JP2002097930A - Exhaust emission control device for internal combustion engine - Google Patents

Abstract

PROBLEM TO BE SOLVED: To execute forced regeneration in the proper timing, by precisely grasping a capture amount of particulates by continuous combustion. SOLUTION: A particulate filter capturing exhaust particulates is interposed in an exhaust passage, and in the upstream thereof, an oxidation catalyst is arranged, NO2 converted by catalytic action from NO in exhaust is utilized, continuous combustion of particulates is performed from the lower temperature. A particulate generation amount B and a combustion speed constant R corresponding to an operating condition are read from a map (step 2), this time particulate capture amount D0 is estimated by a prescribed operation expression (step 3) When this amount is increased to an upper limit value Dlmt or more, forced regeneration is started. Here in each regeneration condition comprising combination of a plurality of regeneration means, the particulate capture amount is calculated, the regeneration condition making the estimated particulate capture amount come to the smallest value is selected as that of the best efficiency.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an exhaust gas purifying apparatus for an internal combustion engine which collects and removes exhaust particulates (particulates) which are particularly problematic in a diesel engine. The present invention relates to an exhaust gas purifying apparatus which continuously burns and removes during the operation of the apparatus, and sequentially and accurately grasps the amount of trapped fine particles, and performs forced regeneration at an appropriate time when necessary. .

[0002]

2. Description of the Related Art In recent years, in diesel engines, treatment of exhaust fine particles contained in exhaust gas has become a major problem. Most of the exhaust particles are a composite of carbon and a soluble organic substance (SOF), and the size is usually about several μm to several tens μm. In order to prevent the emission of these exhaust particulates into the atmosphere,
It is effective to provide a filter that collects exhaust particulates, a so-called diesel particulate filter.
Since this type of filter causes so-called clogging with the collection of exhaust particulates, it is necessary to remove the exhaust particulates collected by some means and regenerate the filter. Is a major technical issue.

When the fine particles collected by the filter are heated to about 600 ° C. or more in the presence of oxygen, they react with oxygen and can be easily burned and incinerated, but the temperature of exhaust gas alone is generally insufficient. It is difficult to completely burn the fine particles.

For this reason, many methods for regenerating a filter using a forced heating means have been proposed.
In Japanese Utility Model Laid-Open Publication No. 1-144427, a filter is divided into two sections, an electric heater is arranged on the front of each section, and when a predetermined amount of exhaust fine particles is collected, the electric heater is energized for each section. A configuration is disclosed in which the amount of exhaust gas flowing to the section being regenerated is limited to a small amount while heating.

Japanese Patent Application Laid-Open No. Hei 6-123216 discloses a technique in which the pressure loss of a diesel particulate filter is detected by a pressure sensor, and the engine speed at that time and the total operating time since the previous forced regeneration were taken into consideration. Thus, there has been disclosed an abnormality detection device which detects abnormal clogging, breakage of a filter element, and the like.

Japanese Patent Application Laid-Open No. 11-13455 discloses that the amount of generated particulates is detected with high accuracy in accordance with the operating state of the engine and the amount of generated particulates per unit time is integrated, so that the amount of the collected filter is reduced. There is disclosed a diesel particulate filter device in which the heating means is operated to regenerate the filter when the estimated value reaches a predetermined value.

On the other hand, Japanese Patent No. 3012249 discloses that
A filter regeneration method has been disclosed in which particulates trapped in a diesel particulate filter are burned at a lower exhaust gas temperature. This is because nitrogen dioxide N 2 is catalyzed by NO and O 2 in exhaust gas.
O2 is generated, and the strong oxidizing NO2 is caused to act on the exhaust particulates on the filter, thereby burning the particulates.
Combustion is possible at an exhaust temperature of about 400 ° C. Therefore, regeneration is performed continuously during operation.

