A sensing dpf system with soot and ash detection function and a control method thereof

Abstract

The application discloses a sensing DPF system with soot and ash detection function and a control method thereof. The system comprises a metal packaging shell, a DPF carrier arranged in the metal packaging shell, two or more detection electrodes arranged in the DPF carrier, and a controller. The two or more detection electrodes and the metal packaging shell divide the DPF carrier into multiple electrode areas, and the detection electrodes are connected to the controller. The system and the control method directly detect the soot deposition amount and the soot distribution by detecting the physical characteristics of the soot itself, trigger and stop DPF regeneration, trigger the ash calculation process according to the calculated soot deposition amount and soot distribution, and calculate the ash deposition in the DPF according to the pressure difference between the two ends of the DPF. Since the soot amount is directly detected, the system is basically not affected by the soot distribution, the soot shape, the environmental parameter change, the error between engine parts, and the engine aging.

Description

TECHNICAL FIELD

[0001] The application belongs to the technical field of tail gas treatment, and particularly relates to a sensing DPF system with soot and ash detection function and a control method thereof. BACKGROUND

[0002] In order to meet the requirements of emission regulations, a diesel particulate filter (DPF) needs to be installed in an engine tail gas treatment system to remove the soot generated by combustion. The soot will accumulate in the DPF, and when it reaches a certain degree, it will increase the back pressure of the engine system and affect the operation of the engine. Therefore, the soot in the DPF needs to be removed regularly. The process of removing the soot in the DPF is called DPF regeneration. In diesel engine applications, there are two forms of DPF regeneration: passive regeneration and active regeneration. Passive regeneration is the reaction of nitrogen oxides (NOx) in the exhaust gas with soot, thereby removing the soot, and active regeneration is the reaction of residual oxygen in the exhaust gas with soot. Compared with active regeneration, passive regeneration requires a lower regeneration temperature, but the window is narrower (the efficient interval is 300 to 350 degrees Celsius), and also because the amount of NOx in the exhaust gas is not easy to control, the main form of regeneration is usually active regeneration.

[0003] There are two conditions for active regeneration control of the DPF: DPF regeneration trigger condition and DPF regeneration end condition. The DPF regeneration trigger condition is generally evaluated by combining the results of two estimations of the DPF soot deposition amount. One is based on the estimation of the pressure difference between the two ends of the DPF, which uses the relationship between the pressure difference and the exhaust gas flow to estimate the soot deposition amount; the other is based on a model of the soot concentration generated by the engine, which calculates the possible soot deposition amount. However, both estimations are indirect estimations. The relationship between the pressure difference and the exhaust gas flow is affected by the pressure resistance, which is not directly related to the soot deposition amount. Only when the soot is uniformly distributed in the DPF and the soot morphology does not change much, there is a definite correlation. The soot deposition amount calculated based on the soot model is affected by many factors such as errors between engine parts, engine aging, changes in environmental parameters, and the accuracy is also greatly limited.

[0004] During the active regeneration process of the DPF, the pressure difference detection will have a large deviation due to the influence of soot redistribution, so the estimation result of the soot model is generally used as the stop condition. However, the inaccuracy of the soot model will lead to uncertainty of the stop time. In order to tolerate these uncertainties, the stop time is often extended, which causes an increase in the fuel consumption of the engine.

[0005] In the DPF, in addition to the soot, there is also the deposition of ash. The sources of ash include inorganic matter generated by oil consumption, salt generated by coolant leakage, particles generated by aging of the engine system and upstream catalyst, and dust in the air, etc. These ashes cannot be removed in the DPF regeneration, but will affect the back pressure, and if not cleaned in time, will cause frequent regeneration and DPF temperature resistance, etc. SUMMARY

[0006] The technical problem to be solved by the present application is to provide a sensing DPF system with soot and ash detection function and a control method thereof.

[0007] To solve the above technical problems, the first aspect discloses a sensing DPF system with soot and ash detection function, comprising a metal packaging shell, a DPF carrier arranged in the metal packaging shell, two or more detection electrodes arranged in the DPF carrier, and a controller; the two or more detection electrodes and the metal packaging shell divide the DPF carrier into a plurality of electrode regions, and the detection electrodes are connected to the controller.

[0008] Further, the detection electrode comprises a probe, an electrode connecting column and a terminal post, one end of the probe is connected with the electrode connecting column, and the part away from the one end penetrates into the channel of the DPF carrier, and the electrode connecting column is fixedly connected with the terminal post.

[0009] Further, the detection electrode further comprises a bolt and an insulating sheet, and the terminal post is fixed on the metal packaging shell through the bolt and the insulating sheet, and is electrically insulated from the metal packaging shell.

[0010] Further, it further comprises a common ground electrode, which is installed on the metal packaging shell and connected with the controller through a sixth signal line.

[0011] Further, it further comprises a first exhaust temperature sensor, a second exhaust temperature sensor and a differential pressure sensor, the first exhaust temperature sensor is arranged upstream of the DPF carrier, the second exhaust temperature sensor is arranged downstream of the DPF carrier, and the two measuring ends of the differential pressure sensor are connected with the two ends of the DPF carrier through a detection tube; the first exhaust temperature sensor is connected with the controller through a third signal line, the second exhaust temperature sensor is connected with the controller through a first signal line, and the differential pressure sensor is connected with the controller through a second signal line.

[0012] Further, the first and second detecting electrodes are connected with the controller through the fourth and fifth signal lines respectively, the second detecting electrode and the metal packaging shell form an electrode area 1, the first detecting electrode and the metal packaging shell form an electrode area 3, and the first and second detecting electrodes form an electrode area 2.

