Calculation method of DPF passive regeneration rate

Abstract

The present invention belongs to the technical field of engine aftertreatment systems and discloses a DPF passive regeneration rate calculation method. The DPF passive regeneration rate calculation method includes the following steps: obtaining an initial passive regeneration rate of a deep bed layer; correcting the initial passive regeneration rate of the deep bed layer based on the ash mass and exhaust gas flow rate of the deep bed layer to obtain a final passive regeneration rate of the deep bed layer; obtaining a filter cake layer passive regeneration rate; determining whether the number of active regenerations is greater than a set number; if the number of active regenerations is greater than the set number, the DPF passive regeneration rate is the sum of the initial passive regeneration rate of the deep bed layer and the passive regeneration rate of the filter cake layer; if the number of active regenerations is less than or equal to the set number, the DPF passive regeneration rate is the sum of the final passive regeneration rate of the deep bed layer and the passive regeneration rate of the filter cake layer. The method improves the accuracy of calculating the DPF passive regeneration rate, thereby improving the accuracy of estimating carbon load and improving the determination of optimizing the timing of active regeneration.

Description

Technical Field

[0001] The present invention relates to the technical field of engine after-treatment systems, and in particular to a method for calculating a DPF passive regeneration rate. Background Art

[0002] DPF (Diesel Particulate Filter) after-treatment technology is the primary means of reducing soot in engine exhaust. Its basic principle is to capture soot in exhaust gas flowing through the DPF through its wall-flow structure, thereby purifying the engine's exhaust. The DPF's passive regeneration rate is a key parameter for estimating carbon loading and determining the timing of active regeneration. Therefore, the accuracy of the DPF's passive regeneration rate calculation affects both the accuracy of carbon loading estimation and the timing of active regeneration.

[0003] Among them, for the calculation method of DPF passive regeneration rate, the existing technology usually adopts exhaust temperature and exhaust flow to correct the value of DPF passive regeneration rate, but this method of calculating DPF passive regeneration rate does not take into account the influence of the number of active regenerations on DPF passive regeneration rate, the influence of ash on the passive regeneration of NO2 and soot particle surface, and the influence of NO2 reverse diffusion in exhaust gas on DPF passive regeneration, etc., wherein, reverse diffusion means that NO2 in exhaust gas will re-enter the deep bed layer and participate in the continuous regeneration reaction of soot particles and NO2, resulting in low accuracy of the calculated DPF passive regeneration rate, thereby reducing the accuracy of carbon load estimation, which is not conducive to optimizing the determination of active regeneration timing. Summary of the Invention

[0004] The object of the present invention is to provide a method for calculating the passive regeneration rate of a DPF, so as to solve the problem of low accuracy of the DPF passive regeneration rate calculated by the method for calculating the passive regeneration rate of a DPF in the prior art.

[0005] To achieve this object, the present invention adopts the following technical solutions:

[0006] The DPF passive regeneration rate calculation method includes the following:

[0007] Obtain the initial passive regeneration rate of the deep bed;

[0008] Correcting the initial passive regeneration rate of the deep bed according to the ash mass and exhaust gas flow rate of the deep bed to obtain the final passive regeneration rate of the deep bed;

[0009] Obtain the passive regeneration rate of the filter cake layer;

[0010] Determine whether the number of active regenerations is greater than the set number;

[0011] If the number of active regenerations is greater than the set number, the DPF passive regeneration rate is the sum of the initial passive regeneration rate of the deep bed layer and the passive regeneration rate of the filter cake layer;

[0012] If the number of active regenerations is less than or equal to the set number, the DPF passive regeneration rate is the sum of the final passive regeneration rate of the deep bed layer and the passive regeneration rate of the filter cake layer.

[0013] Preferably, the specific steps of obtaining the initial passive regeneration rate of the deep bed include:

[0014] Obtain MAP1 formed by exhaust temperature, exhaust gas flow rate and passive regeneration rate of the first deep bed;

[0015] According to the current exhaust temperature and the current exhaust gas flow rate, the corresponding first deep bed passive regeneration rate is retrieved from the MAP1;

[0016] Correcting the passive regeneration rate of the first deep bed layer according to the soot mass of the current deep bed layer to obtain the passive regeneration rate of the second deep bed layer;

[0017] Calculate the current NO2 volume fraction;

[0018] The passive regeneration rate of the second deep bed is corrected according to the current NO2 volume fraction to obtain the initial passive regeneration rate of the deep bed.

[0019] Preferably, the specific steps of correcting the first deep bed passive regeneration rate according to the soot mass of the current deep bed to obtain the second deep bed passive regeneration rate include:

[0020] Get the soot mass of the deep bed and the first correction coefficient Cur1;

[0021] According to the soot mass of the current deep bed layer, the corresponding first correction coefficient is retrieved from Cur1;

[0022] Correcting the first deep bed passive regeneration rate according to the first correction coefficient to obtain a second deep bed passive regeneration rate;

[0023] The passive regeneration rate of the second deep bed layer = the first correction coefficient * the passive regeneration rate of the first deep bed layer.

