CN112963226B - DPF active regeneration safety control method - Google Patents
DPF active regeneration safety control method Download PDFInfo
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- CN112963226B CN112963226B CN202110325935.7A CN202110325935A CN112963226B CN 112963226 B CN112963226 B CN 112963226B CN 202110325935 A CN202110325935 A CN 202110325935A CN 112963226 B CN112963226 B CN 112963226B
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- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F01—MACHINES OR ENGINES IN GENERAL; ENGINE PLANTS IN GENERAL; STEAM ENGINES
- F01N—GAS-FLOW SILENCERS OR EXHAUST APPARATUS FOR MACHINES OR ENGINES IN GENERAL; GAS-FLOW SILENCERS OR EXHAUST APPARATUS FOR INTERNAL COMBUSTION ENGINES
- F01N3/00—Exhaust or silencing apparatus having means for purifying, rendering innocuous, or otherwise treating exhaust
- F01N3/02—Exhaust or silencing apparatus having means for purifying, rendering innocuous, or otherwise treating exhaust for cooling, or for removing solid constituents of, exhaust
- F01N3/021—Exhaust or silencing apparatus having means for purifying, rendering innocuous, or otherwise treating exhaust for cooling, or for removing solid constituents of, exhaust by means of filters
- F01N3/023—Exhaust or silencing apparatus having means for purifying, rendering innocuous, or otherwise treating exhaust for cooling, or for removing solid constituents of, exhaust by means of filters using means for regenerating the filters, e.g. by burning trapped particles
- F01N3/029—Exhaust or silencing apparatus having means for purifying, rendering innocuous, or otherwise treating exhaust for cooling, or for removing solid constituents of, exhaust by means of filters using means for regenerating the filters, e.g. by burning trapped particles by adding non-fuel substances to exhaust
- F01N3/0293—Exhaust or silencing apparatus having means for purifying, rendering innocuous, or otherwise treating exhaust for cooling, or for removing solid constituents of, exhaust by means of filters using means for regenerating the filters, e.g. by burning trapped particles by adding non-fuel substances to exhaust injecting substances in exhaust stream
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- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F01—MACHINES OR ENGINES IN GENERAL; ENGINE PLANTS IN GENERAL; STEAM ENGINES
- F01N—GAS-FLOW SILENCERS OR EXHAUST APPARATUS FOR MACHINES OR ENGINES IN GENERAL; GAS-FLOW SILENCERS OR EXHAUST APPARATUS FOR INTERNAL COMBUSTION ENGINES
- F01N9/00—Electrical control of exhaust gas treating apparatus
- F01N9/002—Electrical control of exhaust gas treating apparatus of filter regeneration, e.g. detection of clogging
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- Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
- Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
- Y02T—CLIMATE CHANGE MITIGATION TECHNOLOGIES RELATED TO TRANSPORTATION
- Y02T10/00—Road transport of goods or passengers
- Y02T10/10—Internal combustion engine [ICE] based vehicles
- Y02T10/40—Engine management systems
Abstract
The invention discloses a DPF active regeneration safety control method, and belongs to the technical field of regeneration safety. The DPF active regeneration safety control method comprises the following steps: s10: judging the regeneration condition: when one of the operating condition parameters of the engine reaches a regeneration threshold corresponding to the parameter, the DPF enters active regeneration; s20: judging HC injection conditions: when T is4≥T7Satisfying HC injection conditions; s30: calculation needs to reach T0Amount of HC required to be injected
T1＝T0‑T2，T2Is a buffer of temperature, and T2With decreasing carbon loading and regeneration time t1Gradually decreases to 0; s40: temperature control: when T is0＜T5≤T3When the initial HC injection amount is decreased, the change rate of HC injection is decreased; when T is3＜T5≤T6When the amount of HC injected is reduced, the amount of exhaust gas discharged into the DPF by the engine is increased; when T is6＜T5When this occurs, the injection of HC is stopped and the amount of exhaust gas discharged into the DPF by the engine is increased. Has the following beneficial effects: the safety of the active regeneration of the DPF can be made high.
Description
Technical Field
The invention relates to the technical field of regeneration safety, in particular to a DPF active regeneration safety control method.
