JP2010101205A - Dpf regeneration timing determination method and determination device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a DPF regeneration timing determination method and device, which accurately determines a DPF regeneration timing by accurately estimating a PM amount and a SOOT deposition amount of an important element to determine the DPF regeneration timing. <P>SOLUTION: The DPF regeneration timing determination device is provided with a DPF for collecting a PM, in an exhaust passage of an internal combustion engine, and determines the regeneration timing for burning and removing the PM deposited on the DPF, and also is provided with: a SOF exhaust amount map 23, a SOOT exhaust amount map 25; a SOF regeneration amount map 27; a SOOT regeneration amount map 29; and a SOF deposition amount correction means for calculating a SOF content and SOOT content deposited on the DPF from a difference between the discharge amount and regeneration amount of the SOF content and SOOT content calculated from each map, and for correcting a volatilization or oxidative combustion content of the SOF content with the delay of time by a temperature history of the DPF during engine operation, or an oxidative combustion content in the DOC. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention accurately estimates the amount of PM (particulate matter) deposited on a DPF (diesel particulate filter) used as an exhaust gas aftertreatment device of a diesel engine, in particular, the amount of SOOT deposited in the PM, and determines the regeneration timing of the DPF. The present invention relates to a determination method and a determination apparatus.

The DPF is generally used for removing PM discharged from a diesel engine from exhaust gas, and is formed by molding ceramic or the like into a honeycomb monolith. When PM accumulates in this DPF during operation, and the accumulated amount eventually exceeds the allowable value, clogging occurs and the exhaust pressure rises, adversely affecting the drivability, so the DPF captures a certain amount of PM. A regeneration operation (DPF forced regeneration) for burning and removing PM after collection is necessary.
When performing forced regeneration of the DPF, it is necessary to keep the temperature of the gas flowing into the DPF high. Fuel supply to the exhaust gas after-treatment device (DOC (diesel oxidation catalyst) + DPF), that is, combustion, to increase the gas temperature Post injection into the room, addition of light oil into the exhaust passage upstream of the DOC, and the like are performed.
Accurate estimation of the accumulation amount of SOOT (black smoke in PM), which is an index for instructing forced regeneration of the DPF, is important in accurately determining the timing of PM combustion removal.

  For estimating the PM or SOOT accumulation amount, an estimation method based on operating time, fuel injection amount, pressure loss data, and the like is known. However, in the detection by the differential pressure across the DPF, the PM accumulation amount and the DPF in FIG. As shown in the relationship with the front-rear differential pressure, when the temperature changes, even if the PM deposition amount is the same, the differential pressure changes. Therefore, there is a problem that the deposition amount cannot be detected accurately.

On the other hand, Patent Document 1 (Japanese Patent Application Laid-Open No. 7-310524) is known as a technique for detecting the amount of diesel particulate trapped. The Patent Document 1 discloses a low load even when the amount of clogging is the same depending on the operating state. PM component correction based on operating conditions based on the relationship that the SOF (combustible organic matter) ratio is large in operation, the PM collection amount is small, and the dry soot ratio is large in high-load operation. It is shown that a coefficient is used, and further, it is shown that the regeneration timing of the filter is determined by the amount of heat generated by the particulates.
In Patent Document 2 (Japanese Patent Laid-Open No. 2003-314249), the DPF is heated to a temperature higher than the temperature at which the SOF content in the PM can be removed and held for a predetermined time, and then the difference between the front and back of the DPF is detected by the pressure difference detection device. Since the PM collection amount is calculated by detecting the pressure, it is shown that the collection amount can be calculated in a state where the influence of the SOF content in the PM is excluded.

JP-A-7-310524 JP 2003-314249 A

  However, in the detection based on the differential pressure across the DPF as described above, since the differential pressure changes even if the PM deposition amount is the same when the temperature changes, it is impossible to accurately detect the deposition amount. Further, Patent Document 1 shows that the PM component correction coefficient according to the operating state is used and that the PM deposition amount is estimated by the amount of heat generated by the particulates, but the PM is accurately estimated by focusing on the SOOT amount. In addition, it is not sufficient as a technique for performing such a process, and after raising the temperature to a temperature at which the SOF component can be removed as in Patent Document 2 and holding it for a predetermined time, the pressure difference detection device detects the differential pressure across the DPF and PM. Since the configuration is such that the amount collected is calculated, heating for removing the SOF component is necessary, and this is not sufficient as a method for always estimating the SOOT component accurately, and a method for estimating the SOOT amount and the PM amount with high accuracy is desired. It was rare.

  In view of the problems of the prior art, the present invention provides a DPF regeneration timing determination method and a determination apparatus for accurately estimating the DPF regeneration timing by accurately estimating the SOOT accumulation amount and the PM amount, which are important elements for the determination of the DPF regeneration timing. The purpose is to provide.

  The present invention solves such a problem, and the first invention relates to a DPF regeneration timing determination device, and a DPF (diesel particulate filter) that collects PM (particulate matter) in an exhaust passage of an internal combustion engine. In a DPF regeneration timing determination device that includes an exhaust gas aftertreatment device for a diesel engine and that determines a regeneration timing for burning and removing PM accumulated in the DPF, an SOF component (combustible organic matter) consisting of oil or unfueled fuel in the PM SOF emission map in which the amount of emissions for the engine operating state is set, the SOOT emission map in which the amount of SOOT in the PM (black smoke) is set for the engine operating state, and the DPF SOF regeneration amount map that sets the regeneration amount for SOF at the exhaust gas temperature of the exhaust gas, and the regeneration amount for SOOT at the exhaust gas temperature at the DPF SOOT regeneration amount calculating means for calculating SOF content and SOOT content deposited on the DPF from the difference between the SOF amount calculated by each map and the calculation means and the discharge amount of SOOT and the regeneration amount, and calculating the calculated value SOF deposit amount calculating means and SOOT deposit amount calculating means for determining the accumulated amount of SOF and SOOT, and the SOF calculated by the SOF deposit amount calculating means is the temperature of the DPF during engine operation. SOF accumulation amount correcting means for correcting volatilization or oxidative combustion with time delay according to the history, and regeneration determining means for determining the DPF regeneration timing based on the corrected SOF deposition amount and the calculated SOOT deposition amount And.