[0008]

When a diesel particulate filter is forcibly regenerated by some means, it is necessary to accurately detect the amount of collected fine particles in the filter, that is, the amount of fine particles deposited on the filter. is important. Generally, when the amount of collected fine particles reaches a predetermined level, regeneration promotion such as heating by an electric heater is started, but before it reaches the predetermined level before it actually reaches the predetermined level, The number of times of heating of the filter by the heating means is unnecessarily increased, the consumption of energy such as electric power required for the heating means is increased, and the durability of the filter is reduced due to excessive repetition of heating. Conversely, if it is determined that the level of collection of fine particles of the filter reaches the predetermined level after reaching the predetermined level, the filter may be clogged and exhaust pressure loss may increase. , Fuel economy deteriorates.

In the configuration disclosed in Japanese Patent Application Laid-Open No. Hei 6-123216 and Japanese Patent Application Laid-Open No. 60-85214, the engine speed and load fluctuate with the running of the vehicle.
Since the pressure acting on the filter also fluctuates due to a change in the exhaust gas flow rate, highly accurate detection of the amount of trapped fine particles is almost impossible.

[0010] Further, in the method of paying attention to the discharge amount of the fine particles as disclosed in Japanese Patent Application Laid-Open No. 11-13455, as disclosed in the above-mentioned Japanese Patent No. 301,249, the fine particles collected by the filter are in operation. In the so-called continuous combustion system in which the particles are continuously burned, the amount of continuous removal of fine particles is not reflected, and the amount of collected fine particles cannot be accurately grasped.

According to the present invention, even in a so-called continuous combustion system, the amount of trapped fine particles remaining in a filter can be accurately grasped, and if necessary, forced regeneration is performed at an appropriate time. The purpose is to do.

[0012]

According to a first aspect of the present invention, there is provided an exhaust gas purifying apparatus for an internal combustion engine, which is disposed in an exhaust passage of the engine and collects fine particles in the exhaust gas flowing into the exhaust gas. The apparatus has a particulate collection unit removed by combustion, and a combustion model showing the combustion characteristics of the particulates collected by the particulate collection unit. The amount of particulate collection present in the particulate collection unit is determined by the combustion model. And a means for estimating the amount of trapped fine particles based on the estimated amount.

In the second aspect of the invention, which is a more specific version of the first aspect, the combustion model is a function including a burning rate constant indicating a probability that the fine particles collected by the fine particle collecting means will burn. It is characterized by having.

According to a third aspect of the present invention, the combustion model is:
The method is characterized in that the function is a function including a fine particle generation amount indicating an amount of fine particles newly collected while the fine particles collected by the fine particle collecting means is burning.

According to a fourth aspect of the present invention, the combustion rate constant is set in accordance with the state of the exhaust gas flowing into the particulate collection means.

According to a fifth aspect of the present invention, a plurality of types of regenerating means for controlling the state of the exhaust gas flowing into the fine particle collecting means to promote the regeneration of the fine particle collecting means, Playback control means for executing playback by combining one or a plurality of types of playback means,
The combustion rate constant is set for each regeneration condition comprising one or a combination of the regeneration means.

In the invention of claim 6 which embodies the invention of claim 5, the means for estimating the amount of trapped fine particles is based on a plurality of combustion rate constants corresponding to each regeneration condition. Is estimated for each regenerating condition, and the regenerating control means selects the regenerating condition corresponding to the smallest value among the plurality of estimated particulate collection amounts and executes the regenerating.

According to a seventh aspect of the present invention, the combustion rate constant is:
It is characterized in that it is set in accordance with the engine speed and the load.

According to the invention of claim 8, the combustion rate constant is:
It is characterized in that the temperature increases with an increase in the temperature of the exhaust gas flowing into the particulate collection means.

According to a ninth aspect of the present invention, the combustion rate constant is:
It is characterized in that it increases with an increase in the amount of NO2 in the exhaust gas flowing into the particulate collection means.

According to a tenth aspect of the present invention, the combustion rate constant increases with an increase in the amount of O2 in the exhaust gas flowing into the particulate collection means.

The invention of claim 11 is characterized in that the combustion rate constant increases as the flow rate of the exhaust gas flowing into the particulate collection means increases.