[0013] The second aspect discloses a sensing DPF system control method with carbon smoke and ash detection function, comprising:

[0014] Step 1, respectively calculating the carbon smoke deposition amounts of multiple electrode areas;

[0015] Step 2, judging whether the first condition is met according to the carbon smoke deposition amounts of multiple areas, and stopping DPF regeneration if the first condition is met.

[0016] Further, the step 1 comprises detecting the amount of carbon smoke in the electrode area by measuring the impedance or dielectric constant of the electrode area.

[0017] Further, the impedance coefficient Cs of the electrode area is a parameter for representing the carbon smoke deposition amount in the electrode area, and the calculation formula is as follows:

[0018] Cs=Zm / Z0(F1)

[0019] Wherein, Zm is the area impedance value of the electrode area measured and calculated; Z0 is the area impedance value of the clean carrier in the electrode area when the carbon smoke is 0 and the temperature is the regeneration temperature.

[0020] Further, the carbon smoke deposition amounts of multiple electrode areas are respectively represented as S1, S2, …, SN. N Wherein, N represents the number of electrode areas, and the first condition in step 2 comprises:

[0021] sum(S1, S2, …, SN) < Thd_SumES(Cond4) N

[0022] and max(S1, S2, …, SN) < Thd_minS(Cond5) N

[0023] and max(S1, S2, …, SN) - min(S1, S2, …, SN) < Thd_deltaES(Cond6) N N

[0024] Wherein, Thd_SumES, Thd_minS and Thd_deltaES are threshold constants, sum() is the sum calculation, max() is the maximum value calculation, and min() is the minimum value calculation.​​​​

[0025] According to condition (Cond4), the total soot amount in the DPF carrier (152) is lower than threshold Thd_sumES; according to condition (Cond5), the highest soot deposition amount in the plurality of electrode regions is lower than Thd_minS; according to condition (Cond6), the difference between the maximum soot deposition amount and the minimum soot deposition amount in the plurality of electrode regions is lower than Thd_deltaES; if all the three conditions are satisfied, the DPF regeneration is stopped.

[0026] Further, the step 1 includes: correcting the impedance coefficient Cs to obtain the soot deposition amount Ms, and the calculation formula is as follows:

[0027] Cst = Tbl1(Cs, T141) (F2)

[0028] Mw = m_fa * (Tbl2(Ta) * RH / Pa + K / Lambda) (F3)

[0029] Ms = Tbl3(Cst, Mw) (F4)

[0030] Wherein, Cst is the temperature-corrected impedance coefficient, T141 is the exhaust temperature measured by the first exhaust temperature sensor 141; Mw is the calculated water content in the exhaust gas, Ta is the ambient temperature of the engine, Pa is the ambient pressure of the engine, m_fa is the fresh air mass flow, RH is the relative humidity of the environment, K is a constant, Lambda is the air excess coefficient of the engine combustion, Tbl1(), Tbl2(), Tbl3() are table lookups.

[0031] Further, it further includes step 3, if the second condition is satisfied, triggering the DPF regeneration.

[0032] Let the soot deposition amounts of the plurality of electrode regions be S1, S2, …, SN respectively, and the maximum soot deposition amount of the plurality of electrode regions be max(S1, S2, …, SN). N Wherein N represents the number of electrode regions, and the second condition in step 3 includes:

[0033] sum(S1, S2, …, SN) < Thd_sumBS (Cond1) N

[0034] or max(S1, S2, …, SN) < Thd_maxS (Cond2) N

[0035] or max(S1, S2, …, SN) - min(S1, S2, …, SN) < Thd_deltaBS (Cond3) N N

[0036] ​​​​Among them, Thd_sumBS, Thd_maxS and Thd_deltaBS are threshold constants; sum() is the summation function, max() is the maximum value function, and min() is the minimum value function.

[0037] According to condition (Cond1), DPF regeneration is triggered when the total amount of soot in the DPF carrier is higher than the threshold Thd_sumBS; according to condition (Cond2), DPF regeneration is triggered if the soot deposition in any of the multiple electrode regions is higher than Thd_maxS; according to condition (Cond3), DPF regeneration is triggered if the maximum and minimum soot deposition in the multiple electrode regions are higher than Thd_deltaBS.

[0038] Furthermore, it also includes step 3, which triggers DPF deep regeneration if the first condition is met.

[0039] Furthermore, it also includes step 4: after triggering DPF deep regeneration, determining whether a third condition is met; the third condition includes:

[0040] max(S1,S2,…,S N ) <Thd_deepS(Cond7)

[0041] and max(S1,S2,…,S) N )-min(S1,S2,…,S N ) <Thd_deltaDS(Cond8)

[0042] Among them, Thd_deepS and Thd_deltaDS are threshold constants.

[0043] Furthermore, step 5 is included, whereby if the third condition is met, the ash deposition amount Ma is calculated:

[0044] Tbed=(T141+T142) / 2 (F5)

[0045] Qe=(m_fa+m_fu)*Tbl4(Tbed,P+dP / 2) (F6)

[0046] Ma = Tbl5(ddP / dQe) - M0 (F7)

[0047] In the formula, T142 is the exhaust gas temperature measured by the second exhaust temperature sensor, Tbed is the calculated temperature of the DPF carrier, m_fu is the fuel injection amount, P and dP are the pressure and pressure difference measured by the differential pressure sensor, Qe is the calculated exhaust gas volume flow, dQe is the change amount of the exhaust gas volume flow Qe, ddP is the change amount of the differential pressure dP corresponding to dQe, M0 is the ash value of the clean DPF carrier (initial ash value), Tbl4() and Tbl5() are two table calculations.