[0024] Preferably, the soot mass of the deep bed layer = total soot mass * soot mass distribution coefficient; wherein, 0 < soot mass distribution coefficient <1.

[0025] Preferably, the specific steps of calculating the current NO2 volume fraction include:

[0026] Get the current volume fraction of NO;

[0027] Obtain MAP2 formed by exhaust temperature, exhaust gas flow rate and conversion efficiency of NO to NO2;

[0028] According to the current exhaust temperature and the current exhaust gas flow rate, the corresponding NO to NO2 conversion efficiency is obtained from the MAP2;

[0029] Obtain Cur2 formed by the total mass of ash and the catalyst active surface ratio coefficient;

[0030] According to the current total ash mass, the corresponding catalyst active surface ratio coefficient is obtained from Cur2;

[0031] Calculate the current NO2 volume fraction based on the current NO volume fraction, the NO to NO2 conversion efficiency, and the catalyst surface activity coefficient;

[0032] Among them, the current NO2 volume fraction = the current NO volume fraction * the conversion efficiency of NO to NO2 * the catalyst surface activity ratio coefficient.

[0033] Preferably, the passive regeneration rate of the second deep bed is corrected according to the current NO2 volume fraction, and the calculation formula for the initial passive regeneration rate of the deep bed is obtained as follows:

[0034] The initial passive regeneration rate of the deep bed layer = the current NO2 volume fraction * the second passive regeneration rate of the deep bed layer.

[0035] Preferably, the specific steps of correcting the initial passive regeneration rate of the deep bed according to the ash mass and exhaust gas flow rate of the deep bed to obtain the final passive regeneration rate of the deep bed include:

[0036] Get Cur3 formed by the ash mass of the deep bed and the ratio of the surface of the first soot particle covered by ash;

[0037] Obtaining the corresponding first soot particle surface coverage coefficient of ash from Cur3 according to the current deep bed ash mass;

[0038] Obtain MAP3 formed by deep bed ash mass, exhaust gas flow rate and back diffusion correction coefficient;

[0039] Obtaining a corresponding reverse diffusion correction coefficient from the MAP3 according to the current deep bed ash mass and the current exhaust gas flow rate;

[0040] Calculating the final passive regeneration rate of the deep bed layer based on the ratio coefficient of the surface of the first soot particle covered by ash, the back diffusion correction coefficient, and the initial passive regeneration rate of the deep bed layer;

[0041] The final passive regeneration rate of the deep bed layer = the ratio of the surface of the first soot particle covered by ash * the reverse diffusion correction coefficient * the initial passive regeneration rate of the deep bed layer.

[0042] Preferably, the ash mass of the deep bed layer = total ash mass * ash distribution coefficient; wherein, 0 < ash distribution coefficient < 1.

[0043] Preferably, the specific steps of obtaining the passive regeneration rate of the filter cake layer include:

[0044] Obtain MAP4 formed by exhaust temperature, exhaust gas flow rate and passive regeneration rate of the first filter cake layer;

[0045] According to the current exhaust temperature and the current exhaust gas flow rate, the corresponding passive regeneration rate of the first filter cake layer is retrieved from the MAP4;

[0046] Correcting the passive regeneration rate of the first filter cake layer according to the soot mass of the filter cake layer to obtain the passive regeneration rate of the second filter cake layer;

[0047] Correcting the passive regeneration rate of the second filter cake layer according to the ash mass of the filter cake layer to obtain the passive regeneration rate of the third filter cake layer;

[0048] Calculate the current NO2 volume fraction;

[0049] The passive regeneration rate of the third filter cake layer is corrected according to the current NO2 volume fraction to obtain the passive regeneration rate of the filter cake layer.

[0050] Preferably, the soot mass of the filter cake layer = the total soot mass * (1-soot mass distribution coefficient); wherein 0 < soot mass distribution coefficient < 1;

[0051] The ash mass of the filter cake layer = total ash mass * (1-ash distribution coefficient); wherein 0 < ash distribution coefficient < 1.

[0052] Beneficial effects of the present invention:

[0053] The object of the present invention is to provide a method for calculating the passive regeneration rate of DPF. The method for calculating the passive regeneration rate of DPF determines a specific method for calculating the passive regeneration rate of DPF based on the number of active regenerations. Specifically, if the number of active regenerations is less than or equal to a set number, the passive regeneration rate of DPF is the sum of the final passive regeneration rate of the deep bed layer and the passive regeneration rate of the filter cake layer. If the number of active regenerations is greater than the set number, the passive regeneration rate of DPF is the sum of the initial passive regeneration rate of the deep bed layer and the passive regeneration rate of the filter cake layer. Among them, when the number of active regenerations exceeds the set number, the active regeneration temperature is high. Affected by the active regeneration temperature and exhaust gas flow rate, the ash is mainly deposited in the filter cake layer, which has little effect on the passive regeneration of the deep bed layer. Therefore, the effect of ash on the initial passive regeneration rate of the deep bed layer can be ignored, and the sum of the initial passive regeneration rate of the deep bed layer and the passive regeneration rate of the filter cake layer is used as the DPF passive regeneration rate; when the number of active regenerations is less than or equal to the set number, ash is deposited in both the deep bed layer and the filter cake layer. The ash has an impact on the passive regeneration of both the deep bed layer and the filter cake layer and cannot be ignored. The initial passive regeneration rate of the deep bed layer is corrected according to the ash mass and exhaust gas flow rate to obtain the final passive regeneration rate of the deep bed layer. The sum of the final passive regeneration rate of the deep bed layer and the passive regeneration rate of the filter cake layer is then used as the DPF passive regeneration rate. This setting improves the accuracy of calculating the DPF passive regeneration rate, thereby improving the estimation accuracy of the carbon load and improving the determination of the optimal active regeneration timing. BRIEF DESCRIPTION OF THE DRAWINGS

[0054] Figure 1 The process of the DPF passive regeneration rate calculation method provided by the specific embodiment of the present invention is Figure 1 ;

[0055] Figure 2 The process of the DPF passive regeneration rate calculation method provided by the specific embodiment of the present invention is Figure 2 ;

[0056] Figure 3 The process of the DPF passive regeneration rate calculation method provided by the specific embodiment of the present invention is Figure 3 ;

[0057] Figure 4 The process of the DPF passive regeneration rate calculation method provided by the specific embodiment of the present invention is Figure 4 . DETAILED DESCRIPTION

[0058] The present invention will be further described in detail below with reference to the accompanying drawings and examples. It will be understood that the specific embodiments described herein are intended only to illustrate the present invention and are not intended to limit the present invention. It should also be noted that, for ease of description, the accompanying drawings only illustrate portions relevant to the present invention, not all structures.

[0059] In the description of the present invention, unless otherwise expressly specified or limited, the terms "connected," "connected," and "fixed" should be understood in a broad sense. For example, they may refer to fixed connections, detachable connections, or integration; mechanical connections or electrical connections; direct connections or indirect connections through an intermediate medium; and internal communication between two components or interaction between two components. Those skilled in the art will understand the specific meanings of the above terms in the present invention in specific circumstances.

[0060] In the present invention, unless otherwise expressly specified or limited, a first feature being "above" or "below" a second feature may include the first and second features being in direct contact, or may include the first and second features being in contact not directly but through another feature between them. Furthermore, a first feature being "above," "above," and "above" a second feature may include the first feature being directly above or obliquely above the second feature, or may simply mean that the first feature is higher in level than the second feature. A first feature being "below," "below," and "below" a second feature may include the first feature being directly below or obliquely below the second feature, or may simply mean that the first feature is lower in level than the second feature.

[0061] In the description of this embodiment, the terms "upper," "lower," "right," and other orientations or positional relationships are based on the orientations or positional relationships shown in the accompanying drawings and are intended solely for ease of description and simplified operation. They do not indicate or imply that the devices or components referred to must have, be constructed, or operate in a specific orientation. Therefore, they should not be construed as limitations on the present invention. Furthermore, the terms "first" and "second" are used solely for descriptive purposes and have no special meanings.

[0062] Regarding the calculation method of the DPF passive regeneration rate, the existing technology usually adopts the exhaust temperature and exhaust flow to correct the value of the DPF passive regeneration rate. However, this calculation method of the DPF passive regeneration rate does not take into account the influence of the number of active regenerations on the DPF passive regeneration rate, the influence of ash on the passive regeneration of NO2 and the surface of soot particles, and the influence of the back diffusion of NO2 in the exhaust gas on the DPF passive regeneration, etc., wherein the back diffusion means that the NO2 in the exhaust gas will re-enter the deep bed layer and participate in the continuous regeneration reaction of soot particles and NO2, resulting in low accuracy of the calculated DPF passive regeneration rate, thereby reducing the accuracy of carbon load estimation, which is not conducive to optimizing the determination of the timing of active regeneration.

[0063] Among them, soot refers to black carbon smoke, which is particulate matter produced by incomplete combustion of fuel in the engine system; ash comes from the oil additive substances accumulated in the particulate filter of the engine system, which mainly comes from the engine oil.