According to a twelfth aspect of the invention, one of the regenerating means is a means for heating the exhaust gas flowing into the fine particle collecting means when the fine particle collecting means is regenerating. It is.

According to a thirteenth aspect of the present invention, one of the regenerating means is a means for reducing the intake air amount of the engine when the particulate collecting means is regenerated.

In one embodiment of the present invention, one of the regenerating means is a means for injecting a fixed amount of fuel after the main injection of the fuel at the time of regenerating the particulate collecting means.

In one embodiment of the present invention, one of the regeneration means is a means for recirculating exhaust gas from an exhaust passage to an intake passage.

In the invention according to claim 16, an oxidation catalyst means for oxidizing NO in the exhaust gas flowing into and generating NO2 is further provided upstream of the means for trapping fine particles.

The most remarkable point in the present invention is that the amount of burned-out particulates is grasped by using a burning rate constant set in advance by experiments.

FIG. 1 shows a particulate filter in which carbon C and soluble organic substance SOF fine particles have been attached in advance in an actual internal combustion engine by using a model gas evaluation device at a constant atmosphere temperature of 300 ° C. and a constant mixed gas ( NO2 + N
2) This shows the combustion characteristics of fine particles when exposed to an atmosphere. Note that the present invention is not limited to regeneration by continuous combustion using NO2, and it goes without saying that various regeneration methods can be applied.

In FIG. 1, the vertical axis represents the production amounts of CO and CO2, and shows the behavior in which the combustion amount of the fine particles by the oxygen constituting NO2 decreases with time.

Here, the decrease in the amount of particulate burned does not become a linear change, but the amount of particulate burned per unit time after a lapse of time is greater than the amount of particulate burned per unit time immediately after the start of combustion. , Tend to be less.

This is because the amount of particulates burned per unit time is proportional to the amount of particulates on the filter (the amount of trapped particulates) (see the right side of Equation 1 described later). When the amount of trapped fine particles decreases, the amount of burning fine particles per unit time decreases, and as a result, the amount of burning fine particles per unit time gradually changes.

This indicates that, in the actual engine, the amount of fine particles burned by continuous combustion differs depending on the amount of collected fine particles even under the same operating conditions.
This is because it is difficult to grasp the amount of collected fine particles during continuous combustion.

In order to solve this problem, a combustion model showing the combustion characteristics of the fine particles trapped by the filter has been set up. This will be described below.

Assuming that the amount of collected fine particles at time t is D (t) and the probability that the fine particles collected by the filter burn in a unit time is R, the amount of the burned fine particles per unit time is multiplied by these. , RD (t). In the case of this experiment, the above combustion probability R is a constant value because the atmospheric conditions are constant.

On the other hand, the amount of change per unit time of the fine particles collected by the filter, that is, the amount of collected fine particles D (t)
Can be described as dD (t) / dt.

Since the change in the amount of trapped fine particles D (t) is a decrease due to combustion, the relationship between the amount of burned fine particles per unit time and the amount of change in fine particles per unit time is expressed by the following differential equation. Indicated by

DD (t) / dt = −R · D (t) (1) When this differential equation is solved, D (t) = A · exp (−R · t) (2) Substituting t = 0 into this equation 2, D (t = 0) = D0 = A.exp (0) = A (3) where A is the amount of collected fine particles when t = 0. D, that is, the initial fine particle collection amount D0. Therefore, from Equations 2 and 3, a combustion model is derived as follows.

D (t) = D0 · exp (−R · t) (4) Here, the above R is referred to as a combustion rate constant.

From the above findings, the combustion characteristics of the fine particles trapped by the filter are uniquely determined if the initial amount of trapped fine particles and the burning rate constant are known when the atmosphere is constant. This shows that the amount of collected fine particles over time can be predicted.

Next, from the actual experimental results, the burning rate constant R
Ask for. First, assuming that the curve observed in the experiment is G (t), this is the concentration when the burned fine particles turn into a gas, and the amount of burned fine particles is RD (t). Is obtained.