  The second invention relates to a DPF regeneration timing determination method corresponding to the first invention, and is a diesel engine provided with a DPF (diesel particulate filter) for collecting PM (particulate matter) in an exhaust passage of an internal combustion engine. In a DPF regeneration timing determination method that includes an exhaust gas aftertreatment device for an engine and determines a regeneration timing for burning and removing PM accumulated in the DPF, an SOF component (combustible organic matter component) of oil or unfueled fuel in the PM is used. Emissions are calculated using the SOF emission map set for the engine operating state, and the SOOT (black smoke) emission amount in the PM is calculated using the SOOT emission map set for the engine operating state. The regeneration amount of the SOF at the exhaust gas treatment temperature in the DPF is calculated by the SOF regeneration amount map, and the exhaust gas treatment temperature in the DPF is calculated. The SOOT regeneration amount is calculated by the SOOT regeneration amount calculating means, and the SOF and SOOT components deposited on the DPF are calculated from the difference between the calculated SOF and SOOT emission and regeneration, and the calculated value The amount of SOF accumulated and the amount of SOOT accumulated is calculated to calculate the amount of volatile or oxidative combustion with a time delay based on the temperature history of the DPF during engine operation. The correction time is corrected, and the reproduction time is determined using the corrected SOF and the calculated SOOT.

  According to the first and second aspects of the present invention, the SOOT and SOF emissions from the engine and the regeneration amount of the DPF in the PM are preliminarily represented by maps in the engine operating state and the exhaust gas temperature, respectively. Since it is set or calculated by the calculation means, the SOOT amount and SOF amount deposited on the DPF can be easily and reliably calculated from the difference between the discharge amount and the regeneration amount, and the calculated value is accumulated for the elapsed time. The SOOT deposition amount and the SOF deposition amount in the DPF can be calculated.

Further, the amount of accumulated SOF calculated by the map or the calculation means is corrected to volatile or oxidative combustion with a time delay based on the temperature history of the DPF while the engine is operating, so that the differential pressure across the DPF is corrected. It becomes possible to accurately grasp the deposition ratio relationship between the amount of SOOT and the amount of SOF in the detected pressure difference.
That is, since the SOF component in the SOOT and SOF deposited on the DPF is mainly combustible organic matter, a phenomenon of gradual volatilization or oxidative combustion occurs with a time delay. Therefore, when the temperature history of the DPF rises, it is necessary to correct the decrease in the amount of SOF calculated as the deposition amount. In addition, when it descends after it has risen to a high temperature, it evaporates with time, but since it has already risen once to a high temperature, the rate of decrease is greater than that at the time of temperature rise.
As described above, since an accurate SOF deposition amount can be calculated in consideration of the SOF volatilization or oxidative combustion, the regeneration timing is accurately determined using the corrected SOF component and the calculated SOOT component. Will be able to.

  In the first invention, preferably, a SOOT / SOF ratio calculating means for calculating a ratio between the corrected SOF accumulation amount and the SOOT accumulation amount, and a difference in front and back of the DPF with the SOOT / SOF ratio as a parameter for each exhaust gas temperature in advance. A SOOT / SOF ratio map in which the relationship between the pressure and the SOOT deposition amount is set, and a detected value from a differential pressure sensor that detects a differential pressure before and after the DPF, a detected value from an exhaust gas temperature sensor, and the SOOT / Based on the calculated value of the SOOT / corrected SOF ratio by the SOF ratio calculating means, the SOOT / SOF ratio map is used to calculate the deposition amount for the SOOT, and the regeneration timing is determined based on the SOOT.

  In the second invention, preferably, a ratio between the SOOT component and the corrected SOF component is calculated, and the relationship between the differential pressure before and after the DPF and the SOOT deposition amount with the SOOT / SOF ratio as a parameter for each exhaust gas temperature in advance. Is prepared, and based on the detected value from the differential pressure sensor, the detected value from the exhaust gas temperature sensor, and the calculated value of the SOOT / corrected SOF ratio, the SOOT / SOF ratio map is prepared. It is preferable to calculate the accumulation amount for SOOT and determine the regeneration time based on the SOOT amount.

According to each of the inventions, a SOOT / SOF ratio map in which the relationship between the differential pressure across the DPF and the SOOT deposition amount is set in advance using the SOOT / SOF ratio as a parameter for each exhaust gas temperature in advance is used. The SOOT deposition amount can be accurately estimated using a signal from the differential pressure sensor of the DPF.
Further, as described above, by correcting the SOF component that volatilizes or oxidizes and burns with a time delay based on the temperature history of the DPF, the amount of SOOT in the pressure difference detected as the differential pressure across the DPF Since it becomes possible to accurately calculate the deposition ratio relationship with the amount of SOF, it is possible to accurately calculate the amount of SOOT using the SOOT / SOF ratio map based on the result. Further, the PM deposition amount can be estimated with higher accuracy.

  In the first aspect of the invention, preferably, the corrected SOF accumulation amount may be obtained by multiplying the SOF accumulation amount by a correction coefficient to correct the SOF volatilization or oxidation combustion, and the correction coefficient has a temperature rise history in the DPF. It is better to set the value at the time of the temperature rise history to a value smaller than that at the time of the temperature fall history.

For example, the SOF content accumulated in the DPF is calculated from the difference between the SOF and SOOT emission amounts calculated by the maps and the calculation means and the regeneration amount, and the accumulated value of the calculated value with time is obtained to obtain the SOF component (Qs). Is calculated by applying a correction coefficient (K (t, R)) according to the temperature history (R) of the DPF within the elapsed time (t) in which the accumulated amount is calculated. Qsf) = Qs (1−K (t, R)).
The correction coefficient (K (t, R)) is set to be larger when the elapsed time (t) for calculating the accumulated amount with time is longer, and is set to be smaller when the temperature history (R) of the DPF is increased than when it is decreased. .

Thus, the amount of decrease in the SOF due to the volatile phenomenon due to the time delay has a greater effect as the elapsed time (t) becomes longer. Therefore, the time t is set as a parameter so as to greatly decrease according to the time. Once the temperature rises in the history, the volatilization phenomenon has a large effect, so the degree of temperature rise is different from the degree of temperature rise and the degree of temperature rise is small, and the amount of decrease due to volatilization or oxidative combustion is small. To correct it.
Note that the elapsed time (t) is not limited to the time for calculating the accumulated amount with time, and may be determined arbitrarily.