[0048] Further, the method further comprises step 6: judging whether the fourth condition is met according to the ash deposition amount, and triggering the DPF maintenance signal if the fourth condition is met; the fourth condition comprises: Ma>Thd_ma, wherein Thd_ma is a threshold constant.

[0049] Further, step 3 further comprises: if the first condition is not met, judging whether the DPF regeneration time is too long, and triggering the alarm signal if the DPF regeneration time is too long.

[0050] Further, step 5 further comprises: if the third condition is not met, judging whether the DPF deep regeneration time is too long, and triggering the alarm signal if the DPF deep regeneration time is too long.

[0051] Beneficial effects:

[0052] The application provides a sensing DPF system with soot and ash detection function and a control method thereof, which directly detects the soot deposition amount and soot distribution by detecting the physical characteristics of soot itself. Since the soot amount is directly detected, the soot distribution, soot morphology, environmental parameter change, error between engine parts, and engine aging have little effect.

[0053] Further, the system and the control method thereof trigger and end the DPF regeneration process according to the detected soot deposition amount and soot distribution, so the environmental parameter change, the error between engine parts, and the engine aging have little effect.

[0054] Further, the detection of the physical parameters of the soot deposition amount by the system and the control method thereof can be combined with the DPF pressure drop result detected by the differential pressure sensor to detect the ash deposition amount in the DPF, and a DPF maintenance signal is generated according to the ash deposition amount. BRIEF DESCRIPTION OF DRAWINGS

[0055] The above and / or other aspects of the application will become more apparent by describing in detail the preferred embodiments thereof with reference to the attached drawings.

[0056] Figure 1A structure schematic diagram of a sensing DPF system with soot and ash detection function provided by an embodiment of the present application.

[0057] Figure 2 An upstream end surface structure schematic diagram of a DPF carrier in a sensing DPF system with soot and ash detection function provided by an embodiment of the present application.

[0058] Figure 3 A detection electrode structure schematic diagram in a sensing DPF system with soot and ash detection function provided by an embodiment of the present application.

[0059] Figure 4 A DPF carrier cross section schematic diagram in a sensing DPF system with soot and ash detection function provided by an embodiment of the present application.

[0060] Figure 5 A three detection electrode distribution schematic diagram in a sensing DPF system with soot and ash detection function provided by an embodiment of the present application.

[0061] Figure 6 A four detection electrode distribution schematic diagram in a sensing DPF system with soot and ash detection function provided by an embodiment of the present application.

[0062] Figure 7 A control method flowchart schematic diagram of a sensing DPF system with soot and ash detection function provided by an embodiment of the present application. DETAILED DESCRIPTION

[0063] Embodiments of the present application will be described below with reference to the accompanying drawings.

[0064] The first embodiment of the present application discloses a sensing DPF system with soot and ash detection function, comprising a metal packaging shell 107, a DPF carrier 152 arranged in the metal packaging shell 107, two or more detection electrodes arranged in the DPF carrier 152 and penetrating into the DPF carrier 152, and a controller 130; the two or more detection electrodes and the metal packaging shell 107 divide the DPF carrier 152 into multiple electrode regions, and the detection electrodes are connected to the controller 130.

[0065] The controller 130 is configured to measure the impedance between the detection electrodes and between the detection electrodes and the metal packaging shell 107, and calculate the soot deposition amount and soot distribution in the DPF carrier 152 according to the measured impedance; the controller 130 further triggers and stops DPF regeneration according to the calculated soot deposition amount and soot distribution.

[0066] The controller 130 further triggers an ash calculation process according to the calculated soot deposition amount and soot distribution, in which the DPF is deeply regenerated, and calculates the ash deposition amount in the DPF according to the differential pressure between the two ends of the DPF.

[0067] The two or more detection electrodes and the metal packaging shell 107 divide the DPF carrier 152 into multiple electrode regions, wherein the electrode region can be a region surrounded by one detection electrode and the metal packaging shell 107, or a region surrounded by two detection electrodes and the metal packaging shell 107, or a region surrounded by multiple detection electrodes, such as the detection electrode distribution diagram shown in Figure 2 、 Figure 5 and Figure 6 Two detection electrodes and the metal packaging shell 107 can divide the carrier 152 into three regions, three detection electrodes and the metal packaging shell 107 can divide the carrier 152 into four regions, four detection electrodes and the metal packaging shell 107 can divide the carrier 152 into five regions, and so on. There can be more detection electrodes to divide the carrier 152 into more electrode regions. The more the number of detection electrodes, the more accurate the calculation of soot deposition amount and soot distribution, and the more precise the triggering and ending of DPF regeneration, but the calculation is more complex and the cost is higher.

[0068] The detection electrode includes a probe 116 (needle electrode), an electrode connecting column 118, and a terminal post 115. One end of the probe 116 is connected to the electrode connecting column 118, and the part away from the one end penetrates into the channel of the DPF carrier 152. The probe 116 includes one or more than two, and if there are more than two, the probe 116 and the electrode connecting column 118 form a comb structure. The electrode connecting column 118 is fixedly connected to the terminal post 115.