[0064] Therefore, the present invention provides a method for calculating the passive regeneration rate of DPF, taking into account the influence of the number of active regenerations on the passive regeneration rate of DPF, the influence of ash on the passive regeneration of NO2 and soot particle surfaces, and the influence of the back diffusion of NO2 in the exhaust gas on the passive regeneration of DPF, a specific method for calculating the passive regeneration rate of DPF is determined based on the number of active regenerations. Specifically, if the number of active regenerations is less than or equal to the set number, the passive regeneration rate of DPF is the sum of the final passive regeneration rate of the deep bed layer and the passive regeneration rate of the filter cake layer. If the number of active regenerations is greater than the set number, the passive regeneration rate of DPF is the sum of the initial passive regeneration rate of the deep bed layer and the passive regeneration rate of the filter cake layer. Among them, when the number of active regenerations exceeds the set number, the active regeneration temperature is high. Affected by the active regeneration temperature and exhaust gas flow rate, the ash is mainly deposited in the filter cake layer, with little effect on the passive regeneration of the deep bed layer. Therefore, the effect of ash on the initial passive regeneration rate of the deep bed layer can be ignored, and the sum of the initial passive regeneration rate of the deep bed layer and the passive regeneration rate of the filter cake layer is used as the DPF passive regeneration rate. When the number of active regenerations is less than or equal to the set number, ash is deposited in both the deep bed layer and the filter cake layer. The ash has an impact on the passive regeneration of both the deep bed layer and the filter cake layer and cannot be ignored. The initial passive regeneration rate of the deep bed layer is corrected based on the ash mass and exhaust gas flow rate to obtain the final passive regeneration rate of the deep bed layer. The sum of the final passive regeneration rate of the deep bed layer and the passive regeneration rate of the filter cake layer is then used as the DPF passive regeneration rate. This effectively improves the accuracy of calculating the DPF passive regeneration rate, thereby improving the estimation accuracy of the carbon load and improving the determination of the optimal active regeneration timing. Among them, the DPF coating includes a deep bed layer and a filter cake layer. The specific structure of the DPF belongs to the prior art and will not be repeated here.

[0065] Specifically, if Figure 1 As shown, the DPF passive regeneration rate calculation method includes:

[0066] S100. Obtain the initial passive regeneration rate of the deep bed layer.

[0067] S200, correcting the initial passive regeneration rate of the deep bed according to the ash mass and exhaust gas flow rate of the deep bed to obtain the final passive regeneration rate of the deep bed.

[0068] S300: Obtain the passive regeneration rate of the filter cake layer.

[0069] S400: Determine whether the number of active regenerations is greater than the set number.

[0070] If the number of active regenerations is greater than the set number, proceed to S410.

[0071] S410, DPF passive regeneration rate is the sum of the initial passive regeneration rate of the deep bed layer and the passive regeneration rate of the filter cake layer.

[0072] If the number of active regenerations is less than or equal to the set number, proceed to S420.

[0073] S420, DPF passive regeneration rate is the sum of the final passive regeneration rate of the deep bed layer and the passive regeneration rate of the filter cake layer.

[0074] In this embodiment, only step S100, step S200, step S300 and step S400 are performed sequentially as an example. In other embodiments, step S100, step S300 and step S400 may also be performed simultaneously.

[0075] Among them, Figure 2 As shown in Figure 2, the specific steps for obtaining the initial passive regeneration rate of the deep bed include:

[0076] S110: Obtain MAP1 formed by exhaust gas temperature, exhaust gas flow rate, and passive regeneration rate of the first deep bed layer. That is, obtain a spatial rectangular coordinate graph formed by exhaust gas temperature, exhaust gas flow rate, and passive regeneration rate of the first deep bed layer.

[0077] Among them, MAP1 formed by exhaust temperature, exhaust gas flow rate and passive regeneration rate of the first deep bed was obtained from a large number of previous experiments.

[0078] S120: Query the corresponding first deep bed passive regeneration rate from MAP1 based on the current exhaust temperature and the current exhaust gas flow rate. As an alternative, the first deep bed passive regeneration rate may be calculated based on the current exhaust temperature and the current exhaust gas flow rate. The formula for calculating the first deep bed passive regeneration rate based on the current exhaust temperature and the current exhaust gas flow rate is prior art and will not be described in detail here.

[0079] S130. Correct the passive regeneration rate of the first deep bed layer according to the soot mass of the current deep bed layer to obtain the passive regeneration rate of the second deep bed layer.

[0080] The specific steps of correcting the passive regeneration rate of the first deep bed layer according to the soot mass of the current deep bed layer to obtain the passive regeneration rate of the second deep bed layer include:

[0081] S131. Obtain Cur1 of the soot mass of the deep bed layer and the first correction coefficient. That is, obtain a table of the soot mass of the deep bed layer and the first correction coefficient.

[0082] The soot mass of the deep bed layer = the total soot mass * the soot mass distribution coefficient, where 0 < the soot mass distribution coefficient < 1. The total soot mass is calculated using a physical model, which is known in the art and will not be described in detail here.

[0083] Specifically, the relationship between the total soot mass and the soot mass distribution coefficient was tabulated based on a large number of previous experiments. That is, the soot mass distribution coefficient is related to the total soot mass: the larger the total soot mass, the larger the soot mass distribution coefficient.

[0084] S132. Obtain the corresponding first correction coefficient from Cur1 according to the current soot mass of the deep bed.

[0085] S133. Correct the passive regeneration rate of the first deep bed layer according to the first correction coefficient to obtain the passive regeneration rate of the second deep bed layer.