Background
A Diesel Particulate Filter (DPF) is currently recognized as the most effective technology for treating Particulate matters in Diesel exhaust; the DPF, although capable of filtering carbon particles in the exhaust gas from the exhaust gas of the diesel engine to deposit them in the carrier, does not remove the carbon particles by itself. When more and more carbon particles are accumulated in the carrier, the flow resistance of exhaust gas is gradually increased, so that the exhaust back pressure of the diesel engine is increased, the power output of the diesel engine is influenced, and the fuel consumption is increased. Therefore, the carbon particles must be removed in time to restore the flow resistance of the exhaust gas; although there is always a passive regeneration process at exhaust temperatures within a certain range, active regeneration is required periodically in order to be able to fully ensure regeneration of the particulate matter deposited in the DPF.
The existing DPF active regeneration safety control method is mainly used by matching a Diesel Oxidation Catalyst (DOC) with a DPF. The DOC is characterized in that a honeycomb ceramic carrier is coated with a precious metal catalyst, so that certain HC is sprayed into an exhaust pipeline, after the HC is uniformly mixed in exhaust, the sprayed HC can be oxidized by the precious metal on the DOC, a large amount of heat is released, the exhaust temperature can be raised to more than 550 ℃, carbon particles in the carrier and oxygen in the exhaust are combusted at high temperature, and the carbon particles are regenerated. Because the temperature required by the reaction of the carbon particles and the oxygen is high, the temperature of the DPF needs to be controlled, so that the problem that the whole exhaust treatment is invalid due to burning of the DPF due to overhigh temperature in the regeneration process is solved.
At present, the temperature control of the DPF is mainly to calculate and control the injection amount of HC according to the regeneration temperature of the DPF and by combining a PID (proportion integration differentiation) closed-loop control algorithm or a DOC (catalyst oxidation) blocking and modeling algorithm so as to ensure the regeneration safety of the DPF.
However, the HC injection amount calculated in the initial injection stage by the current HC injection is large, which easily causes that too much HC injection amount is instantaneously injected due to the large initial carbon loading of the DPF, and the excessive HC injection amount is instantaneously injected easily causes that the temperature of the DPF is instantaneously increased, thereby causing the safety problem of DPF regeneration, and leading the safety of active regeneration of the DPF to be low; in the DPF active regeneration process, due to the fact that various complex working conditions easily cause abnormal fluctuation of DPF temperature, the DPF temperature is raised instantly, the safety problem that the DPF is burnt easily occurs, and therefore the safety of active regeneration of the DPF is low.
In view of the above, it is desirable to design a DPF active regeneration safety control method to solve the above problems.
Disclosure of Invention
The invention aims to provide a DPF active regeneration safety control method, which can enable the safety of DPF active regeneration to be high and can ensure thorough DPF regeneration reaction.
In order to achieve the purpose, the invention adopts the following technical scheme:
a DPF active regeneration safety control method comprises the following steps:
s10: judging the regeneration condition: when one of the operating condition parameters of the engine reaches a regeneration threshold corresponding to the parameter, the DPF enters active regeneration;
s20: judging HC injection conditions: when inlet temperature T of DOC4Not less than the light-off temperature T required for oxidation of HC7HC injection condition is satisfied, and HC is injected to raise the inlet temperature T of the DPF5；
S30: calculating the regeneration target temperature T needed to reach DPF0Amount of HC required to be injected Q:
wherein C is specific heat capacity of exhaust gas, and q is heat value of diesel oil; eta is DOC oxidation efficiency, T1A target temperature for stepwise regeneration, and T1＝T0-T2，T2To buffer the temperature, T2Regeneration time t of DPF1And the carbon loading accumulated in the DPF, and2with decreasing carbon loading and regeneration time t1Gradually decreases to 0;
s40: temperature control: during HC injection, when T0＜T5Less than or equal to the first safety threshold T3When the initial HC injection amount is decreased and the change rate of HC injection is decreased to control the inlet temperature T of the DPF5Generating a wave;
when T is3＜T5Less than or equal to a second safety threshold T6When the amount of HC injected is reduced, the amount of exhaust gas discharged into the DPF by the engine is increased;
when T is6＜T5When this occurs, the injection of HC is stopped and the amount of exhaust gas discharged into the DPF by the engine is increased.