  Next, the third aspect of the invention relates to a DPF regeneration timing determination device, which is an exhaust gas post-treatment for a diesel engine provided with a DPF (diesel particulate filter) for collecting PM (particulate matter) in an exhaust passage of the internal combustion engine. In a DPF regeneration timing determination device for determining a regeneration timing for burning and removing PM accumulated in the DPF, an engine operation is performed for the amount of SOF (combustible organic matter) that is composed of oil and unfueled fuel in the PM. SOF emission map set for the state, SOOT emission map in which the amount of SOOT (black smoke) emission in the PM is set for the engine operating state, and the SOF amount at the exhaust gas temperature in the DPF An SOF regeneration amount map in which the regeneration amount is set, and SOOT regeneration amount calculation means for calculating the regeneration amount for SOOT at the exhaust gas temperature in the DPF. The SOF and SOOT components accumulated in the DPF are calculated from the difference between the SOF and SOOT emission amounts calculated by the respective maps and the calculation means and the regeneration amount, and the accumulated values of the calculated values with time are calculated to obtain the SOF. SOF deposit amount calculating means and SOOT deposit amount calculating means for determining the deposit amount and SOOT deposit amount, and a DOC (diesel oxidation catalyst) catalyst in which the SOF component calculated by the SOF deposit amount calculating means is provided upstream of the DPF SOF deposition amount correction means for correcting the purification amount due to oxidative combustion by reaction, and regeneration determination means for determining the regeneration timing of the DPF based on the corrected SOF deposition amount and the calculated SOOT deposition amount It is characterized by that.

  The fourth invention relates to a DPF regeneration timing determination method corresponding to the third invention, and is a diesel engine provided with a DPF (diesel particulate filter) for collecting PM (particulate matter) in an exhaust passage of an internal combustion engine. In a DPF regeneration timing determination method that includes an exhaust gas aftertreatment device for an engine and determines a regeneration timing for burning and removing PM accumulated in the DPF, an SOF component (combustible organic matter component) of oil or unfueled fuel in the PM is used. Emissions are calculated using the SOF emission map set for the engine operating state, and the SOOT (black smoke) emission amount in the PM is calculated using the SOOT emission map set for the engine operating state. The regeneration amount of the SOF at the exhaust gas treatment temperature in the DPF is calculated by the SOF regeneration amount map, and the exhaust gas treatment temperature in the DPF is calculated. The SOOT regeneration amount calculation means calculates the SOOT regeneration amount by means of the SOOT regeneration amount calculation means, calculates the SOF component and SOO component deposited on the DPF from the difference between the calculated SOF component and the SOOT discharge amount and the regeneration component, and calculates the calculated value. The amount of SOF accumulated over time is calculated to calculate the amount of SOF and SOOT accumulated, and the SOF is purified by oxidative combustion by the catalytic reaction of a DOC (diesel oxidation catalyst) provided upstream of the DPF. The minute is corrected, and the regeneration timing is determined based on the corrected SOF and the calculated SOOT.

  According to the third and fourth aspects of the present invention, the exhaust amount of the SOOT component and the SOF component in the PM and the regeneration amount in the DPF are preliminarily represented by a map in the engine operating state and the exhaust gas temperature, respectively. Since it is set or calculated by the calculation means, the SOOT amount and SOF amount deposited on the DPF can be easily and reliably calculated from the difference between the discharge amount and the regeneration amount, and the calculated value is accumulated for the elapsed time. The SOOT deposition amount and the SOF deposition amount in the DPF can be calculated.

  Further, from the accumulated amount of SOF content calculated by the map or the calculation means, the purified SOF content by correcting the oxidative combustion due to the catalytic reaction of the DOC (diesel oxidation catalyst) provided upstream of the DPF is corrected. Since the reproduction time is determined based on the calculated SOOT, the reproduction time can be accurately determined.

  Further, according to the third and fourth inventions, the SOOT amount or the PM deposition amount can be accurately estimated without detecting the differential pressure across the DPF using the differential pressure sensor as in the first and second inventions. Therefore, the system and logic are simplified.

  In the third and fourth inventions, preferably, when the outlet temperature of the DOC provided upstream of the DPF is equal to or lower than a preset threshold value, the sum of the corrected SOF component and the SOOT component is used. Further, when the threshold value is exceeded, the reproduction time may be determined based on the SOOT.

  By configuring in this way, at a temperature exceeding about 300 ° C. having a sufficient SOF oxidative combustion function in DOC, most of the SOF content is oxidized and combusted, and in the DPF, the particulates are mostly regarded as SOOT, and the deposited amount Can be estimated. In addition, at a temperature having a sufficient SOF oxidation combustion function in DOC (approximately 300 ° C.) or less, the regeneration time is estimated by the sum of the SOOT amount calculated by the map and the calculation means and the corrected SOF amount, so that the accuracy is high. The reproduction time can be determined.

Further, the SOOT regeneration amount calculation means in the first, second, third and fourth inventions is set so that the SOOT regeneration amount can be obtained from the DPF temperature and the nitrogen dioxide (NO ₂ ) concentration at the DPF. The DPF temperature (T), the exhaust gas flow rate (Q) flowing into the DPF, the nitrogen dioxide (NO ₂ ) concentration and the oxygen (O ₂ ) concentration in the exhaust gas are used as parameters. You may be comprised so that it may calculate by a SOOT combustion rate type | formula.

According to such a configuration, the SOOT regeneration amount is estimated based on the nitrogen dioxide (NO ₂ ) concentration using the calculation means, that is, nitrogen dioxide (NO ₂ ) burns the SOOT component (mostly carbon) at a low temperature. Therefore, it is possible to estimate the SOOT regeneration amount with high accuracy by estimating based on the nitrogen dioxide (NO ₂ ) concentration as an index directly related to the SOOT deposition amount.

  According to the present invention, it is possible to accurately estimate the SOOT deposition amount and the PM amount, which are important factors for the determination of the DPF regeneration timing, by correcting the decrease in the deposition amount due to the volatilization and oxidation combustion of the SOF constituting the PM. It is possible to provide a DPF regeneration timing determination method and determination apparatus that accurately determine the DPF regeneration timing.