G (t) = N · R · D (t) = N · R · D0 · exp (−R · t) = G0 · exp (−R · t) (5) where N is It is a conversion coefficient to gas concentration determined for each experimental condition (gas flow rate).

When the curve obtained in the actual experiment is directly approximated to the form of Equation 5, G (t) = 408.5375 · exp (−0.000137t) (6), and R = 0.000137, G0 = 408.537
It was 5.

The correlation coefficient is as high as 0.9985, which means that there is almost no error factor for the model (for example, a phenomenon in which R changes when the amount of collected fine particles D (t) changes). Is shown.

The above equation (4) takes into account only the reduction of fine particles due to continuous combustion. This equation (4) calculates the amount of collected fine particles when it is assumed that no new particles will flow into the filter. can do. However, in an actual machine, it is necessary to take this into consideration because the particulates continuously flow into the filter even during the combustion of the particulates collected by the filter. Assuming that the amount of fine particles flowing into the filter per unit time, that is, the amount of generated fine particles of the internal combustion engine is B, the above-described Expression 1 is represented by the following Expression 7.

DD (t) / dt = BR-D (t) (7) By solving the differential equation of this equation 7, the particle collection amount D (t) at a certain time t is expressed by the following equation 8. Is done.

D (t) = (D0−B / R) · exp (−R · t) + B / R (8) Therefore, according to this equation 8, it is assumed that the inflow of new fine particles is considered. The collection amount can be estimated with high accuracy.

As another method, the amount of trapped fine particles when the fine particles continuously flow into the burning filter can be calculated using an approximate expression.

That is, when calculating the amount of trapped fine particles after a unit time, the unit time on the time axis when estimating the amount of fine particles can be treated as a very small amount. Is added to the initial particulate matter collection amount D0 in advance, and if Expression 4 is an approximate expression such as the following Expression 9, it is possible to estimate the particle collection amount in consideration of both combustion and inflow by the following expression. .

D (t) = (D0 + B) · exp (−R) (9) If the calculation interval at the time of the estimation in the actual engine control unit is, for example, about 1 second, the results obtained by Expressions 8 and 9 are obtained. Are almost equal. In general, Equation 9 requires a smaller amount of calculation, and the calculation load on the engine control unit is smaller.

Next, the relationship between the burning rate constant R and the atmosphere during burning will be described.

As described above, the physical meaning of the burning rate constant R is the burning probability of fine particles. Therefore, if the atmosphere during burning changes, the burning probability changes, and the burning rate constant R also changes. It can be said that the larger the burning rate constant R, the faster the burning rate when compared with the same amount of collected fine particles.

2 to 5 show the relationship between various atmospheric conditions and the burning rate constant R.

FIG. 2 shows the relationship with the ambient temperature. The combustion rate constant R increases as the temperature increases. From this figure, it can be seen that the combustion of fine particles by oxygen constituting NO2 starts at around 200 ° C.
It can be seen that the temperature starts around ℃. Also, the reason that the combustion with O2 has a steeper slope is that in this experiment, the O2 concentration was N
This is because the O2 concentration is 500 times.

FIG. 3 shows the relationship with the NO2 concentration. The combustion rate constant R increases as the NO2 concentration increases.

FIG. 4 shows the relationship with the O2 concentration.
The combustion rate constant R increases as the O2 concentration increases.

FIG. 5 shows the relationship with the space velocity SV of the filter. The combustion velocity constant R increases as the space velocity SV increases.

In the actual machine, the above-mentioned atmospheric conditions and the quality of the fine particles change in various combinations due to the control for forcibly promoting the regeneration of the filter. These relationships are summarized as follows. Become. That is, the left parameter is affected by the right parameter associated with the playback control. Then, in response to the change of the left parameter, the combustion rate constant R changes according to the above-described tendency.