[0069] The sensing DPF system further includes a first exhaust temperature sensor 141, a second exhaust temperature sensor 142, and a differential pressure pressure sensor 143. The first exhaust temperature sensor 141 is arranged upstream of the DPF carrier 152, the second exhaust temperature sensor 142 is arranged downstream of the DPF carrier 152, and the two measurement ends of the differential pressure pressure sensor 143 (dP&P sensor) are connected to the two ends of the DPF carrier 152 through detection tubes, respectively. In the specific implementation process, as shown in Figure 1As shown, the DPF sensing system includes a DOC (Diesel Oxidation Catalyst) 151, with a first exhaust temperature sensor 141 arranged in the downstream package of the DOC 151. Downstream of this is the DPF carrier 152, and a second exhaust temperature sensor 142 is used to sense the outlet exhaust gas temperature of the DPF carrier 152. The pressure difference across the DPF and the downstream pressure are measured by a differential pressure sensor 143, which, along with the first and second exhaust temperature sensors 141 and 142, are connected to a controller 130 via a second signal line 132, a third signal line 133, and a first signal line 131, respectively. A sensing harness 120 from the DPF carrier 152 is also connected to the controller 130.

[0070] The upstream end face of DPF carrier 152 is as follows Figure 2 As shown. The DPF includes a DPF catalyst 105 and a metal encapsulation shell 107. A common ground electrode 101 (electrode G) is mounted on the metal encapsulation shell 107, and a first detection electrode 106 (detector electrode B) and a second detection electrode 102 (detector electrode A) are sequentially arranged in the pointer direction on the upstream end face of the DPF catalyst 105. The first detection electrode 106, the second detection electrode 102, and the common ground electrode 101 are respectively connected by a wire harness 120 ( Figure 1 The fourth signal line 123, the fifth signal line 121, and the sixth signal line 122 in the DPF carrier 152 are connected to the controller 130. The second detection electrode 102 and the metal package housing 107 form an electrode region 1, while the first detection electrode 106 and the metal package housing 107 form an electrode region 3. Electrode region 2 is formed by the first detection electrode 106 and the second detection electrode 102. These three electrode regions cover almost all of the DPF carrier 152.

[0071] The first detection electrode 106 and the second detection electrode 102 have similar structures. Taking the second detection electrode 102 as an example, as... Figure 3 As shown, the first detection electrode 106 includes a probe 116, an electrode connection post 118, and a terminal post 115. The probe 116 extends into the channel of the DPF carrier 152, forming a comb-like structure together with the electrode connection post 118. This comb-like structure is further secured to the terminal post 115 by fixing screws 117. The metal package housing 107 has an opening 113, through which the terminal post 115 passes and is fixed to the metal package housing 107 by bolts 112 and insulating sheet 111, and is electrically insulated from the metal package housing 107.

[0072] The second embodiment of this application discloses a control method for a sensing DPF system with carbon soot and ash detection functions, applied to the aforementioned sensing DPF system with carbon soot and ash detection functions, including:

[0073] Step A: Calculate the amount of soot deposited in multiple electrode regions respectively;

[0074] Step B involves further controlling the DPF regeneration process based on the calculated carbon soot deposition in multiple regions.

[0075] like Figure 4 As shown, in the DPF carrier 152 (not shown), the probe 116 and the metal encapsulation shell 107 form a pair of electrode regions. Since soot and DPF materials have very different conductivity properties, the amount of soot 131 in this pair of electrode regions can be detected by measuring the impedance or dielectric constant of the pair of electrode regions.

[0076] Taking impedance calculation as an example, in one embodiment, an impedance coefficient Cs is first calculated.

[0077] Cs = Zm / Z0(F1)

[0078] Where Zm is the measured and calculated regional impedance value of the electrode region; Z0 is the regional impedance value of the electrode region in the clean carrier when the soot is 0 and the temperature is the regeneration temperature. The impedance coefficient Cs is a parameter characterizing the amount of soot deposition in the region, but in addition to being related to the amount of soot deposition, Cs is also affected by the humidity and temperature of the exhaust gas. To eliminate this influence, further correction is needed to obtain the amount of soot deposition Ms. Ms can be calculated using the following formula:

[0079] Cst = Tbl1(Cs, T141) (F2)

[0080] Mw=m_fa*(H_abs+K / Lambda)=m_fa*(Tbl2(Ta)*RH / Pa+K / Lambda) (F3)

[0081] Ms = Tbl3(Cst, Mw) (F4)

[0082] Where Cst is the temperature corrected impedance coefficient, T141 is the exhaust gas temperature measured by the first exhaust temperature sensor 141, Mw is the calculated water content in the exhaust gas, H_abs is the absolute humidity value in the fresh air intake of the engine, Ta is the ambient air temperature where the engine is located, Pa is the ambient air pressure where the engine is located, m fa is the mass flow of the fresh air intake of the engine, RH is the relative humidity of the environment, K is a constant, Lambda is the air excess coefficient of the engine combustion, Tbl1(), Tbl2(), and Tbl3() are table calculations, wherein the table values of Tbl1() and Tbl3() can be calculated by the data obtained from the carbon accumulation experiment under the working condition of the engine 13, and the table value of Tbl2() can be calculated by the relationship between the relative humidity and the absolute humidity. Ta and Pa can be measured by a T-MAP sensor (not shown) at the intake end of the engine, m fa can be measured by a flow sensor (not shown) installed in the intake passage of the engine or calculated by the engine ECU (Electronic Control Unit), RH can be measured by a separate ambient humidity sensor (not shown), and Lambda can be measured by a NOx sensor or a wide-range oxygen sensor (not shown) of the exhaust treatment system.