Preferably, the method further comprises the following steps before step S10:
s5: collecting working parameters: collection of DOC Inlet temperature T4DPF inlet temperature T5Target regeneration temperature T of DPF0DPF carbon-supported model calculation amount and DPF regeneration time t1And obtaining the operating condition parameters of the engine.
Preferably, the following steps are further included after step S40:
s50: ending DPF active regeneration: when regeneration time t of DPF1And when the time is greater than the time calibration threshold or the carbon loading accumulated in the DPF is less than the carbon loading calibration threshold, finishing the active regeneration of the DPF, and stopping injecting HC.
Preferably, the regeneration target temperature T of the DPF0Obtained from a MAP table lookup of the engine.
Preferably, the buffer temperature T2: when the regeneration time t1＝0-10min，T2The temperature is higher than 40 ℃; when the regeneration time t1＝12-15min，T220 ℃ is set; when the regeneration time t1≥16min，T2＝0℃。
Preferably, in step S20:
when the regeneration condition is satisfied but T4＜T7By reducing the amount of exhaust gas emitted by the engine into the DOCAnd releasing near-after injection by the oil injector to improve the inlet temperature T of the DOC4So that T is4≥T7。
Preferably, in step S20:
when T is4≥T7When in use, the fuel injector releases far-rear injection or the HC injection system injects HC into DOC to increase the inlet temperature T of DPF5。
Preferably, in step S40:
when T is3＜T5≤T6In the method, the amount of exhaust gas discharged into the DPF by the engine is increased by reducing the opening of a supercharger exhaust valve of the engine, reducing the opening of an intake throttle valve and reducing the opening of an exhaust throttle valve, so as to reduce the inlet temperature T of the DPF5。
Preferably, in step S40:
when T is6＜T5In the process, the amount of tail gas discharged into the DPF by the engine is increased by closing a supercharger air release valve, an air inlet throttle valve and an air outlet throttle valve so as to reduce the inlet temperature T of the DPF5。
Preferably, the operating condition parameters of the engine comprise the operating mileage, the driving time, the accumulated oil amount, the pressure difference between the upstream and the downstream of the DPF and the carbon load model of the engine.
The invention has the beneficial effects that:
when one of the operating condition parameters of the engine reaches a regeneration threshold corresponding to the parameter, the DPF enters active regeneration; and when the inlet temperature T of the DOC4Not less than the light-off temperature T required for oxidation of HC7And HC is injected into the DOC under the condition of HC injection, and the injected HC can be oxidized by the noble metal on the DOC to release a large amount of heat, so that the temperature of gas exhausted by an engine passing through the DOC can be increased to improve the inlet temperature T of the DPF5So that the carbon particles deposited in the DPF are combusted with high-temperature oxygen in the gas, thereby performing active regeneration of the carbon particles; due to the arrangement of the regeneration time t along with the reduction of the carbon loading1Is gradually decreased to a buffer temperature T of 02So that the amount of HC passing through the injection
T1＝T0-T2The calculated HC injection amount is gradually and slowly increased in a process of decreasing firstly and then increasing more gradually, so that the problem that the temperature in the DPF is instantly increased due to excessive HC injection amount under the condition that the carbon loading amount is large at the initial moment of the DPF can be solved, the DPF can be prevented from being burnt out, and the safety of active regeneration of the DPF is high; on the other hand, after the carbon loading is gradually reduced along with the progress of the regeneration reaction, the HC injection amount can be increased so as to ensure that the carbon loading deposited in the DPF is cleared, so that the active regeneration reaction can be fully and thoroughly carried out; and due to the buffer temperature T2The buffer temperature T is therefore determined taking into account the possible deviations in the calculation of the carbon loading2Not only considering the carbon loading capacity, but also introducing the regeneration time, and comprehensively calculating the two conditions to obtain the buffer temperature T2Can ensure the step regeneration target temperature T by arranging DPF1The effectiveness of DPF regeneration safety protection can not only ensure that the whole regeneration reaction is smoothly carried out, but also protect the DPF; meanwhile, during the HC injection, when T is0＜T5≤T3At the time of the start of the HC injection, the inlet temperature T of the DPF is controlled by reducing the initial HC injection amount and reducing the variation rate of the HC injection5Generating a wave; when T is3＜T5≤T6When the amount of injected HC is decreased and the amount of exhaust gas discharged into the DPF by the engine is increased, the inlet temperature T5 of the DPF is decreased; when T is6＜T5When the method is used, HC injection is stopped, the amount of exhaust gas discharged into the DPF by an engine is increased, so that the inlet temperature T5 of the DPF is reduced, the safety problem that the DPF is burnt easily due to the fact that the temperature of the DPF is abnormally fluctuated easily under various complex working conditions and the temperature of the DPF is instantly raised can be avoided, and the safety of active regeneration of the DPF is further high; that is, by providing the stepped regeneration target temperature T1 of the DPF to control the HC injection amount and providing three temperature protection stages, the safety of the active regeneration of the DPF can be made high.