Temperature: Post injection amount, energization temperature rise, intake throttle NO2 amount: EGR amount, temperature (=) O2 amount: EGR amount Exhaust flow rate: intake throttle

[0060]

According to the present invention, it is possible to successively and accurately estimate the amount of collected fine particles by the fine particle collecting means based on the combustion rate constant determined from the combustion model. Even in a continuous combustion system in which the combustion of fine particles is performed, the amount of collected fine particles can be reliably estimated. Therefore, when some kind of regeneration control is performed when the amount of trapped fine particles reaches a predetermined level, the regeneration control can be started at an appropriate timing.

In particular, according to the third aspect of the present invention, the amount of trapped fine particles can be accurately estimated in consideration of the amount of newly introduced fine particles during regeneration.

Further, according to the invention of claims 5 to 11, by setting the combustion rate constant in advance according to the means for promoting regeneration, the change in the amount of collected fine particles due to regeneration can be more accurately determined. It becomes possible to grasp.

[0063]

Next, an embodiment of the present invention will be described.

FIG. 6 is a structural explanatory view showing one embodiment of a diesel engine provided with the exhaust gas purifying apparatus according to the present invention. In the exhaust gas passage 2 connected to the engine body 1, carbon
A particulate filter 3 for trapping exhaust particulates mainly composed of water and soluble organic substance SOF is interposed, and an oxidation catalyst 4 is disposed upstream of the filter 3. The oxidation catalyst 4 functions to convert NO in the exhaust gas to NO2, and the NO2 comes in contact with the fine particles collected on the filter 3, thereby enabling continuous combustion of the fine particles from a lower temperature. ing. In addition, the intake passage 5
Is provided with an intake throttle valve 6 for suppressing the intake flow rate and hence the exhaust flow rate. As an exhaust gas recirculation device, an exhaust gas recirculation passage 7 is provided from the exhaust gas passage 2 to the intake passage 5, and an exhaust gas recirculation control valve 8 for variably controlling the exhaust gas recirculation rate is provided.

This diesel engine is provided with a so-called common rail type fuel injection device 9. That is, the fuel in the fuel tank 10 is stored in the common rail 11 in a state of being pressurized to a high pressure, and is injected from the fuel injection nozzle 12.

Further, the filter 3 is provided with an electric heater 18 at an appropriate position in order to increase the temperature.

The fuel injection nozzle 12, the exhaust gas recirculation control valve 8, the intake throttle valve 6, the additive control valve 14, and the electric heater 18
Are appropriately controlled by the engine control unit 15 as a reproducing means. The engine control unit 15 receives various detection signals from the rotation speed sensor 16, the accelerator opening sensor 17, and the like, which indicate engine operating conditions. The estimation of the amount of collected fine particles and the regeneration control are performed.

FIG. 7 is a numerical graph in which the particle generation amount (production amount per unit time) B corresponding to the engine operating conditions, specifically, the engine speed and the fuel flow rate is obtained in advance through experiments or the like and assigned. FIG. 8 is a numerical graph in which the combustion rate constant R corresponding to the engine speed and the fuel flow rate is obtained in advance through experiments or the like and assigned.

Next, the continuous regeneration control in the exhaust gas purifying apparatus of this embodiment will be described.

FIG. 9 shows the engine control unit 1.
5 is a flowchart showing a routine for estimating the amount of trapped fine particles in FIG. This routine is repeatedly executed by the engine control unit 15 at one-second intervals.

First, in step 1, each sensor signal is read. The engine speed at that time is indicated by a suffix a, and the accelerator opening is indicated by a suffix b. next,
In step 2, the particulate generation amount Bab and the burning rate constant Rab corresponding to the current engine operating state are calculated by using FIGS. 7 and 8.
From the characteristic map.

Then, in step 3, the trapped amount D0 of the fine particles is estimated based on the above-mentioned formula 9 using the generated amount Bab of the fine particles and the burning rate constant Rab. In step 3, it is assumed that all of the fine particles discharged from the engine are collected by the particulate filter 3. However, since the actual collection rate is about 90% of the generated amount, the accuracy is higher. In order to increase the value, it is desirable to calculate the generation amount Bab after correcting the collection ratio by multiplying the value of the generation amount Bab obtained from the map by the collection ratio ηpm, and calculate the particle collection amount D0 from this. Alternatively, the value of the generation amount Bab preset in the map of FIG. 7 may be set as a value in consideration of the collection rate.