[0086] Wherein, the passive regeneration rate of the second deep bed layer = the first correction coefficient * the passive regeneration rate of the first deep bed layer.

[0087] S140: Calculate the current NO2 volume fraction.

[0088] The specific steps for calculating the current NO2 volume fraction include:

[0089] S141. Obtain the current volume fraction of NO.

[0090] The specific method for calculating the volume fraction of NO belongs to the prior art and will not be described in detail here.

[0091] S142: Obtain MAP2 formed by exhaust gas temperature, exhaust gas flow rate, and conversion efficiency of NO to NO2. That is, obtain a spatial rectangular coordinate graph formed by exhaust gas temperature, exhaust gas flow rate, and conversion efficiency of NO to NO2.

[0092] Among them, MAP2 formed by exhaust temperature, exhaust gas flow and conversion efficiency of NO to NO2 was obtained from a large number of previous experiments.

[0093] S143. According to the current exhaust temperature and the current exhaust gas flow rate, the corresponding NO to NO2 conversion efficiency is retrieved from MAP2.

[0094] S144: Obtain Cur2 formed by the total ash mass and the catalyst active surface ratio coefficient. That is, obtain a table formed by the total ash mass and the catalyst active surface ratio coefficient.

[0095] The total ash mass is calculated by combining the test data from the oil consumption test and the DPF ash test. The physical model used for this calculation is also known from the prior art and will not be further described here.

[0096] Among them, Cur2 formed by the total mass of ash and the ratio of the active surface area of ​​the catalyst was obtained from a large number of previous experiments.

[0097] Herein, the catalyst active surface refers to the DPF catalyst active surface; or the catalyst active surface refers to the DPF catalyst active surface and the DOC catalyst active surface.

[0098] The catalyst active surface ratio coefficient refers to the ratio of the active surface of the DPF catalyst to the total surface of the DPF catalyst.

[0099] S145. According to the current total ash mass, the corresponding catalyst active surface ratio coefficient is retrieved from Cur2.

[0100] S146. Calculate the current NO2 volume fraction based on the current NO volume fraction, the NO to NO2 conversion efficiency, and the catalyst surface activity ratio.

[0101] Among them, the current NO2 volume fraction = the current NO volume fraction * the conversion efficiency of NO to NO2 * the catalyst surface activity ratio coefficient.

[0102] In this embodiment, steps S141 to S146 are performed sequentially. In other embodiments, steps S141 to S143 and steps S144 to S145 may be performed in parallel before step S146 is performed.

[0103] S150. Correct the passive regeneration rate of the second deep bed layer according to the current NO2 volume fraction to obtain the initial passive regeneration rate of the deep bed layer.

[0104] Among them, the initial passive regeneration rate of the deep bed = the current NO2 volume fraction * the passive regeneration rate of the second deep bed.

[0105] Specifically, the initial passive regeneration rate of the deep bed = the current NO2 volume fraction * the second deep bed passive regeneration rate = (the current NO volume fraction * the conversion efficiency of NO to NO2 * the catalyst surface activity ratio coefficient) * (the first deep bed passive regeneration rate * the first correction coefficient).

[0106] It can be understood that in the process of calculating the initial passive regeneration rate of the deep bed, the effects of exhaust temperature, exhaust gas flow rate, soot mass of the deep bed and NO2 volume fraction on the initial passive regeneration rate of the deep bed are comprehensively considered, which effectively improves the accuracy of calculating the initial passive regeneration rate of the deep bed.

[0107] Among them, Figure 3 As shown in FIG, the specific steps for correcting the initial passive regeneration rate of the deep bed according to the ash mass and exhaust gas flow rate of the deep bed to obtain the final passive regeneration rate of the deep bed include:

[0108] S210: Obtain Cur3 formed by the ash mass of the deep bed layer and the coefficient of the surface coverage of the first soot particle by ash. That is, obtain a table formed by the ash mass of the deep bed layer and the coefficient of the surface coverage of the first soot particle by ash.

[0109] Among them, the ash mass of the deep bed layer = total ash mass * ash distribution coefficient; among them, 0 < ash distribution coefficient < 1.

[0110] The first soot particle surface coverage coefficient of ash refers to the ratio of the area covered by ash on the surface of the soot particles in the deep bed to the surface area of ​​the soot particles in the deep bed.

[0111] Specifically, the corresponding relationship between the total ash mass and the ash distribution coefficient was tabulated based on a large number of previous experiments. That is, the ash distribution coefficient is related to the total ash mass. The larger the total ash mass, the larger the ash distribution coefficient.

[0112] S220 , obtaining the corresponding first soot particle surface coverage coefficient of ash from Cur3 based on the current deep bed ash mass.

[0113] S230, obtaining MAP3 formed by the ash mass of the deep bed, the exhaust gas flow rate, and the reverse diffusion correction coefficient.

[0114] Among them, MAP3 formed by the ash mass of the deep bed, exhaust gas flow rate and back diffusion correction coefficient was obtained from a large number of previous experiments.