[0083] The calculated Ms value can be further used to control the regeneration of the DPF. The regeneration control of the DPF has two conditions: a DPF regeneration triggering condition and a DPF regeneration ending condition. The DPF regeneration triggering condition is generally evaluated by two estimates of the soot deposition amount of the DPF. One is an estimate based on the pressure difference between the two ends of the DPF, which estimates the soot deposition amount by using the relationship between the pressure difference and the exhaust flow rate; the other is an estimate based on a model of the soot concentration generated by the engine, which calculates the possible soot deposition amount. However, both of these estimates are indirect estimates. The relationship between the pressure difference and the exhaust flow rate is affected by the pressure resistance, which is not directly related to the soot deposition amount. Only when the soot is uniformly distributed in the DPF and the soot morphology does not change much, there is a definite correlation. The soot deposition amount calculated based on the soot model is affected by many factors such as the error between engine parts, engine aging, and changes in environmental parameters, and the accuracy is also greatly limited. The detection method provided in this embodiment is a direct detection, which detects the electrical conductivity of the soot itself, and therefore has better reliability and accuracy.

[0084] Let the soot deposition amounts of the plurality of electrode regions be S1, S2, …, S N Where N represents the number of electrode regions, and the regeneration can be triggered under the following conditions in step B:

[0085] sum(S1, S2, …, S N )> Thd_sumBS(Cond1)

[0086] or max(S1, S2,..., S N )> Thd_maxS (Cond2)

[0087] or max(S1, S2,..., S N )- min(S1, S2,..., S N )> Thd_deltaBS (Cond3)

[0088] where Thd_sumBS, Thd_maxS and Thd_deltaBS are threshold constants, which can be determined during system calibration according to the requirements of the application; sum() is the sum calculation, max() is the maximum value calculation, and min() is the minimum value calculation.

[0089] According to condition (Cond1), when the total soot amount in the DPF carrier (152) is higher than the threshold Thd_sumBS, the DPF regeneration is triggered; according to condition (Cond2), as long as the soot deposition amount of one of the multiple electrode regions is higher than Thd_maxS, the DPF regeneration is triggered; according to condition (Cond3), when the maximum soot deposition amount and the minimum soot deposition amount of the multiple electrode regions are higher than Thd_deltaBS, the DPF regeneration is triggered.

[0090] During the DPF regeneration process, the following conditions can be used to determine whether to end the regeneration:

[0091] sum(S1, S2,..., S N )< Thd_SumES (Cond4)

[0092] and max(S1, S2,..., S N )< Thd_minS (Cond5)

[0093] and max(S1, S2,..., S N )- min(S1, S2,..., S N )< Thd_deltaES (Cond6)

[0094] where Thd_SumES, Thd_minS and Thd_deltaES are threshold constants, which can be determined during system calibration according to the requirements of the application. According to condition (Cond4), when the total soot amount in the DPF carrier (152) is lower than the threshold Thd_sumES; according to condition (Cond5), when the highest soot deposition amount of the multiple electrode regions is lower than Thd_minS; according to condition (Cond6), when the difference between the maximum soot deposition amount and the minimum soot deposition amount of the multiple electrode regions is lower than Thd_deltaES; and when all the three conditions are met, the DPF regeneration is stopped.

[0095] If the first condition is not satisfied, i.e. the conditions (Cond4), (Cond5) or (Cond6) are not satisfied, it is determined whether the DPF regeneration time is too long, and if the DPF regeneration time is too long, an alarm signal is triggered.

[0096] If the DPF regeneration is ended by the conditions (Cond4), (Cond5) and (Cond6), a DPF deep regeneration, i.e. a high-temperature or prolonged-time regeneration, can be further triggered after this regeneration.

[0097] The DPF deep regeneration can be ended by the following conditions:

[0098] max(S1, S2, …, S N )< Thd_deepS (Cond7)

[0099] and max(S1, S2, …, S N )- min(S1, S2, …, S N )< Thd_deltaDS (Cond8)

[0100] wherein Thd_deepS and Thd_deltaDS are threshold constants which can be determined according to the requirements of the application in the system calibration process.

[0101] After the DPF satisfies the conditions (Cond7) and (Cond8), the ash deposition amount Ma can be further calculated by the following formula:

[0102] Tbed = (T141 + T142) / 2 (F5)

[0103] Qe = (m_fa + m_fu) * Tbl4 (Tbed, P + dP / 2) (F6)

[0104] Ma = Tbl5 (ddP / dQe) - M0 (F7)

[0105] wherein T142 is the exhaust gas temperature measured by the second exhaust temperature sensor (142), Tbed is the calculated bore temperature of the DPF carrier (152), m_fu is the fuel injection amount which can be provided by the engine ECU, P and dP are the pressure and pressure difference measured by the differential pressure sensor (143), Qe is the calculated exhaust gas volume flow, dQe is the change amount of the exhaust gas volume flow Qe, ddP is the change amount of the differential pressure dP corresponding to dQe, M0 is the ash value of the clean DPF carrier, Tbl4 () and Tbl5 () are two table calculations, and the table values can be calculated by the data obtained in the carbon accumulation experiment under the engine 13 working condition.

[0106] If the third condition is not satisfied, i.e. condition (Cond7) or Cond8) is not satisfied, it is determined whether the DPF depth regeneration time is too long, and if the DPF depth regeneration time is too long, an alarm signal is triggered.

[0107] According to the ash deposition amount, the DPF maintenance signal can also be triggered by the following condition: Ma>Thd_ma, wherein Thd_ma is a threshold constant, which can be determined according to the requirements of the application during the system calibration process.