  Hereinafter, the present invention will be described in detail with reference to the embodiments shown in the drawings. However, the dimensions, materials, shapes, relative arrangements, and the like of the components described in this embodiment are not intended to limit the scope of the present invention only to specific examples unless otherwise specified. Only.

(First embodiment)
FIG. 1 shows an overall configuration diagram of an exhaust gas aftertreatment device 3 installed in an exhaust passage 1 of a diesel engine. A DOC (diesel engine oxidation catalyst) 5 is installed upstream of an exhaust gas flow, and a DPF (diesel particulate filter). 7 is installed downstream of the exhaust gas flow.
Then, PM in the exhaust gas is collected and accumulated in the DPF 7, and is combusted and removed when a predetermined amount is accumulated. When the PM in the exhaust gas accumulated in the DPF 7 is regenerated, the light oil is added to the exhaust passage, the post fuel is injected into the combustion chamber, etc., and the exhaust gas is discharged from the DOC 5 installed upstream of the exhaust gas flow. The exhaust gas is heated by oxidation heat generated when the fuel inside is oxidized, and the heated exhaust gas raises the exhaust gas temperature fed to the DPF 7 to about 600 ° C. sufficient for PM to burn. To process. Furthermore, when the catalyst activation temperature of the DOC 5 is not reached, control operations such as throttle of the intake valve, throttle of the exhaust valve, and early post injection amount are performed.
A DPF inlet temperature sensor 9, a DPF outlet temperature sensor 11, and a differential pressure sensor 13 for detecting front-rear differential pressure are installed at the inlet and outlet of the DPF 7, respectively. A DOC inlet temperature sensor 17 is installed at the inlet of the DOC 5.

  The regeneration process of the PM deposited on the DPF 7 is performed by a regeneration control device (not shown). In the regeneration control device, it is determined whether or not the PM deposition amount has accumulated to a specified amount that requires regeneration. A reproduction time determination device 21 that starts reproduction according to the result is provided. The regeneration timing determination device 21 will be described with reference to FIG.

  The regeneration timing determination device 2 includes an SOF emission map 23 in which the emission amount of SOF (combustible organic matter) consisting of oil and unfueled fuel in the PM is set with respect to the engine operating state, and the SOOT emission amount in the PM ( The SOOT emission amount map 25 in which the amount of emission of black smoke) is set with respect to the engine operating state, the SOF regeneration amount map 27 in which the regeneration amount of the SOF at the exhaust gas temperature in the DPF is set, and the exhaust gas temperature in the DPF And a SOOT playback amount map 29 in which the playback amount for SOOT is set.

The SOF emission map 23 is a three-dimensional map in which the SOF emission amount is set with respect to the engine speed indicating the engine operating state and the fuel supply amount to the combustion chamber. Similarly, the SOOT emission amount map 25 is a three-dimensional map in which the SOOT emission amount is set with respect to the engine speed indicating the engine operating state and the fuel supply amount to the combustion chamber.
The SOF regeneration amount map 27 indicates the inlet temperature of the DPF 7 by the DPF inlet temperature sensor 9 and the exhaust gas flow rate flowing into the DPF 7 (the exhaust gas flow rate calculated by the intake flow rate and the fuel injection amount by an unillustrated intake flow rate sensor (air flow sensor)). Is a three-dimensional map in which the regeneration amount (evaporation amount or oxidation combustion) of SOF is set. Similarly, the SOOT regeneration amount map 29 is also a three-dimensional map in which the regeneration amount of SOOT is set with respect to the inlet temperature of the DPF 7 by the DPF inlet temperature sensor 9 and the exhaust gas flow rate flowing through the DPF 7.

  Also, the SOF amount accumulated in the DPF 7 is calculated from the difference between the SOF emission amount calculated from the SOF emission map 23 and the SOF regeneration amount map 27 and the regeneration amount, and the accumulated amount of the calculated value with time is obtained to obtain the SOF component. SOF accumulation amount calculating means 31 for obtaining the accumulation amount is provided. Further, for the SOOT, the DPF 7 is provided with a difference between the SOOT emission amount calculated from the SOOT emission amount map 25 and the SOOT regeneration amount map 29 and the regeneration amount. SOOT deposition amount calculation means 33 is provided for calculating the accumulated SOOT amount, obtaining the accumulated amount of the calculated value with time, and obtaining the accumulated amount of SOOT.

  Then, the SOF accumulation amount correction means 35 for correcting the amount of the SOF accumulation amount calculated by the SOF accumulation amount calculation means 31 that volatilizes or oxidizes and burns with a time delay according to the temperature history of the DPF during engine operation. The regeneration determination means 37 for determining the regeneration timing of the PM of the DPF 7 based on the corrected SOF accumulation amount and the SOOT accumulation amount calculated by the SOOT accumulation amount calculation means 33 is provided.

  This regeneration timing is determined by calculating the ratio between the corrected SOF accumulation amount and the SOOT accumulation amount by the SOOT / SOF ratio calculating means 39, and by using the SOOT / SOF ratio as a parameter for each exhaust gas temperature in advance and the differential pressure across the DPF. A SOOT / SOF ratio map 41 in which a relationship with the SOOT deposition amount is set is provided, and is calculated by the detected value from the differential pressure sensor 13, the detected value from the DPF inlet temperature sensor 9, and the SOOT / SOF ratio calculating means. On the basis of the corrected SOF value, the SOOT / SOF ratio map 41 is used to calculate the SOOT deposit amount 38 based on the calculated value of the SOOT / corrected SOF ratio. Determine the time.

  The SOOT / SOF ratio map 41 is created for each inlet temperature of the DPF 7 (for example, 200 ° C., 300 ° C., 400 ° C., etc.). At each temperature, the SOOT / SOF ratio is a parameter, and the vertical axis of the DPF 7 The pressure difference between the front and rear is taken, the amount of SOOT is taken on the horizontal axis, and the relationship is set. Then, the SOOT / corrected SOF ratio calculated by the differential pressure sensor 13, the DPF inlet temperature sensor 9, and the SOOT / SOF ratio calculating means 39 is inputted, and an accurate SOT accumulation amount in the detected value of the differential pressure sensor 13 is calculated. Is done.