[0115] Among them, reverse diffusion means that NO2 in the exhaust gas will re-enter the deep bed layer and participate in the continuous regeneration reaction of soot particles and NO2.

[0116] S240 . Obtain a corresponding reverse diffusion correction coefficient from MAP3 based on the current ash mass of the deep bed layer and the current exhaust gas flow rate.

[0117] S250. Calculate the final passive regeneration rate of the deep bed based on the ratio coefficient of the surface of the first soot particle covered by ash, the reverse diffusion correction coefficient, and the initial passive regeneration rate of the deep bed.

[0118] The final passive regeneration rate of the deep bed = the ratio of the surface of the first soot particle covered by ash * the reverse diffusion correction coefficient * the initial passive regeneration rate of the deep bed.

[0119] When the number of active regenerations is less than or equal to the set number, ash is deposited in both the deep bed layer and the filter cake layer. The ash has an impact on the passive regeneration of both the deep bed layer and the filter cake layer and cannot be ignored. With this setting, the initial passive regeneration rate of the deep bed layer is corrected according to the ash mass and exhaust gas flow rate to obtain the final passive regeneration rate of the deep bed layer, which effectively improves the accuracy of the final passive regeneration rate of the deep bed layer, thereby improving the accuracy of calculating the DPF passive regeneration rate.

[0120] In this embodiment, steps S210 to S250 are performed sequentially for illustrative purposes only. In other embodiments, steps S210 to S220 and steps S230 to S240 may be performed simultaneously before step S250 is performed.

[0121] Among them, Figure 4 As shown in FIG, the specific steps for obtaining the passive regeneration rate of the filter cake layer include:

[0122] S310: Obtain a MAP 4 formed by the exhaust temperature, the exhaust gas flow rate, and the passive regeneration rate of the first filter cake layer. That is, obtain a spatial rectangular coordinate graph formed by the exhaust temperature, the exhaust gas flow rate, and the passive regeneration rate of the first filter cake layer.

[0123] Among them, MAP4 formed by exhaust temperature, exhaust gas flow rate and passive regeneration rate of the first filter cake layer was obtained from a large number of previous experiments.

[0124] S320: Query the corresponding passive regeneration rate of the first filter cake layer from MAP4 based on the current exhaust temperature and the current exhaust gas flow rate. As an alternative, the passive regeneration rate of the first filter cake layer can also be calculated based on the current exhaust temperature and the current exhaust gas flow rate. The formula for calculating the passive regeneration rate of the first filter cake layer based on the current exhaust temperature and the current exhaust gas flow rate is prior art and will not be described in detail here.

[0125] S330, correcting the passive regeneration rate of the first filter cake layer according to the soot mass of the filter cake layer to obtain the passive regeneration rate of the second filter cake layer.

[0126] The specific steps of correcting the passive regeneration rate of the first filter cake layer according to the soot mass of the filter cake layer to obtain the passive regeneration rate of the second filter cake layer include:

[0127] S331, obtaining Cur4 of the soot mass and the second correction coefficient of the filter cake layer. That is, obtaining a table of the soot mass and the second correction coefficient of the filter cake layer.

[0128] The soot mass of the filter cake layer = the total soot mass * (1-soot mass distribution coefficient); wherein 0 < soot mass distribution coefficient < 1.

[0129] Specifically, the relationship between the total soot mass and the soot mass distribution coefficient was tabulated based on a large number of previous experiments. That is, the soot mass distribution coefficient is related to the total soot mass: the larger the total soot mass, the larger the soot mass distribution coefficient.

[0130] S332. Obtain the corresponding second correction coefficient from Cur4 according to the current soot mass of the filter cake layer.

[0131] S333. Correct the passive regeneration rate of the first filter cake layer according to the second correction coefficient to obtain the passive regeneration rate of the second filter cake layer.

[0132] The passive regeneration rate of the second filter cake layer = the second correction coefficient * the passive regeneration rate of the first filter cake layer.

[0133] S340. Correct the passive regeneration rate of the second filter cake layer according to the ash mass of the filter cake layer to obtain the passive regeneration rate of the third filter cake layer.

[0134] The specific steps of correcting the passive regeneration rate of the second filter cake layer according to the ash mass of the filter cake layer to obtain the passive regeneration rate of the third filter cake layer include:

[0135] S341. Obtain Cur5 formed by the ash mass of the filter cake layer and the ratio coefficient of the surface of the second soot particle covered by the ash.

[0136] The ash mass of the filter cake layer = the total ash mass * (1-ash distribution coefficient); wherein 0 < ash distribution coefficient < 1.

[0137] The second soot particle surface coverage coefficient of ash refers to the ratio of the area covered by ash on the surface of the soot particles in the filter cake layer to the surface area of ​​the soot particles in the filter cake layer.

[0138] Specifically, the correspondence between the total ash mass and the ash distribution coefficient was tabulated based on a large number of previous experiments. That is, the ash distribution coefficient is related to the total ash mass: the larger the total ash mass, the larger the ash distribution coefficient.