[0108] In one specific embodiment, the DPF carrier 152 is divided into three electrode regions by two probe electrodes and a metal packaging shell 107, and the number of probe electrodes can also be other numbers, and the electrode regions are adjusted accordingly, which does not affect the implementation of the embodiments of the present application. According to conditions (Cond1) and (Cond2), the following conditions can be used as regeneration triggering conditions: Figure 2

[0109] sum(Sag,Sbg,Sab)>Thd_sumBS(CondE1)

[0110] max(Sag,Sbg,Sab)>Thd_maxS(CondE2)

[0111] In the formula, Sag, Sbg, and Sab are the impedances between the second probe electrode 102 and the common ground electrode 101, the first probe electrode 106 and the common ground electrode 101, and the second probe electrode 102 and the first probe electrode 106, respectively. After calculating the corresponding region impedance Zm value, the soot deposition amount Ms value of electrode region 1, electrode region 2, and electrode region 3 is calculated by formula (F1), (F2), (F3), and (F4).

[0112] Assuming that the impedance Z1 between the second probe electrode 102 and the common ground electrode 101, the impedance Z2 between the second probe electrode 102 and the first probe electrode 106, and the impedance Z3 between the first probe electrode and the common ground electrode 101 are measured using a certain single frequency, then the region impedance values Zm1, Zm2, and Zm3 of electrode region 1, electrode region 2, and electrode region 3 at this frequency can be calculated by the following formula:

[0113] Zm1=(-2*Z2*Z3+Z1*Z3+sqrt(Z1*Z3*(4*Z2^2+Z1*Z3))) / (2*Z3) (F8)

[0114] Zm2=Z2 (F9)

[0115] ​Zm3 = (-2*Z2*Z1 + Z1*Z3 + sqrt(Z1*Z3*(4*Z2^2 + Z1*Z3))) / (2*Z1) (F10)

[0116] where Sqrt() is square root operation and ^ is power operation.

[0117] According to condition (CondE1), if the total amount of soot in DPF carrier 152 is higher than threshold Thd_sumBS, regeneration needs to be triggered; and according to condition (CondE2), if the amount of soot deposited in any one of zones 1-5 is higher than Thd_maxS, regeneration needs to be triggered. Condition (CondE1) is a total soot amount condition, and condition (CondE2) is a non-uniformity condition. These two conditions can be in an "or" relationship, i.e., as long as one of the conditions is met, regeneration is triggered. In this way, both the total soot amount and the local soot amount can be prevented from being too high, and uncontrolled regeneration can be prevented.

[0118] In DPF carrier 152, if the soot distribution is very non-uniform, the pores with more soot deposited therein can still have a lot of soot after regeneration, and these soot can be even more difficult to remove during the next regeneration, which can result in a decrease in efficiency and uncontrolled regeneration over time. Therefore, in addition to conditions (CondE1) and (CondE2), condition (Cond3) can be added to increase the non-uniformity condition:

[0119] max(Sag, Sbg, Sab) - min(Sag, Sbg, Sab) > Thd_deltaBS (CondE3)

[0120] During DPF regeneration, due to the influence of soot redistribution, the pressure difference detection can have a large deviation, and therefore the estimated results of the soot model are generally used as the stop condition. However, the inaccuracy of the soot model can result in uncertainty of the regeneration stop time. In order to tolerate these uncertainties, the stop time is often extended, which can result in an increase in fuel consumption of the engine. The sensing DPF system provided in the first embodiment of the present application can directly detect the amount of soot deposited, and therefore the regeneration stop time can be more accurately determined. According to conditions (Cond4) and (Cond5), the following conditions can be used to stop DPF regeneration:

[0121] sum(Sag, Sbg, Sab) < Thd_SumES (CondE4)

[0122] max(Sag, Sbg, Sab) < Thd_minS (CondE5)

[0123] Similarly, in order to control the non-uniformity of the soot distribution, according to condition (Cond6), the following condition can be added:

[0124] max(Sag, Sbg, Sab) - min(Sag, Sbg, Sab) < Thd_deltaES (CondE6)

[0125] Unlike the regeneration trigger condition, in the regeneration stop condition, the conditions (CondE4), (CondE5), (CondE6) need to be "and" relationship, that is, after meeting the three conditions at the same time, the regeneration can stop.

[0126] After DPF regeneration, the remaining soot amount in the DPF can be determined by measuring the soot amount. This remaining soot amount, combined with the pressure difference at both ends of the DPF, can be used to detect the ash deposition amount in the DPF. If more accurate detection of the ash deposition amount in the DPF is required, according to conditions (Cond7) and (Cond8), the DPF can be deeply regenerated, that is, high-temperature or long-time regeneration, until the conditions are met:

[0127] max(Sag, Sbg, Sab) < Thd_deepS (CondE7)

[0128] and

[0129] max(Sag, Sbg, Sab) - min(Sag, Sbg, Sab) < Thd_deltaDS (CondE8)

[0130] At this time, the relationship between the DPF pressure difference and the exhaust gas flow rate is re-detected, and the ash deposition amount Ma value can be obtained through formulas (F5), (F6), (F7).