A determination method in the regeneration timing determination apparatus 21 according to the first embodiment configured as described above will be described with reference to the flowchart of FIG.
In FIG. 3, when starting, first, in step S2, the SOOT and SOF emissions during operation of the engine are calculated from the SOOT emission map 25 and the SOF emission map 23, and the SOOT and SOF regeneration in step S3. The amount is calculated by the SOOT regeneration amount map 29 and the SOF regeneration amount map 27. Next, in step S4, the SOF amount and SOOT portion accumulated in the DPF are calculated from the difference between the SOF amount and the SOOT emission amount and the regeneration amount. Then, the accumulated amount of the calculated value with time is obtained, and the accumulation amount for SOF and SOOT is obtained.

  Emissions from the engine for SOOT and SOF in the PM and the regeneration amount in the DPF 7 are calculated based on data set in advance by a map, so it is easy from the difference between the emission amount and the regeneration amount. In addition, the DPF can be calculated with certainty, and the calculated values can be accumulated over time to calculate the SOOT deposition amount and the SOF deposition amount in the DPF, so that the SOOT deposition amount and the SOF deposition amount can be reliably and easily estimated. It becomes like this.

Next, in step S5, the SOF deposition amount correction means 35 multiplies the SOF deposition amount calculated by the SOF deposition amount calculation means 31 by a correction coefficient to correct the decrease due to volatilization or oxidation combustion of the SOF.
The SOF component (Qs) is calculated by obtaining the map value accumulated amount over time. The correction coefficient (K (t (t)) is determined according to the temperature history (R) of the DPF within the elapsed time (t) for calculating the accumulated value over time. , R)) to calculate the corrected SOF component (Qsf) = Qs (1−K (t, R)).
Then, the correction coefficient (K (t, R)) is increased if the elapsed time (t) for calculating the accumulated amount over time is long as shown in FIG. 4A, and further, the correction coefficient (K (t, R)) is further increased as shown in FIG. When the temperature history (R) is increasing, it is set smaller than when it is decreasing.
The elapsed time (t) is an elapsed time for calculating the deposition amount in step S4, set to an arbitrary time interval, and a correction coefficient according to the time length and the temperature history within the time interval. Set.

Of SOOT and SOF deposited on the DPF, the SOF content is mainly combustible organic matter, and therefore, a phenomenon of volatile or oxidative combustion gradually occurs with a time delay. Therefore, since the amount of decrease in SOF due to volatilization due to time delay or oxidative combustion has a greater effect as the elapsed time (t) becomes longer, the time t is set as a parameter so as to greatly decrease with time.
In addition, it is necessary to correct the calculated amount of SOF in accordance with the temperature history of the DPF, but once the temperature history has risen to a high temperature, the rate of decrease due to volatilization or oxidative combustion has a large effect. The degree of correction factor at the time of temperature rise is different from the degree of correction factor at the time of fall to reduce the case when the temperature rises and increase the case when the temperature falls to compensate for the decrease due to volatilization or oxidative combustion. Yes.
Therefore, an accurate SOF amount can be calculated in consideration of the amount of decrease in SOF due to volatilization due to time delay or oxidation combustion. As a result, it becomes possible to accurately grasp the deposition ratio relationship between the SOOT amount and the SOF amount in the pressure difference detected as the differential pressure across the DPF 7.

Next, the process proceeds to step 6 where the SOOT / SOF ratio calculating means 39 calculates the SOT / corrected SOF ratio deposited on the DPF 7, and the detected value from the differential pressure sensor 13 and the detected value from the DPF inlet temperature sensor 9. Then, using the SOOT / SOF ratio for each exhaust gas temperature as a parameter, the SOOT / SOF ratio map 41 in which the relationship between the differential pressure before and after the DPF and the SOOT deposition amount is set is calculated.
The comparison result between the estimated value of the SOOT deposition amount according to the first embodiment and the actual measured value of SOOT deposition is compared with the conventional method using only the differential pressure in FIG. Thus, it was confirmed that using the SOOT / SOF ratio map in consideration of volatilization of SOF or oxidation combustion, the accuracy was improved within an error range of about ± 30% with respect to the actual measurement value.

(Second Embodiment)
Next, a second embodiment will be described with reference to FIGS.
In the first embodiment, the amount of volatilization or oxidation combustion with a time delay is corrected by the temperature history of the DPF 7, whereas in the second embodiment, the activation state of the DOC 5 arranged on the upstream side of the DPF 7 The amount of oxidative combustion of the SOF that passes through the DOC 5 is corrected.

The same components as those in the first embodiment are denoted by the same reference numerals and description thereof is omitted.
In FIG. 6, the processing up to the calculation of the SOF deposition amount by the SOF deposition amount calculation means 50 and the calculation of the SOT deposition amount by the SOOT deposition amount calculation means 52 are the same as in the first embodiment. In the second embodiment, there is provided SOF deposition amount correction means 54 for correcting the amount of purification due to oxidative combustion due to the catalytic reaction of DOC (diesel oxidation catalyst) provided upstream of the DPF.

  As shown in the SOF accumulation amount correction means 54 in FIG. 6, the exhaust gas temperature that has passed through the DOC 5 is detected by the DPF inlet temperature sensor 9 at the outlet of the DOC 5, that is, the inlet temperature of the DPF 7, and the temperature is approximately 200 ° C. to 300 ° C. In this case, since the SOF oxidation combustion rate by DOC5 varies between 0 and 80 to 100%, the SOF accumulation amount correction means 54 sets the correction coefficient J as a function of the exhaust gas temperature that has passed through DOC5. Then, the corrected SOF component (Qsg) is calculated as Qsg = Qs × J (T) (0 to 0.2 ≦ J ≦ 1), and oxidative combustion occurs in the process in which a part of the SOF deposition amount passes through the DOC5. Correct so that it decreases.

  When the exhaust gas temperature T passing through the DOC 5 is 200 ° C. or lower, J = 1, and there is no volatilization in the DOC 5 and the SOF deposition amount by the SOF deposition amount calculation means 50 is output as it is. Further, when it exceeds 300 ° C., J = 0 and all SOF components are volatilized to zero, so that the total deposition amount is only SOOT components.

  Therefore, when the outlet temperature of the DOC 5 exceeds 300 ° C. in the SOF deposition amount correction means 54, most of the SOF component is oxidized and burned when passing through the DOC 5, and the deposition amount can be estimated as all SOOT. Also, below the temperature at which the DOC 5 has a sufficient SOF oxidation combustion function (approximately 300 ° C.), a part of the SOF deposition amount by the SOF deposition amount calculating means 50 volatilizes and decreases when passing through the DOC 5 and passes. Therefore, since the total accumulation amount 56 of the sum of the SOOT and the corrected SOF is calculated and the regeneration timing is estimated by the regeneration determining means 58, the regeneration timing can be accurately determined.

