0040] At this point, step S1, which determines the calibration factor F, includes:

[0041] Step S11, obtain the dust level L within DPF 48. S And the exhaust temperature T upstream of DPF 48 48UP And query Figure 4a The first factor F1 is determined by the first sub-calibration factor table;

[0042] Step S12, obtain the above R NO2 / Soot And the exhaust temperature T upstream of DPF 48 48UP And query Figure 4b The second factor F2 is determined by the second sub-calibration factor table; and

[0043] Step S13: Multiply the first factor F1 and the second factor F2 to obtain the above calibration factor F.

[0044] After obtaining the calibration factor F, in step S2, the first urea metering injection quantity M determined by the first urea metering and injection device 25 is obtained. 25ini Then multiply it by this calibration factor F to obtain the first urea calibration injection quantity M. 25cor .

[0045] Because the calibration factor F is a value less than or equal to 1 within the range of 0-1, the first urea calibration injection quantity M... 25cor Typically less than or equal to the first urea metering injection volume M 25ini This means that the amount of urea injected into the exhaust gas upstream of the first SCR 24 of the cc-ATS 20 is reduced. Therefore, the first SCR 24 of the cc-ATS 20 can remove NO through a reduction reaction. X The amount of NOx decreases, and the NOx content in the exhaust gas entering the uf-ATS 40 increases as the amount of NOx discharged from the cc-ATS 20 increases. 40up Increased NOx content in exhaust gas is beneficial for the passive regeneration of DPF 48 in uf-ATS 40.

[0046] The calibration method of this application further includes determining the first urea calibration injection quantity M in step S2. 25cor after:

[0047] Step S3, based on the first urea calibration injection quantity M25cor Achieving the efficiency η of cc-ATS 20 20 Alternatively, the NOx content in the upstream exhaust of the uf-ATS40, which is the NOx content (N) in the exhaust entering the uf-ATS 40. 40up ;

[0048] Step S4, based on the efficiency η of cc-ATS 20 20 Or uf-ATS 40 upstream exhaust NOx content N 40up and the permissible NOx content threshold T corresponding to specific emission requirements. threshold Determine the required second urea metering injection quantity M for uf-ATS 40 45 ;

[0049] In step S5, the NOx content (N) in the exhaust gas emitted from uf-ATS 40, specifically from the second ASC 46, is determined. final Whether it meets specific emission requirements, i.e., whether it is within the allowable NOx content threshold N. threshold Within. If N final Less than or equal to N threshold If the emission requirements are met, then step S6 is executed to end the process. Otherwise, if N... final Exceeding or exceeding N threshold Then proceed to step S7.

[0050] In step S7, based on N final and N threshold The amount of urea M determined by the updated first urea metering and injection device 25 25ini Specifically, it involves adding. Then, the process is repeated starting from step S1. Figure 2 The method flowchart.

[0051] According to the calibration method of this application, a calibration factor in the range of 0-1 is provided based on some real-time parameters of the engine and the exhaust gas emitted from the engine. This factor is used to modify, in particular, reduce, the amount of urea injected into the exhaust gas upstream of the first SCR in the closed-coupled aftertreatment system, thereby reducing the amount of NOx that the first SCR can reduce and remove. This increases the NOx content in the exhaust gas entering the DPF (Diesel Particulate Filter) of the underground aftertreatment system located downstream of the closed-coupled aftertreatment system, promoting passive regeneration of the DPF. The increase in passive regeneration reduces the need for active regeneration, correspondingly saving the fuel required for active regeneration.

[0052] At least some steps of the method of the present invention can be implemented using hardware and software, or a combination of both. When the method of the present invention is implemented or partially implemented using software, the software can be used to perform the various steps of the method of the present invention. The required software and data can be stored in memory and executed by a suitable instruction execution system, apparatus, or device (e.g., a single-core or multi-core processor or microprocessor or processor system). The software may include an arranged list of executable instructions for implementing logical functions, which may be embodied in any processor-readable medium for use by the instruction execution system, apparatus, or device. These systems can access and execute these instructions.

[0053] Some or all of the steps in the above methods can be achieved by, for example Figure 5 The calibration module 50 shown is used to perform the above method. This calibration module 50 can be integrated into the vehicle's electronic control unit (ECU), meaning that the above method can be performed by the vehicle's electronic control unit.

[0054] It should be understood that the calibration module 50 may also be provided independently of the vehicle's electronic control unit; for example, the control module 50 may be a microcontroller. The control module 50 may include a processor 52 and a memory 54 storing executable instructions and algorithms for each calculation step.

[0055] The calibration module 50 can communicate directly with the relevant sensors to obtain the parameters required for each step, or it can obtain the parameters from the vehicle electronic control unit (ECU) connected to the sensors. When the executable instructions in the memory 54 of the calibration module 50 are executed, the processor 52 obtains the parameters required for calculation from the sensors or the vehicle ECU and retrieves the relevant algorithms from the memory 54, executing them sequentially as follows: Figure 2 and 3 The calibration method shown.