[0131] The functions of DPF regeneration trigger and end based on soot deposition amount and distribution, DPF ash estimation and ash cleaning signal generation, and alarm signal trigger can be implemented by programs running in the controller 130. Figure 7is a flow chart of one embodiment of the program. After the program starts, the values of Sag, Sbg, and Sab are calculated according to the formulas (F8)-(F10) and (F1)-(F4), and then it is determined whether one of the conditions (CondE1), (CondE2), and (CondE3) is satisfied. If none of the conditions is satisfied, the program stops, otherwise, DPF regeneration is triggered. After DPF regeneration is triggered, it is continuously determined whether the conditions (CondE4), (CondE5), and (CondE6) are simultaneously satisfied, if one of the conditions is not satisfied, it is determined whether the regeneration time is too long. If the regeneration time is too long, an alarm signal is triggered and then the program stops, otherwise, the program returns to the determination of the conditions (CondE4), (CondE5), and (CondE6). If the three conditions are simultaneously satisfied, it is checked whether there is a command for measuring the ash content, if there is no such command, the program stops, otherwise, DPF deep regeneration (increasing the regeneration temperature and prolonging the regeneration time) is triggered. After DPF deep regeneration is triggered, it is determined whether the conditions (CondE7) and (CondE8) are simultaneously satisfied, if the two conditions cannot be simultaneously satisfied, it is determined whether the deep regeneration time is too long. If the time is too long, an alarm signal is triggered and then the program stops, otherwise, the program returns to the determination of the conditions (CondE7) and (CondE8). If the two conditions are simultaneously satisfied, the ash deposition amount Ma is calculated according to the formulas (F5)-(F7), and then it is determined whether the value of Ma is greater than the threshold Thd ma, if Ma is greater than Thd ma, a DPF maintenance signal is triggered, otherwise, the program stops.

[0132] In specific implementations, the present application provides a computer storage medium and a corresponding data processing unit, wherein the computer storage medium can store a computer program, and the computer program can run the invention content of the control method of the sensing DPF system with carbon soot and ash detection function and some or all steps in each embodiment of the present application when executed by the data processing unit. The storage medium can be a magnetic disk, an optical disk, a read-only memory (ROM), a random access memory (RAM), or the like.

[0133] Those skilled in the art can clearly understand that the technical solutions in the embodiments of the present application can be realized by means of a computer program and its corresponding general hardware platform. Based on such understanding, the technical solutions in the embodiments of the present application can be embodied in the form of a computer program, i.e., a software product, which can be stored in a storage medium and includes a plurality of instructions for causing a device (which can be a personal computer, a server, a single-chip microcomputer, a MUU, or a network device, etc.) comprising a data processing unit to execute the method described in each embodiment or some parts of the embodiments of the present application.

[0134] The present application provides a sensing DPF system with soot and ash detection function and a control method thereof. There are many methods and approaches to realize the technical solution. The above description is only a specific embodiment of the present application. It should be pointed out that for ordinary skilled in the art, without departing from the principles of the present application, several improvements and refinements can be made. These improvements and refinements should also be considered as the protection scope of the present application. The components not explicitly described in the embodiment can be realized by existing technology.

Claims

1. A sensing DPF system with carbon soot and ash detection functions, characterized in that, The device includes a metal encapsulation housing (107), a DPF carrier (152) disposed within the metal encapsulation housing (107), two or more detection electrodes disposed within the DPF carrier (152), and a controller (130); the two or more detection electrodes and the metal encapsulation housing (107) divide the DPF carrier (152) into multiple electrode regions, and the detection electrodes are connected to the controller (130); the detection electrodes include a probe (116), an electrode connection post (118), and a terminal block (115); one end of the probe (116) is connected to the electrode connection post (118), and the portion away from the one end is arranged in a channel of the DPF carrier (152); the electrode connection post (118) is fixedly connected to the terminal block (115); The controller (130) is used to measure the impedance between the probe electrodes and between the probe electrodes and the metal encapsulation shell (107), and to calculate the amount of soot deposition and soot distribution in the DPF carrier (152) based on the measured impedance; The sensing DPF system uses the following control method: Step 1: Calculate the amount of soot deposited in multiple electrode regions respectively; Step 2: Based on the amount of soot deposited in multiple areas, determine whether the first condition is met. If the first condition is met, stop DPF regeneration. Let the carbon soot deposition amounts in multiple electrode regions be S1, S2, …, S N Where N represents the number of electrode regions, the first condition in step 2 includes: sum(S1, S2, …, S N ) < Thd_SumES (Cond4) and max(S1, S2, …, S N ) < Thd_minS (Cond5) and max(S1, S2, …, S N ) - min(S1, S2, …, S N ) < Thd_deltaES (Cond6) Among them, Thd_SumES, Thd_minS and Thd_deltaES are threshold constants, sum() is the summation function, max() is the maximum value function, and min() is the minimum value function. According to condition (Cond4), the total amount of soot in the DPF carrier (152) is lower than the threshold Thd_sumES; according to condition (Cond5), the highest amount of soot deposition in multiple electrode regions is lower than Thd_minS; according to condition (Cond6), the difference between the maximum and minimum amount of soot deposition in the multiple electrode regions is lower than Thd_deltaES; if all three conditions are met, DPF regeneration is stopped.

2. The sensing DPF system with carbon soot and ash detection function according to claim 1, characterized in that, The detection electrode also includes a bolt (112) and an insulating sheet (111). The terminal (115) is fixed to the metal encapsulation shell (107) by the bolt (112) and the insulating sheet (111) and is electrically insulated from the metal encapsulation shell (107).

3. The sensing DPF system with carbon soot and ash detection function according to claim 2, characterized in that, It also includes a common ground electrode (101), which is mounted on a metal enclosure (107) and connected to the controller (130) via a sixth signal line (122).

4. The sensing DPF system with carbon soot and ash detection function according to claim 3, characterized in that, It also includes a first exhaust temperature sensor (141), a second exhaust temperature sensor (142), and a differential pressure sensor (143). The first exhaust temperature sensor (141) is arranged upstream of the DPF carrier (152), the second exhaust temperature sensor (142) is arranged downstream of the DPF carrier (152), and the two measuring ends of the differential pressure sensor (143) are connected to the two ends of the DPF carrier (152) through probe tubes respectively. The first exhaust temperature sensor (141) is connected to the controller (130) through the third signal line (133), the second exhaust temperature sensor (142) is connected to the controller (130) through the first signal line (131), and the differential pressure sensor (143) is connected to the controller (130) through the second signal line (132).