Next, a determination method in the regeneration timing determination device 60 in the second embodiment will be described with reference to the flowchart of FIG.
In FIG. 7, first, when starting, it is determined in step S2 whether the outlet temperature of the DOC 5, that is, the inlet temperature (T) of the DPF 7, exceeds T _B (300 ° C.). If it exceeds, the SOF is mostly oxidized and burned in the DOC 5 and is only for SOOT, so the SOOT emission amount is calculated from the SOOT emission map 25 in step S3. Next, in step S4, the SOOT playback amount is calculated from the SOOT playback amount map 29. In step S5, the SOOT amount deposited on the DPF is calculated from the difference between the discharge amount and the regeneration amount for the SOOT, and the accumulated amount of the calculated value with time is obtained to obtain the deposit amount for the SOOT. Next, in step S6, it is determined whether or not the sum Q of the calculated deposition amount of SOOT and SOF exceeds the reference value QB, and if so, regeneration processing of the DPF 7 is started in step S7. In step S7, if the reference value QB is not exceeded, the process returns to step S2 and is repeated from the beginning.

On the other hand, in step S2, the outlet temperature of DOC5, i.e. DPF7 inlet temperature (T) _is, if not exceed T B (300 ℃), in step S9, SOOT during operation with an engine, the discharge of SOF The amount is calculated by the SOOT emission amount map 25 and the SOF emission amount map 23, the SOOT and SOF regeneration amounts are calculated by the SOOT regeneration amount map 29 and the SOF regeneration amount map 27 in step S10, and then in step 11. Then, the SOF and SOOT components deposited on the DPF are calculated from the difference between the discharge amount and the regeneration amount of the SOF component and the SOOT component, and the accumulated amount of the calculated value with time is obtained to obtain the deposit amount of the SOF component and the SOOT component.

Next, in step S12, it is corrected on the basis of the SOF deposition amount calculated in step S11 to the outlet temperature _{T B} of DOC5. As described above, this correction is performed by the SOF accumulation amount correction means 54 by setting the correction coefficient J as a function of the exhaust gas temperature that has passed through the DOC 5, and the corrected SOF component (Qsg) is Qsg = Qs × J ( T) (0 to 0.2 ≦ J ≦ 1) is calculated and corrected so that a part of the SOF deposition amount is reduced by oxidation combustion in the process of passing through the DOC 5.

Next, in step S13, it is determined whether the outlet temperature of DPF7 exceeds the reference value T _C, the flow proceeds further to step S14 if it does, if not exceeded, the process proceeds to step S6. The outlet temperature of the DPF 7 is detected by the DPF outlet temperature sensor 11.

In step S14, the time _{T time} in a state where the outlet temperature of DPF7 a condition in step S13 is greater than the reference value _{T C is,} to determine exceeds _{T Timed,} if it exceeds the step S15 Then, the corrected SOF deposition amount calculated in step S12 is reset to zero, and the process proceeds to step S6. That is, even when the total accumulation amount is calculated and determined by the sum of the accumulation amounts of SOOT and corrected SOF, the outlet temperature of the DPF 7 becomes a temperature at which the SOF component volatilizes, for example, approximately 300 ° C. or more, If this state is maintained for a certain period of time, it is assumed that it has become zero after volatilization or oxidation combustion, and the corrected SOF deposition amount is reset to zero in step S15, and the total deposition amount is determined only by the amount of SOOT. To do.

  Next, in step S6, it is determined whether or not the sum Q of the calculated amount of SOOT and SOF exceeds the reference value QA. If so, the regeneration process of the DPF 7 is started in step S7. In step S7, if the reference value QA is not exceeded, the process returns to step S2 and is repeated from the beginning.

According to the second embodiment as described above, the purification amount due to oxidative combustion by the catalytic reaction of the DOC (diesel oxidation catalyst) provided upstream of the DPF is calculated from the accumulated amount of SOF calculated by the map or calculating means. Since the reproduction time is determined based on the corrected SOF and the calculated SOOT, the reproduction time can be accurately determined.
Furthermore, since the SOOT amount or the PM deposition amount can be accurately estimated using the differential pressure sensor 13 without detecting the differential pressure across the DPF 7 as in the first embodiment, the system and logic are simplified.

Further, at a temperature exceeding about 300 ° C. at which the DOC 5 has a sufficient SOF oxidation combustion function, the SOF content is mostly volatilized or oxidized combustion, and the DPF 7 assumes that all the particulates are SOOT, and the deposition amount can be estimated. In addition, at a temperature having a sufficient SOF oxidation combustion function in DOC5 (approximately 300 ° C.) or less, the regeneration time is estimated by the sum of the SOOT amount calculated by the map and the calculating means and the corrected SOF amount. Therefore, it is possible to accurately determine the reproduction time in consideration of the volatile matter.
Note that a highly accurate reproduction time determination device may be configured by combining the first embodiment and the second embodiment.

(Third embodiment)
Next, the SOOT regeneration amount map 29 in the first and second embodiments is a three-dimensional map in which the regeneration amount of SOOT is set with respect to the inlet temperature of the DPF 7 and the exhaust gas flow rate flowing through the DPF 7. However, in the third embodiment, the SOOT regeneration amount map 61 is set so that the SOOT regeneration amount is obtained for the inlet temperature of the DPF 7 and the nitrogen dioxide (NO ₂ ) concentration in the DPF 7. Yes.

As shown in FIG. 8, the exhaust gas flow rate nitrogen dioxide (NO ₂ ) concentration is determined based on the NO ₂ conversion rate map 63 based on the exhaust gas flow rate flowing through the DPF 7 and the DOC inlet temperature from the DOC inlet temperature sensor 17. The NO ₂ conversion rate is calculated.
On the other hand, with NO _x emissions amount map 65 NOx concentration is calculated based on the rotational speed and the load signal of the engine operating condition, by said NOx concentration and the NO ₂ conversion, the nitrogen dioxide (NO ₂₎ concentration calculate.