Drawings
FIG. 1 is a first schematic flow chart of a DPF active regeneration safety control method provided by the present invention;
FIG. 2 is a second schematic flow chart of the DPF active regeneration safety control method provided by the present invention.
Detailed Description
All of the features disclosed in this specification, or all of the steps in any method or process so disclosed, may be combined in any combination, except combinations of features and/or steps that are mutually exclusive.
Any feature disclosed in this specification may be replaced by alternative features serving equivalent or similar purposes, unless expressly stated otherwise. That is, unless expressly stated otherwise, each feature is only an example of a generic series of equivalent or similar features. Like reference numerals refer to like elements throughout the specification.
In order to make the technical problems solved, the technical solutions adopted and the technical effects achieved by the present invention clearer, the technical solutions of the present invention are further described below by way of specific embodiments with reference to the accompanying drawings.
The embodiment provides a safety control method for DPF active regeneration, which can avoid burning out of a DPF due to overhigh temperature, so that the safety of the DPF in an active regeneration process is higher; and the thorough regeneration reaction of the DPF can be ensured.
Specifically, as shown in fig. 1, the DPF active regeneration safety control method includes the steps of:
s10: judging the regeneration condition: in the running process of the engine, when one of the parameters of the running working conditions of the engine reaches a regeneration threshold corresponding to the parameter, the engine automatically enters a regeneration mode, namely the DPF enters active regeneration;
s20: judging HC injection conditions: when inlet temperature T of DOC4Not less than the light-off temperature T required for oxidation of HC7In this case, the HC injected into the DOC can be oxidized by the noble metal on the DOC to release a large amount of heat to increase the inlet temperature T of the DPF5To provide a regeneration target temperature T of the DPF required for the regeneration reaction0At this time, HC can be injected into the DOC, and HC injection conditions are met; wherein, DOC outlet temperature and DPF inlet temperature T5Both refer to the measured values of the temperature sensor disposed between the DOC and the DPF;
s30: calculating the regeneration target temperature T needed to reach DPF0Amount of HC required to be injected Q:
wherein C is specific heat capacity of exhaust gas, and q is heat value of diesel oil; eta is DOC oxidation efficiency, T1A target temperature for stepwise regeneration, and T1＝T0-T2，T2To buffer the temperature, T2Regeneration time t of DPF1And the carbon loading accumulated in the DPF, and2with decreasing carbon loading and regeneration time t1Is gradually decreased to 0 so that the stepped regeneration target temperature T is gradually decreased1Gradually rises so that the HC injection amount Q gradually increases.
S40: temperature control: during HC injection, when T0＜T5Less than or equal to the first safety threshold T3Controlling initial HC injection amount and controlling variation rate of HC injection to control inlet temperature T of DPF5Generating a wave;
when T is3＜T5Less than or equal to a second safety threshold T6When the amount of HC injected is reduced, the amount of exhaust gas discharged into the DPF by the engine is increased;
when T is6＜T5When the injection of HC is stopped and the amount of exhaust gas emitted into the DPF by the engine is maximally increased.