In step 4, it is determined whether or not the amount of trapped particulate D0 calculated in step 3 is lower than a predetermined upper limit Dlmt. This upper limit value Dlmt is set to a level at which adverse effects on engine operation due to clogging of the filter 3 become significant. Here, if Yes, this routine for estimating the amount of trapped fine particles is repeated. On the other hand, if it exceeds the upper limit value Dlmt, the routine proceeds to the routine of FIG. 20 for selecting a control in which fine particles are more easily burned and removed.

The routine of FIG. 20 is also repeatedly executed by the engine control unit 15 every second.

First, in step 11, each sensor signal is read. Next, in step 12, using the combustion rate constant R and the particulate generation amount B set for each of the plurality of regeneration conditions, the particulate collection amount Zx when some regeneration means are applied is calculated. That is, FIG. 10 is a numerical graph in which the particulate matter generation amount BE corresponding to the engine speed and the fuel flow rate under the condition of the exhaust gas recirculation is obtained in advance by experiment or the like and assigned, and FIG. 9 is a numerical graph in which a combustion rate constant RE corresponding to the engine speed and the fuel flow rate under the conditions performed is obtained in advance through experiments and the like and assigned. Similarly, FIG. 12 and FIG. 13 are numerical graphs of the particulate generation amount BEP and the burning rate constant REP under the condition of performing exhaust gas recirculation and post-injection (additional fuel injection in the latter stage of the combustion stroke). FIG. 15 is a numerical graph of the particulate generation amount BEPI and the combustion rate constant REPI under the conditions of exhaust gas recirculation, post-injection, and intake throttling. FIGS. 16 and 17 show the conditions of exhaust gas recirculation and intake throttling. Numerical graphs of the particle generation amount BEI and the combustion rate constant REI below, and FIGS. 18 and 19 show the particle generation amount BEK and the combustion under the condition that the exhaust gas is recirculated and the temperature is increased by energizing the electric heater 18. It is a numerical graph of a speed constant REK. That is, the fine particle generation amount B
And the subscripts E, P, I, K and L of the combustion rate constant R are
E: EGR, P: post injection, I: intake throttle, K: energization temperature rise, respectively.

In step 12, the amount of collected fine particles Zx under the respective regeneration conditions is estimated on the basis of the aforementioned equation 9 using the generated amount of fine particles B and the burning rate constant R. It should be noted that the above-mentioned combination of the reproducing means is only an example, and other combinations of the reproducing means or each reproducing means can be used alone.

After obtaining a plurality of fine particle collection amounts Zx in step 12 as described above, in step 13 the smallest one is selected. The regeneration condition (combination of regeneration means) at which the amount of collected fine particles Zx is the minimum is the regeneration condition under which the filter 3 can be regenerated with the highest efficiency under the operating conditions at that time. Therefore, the energization of the selected reproducing unit, for example, the electric heater 18 is performed by another routine not shown.

The flowchart of FIG. 21 shows a routine for estimating the amount of trapped fine particles Zx performed during the execution of the forced regeneration means. This routine is repeatedly executed by the engine control unit 15 at one-second intervals.

First, in step 21, each sensor signal is read. Next, step 22
And the amount of generated fine particles BXa corresponding to the current engine operating state.
b and the burning rate constant RXab are obtained from the corresponding maps in FIGS. This is, of course, the reproduction condition selected as the optimal one in step 13, that is, the value of the map corresponding to the reproducing means being executed.

Then, in step 23, the trapped amount D0 of the fine particles is estimated based on the above-mentioned equation 9 using the generated amount BXab of the fine particles and the burning rate constant RXab. It is desirable to consider the collection rate ηpm of the filter 3,
This is the same as the case described above.