In the present embodiment, since the SOOT regeneration amount is calculated based on the nitrogen dioxide (NO ₂ ) concentration, that is, nitrogen dioxide (NO ₂ ) burns the SOOT component (mostly carbon) at a low temperature. In addition, a high-precision SOOT regeneration amount can be estimated by estimating based on the nitrogen dioxide (NO ₂ ) concentration as an index directly related to the SOOT deposition amount.
Further, when the engine is changed, it is only necessary to change the NO _x emission map 65, so that the engine can be easily changed.

(Fourth embodiment)
Next, in the third embodiment, the SOOT regeneration amount map 61 is a three-dimensional map in which the regeneration amount of SOOT is set with respect to the inlet temperature of the DPF 7 and the exhaust gas flow rate flowing through the DPF 7. In the fourth embodiment, the SOOT regeneration amount is directly calculated using the relational expression S = f (NO ₂ + O ₂ + exhaust gas flow rate (LV) + DPF temperature (T)) for SOOT regeneration without using a map. .

That is, as shown in FIG. 9, the exhaust gas flow velocity (LV), the DOC inlet temperature (T) from the DOC inlet temperature sensor 17, the nitrogen dioxide (NO ₂ ) concentration, and the oxygen (O ₂ ) concentration in the exhaust gas It is calculated by a SOOT combustion rate equation using as a parameter.
The calculation of the nitrogen dioxide (NO ₂ ) concentration is the same as that in the third embodiment, and the calculation of the oxygen (O ₂ ) concentration is performed by using the O ₂ emission map 67 and the engine speed and load signals. Is calculated based on

According to this embodiment, as a calculation means for regeneration amount of SOOT, since estimates based on nitrogen dioxide (NO ₂₎ concentration, i.e., nitrogen dioxide (NO ₂₎ is SOOT component (mostly carbon) burning at low temperature Therefore, a highly accurate SOOT regeneration amount can be estimated by estimating based on the nitrogen dioxide (NO ₂ ) concentration as an index directly related to the SOOT deposition amount.
Further, unlike the third embodiment, a map is not required to be created, and the calculation is performed directly from the relational expression, so that a more detailed calculation than the map can be performed.

  According to the present invention, it is possible to accurately estimate the SOOT deposition amount and the PM amount, which are important factors in determining the DPF regeneration timing, by correcting the decrease in the deposition amount due to the volatilization and oxidation combustion of the SOF constituting the PM. Therefore, the DPF regeneration timing can be determined with high accuracy, which is suitable for a DPF regeneration timing determination method and apparatus.

1 is an overall configuration diagram of an exhaust gas aftertreatment device installed in an exhaust passage of a diesel engine. 1 is a block diagram illustrating a configuration of a regeneration time determination device according to a first embodiment. FIG. 3 is a flowchart of a regeneration time determination method according to the first embodiment. It is explanatory drawing of the correction coefficient which concerns on 1st Embodiment. It is explanatory drawing explaining the effect of 1st Embodiment. It is a block diagram of the configuration of the regeneration time determination device according to the second embodiment. It is a flowchart of the reproduction | regeneration time determination method which concerns on 2nd Embodiment. It is a block diagram of the configuration of a regeneration time determination device according to a third embodiment. It is a block diagram of the configuration of the regeneration time determination device according to the fourth embodiment. It is explanatory drawing which shows the prior art of the deposition amount detection by the differential pressure before and behind DPF.

Explanation of symbols

1 Exhaust passage 3 Exhaust gas aftertreatment device 5 DOC (diesel oxidation catalyst)
7 DPF (diesel particulate filter)
9 DPF inlet temperature sensor 11 DPF outlet temperature sensor 13 Differential pressure sensor 21, 60 Regeneration time determination device 23 SOF discharge map 25 SOOT discharge map 27 SOF regeneration map 29, 61 SOOT regeneration map 31, 50 Calculation of SOF accumulation means
33, 52 SOOT deposition amount calculation means 35, 54 SOF deposition amount correction means 39 SOOT / SOF ratio calculation means 41 SOOT / SOF ratio map 63 NO ₂ conversion rate map 65 NO _x emission amount map 67 O ₂ emission amount map

Claims (12)