By the inlet temperature T of the DOC4Not less than the light-off temperature T required for oxidation of HC7When the HC is injected into the DOC, the injected HC can be oxidized by the noble metal on the DOC to emit a large amount of heat, so that the temperature of gas exhausted by an engine passing through the DOC can be raised to improve the inlet temperature T of the DPF5So that the carbon particles deposited in the DPF are combusted with high-temperature oxygen in the gas, thereby performing active combustion of the carbon particlesRegeneration; due to the arrangement of the regeneration time t along with the reduction of the carbon loading1Is gradually decreased to a buffer temperature T of 02So that the amount of HC passing through the injection
T1＝T0-T2The calculated HC injection amount is gradually increased gradually after being decreased, so that on one hand, the problem that the temperature in the DPF is increased instantly due to excessive HC injection amount under the condition that the carbon loading amount is large at the initial moment of the DPF can be avoided, namely, the problem that too much HC amount is injected instantly at the initial stage of injection is avoided, so that the injection rate of HC is properly slowed down, and the problem that too much HC is injected instantly to cause too much heat, so that the temperature of the DPF is increased is avoided, the DPF can be prevented from being burnt out, and the safety of active regeneration of the DPF is high; on the other hand, after the carbon loading is gradually reduced along with the progress of the regeneration reaction, the HC injection amount can be increased so as to ensure that the carbon loading deposited in the DPF is cleared, so that the active regeneration reaction can be fully and thoroughly carried out; and due to the buffer temperature T2The buffer temperature T is therefore determined taking into account the possible deviations in the calculation of the carbon loading2Not only the carbon loading is considered, but also the regeneration time is introduced, and the buffer temperature T is obtained by combining the two conditions2Can ensure the step regeneration target temperature T by arranging DPF1The effectiveness of safety protection for DPF regeneration not only enables the whole regeneration reaction to be smoothly carried out, but also can protect the DPF. In the present embodiment, the light-off temperature T required for oxidizing HC7The temperature was 260 ℃.
Meanwhile, when T is in the HC injection process0＜T5≤T3At the time of the start of the HC injection, the inlet temperature T of the DPF is controlled by reducing the initial HC injection amount and reducing the variation rate of the HC injection5Generating a wave; when T is3＜T5≤T6When the exhaust temperature T of the DPF is lowered, the amount of HC injected is reduced and the amount of exhaust gas discharged into the DPF by the engine is increased5(ii) a When T is6＜T5When HC injection is stopped and the amount of exhaust gas emitted into the DPF by the engine is maximized to reduce the inlet temperature of the DPFT5, the safety problem that the DPF is burnt easily due to the fact that the temperature of the DPF is abnormally fluctuated easily under various complex working conditions and the temperature of the DPF is instantly raised can be avoided, and therefore the safety of active regeneration of the DPF is further high; i.e. by setting the stepped regeneration target temperature T of the DPF1To control the HC injection amount while providing three temperature protection stages to enable higher safety in active regeneration of the DPF. In this example, T3The temperature was 650 ℃. In this example, T6The temperature was 700 ℃.
Specifically, the regeneration target temperature T of the DPF0Is obtained from a MAP table look-up of the engine. The MAP table of the engine refers to commands which are set by calibration technicians and input into the engine to control the operation of the engine, and a plurality of MAPs are required for calibration of one engine. In this example, T0The temperature was 620 ℃.
Specifically, as shown in fig. 1, the method further includes the following steps before step S10: s5: collecting working parameters: collection of DOC Inlet temperature T4DPF inlet temperature T5Target regeneration temperature T of DPF0DPF carbon-supported model calculation amount and DPF regeneration time t1And obtaining various operating condition parameters of the engine. The operating condition parameters of the engine comprise the operating mileage, the running time, the accumulated oil quantity, the pressure difference between the upstream and the downstream of the DPF and a carbon-loaded model of the engine.
In the present embodiment, in the determination of the regeneration condition in step S10, the operating mileage and the running time of the engine are used as the determination conditions; the regeneration threshold value of the running mileage is 3000km, the regeneration threshold value of the running time is 80h, when the running mileage of the engine is more than or equal to 3000km or the running time is more than or equal to 80h, the regeneration condition of the engine is met, and the engine automatically enters an active regeneration mode; and after the regeneration reaction is finished, resetting and restarting the running mileage and the running time of the engine, and once any one of the running mileage and the running time reaches the regeneration threshold value corresponding to the running mileage and the running time again, triggering regeneration again by the DPF, and circulating the steps so as to ensure that the DPF is actively regenerated at regular intervals. In other embodiments, other operating condition parameters of the engine may be used as the determination conditions to determine the initiation of the regeneration reaction.
Further, as shown in fig. 1, the following step S50 is also included after step S40: ending DPF active regeneration: when regeneration time t of DPF1And when the time is greater than the time calibration threshold or the carbon loading amount accumulated in the DPF is less than the carbon loading amount calibration threshold, finishing the active regeneration of the DPF, exiting the regeneration mode of the engine, and stopping injecting HC so as to finish the whole active regeneration process of the DPF.