In step 24, the particulate matter collection amount D0 calculated in step 23 is 30% of the predetermined upper limit Dlmt.
Is determined to be lower than the value of. This value corresponds to a level at which it can be considered that the regeneration of the filter 3 has been sufficiently performed. Here, if NO, this particulate collection amount estimation routine is repeated while continuing the regenerating means such as energizing the electric heater 18. On the other hand, when it becomes lower than the value of Dlmt · 0.3, the process returns to the routine for estimating the amount of trapped fine particles in the normal continuous combustion shown in FIG. Then, in this case, the energization of the reproducing means, for example, the electric heater 18, which is being executed, is stopped by another routine (not shown).

[Brief description of the drawings]

FIG. 1 is a characteristic diagram showing a particulate combustion behavior in a particulate filter to which fine particles are adhered.

FIG. 2 is a characteristic diagram showing a relationship between an ambient temperature and a burning rate constant R.

FIG. 3 is a characteristic diagram showing a relationship between a NO2 concentration and a combustion rate constant R.

FIG. 4 is a characteristic diagram showing a relationship between an O2 concentration and a burning rate constant R.

FIG. 5 is a characteristic diagram showing a relationship between a relationship between a filter volume SV and a combustion rate constant R.

FIG. 6 is a configuration explanatory view of a diesel engine provided with the exhaust gas purification device according to the present invention.

FIG. 7 is a numerical graph of a particulate generation amount B corresponding to an engine speed and a fuel flow rate.

FIG. 8 is a numerical graph of a combustion rate constant R corresponding to an engine speed and a fuel flow rate.

FIG. 9 is a flowchart showing a routine for estimating the amount of trapped fine particles during continuous combustion.

FIG. 10 is a numerical graph of a particulate matter generation amount BE corresponding to an engine speed and a fuel flow rate under the condition of exhaust gas recirculation.

FIG. 11 is a numerical graph of a combustion rate constant RE corresponding to an engine speed and a fuel flow rate under conditions of exhaust gas recirculation.

FIG. 12 is a numerical graph of a particulate generation amount BEP under the conditions of exhaust gas recirculation and post-injection.

FIG. 13 is a numerical graph of a combustion rate constant REP under the conditions of exhaust gas recirculation and post-injection.

FIG. 14 is a numerical graph of the fine particle generation amount BEPI under the conditions of exhaust gas recirculation, post injection, and intake throttle.

FIG. 15 is a numerical graph of a combustion rate constant REPI under the conditions of exhaust gas recirculation, post-injection, and intake throttle.

FIG. 16 is a numerical graph of a particulate generation amount BEI under a condition in which exhaust gas recirculation is performed and an intake throttle is performed.

FIG. 17 is a numerical graph of a combustion rate constant REI under the condition of performing exhaust gas recirculation and performing intake throttle.

FIG. 18 is a diagram illustrating the amount BEK of fine particles generated under the condition that the exhaust gas is recirculated and the temperature is increased by energizing the electric heater 18.
Numerical chart.

FIG. 19 shows a combustion rate constant REK under the condition that the exhaust gas is recirculated and the temperature is increased by energizing the electric heater 18.
Numerical chart.

FIG. 20 is a flowchart showing a routine for selecting a reproduction condition.

FIG. 21 is a flowchart showing a routine for estimating the amount of trapped fine particles during regeneration by the regeneration unit.

[Description of Signs] 3 ... Particulate filter 4 ... Oxidation catalyst 6 ... Intake throttle valve 7 ... Exhaust recirculation passage 9 ... Fuel injection device 15 ... Engine control unit 18 ... Electric heater

──────────────────────────────────────────────────続 き Continued on the front page (51) Int.Cl. ⁷ Identification symbol FI Theme coat ゛ (Reference) F01N 3/02 341 F01N 3/02 341M B01D 46/42 B01D 46/42 B F01N 3/24 F01N 3/24 E F02M 25/07 570 F02M 25/07 570J 570D F term (reference) 3G062 AA01 BA00 BA04 BA06 FA04 GA04 GA06 GA11 GA15 3G090 BA01 BA04 CA01 CB00 DA18 DA20 EA02 EA06 EA07 3G091 AA11 DB04 DB02 DB13 DB13 DC01 DC07 EA01 EA07 EA20 EA21 HA15 HB05 4D058 MA41 MA42 MA51 MA54 SA08 TA06