[0139] S342. Obtain the corresponding second soot particle surface coverage coefficient of ash from Cur5 according to the current ash mass of the filter cake layer.

[0140] S343. Correct the passive regeneration rate of the second filter cake layer according to the ratio of the surface of the second soot particles covered by ash to obtain the passive regeneration rate of the third filter cake layer.

[0141] The passive regeneration rate of the third filter cake layer = the ratio of the surface of the second soot particles covered by ash * the passive regeneration rate of the second filter cake layer.

[0142] S350: Calculate the current NO2 volume fraction.

[0143] The specific steps for calculating the current NO2 volume fraction include:

[0144] Obtain the current volume fraction of NO. The specific method for calculating the volume fraction of NO belongs to the prior art and will not be described in detail here.

[0145] Obtain the MAP2 formed by the exhaust temperature, exhaust gas flow rate, and the conversion efficiency of NO to NO2. Among them, the MAP2 formed by the exhaust temperature, exhaust gas flow rate, and the conversion efficiency of NO to NO2 was obtained from a large number of previous experiments.

[0146] The conversion efficiency of NO to NO2 is obtained from MAP2 according to the current exhaust temperature and the current exhaust gas flow.

[0147] Take the total ash mass and the catalyst active surface ratio to form Cur2. This Cur2 was obtained from a large number of previous experiments. The catalyst active surface refers to the DPF catalyst active surface; alternatively, the catalyst active surface refers to both the DPF catalyst active surface and the DOC catalyst active surface.

[0148] According to the current total ash mass, the corresponding catalyst active surface ratio coefficient is obtained from Cur2.

[0149] The current NO2 volume fraction is calculated based on the current NO volume fraction, the NO to NO2 conversion efficiency, and the catalyst surface activity ratio.

[0150] Among them, the current NO2 volume fraction = the current NO volume fraction * the conversion efficiency of NO to NO2 * the catalyst surface activity ratio coefficient.

[0151] The specific steps for calculating the current NO 2 volume fraction in step S350 are the same as those in steps S141 to S146 described above.

[0152] S360: Correct the passive regeneration rate of the third filter cake layer according to the current NO2 volume fraction to obtain the passive regeneration rate of the filter cake layer.

[0153] Among them, the passive regeneration rate of the filter cake layer = the current NO2 volume fraction * the passive regeneration rate of the third filter cake layer.

[0154] Specifically, the passive regeneration rate of the filter cake layer = the current volume fraction of NO2 * the passive regeneration rate of the third filter cake layer = (the current volume fraction of NO * the conversion efficiency of NO to NO2 * the catalyst surface activity ratio coefficient) * (the ratio coefficient of the second soot particle surface covered by ash * the second correction coefficient * the passive regeneration rate of the first filter cake layer).

[0155] In this way, the calculation of the DPF passive regeneration rate is completed, which effectively improves the accuracy of calculating the DPF passive regeneration rate, thereby improving the estimation accuracy of the carbon load and improving the determination of the optimal active regeneration timing.

[0156] Obviously, the above embodiments of the present invention are merely examples for the purpose of clearly illustrating the present invention and are not intended to limit the embodiments of the present invention. A person skilled in the art would be able to make various obvious changes, readjustments, and substitutions without departing from the scope of protection of the present invention. It is not necessary and impossible to enumerate all embodiments here. Any modifications, equivalent substitutions, and improvements made within the spirit and principles of the present invention shall be included within the scope of protection of the claims of the present invention.

Claims

1. A method for calculating the passive regeneration rate of a DPF, wherein the DPF coating comprises a deep bed layer and a filter cake layer, characterized in that: include: Obtain the initial passive regeneration rate of the deep bed; Correcting the initial passive regeneration rate of the deep bed according to the ash mass and exhaust gas flow rate of the deep bed to obtain the final passive regeneration rate of the deep bed; Obtain the passive regeneration rate of the filter cake layer; Determine whether the number of active regenerations is greater than the set number; If the number of active regenerations is greater than the set number, the DPF passive regeneration rate is the sum of the initial passive regeneration rate of the deep bed layer and the passive regeneration rate of the filter cake layer; If the number of active regenerations is less than or equal to the set number, the DPF passive regeneration rate is the sum of the final passive regeneration rate of the deep bed layer and the passive regeneration rate of the filter cake layer.

2. The DPF passive regeneration rate calculation method according to claim 1, characterized in that: The specific steps to obtain the initial passive regeneration rate of the deep bed include: Obtain MAP1 formed by exhaust temperature, exhaust gas flow rate and passive regeneration rate of the first deep bed; According to the current exhaust temperature and the current exhaust gas flow rate, the corresponding first deep bed passive regeneration rate is retrieved from the MAP1; Correcting the passive regeneration rate of the first deep bed layer according to the soot mass of the current deep bed layer to obtain the passive regeneration rate of the second deep bed layer; Calculate the current NO2 volume fraction; The passive regeneration rate of the second deep bed is corrected according to the current NO2 volume fraction to obtain the initial passive regeneration rate of the deep bed.