[0056] The present invention has been described in detail above with reference to specific embodiments. Obviously, the above description and the embodiments shown in the accompanying drawings should be understood as exemplary and not as limiting the present invention. Those skilled in the art can make various modifications or alterations without departing from the spirit of the present invention, and such modifications or alterations do not depart from the scope of the present invention.

Claims

1. A calibration method for passive regeneration of DPF (48) in an enhanced exhaust aftertreatment system, wherein, The exhaust aftertreatment system includes a tightly coupled aftertreatment system (20) having a first SCR (24) and an underground aftertreatment system (40) including the DPF (48) and a second SCR (44) located downstream of the DPF (48), the method comprising the following steps: Based on the concentration ratio R of NO2 and particulate matter in the exhaust gas upstream of DPF(48) NO2 / Soot The dust level L inside the DPF(48) S The upstream exhaust temperature T of DPF(48) 48UP The first step (S1) is to determine the calibration factor (F) by consulting the calibration factor table or curve; The calibration factor (F) is applied to the first urea metering injection quantity M to be injected into the upstream exhaust gas of the first SCR (24). 25ini Thus, the first urea calibration injection quantity M is obtained. 25cor The second step (S2); Based on the first urea calibration injection quantity M 25cor The efficiency η of the tightly coupled post-processing system (20) is obtained. 20 Or the NOx content in the upstream exhaust gas of the underground aftertreatment system (40) 40up The third step (S3); Based on the efficiency η 20 Or the NOx content in the upstream exhaust gas of the underground aftertreatment system (40) 40up and the permissible NOx content threshold T corresponding to specific emission requirements. threshold The second urea metering injection quantity M is determined in the exhaust gas upstream of the second SCR (44) to be injected into the underground aftertreatment system (40). 45 The fourth step (S4); Determine the final NOx content (N) in the exhaust gas discharged from the underground aftertreatment system (40). final Is it within the permissible NOx content threshold N? threshold The fifth step (S5) within; The final NOx content N final Less than or equal to the permissible NOx content threshold N threshold The sixth ending step (S6) of the time.

2. The calibration method according to claim 1, further comprising the final NOx content N final NOx content greater than the permissible threshold N threshold Based on the final NOx content N final and the permissible NOx content threshold N threshold Update the first urea metering injection quantity M 25ini The seventh step (S7).

3. The calibration method according to claim 2, further comprising injecting an updated first urea metering volume M. 25ini Repeat steps one (S1) to five (S5).

4. The calibration method according to claim 1, wherein, The first step (S1) includes: Based on the dust level L within DPF(48) S The exhaust temperature T upstream of DPF(48) 48UP The first sub-step (S11) for determining the first factor (F1) is performed using the first sub-calibration factor table or curve. Based on the concentration ratio R of the soot NO2 / Soot The exhaust temperature T upstream of DPF(48) 48UP The second sub-step (S12) determines the second factor (F2) using the first sub-calibration factor table or curve; and The third sub-step (S13) involves multiplying the first factor (F1) and the second factor (F2) to obtain the calibration factor (F).

5. The calibration method according to claim 4, wherein, The first factor (F1) and the second factor (F2) are both in the range of 0-1, including the two endpoints of 0 and 1. The calibration factor (F) is a value that is not less than 0 and not greater than 1.

6. The calibration method according to any one of claims 1-5, wherein, The first urea calibration injection quantity M 25cor By adjusting the calibration factor (F) with the first urea metering injection volume M... 25ini Multiply them to get the result.

7. The calibration method according to any one of claims 1-5, wherein, The first urea metering injection volume M 25ini Based at least on the following determination: NO in the upstream exhaust gas of the tightly coupled aftertreatment system (20) X Content N 20UP The upstream exhaust temperature T of the first SCR (24) 24UP The amount of exhaust gas (FL) emitted from the engine of a vehicle.

8. The calibration method according to any one of claims 1-5, wherein, The tightly coupled post-processing system (20) and the underground post-processing system (40) further include a first DOC (22) and a second DOC (42) located upstream of the first SCR (24) and the second SCR (44), respectively.

9. A calibration module, characterized in that, include: processor; as well as A memory storing executable instructions, which, when executed, cause the processor to perform the calibration method according to any one of claims 1 to 8.

10. The calibration module according to claim 9, characterized in that, The calibration module is integrated into the vehicle's electronic control unit or is communicatively connected to the vehicle's electronic control unit.

11. A readable storage medium, characterized in that, It stores executable instructions that, when executed, cause the machine to perform the calibration method according to any one of claims 1 to 8.

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