5. A sensing DPF system with carbon soot and ash detection function according to claim 4, characterized in that, It includes a first detection electrode (106) and a second detection electrode (102). The first detection electrode (106) and the second detection electrode (102) are connected to the controller (130) through the fourth signal line (123) and the fifth signal line (121), respectively. The second detection electrode (102) and the metal encapsulation shell (107) form an electrode region 1, the first detection electrode (106) and the metal encapsulation shell (107) form an electrode region 3, and the first detection electrode (106) and the second detection electrode (102) form an electrode region 2.

6. A sensing DPF system with carbon soot and ash detection function according to claim 5, characterized in that, Step 1 includes: detecting the amount of soot in the electrode region by measuring the impedance or dielectric constant of the electrode region.

7. A sensing DPF system with carbon soot and ash detection function according to claim 6, characterized in that, Step 1 includes: The impedance coefficient Cs of the electrode region is a parameter characterizing the amount of soot deposition in the electrode region, and the calculation formula is as follows: Cs = Zm / Z0 (F1) In formula (F1), Zm is the measured and calculated regional impedance value of the electrode region; Z0 is the regional impedance value of the electrode region in the clean carrier at the regeneration temperature.

8. A sensing DPF system with carbon soot and ash detection function according to claim 7, characterized in that, Step 1 includes: correcting the impedance coefficient Cs to obtain the soot deposition amount Ms, the calculation formula is as follows: Cst=Tbl1(Cs, T141) (F2) Mw=m_fa * (Tbl2(Ta)*RH / Pa + K / Lambda) (F3) Ms = Tbl3(Cst, Mw) (F4) In formulas (F2) to (F4), Cst is the temperature-corrected impedance coefficient, T141 is the exhaust gas temperature measured by the first exhaust temperature sensor (141), Mw is the calculated moisture content in the exhaust gas, Ta is the ambient air temperature where the engine is located, Pa is the ambient air pressure where the engine is located, m_fa is the fresh air mass flow rate, RH is the relative humidity of the environment, K is a constant, Lambda is the excess air coefficient for engine combustion, and Tbl1(), Tbl2(), and Tbl3() are calculated by looking up tables.

9. A sensing DPF system with carbon soot and ash detection function according to claim 8, characterized in that, It also includes step 3, which triggers DPF regeneration if the second condition is met; The second condition includes: sum(S1, S2, …, S N ) > Thd_sumBS (Cond1) Or max(S1, S2, …, S N ) > Thd_maxS (Cond2) or max(S1, S2, …, S N ) - min(S1, S2, …, S N ) > Thd_deltaBS (Cond3) Among them, Thd_sumBS, Thd_maxS, and Thd_deltaBS are threshold constants; According to condition (Cond1), DPF regeneration is triggered when the total amount of soot in the DPF carrier (152) is higher than the threshold Thd_sumBS; according to condition (Cond2), DPF regeneration is triggered if the soot deposition in any of the multiple electrode regions is higher than Thd_maxS; according to condition (Cond3), DPF regeneration is triggered if the difference between the maximum and minimum soot deposition in the multiple electrode regions is higher than Thd_deltaBS.

10. A sensing DPF system with carbon soot and ash detection function according to claim 1, characterized in that, It also includes step 3, which triggers DPF deep regeneration if the first condition is met.

11. A sensing DPF system with carbon soot and ash detection function according to claim 10, characterized in that, It also includes step 4, after triggering DPF deep regeneration, determining whether the third condition is met; the third condition includes: max(S1,S2,…,S N ) < Thd_deepS (Cond7) and max(S1,S2,…,S N ) - min(S1,S2,…,S N ) < Thd_deltaDS (Cond8) In conditions (Cond7) and (Cond8), Thd_deepS and Thd_deltaDS are threshold constants.

12. A sensing DPF system with carbon soot and ash detection function according to claim 11, characterized in that, The process also includes step 5, where if the third condition is met, the ash deposition amount Ma is calculated. Tbed=(T141+T142) / 2 (F5) Qe=(m_fa+m_fu) * Tbl4(Tbed, P+dP / 2) (F6) Ma = Tbl5(ddP / dQe)-M0 (F7) In formulas (F5) to (F7), T142 is the exhaust gas temperature measured by the second exhaust temperature sensor (142), Tbed is the calculated bore temperature of the DPF carrier (152), m_fu is the fuel injection quantity, P and dP are the pressure and differential pressure values ​​measured by the differential pressure sensor (143), Qe is the calculated exhaust gas volumetric flow rate, dQe is the change in exhaust gas volumetric flow rate Qe, ddP is the change in differential pressure dP corresponding to dQe, M0 is the ash content value of the clean DPF carrier, and Tbl4() and Tbl5() are two lookup table calculations.

13. A sensing DPF system with carbon soot and ash detection function according to claim 12, characterized in that, It also includes step 6, which determines whether the fourth condition is met based on the amount of ash deposited. If the fourth condition is met, the DPF maintenance signal is triggered. The fourth condition includes: Ma > Thd_ma, where Thd_ma is a threshold constant.

14. A sensing DPF system with carbon soot and ash detection function according to claim 10, characterized in that, Step 3 also includes: if the first condition is not met, determine whether the DPF regeneration time is too long. If the DPF regeneration time is too long, trigger an alarm signal.

15. A sensing DPF system with carbon soot and ash detection function according to claim 12, characterized in that, Step 5 also includes: if the third condition is not met, determine whether the DPF deep regeneration time is too long. If the DPF deep regeneration time is too long, trigger an alarm signal.

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