3. The DPF passive regeneration rate calculation method according to claim 2, characterized in that: The specific steps of correcting the passive regeneration rate of the first deep bed layer according to the soot mass of the current deep bed layer to obtain the passive regeneration rate of the second deep bed layer include: Get the soot mass of the deep bed and the first correction coefficient Cur1; According to the soot mass of the current deep bed layer, the corresponding first correction coefficient is retrieved from Cur1; Correcting the first deep bed passive regeneration rate according to the first correction coefficient to obtain a second deep bed passive regeneration rate; The passive regeneration rate of the second deep bed layer = the first correction coefficient * the passive regeneration rate of the first deep bed layer.

4. The DPF passive regeneration rate calculation method according to claim 3, characterized in that: The soot mass of the deep bed layer = total soot mass * soot mass distribution coefficient; wherein, 0 < soot mass distribution coefficient <1.

5. The DPF passive regeneration rate calculation method according to claim 2, characterized in that: The specific steps for calculating the current NO2 volume fraction include: Get the current volume fraction of NO; Obtain MAP2 formed by exhaust temperature, exhaust gas flow rate and conversion efficiency of NO to NO2; According to the current exhaust temperature and the current exhaust gas flow rate, the corresponding NO to NO2 conversion efficiency is obtained from the MAP2; Obtain Cur2 formed by the total mass of ash and the catalyst active surface ratio coefficient; According to the current total ash mass, the corresponding catalyst active surface ratio coefficient is obtained from Cur2; Calculate the current NO2 volume fraction based on the current NO volume fraction, the NO to NO2 conversion efficiency, and the catalyst surface activity coefficient; Among them, the current NO2 volume fraction = the current NO volume fraction * the conversion efficiency of NO to NO2 * the catalyst surface activity ratio coefficient.

6. The DPF passive regeneration rate calculation method according to claim 2, characterized in that: The passive regeneration rate of the second deep bed is corrected according to the current NO2 volume fraction, and the calculation formula for the initial passive regeneration rate of the deep bed is obtained as follows: The initial passive regeneration rate of the deep bed layer = the current NO2 volume fraction * the second passive regeneration rate of the deep bed layer.

7. The DPF passive regeneration rate calculation method according to any one of claims 1 to 6, characterized in that: The specific steps of correcting the initial passive regeneration rate of the deep bed according to the ash mass and exhaust gas flow rate of the deep bed to obtain the final passive regeneration rate of the deep bed include: Get Cur3 formed by the ash mass of the deep bed and the ratio of the surface of the first soot particle covered by ash; Obtaining the corresponding first soot particle surface coverage coefficient of ash from Cur3 according to the current deep bed ash mass; Obtain MAP3 formed by deep bed ash mass, exhaust gas flow rate and back diffusion correction coefficient; Obtaining a corresponding reverse diffusion correction coefficient from the MAP3 according to the current deep bed ash mass and the current exhaust gas flow rate; Calculating the final passive regeneration rate of the deep bed layer based on the ratio coefficient of the surface of the first soot particle covered by ash, the back diffusion correction coefficient, and the initial passive regeneration rate of the deep bed layer; The final passive regeneration rate of the deep bed layer = the ratio of the surface of the first soot particle covered by ash * the reverse diffusion correction coefficient * the initial passive regeneration rate of the deep bed layer.

8. The DPF passive regeneration rate calculation method according to claim 7, characterized in that: Ash mass of deep bed layer = total ash mass * ash distribution coefficient; where 0 < ash distribution coefficient < 1.

9. The DPF passive regeneration rate calculation method according to any one of claims 1 to 6, characterized in that: The specific steps for obtaining the passive regeneration rate of the filter cake layer include: Obtain MAP4 formed by exhaust temperature, exhaust gas flow rate and passive regeneration rate of the first filter cake layer; According to the current exhaust temperature and the current exhaust gas flow rate, the corresponding passive regeneration rate of the first filter cake layer is retrieved from the MAP4; Correcting the passive regeneration rate of the first filter cake layer according to the soot mass of the filter cake layer to obtain the passive regeneration rate of the second filter cake layer; Correcting the passive regeneration rate of the second filter cake layer according to the ash mass of the filter cake layer to obtain the passive regeneration rate of the third filter cake layer; Calculate the current NO2 volume fraction; The passive regeneration rate of the third filter cake layer is corrected according to the current NO2 volume fraction to obtain the passive regeneration rate of the filter cake layer.

10. The DPF passive regeneration rate calculation method according to claim 9, characterized in that: The soot mass of the filter cake layer = total soot mass * (1-soot mass distribution coefficient); wherein 0 < soot mass distribution coefficient < 1; The ash mass of the filter cake layer = total ash mass * (1-ash distribution coefficient); wherein 0 < ash distribution coefficient < 1.

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