Claims (16)

[Claims] A particulate collection means disposed in an exhaust passage of an engine for collecting particulates in exhaust gas flowing into the exhaust gas and removing the collected particulates by combustion; A combustion model indicating combustion characteristics of the collected fine particles, and a fine particle collection amount estimating means for estimating the fine particle collection amount present in the fine particle collecting means based on the combustion model. An exhaust gas purification device for an internal combustion engine. 2. The exhaust of an internal combustion engine according to claim 1, wherein the combustion model is a function including a burning rate constant indicating a probability that the fine particles collected by the fine particle collecting means burn. Purification device. 3. The combustion model is a function including a fine particle generation amount indicating an amount of fine particles newly collected while the fine particles collected by the fine particle collecting means are burning. The exhaust gas purifying apparatus for an internal combustion engine according to claim 1 or 2. 4. The exhaust gas purifying apparatus for an internal combustion engine according to claim 2, wherein said combustion rate constant is set according to a state of exhaust gas flowing into said particulate collecting means. 5. A plurality of types of regenerating means for controlling the state of exhaust gas flowing into the particulate collecting means to promote the regeneration of the particulate collecting means, and one or more of the plurality of types of regenerating means. 3. A regeneration control means for performing regeneration in combination, wherein the combustion rate constant is set for each regeneration condition consisting of one or a combination of the regeneration means. An exhaust gas purification device for an internal combustion engine. 6. The particulate collection amount estimating means estimates the particulate collection amount for each regeneration condition based on a plurality of combustion rate constants corresponding to each regeneration condition. The exhaust gas purifying apparatus for an internal combustion engine according to claim 5, wherein the regeneration is performed by selecting a regeneration condition corresponding to a smallest value among the plurality of estimated particulate collection amounts. 7. The combustion rate constant according to claim 2, wherein the combustion rate constant is set according to an engine speed and a load.
An exhaust gas purification device for an internal combustion engine according to any one of the above. 8. The exhaust gas purifying apparatus for an internal combustion engine according to claim 4, wherein the combustion rate constant increases as the temperature of the exhaust gas flowing into the particulate collection means increases. 9. The exhaust gas purifying apparatus for an internal combustion engine according to claim 4, wherein the combustion rate constant increases as the amount of NO2 in the exhaust gas flowing into the particulate collection means increases. 10. The exhaust gas purifying apparatus for an internal combustion engine according to claim 4, wherein the combustion rate constant increases as the amount of O2 in the exhaust gas flowing into the particulate collection means increases. 11. The exhaust gas purifying apparatus for an internal combustion engine according to claim 4, wherein said combustion rate constant increases as the flow rate of exhaust gas flowing into said particulate collection means increases. 12. The internal combustion engine according to claim 5, wherein one of the regenerating means is a means for heating exhaust gas flowing into the fine particle collecting means when the fine particle collecting means is regenerated. Engine exhaust purification device. 13. The exhaust gas purifying apparatus for an internal combustion engine according to claim 5, wherein one of the regenerating means is a means for reducing an intake air amount of the engine when the particulate collecting means is regenerated. . 14. The internal combustion engine according to claim 5, wherein one of said regenerating means is means for injecting a fixed amount of fuel after main injection of fuel when regenerating said particulate trapping means. Engine exhaust purification device. 15. The exhaust gas purifying apparatus for an internal combustion engine according to claim 5, wherein one of the regenerating means is a means for recirculating exhaust gas from an exhaust passage to an intake passage. 16. An apparatus according to claim 1, further comprising an oxidation catalyst means for oxidizing NO in the inflowing exhaust gas to generate NO2, on an upstream side of said particulate collection means.
16. The exhaust gas purification device for an internal combustion engine according to any one of claims 15 to 15.