An exhaust gas aftertreatment device for a diesel engine provided with a DPF (diesel particulate filter) for collecting PM (particulate matter) in an exhaust passage of the internal combustion engine is provided, and a regeneration timing for burning and removing the PM deposited on the DPF is provided. In the DPF regeneration timing determination device for determining,
The SOF emission map that sets the amount of SOF (flammable organic matter) consisting of oil and unfueled fuel in PM with respect to the engine operating state, and the amount of SOOT (black smoke) in PM SOOT emission amount map set for the operating state, SOF regeneration amount map in which the regeneration amount for the SOF at the exhaust gas temperature in the DPF is set, and SOOT regeneration for calculating the regeneration amount for the SOOT in the exhaust gas temperature at the DPF A quantity calculating means,
The SOF and SOOT components accumulated in the DPF are calculated from the difference between the SOF and SOOT emission amounts calculated by the respective maps and the calculation means and the regeneration amount, and the accumulated amount of the calculated values over time is obtained to obtain the SOF component and the SOT component. SOF deposition amount calculation means and SOOT deposition amount calculation means for obtaining a deposition amount for the SOT, and the SOF calculated by the SOF deposition amount calculation means is volatilized or oxidized with a time delay depending on the temperature history of the DPF during engine operation. SOF deposition amount correction means for correcting the amount of combustion, and regeneration determination means for determining the regeneration timing of the DPF based on the corrected SOF deposition amount and the calculated SOOT deposition amount DPF regeneration time determination device.   The relationship between the SOOT / SOF ratio calculating means for calculating the ratio between the corrected SOF deposition amount and the SOOT deposition amount, and the relationship between the differential pressure before and after the DPF and the SOOT deposition amount with the SOOT / SOF ratio as a parameter for each exhaust gas temperature is set in advance. And a detected value from a differential pressure sensor that detects a differential pressure before and after the DPF, a detected value from an exhaust gas temperature sensor, and a SOOT / corrected SOF ratio by the SOOT / SOF ratio calculating means. 2. The DPF regeneration timing determination apparatus according to claim 1, wherein a deposit amount for SOOT is calculated using the SOOT / SOF ratio map based on the calculated value, and the regeneration timing is determined based on the SOOT component.   3. The DPF regeneration timing determination device according to claim 2, wherein the corrected SOF accumulation amount is obtained by multiplying the SOF accumulation amount by a correction coefficient to correct the volatile or oxidative combustion amount of the SOF.   The correction coefficient is different depending on whether the DPF has a temperature increase history or a temperature decrease history, and the correction coefficient is set to a smaller value than the temperature decrease history. The DPF regeneration time determination device according to claim 3. An exhaust gas aftertreatment device for a diesel engine provided with a DPF (diesel particulate filter) for collecting PM (particulate matter) in an exhaust passage of the internal combustion engine is provided, and a regeneration timing for burning and removing the PM deposited on the DPF is provided. In the DPF regeneration timing determination device for determining,
The SOF emission map that sets the amount of SOF (flammable organic matter) consisting of oil and unfueled fuel in PM with respect to the engine operating state, and the amount of SOOT (black smoke) in PM SOOT emission amount map set for the operating state, SOF regeneration amount map in which the regeneration amount for the SOF at the exhaust gas temperature in the DPF is set, and SOOT regeneration for calculating the regeneration amount for the SOOT in the exhaust gas temperature at the DPF A quantity calculating means,
The SOF and SOOT components accumulated in the DPF are calculated from the difference between the SOF and SOOT emission amounts calculated by the respective maps and the calculation means and the regeneration amount, and the accumulated amount of the calculated values over time is obtained to obtain the SOF component and the SOT component. SOF deposition amount calculation means and SOOT deposition amount calculation means for determining the deposition amount for SOT, and the SOF calculated by the SOF deposition amount calculation means is based on a catalytic reaction of a DOC (diesel oxidation catalyst) provided upstream of the DPF. SOF deposition amount correction means for correcting the purification amount due to oxidative combustion, and regeneration determination means for determining the regeneration timing of the DPF based on the corrected SOF deposition amount and the calculated SOOT deposition amount. A DPF regeneration time determination device as a feature.   When the outlet temperature of the DOC provided upstream of the DPF is equal to or lower than a preset threshold value, the regeneration time is determined by the sum of the corrected SOF and SOOT, and when the threshold is exceeded, the regeneration time is determined by the SOOT. 6. The DPF regeneration timing determination device according to claim 5, wherein the determination is performed. The SOOT regeneration amount calculating means, nitrogen dioxide at DPF temperature and DPF (NO ₂₎ concentration of the claims 1 or 5, wherein the composed is constituted by a set map to SOOT regeneration amount is calculated DPF regeneration time determination device. The SOOT regeneration rate calculation means uses a DOT temperature (T), an exhaust gas flow rate (Q) flowing into the DPF, a nitrogen dioxide (NO ₂ ) concentration and an oxygen (O ₂ ) concentration in the exhaust gas as parameters. 6. The DPF regeneration time determination device according to claim 1, wherein the DPF regeneration time determination device is calculated by: An exhaust gas aftertreatment device for a diesel engine provided with a DPF (diesel particulate filter) for collecting PM (particulate matter) in an exhaust passage of the internal combustion engine is provided, and a regeneration timing for burning and removing the PM deposited on the DPF is provided. In the DPF regeneration timing determination method for determining,
Emission amount of SOF (combustible organic matter) consisting of oil and unfueled fuel in PM is calculated by SOF emission map set for engine operating condition, and SOOT (black smoke) emission in PM The amount is calculated by the SOOT emission map set for the engine operating state, the regeneration amount of the SOF at the exhaust gas processing temperature in the DPF is calculated by the SOF regeneration map, and the SOOT component at the exhaust gas processing temperature in the DPF is calculated. Is calculated by the SOOT regeneration amount calculation means, and the SOF and SOOT components deposited on the DPF are calculated from the difference between the calculated SOF and SOOT emissions and the regeneration amount, and the calculated values are accumulated over time. The amount of SOF and SOOT is calculated by calculating the amount of SOF, and the SOF of the calculated SOF is added to the temperature history of the DPF during engine operation. Zui corrects the amount of volatilization or oxidative combustion with a time lag, DPF regeneration timing judging method characterized by determining the regeneration timing by using the SOOT worth of the calculated and SOF component was the correction.   The ratio between the SOOT component and the corrected SOF component is calculated, and a SOOT / SOF ratio map in which the relationship between the differential pressure across the DPF and the SOOT deposition amount is set in advance for each exhaust gas temperature using the SOOT / SOF ratio as a parameter is prepared. Then, based on the detected value from the differential pressure sensor, the detected value from the exhaust gas temperature sensor, and the calculated value of the SOOT / corrected SOF ratio, the deposition amount of SOOT is calculated using the SOOT / SOF ratio map, 10. The DPF regeneration timing determination method according to claim 9, wherein the regeneration timing is determined based on the SOOT amount. An exhaust gas aftertreatment device for a diesel engine provided with a DPF (diesel particulate filter) for collecting PM (particulate matter) in an exhaust passage of the internal combustion engine is provided, and a regeneration timing for burning and removing the PM deposited on the DPF is provided. In the DPF regeneration timing determination method for determining,
Emission amount of SOF (combustible organic matter) consisting of oil and unfueled fuel in PM is calculated by SOF emission map set for engine operating condition, and SOOT (black smoke) emission in PM The amount is calculated by the SOOT emission map set for the engine operating state, the regeneration amount of the SOF at the exhaust gas processing temperature in the DPF is calculated by the SOF regeneration map, and the SOOT component at the exhaust gas processing temperature in the DPF is calculated. Is calculated by the SOOT regeneration amount calculation means, and the SOF and SOO components deposited on the DPF are calculated from the difference between the calculated SOF and SOOT emissions and the regeneration amount, and the calculated values are accumulated over time. The amount of accumulation is calculated by calculating the amount of SOF and SOOT, and among the calculated SOF, the SOF is a DOC provided upstream of the DPF ( The amount of oxidative combustion corrected by diesel catalysis of the oxidation catalyst), DPF regeneration timing judging method characterized by determining the regeneration timing by SOOT worth of the calculated and SOF component was the correction.   When the outlet temperature of the DOC provided upstream of the DPF is equal to or lower than a preset threshold value, the regeneration time is determined by the sum of the corrected SOF component and the SOOT component. The DPF regeneration timing determination method according to claim 11, wherein the determination is performed.

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