In this embodiment, the buffer temperature T2Comprises the following steps: when the regeneration time t1＝0-10min，T2The temperature is higher than 40 ℃; when the regeneration time t1＝12-15min，T220 ℃ is set; when the regeneration time t1≥16min，T20 ℃. In other embodiments, the buffer temperature T2Other temperature values at different regeneration times are also possible. Buffer temperature T2Is required according to specific working conditions and combined with the regeneration time t of the DPF1And the carbon loading accumulated in the DPF.
Further, T is satisfied when the regeneration condition is satisfied in step S204＜T7When necessary, the DOC inlet temperature T needs to be increased4And the injected HC is oxidized by the noble metal on the DOC to emit a large amount of heat, so that the temperature of the gas exhausted by the engine of the DOC can be raised, the carbon particles deposited in the DPF can be combusted with the high-temperature oxygen in the gas, and the active regeneration of the carbon particles can be smoothly carried out. Wherein the inlet temperature T of the DOC is increased by reducing the amount of exhaust gas emitted by the engine into the DOC and releasing near-after-injection by the fuel injector4So that T is4≥T7。
By reducing the amount of exhaust emitted by the engine into the DOC, the flow of gas through the DPF is reduced, thereby reducing the amount of heat removed by the gas flow from the DPF to increase the inlet temperature T of the DOC4(ii) a The near-after injection is a professional term of a diesel engine, the internal combustion engine works in four strokes, corresponds to a piston stroke of 0-720 degrees and can be divided into pre-injection, main injection and after injection according to the angle of the piston stroke; the main injection is typically at compression dead center, i.e., the position where the piston is farthest from the crankshaft or closest to the cylinder head, for injection;combustion is then improved by a two stage pilot injection prior to the main injection timing and the exhaust temperature of the after-processor is increased by a two stage post-injection after the main injection timing. Wherein, the two-stage after-injection refers to near after-injection and far after-injection, the injection time of the near after-injection is relatively backward, so the combustion is relatively poor, namely the heat of the near after-injection combustion of the engine is basically directly discharged to the DOC, thereby the inlet temperature T of the DOC can be improved4(ii) a And the oil injected at the most rear far-rear injection moment is not combusted and directly enters DOC for oxidation so as to increase the inlet temperature T of DPF5Thereby being able to reach the regeneration target temperature T of the DPF0. Among them, the oil injected from the injector is mainly HC.
Specifically, in step S20: when T is4≥T7When in use, the fuel injector releases far-rear injection or the HC injection system injects HC into DOC to increase the inlet temperature T of DPF5. The HC injected by the injector has the same action as the HC injected by the HC injection system, and the HC injection system are used for increasing the inlet temperature T of the DPF5Thereby being able to reach the regeneration target temperature T of the DPF0。
Further, as shown in fig. 1 and 2, in step S40:
when T is0＜T5≤T3On the one hand, the initial HC injection amount is further limited to limit the overall time for the HC injection to change from 0 to the required value, so as to ensure that the initial HC injection amount slowly transits to the calculated required injection amount; on the other hand, the inlet temperature T of the DPF is controlled by controlling the variation rate of HC injection to slow down the initial combustion rate5Fluctuation is generated, and the carbon deposited in the DPF can be stably combusted, so that the regeneration safety of the DPF is realized;
when T is3＜T5≤T6In the method, the amount of exhaust gas discharged into the DPF by the engine is increased by reducing the opening of a supercharger exhaust valve of the engine, reducing the opening of an intake throttle valve and reducing the opening of an exhaust throttle valve, so as to reduce the inlet temperature T of the DPF5(ii) a At this time, the temperature of the exhaust gas discharged from the engine is lower than the temperature in the DPF;
when T is6＜T5During the process, the exhaust gas amount discharged into the DPF by the engine is increased to the maximum extent by closing the supercharger exhaust valve, closing the air inlet throttle valve and closing the exhaust throttle valve, so that the exhaust gas takes away the heat in the DPF, the temperature accumulation in the DPF is avoided, and the inlet temperature T of the DPF is reduced5。
The specific control process of the DPF active regeneration safety control method in this embodiment is as follows: as shown in FIG. 2, firstly, the operating condition parameters of the engine are collected and judged, and when the operating mileage of the engine is more than or equal to 3000km or the running time of the engine is more than or equal to 80h, the engine automatically enters an active regeneration mode.
Thereafter, T after the regeneration condition is satisfied4When the temperature is less than 260 ℃, the inlet temperature T of the DOC is improved by reducing the tail gas quantity discharged into the DOC by the engine and releasing near-back injection by the oil injector4So that T is4Not less than 260 ℃ to meet the HC injection condition.
Then, the regeneration target temperature T of the DPF is looked up according to the MAP table0620 ℃ and then according to the regeneration time t1And the carbon load accumulated in the DPF calculates the buffer temperature T2Comprises the following steps: when the regeneration time t1＝0-10min，T2The temperature is higher than 40 ℃; when the regeneration time t1＝12-15min，T220 ℃ is set; when the regeneration time t1≥16min，T20 ℃ and according to T1＝T0-T2Calculating a step regeneration target temperature T1(ii) a Then according to
Calculating the regeneration target temperature T of DPF0The amount of HC required to be injected Q620 ℃.
Then according to the calculated HC amount Q, HC injection is started in a mode that a fuel injector releases far back injection or an HC injection system injects HC so as to increase the inlet temperature T of the DPF5So that when the exhaust gas discharged from the engine enters the DPF through the high-temperature DOC, the oxygen in the high-temperature gas and the carbon deposited in the DPF can be subjected to a combustion regeneration reaction to remove the carbon deposited in the DPF。
Wherein, the buffer temperature T is set2The HC injection amount gradually rises gradually after being reduced, so that the problem that the temperature in the DPF is increased instantly due to excessive HC injection amount under the condition that the carbon loading amount is large at the initial moment of the DPF can be solved; on the other hand, after the carbon loading is gradually reduced along with the progress of the regeneration reaction, the HC injection amount can be increased to ensure that the carbon loading deposited in the DPF is cleared, so that the active regeneration reaction can be sufficiently and completely performed.
Meanwhile, in the HC injection process, in order to avoid abnormal temperature rise in the DPF caused by unexpected working conditions, multi-section DPF temperature control is carried out, namely, real-time DPF inlet temperature T is obtained5And comparison is carried out:
when the temperature is 620 ℃ and is less than T5At 650 deg.C or less, the inlet temperature T of DPF is controlled by controlling initial HC injection amount and HC injection variation rate5Fluctuation is generated, and the carbon deposited in the DPF can be stably combusted, so that the regeneration safety of the DPF is realized;
when 650 ℃ is less than T5When the temperature is less than or equal to 700 ℃, the exhaust gas quantity discharged into the DPF by the engine is increased by limiting the HC injection quantity, reducing the opening degree of a supercharger air release valve of the engine, reducing the opening degree of an air inlet throttle valve and reducing the opening degree of an exhaust throttle valve so as to reduce the inlet temperature T of the DPF5；
When the temperature is 700 ℃ to less than T5In the process, the exhaust gas quantity discharged into the DPF by the engine is increased to the maximum extent by stopping HC injection and closing a supercharger exhaust valve, an intake throttle valve and an exhaust throttle valve, so that the exhaust gas takes away heat in the DPF, the temperature accumulation in the DPF is avoided, and the inlet temperature T of the DPF is reduced5。
Finally, when the regeneration time t of DPF is1When the time is greater than the time calibration threshold or the carbon loading amount accumulated in the DPF is less than the carbon loading amount calibration threshold, the DPF active regeneration is completed, the engine automatically exits the regeneration mode, HC injection is stopped, and the regeneration is finished so as to complete the whole DPF active regeneration process.
Wherein the target temperature T is regenerated by setting a step of DPF1To control HC injection quantity, while three temperature protection phases are provided to enable control of the inlet temperature T of the DPF5The problem that the DPF is burnt out due to overhigh temperature is avoided, and therefore the safety of the active regeneration of the DPF is high.
The above description is only a preferred embodiment of the present invention, and for those skilled in the art, the present invention should not be limited by the description of the present invention, which should be interpreted as a limitation.
Claims (9)
1. A DPF active regeneration safety control method is characterized by comprising the following steps:
s10: judging the regeneration condition: when one of the operating condition parameters of the engine reaches a regeneration threshold corresponding to the parameter, the DPF enters active regeneration;
s20: judging HC injection conditions: when inlet temperature T of DOC4Not less than the light-off temperature T required for oxidation of HC7HC injection condition is satisfied, and HC is injected to raise the inlet temperature T of the DPF5；
S30: calculating the regeneration target temperature T needed to reach DPF0Amount of HC required to be injected Q:
wherein C is specific heat capacity of exhaust gas, and q is heat value of diesel oil; eta is DOC oxidation efficiency, T1A target temperature for stepwise regeneration, and T1＝T0-T2，T2To buffer the temperature, T2Regeneration time t of DPF1And the carbon loading accumulated in the DPF, and2with decreasing carbon loading and regeneration time t1Gradually decreases to 0;
s40: temperature control: during HC injection, when T0＜T5Less than or equal to the first safety threshold T3When the initial HC injection amount is decreased and the change rate of HC injection is decreased to control the inlet temperature T of the DPF5Generating a wave;
when T is3＜T5Less than or equal to a second safety threshold T6When the amount of HC injected is reduced, the amount of exhaust gas discharged into the DPF from the engine is increased;
when T is6＜T5When the exhaust gas amount is increased, HC injection is stopped and the amount of exhaust gas discharged into the DPF from the engine is increased;
buffer temperature T2: when the regeneration time T1 is 0-10min, T2 is 40 ℃; when the regeneration time T1 is 12-15min, T2 is 20 ℃; when the regeneration time T1 is more than or equal to 16min, T2 is 0 ℃.
2. The DPF active regeneration safety control method of claim 1, further comprising, before the step S10, the steps of:
s5: collecting working parameters: collection of DOC Inlet temperature T4DPF inlet temperature T5Target regeneration temperature T of DPF0DPF carbon-supported model calculation amount and DPF regeneration time t1And obtaining the operating condition parameters of the engine.
3. The DPF active regeneration safety control method of claim 1, further comprising the step of, after the step S40:
s50: ending DPF active regeneration: when regeneration time t of DPF1And when the time is greater than the time calibration threshold or the carbon loading accumulated in the DPF is less than the carbon loading calibration threshold, finishing the active regeneration of the DPF, and stopping injecting HC.
4. The DPF active regeneration safety control method of claim 1, wherein the regeneration target temperature T of the DPF0Obtained from a MAP table lookup of the engine.
5. The DPF active regeneration safety control method of claim 1, wherein in the step S20:
when the regeneration condition is satisfied but T4＜T7By reducing the amount of exhaust gas emitted by the engine into the DOC andincreasing DOC inlet temperature T by near post injection release by injector4So that T is4≥T7。
6. The DPF active regeneration safety control method of claim 5, wherein in the step S20:
when T is4≥T7When in use, the fuel injector releases far-rear injection or the HC injection system injects HC into the DOC to improve the inlet temperature T of the DPF5。
7. The DPF active regeneration safety control method of claim 1, wherein in the step S40:
when T is3＜T5≤T6In the method, the amount of exhaust gas discharged into the DPF by the engine is increased by reducing the opening degree of a supercharger air release valve of the engine, reducing the opening degree of an air inlet throttle valve and reducing the opening degree of an exhaust throttle valve so as to reduce the inlet temperature T of the DPF5。
8. The DPF active regeneration safety control method of claim 7, wherein in the step S40:
when T is6＜T5In the method, the amount of tail gas discharged into the DPF by the engine is increased by closing the supercharger air release valve, the air inlet throttle valve and the air outlet throttle valve so as to reduce the inlet temperature T of the DPF5。
9. The DPF active regeneration safety control method of claim 1, wherein the operating condition parameters of the engine include an operating mileage, a driving time, an accumulated oil amount, a DPF upstream and downstream pressure difference, and a carbon load model of the engine.
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| CN114738093B (en) * | 2022-05-09 | 2023-03-31 | 一汽解放汽车有限公司 | DPF regeneration control method |
| CN115306523A (en) * | 2022-07-14 | 2022-11-08 | 潍柴动力股份有限公司 | Engine DPF control method and device |
| CN115891966B (en) * | 2023-02-15 | 2023-08-18 | 潍柴动力股份有限公司 | DPF parking regeneration control method for hybrid electric vehicle and vehicle |
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