JPH05312022A - Exhaust emission control device for internal combustion engine - Google Patents

Abstract

PURPOSE:To prevent overheating damage of the filter at the regeneration time by accurately obtaining a combustible rate of the particulate after regeneration through fuzzy resoning, minutely correcting a regeneration timing, and avoiding excessive capturing of the particulates. CONSTITUTION:In an exhaust emission control device, particulates in exhaust gas is captured by a filter F, the particulates are ignited by a heating means H with a specified timing, and the filter is regenerated through combustion of supplied regenerating gas. A combustible rate estimating means A fuzzy reasons a combustible rate of the particulates after regeneration of the filter F based on condition parameters of each part of an internal combustion engine. A regeneration timing correcting means B corrects the next regeneration timing according to the estimated combustible rate. As a result, regeneration is executed at a proper timing preventing excessive increase of a temperature at the regeneration time of the filter, and preventing the damage of the filter.

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, and more particularly to estimating a residual amount of unburned particulates after regeneration of a filter for collecting and removing particulates contained in exhaust gas of a diesel engine. , An exhaust gas purifying apparatus for an internal combustion engine capable of correctly executing the following filter regeneration.

[0002]

2. Description of the Related Art Exhaust gas from internal combustion engines such as automobiles, especially diesel engines, contains exhaust particulates (particulates) containing carbon as a main component, which is a cause of exhaust black smoke. From the viewpoint of environmental pollution, it is desirable to remove this particulate, and in recent years, it has been proposed to dispose a diesel filter with a ceramic filter in the exhaust passage of the diesel engine.

[0003] In an exhaust emission control device configured to remove diesel particulates by a ceramic filter arranged in an exhaust passage of a diesel engine, particulates trapped inside the diesel particulates when the particulate filter is used. When the amount of the particulate matter increases, the air permeability is gradually lost and the engine performance deteriorates. Therefore, it is necessary to periodically regenerate the filter in which the particulates are trapped to some extent. Regeneration of this filter is performed by energizing an electric heater or igniting a burner to ignite the particulates collected by the filter, regenerating gas,
For example, it is performed by supplying secondary air and burning it.

The judgment of the regeneration time is based on the mileage of the engine,
Although it may be performed based on the operating time of the engine, etc., in general, in a conventional exhaust gas purification apparatus for an internal combustion engine, the gas permeability of the particulate filter is lost and the pressure of the exhaust gas on the upstream side of the filter is reduced to the downstream side. When the pressure becomes larger than a predetermined value by a predetermined value or more (when the pressure loss becomes a predetermined value or more), it is detected by the pressure sensor, and the particulate regeneration process is performed.

However, since the regeneration process of the particulate filter is propagation combustion, it depends on various conditions during regeneration.
The particulates trapped in the filter may remain unburned without burning. In such a case, the unburned particulate matter is added to the amount of newly collected particulate matter, and the filter temperature rises during the next regeneration, which may cause cracking or melting of the filter. ..

Therefore, the combustion temperature is monitored during regeneration of the particulate filter, and even if the combustion temperature of the filter is within an appropriate range, the pressure loss Δ immediately after the completion of the regeneration process (after recombustion).
There has been proposed a device (Japanese Patent Laid-Open No. 3-18614) that increases and corrects the pressure loss value for determining the next regeneration process when P is equal to or greater than a set value.

[0007]

However, in the conventional technique for correcting the pressure loss value for starting the next regeneration processing by determining the unburned amount by the combustion temperature at the time of filter regeneration or the pressure loss immediately after the regeneration processing, For example, when the filter temperature is near the set temperature such as 590 ° C. when the set temperature is 600 ° C., the regeneration is determined to be unsuccessful, and even if the filter pressure loss value immediately after the regeneration is measured, there is an error depending on the engine operating conditions. However, since the amount of unburned fuel cannot be accurately determined, it is not possible to make a fine correction of the regeneration timing determination based on the filter regeneration condition, and the next particulate filter regeneration process may not be performed normally.

Therefore, the present invention solves the problems of the conventional exhaust gas purifying apparatus for an internal combustion engine, accurately determines the amount of unburned particulates after regeneration of the particulate filter by fuzzy reasoning, and corrects the regeneration time. It is an object of the present invention to provide an exhaust gas purification device capable of avoiding excessive collection of particulates by finely correcting the temperature, preventing overheating of the particulate filter during regeneration, and preventing damage to the particulate filter. To do.

[0009]

FIG. 1 shows the configuration of an exhaust gas purifying apparatus for an internal combustion engine according to the present invention which achieves the above object.
As shown in FIG. 1, the exhaust gas purification apparatus for an internal combustion engine of the present invention collects particulates in the exhaust gas by a filter F provided in an exhaust gas passage G of the internal combustion engine, and uses a heating means H at a predetermined time. In an exhaust emission control device that heats and ignites particulates, and at the same time regenerates a filter by supplying a regenerating gas by the regenerating gas supply means and burning the regenerating gas, the filter regeneration is performed by the state parameter of each part of the internal combustion engine. The remaining burnt amount estimating means A for fuzzy inferring the remaining burnt amount of the particulates in the filter F afterwards and the regeneration timing correction means B for correcting the next regeneration timing according to the estimated unburned residue are provided. It has a feature.

The state parameter is a parameter capable of estimating the unburned residue of the particulate by itself,
When a parameter detected during filter regeneration is used as this parameter, a filter central temperature detecting means for detecting the temperature of the central portion of the filter and an outer peripheral temperature detecting means for detecting the temperature of the outer peripheral portion of the filter are used. The parameter can be detected from, and when a parameter detected when collecting particulates immediately after filter regeneration is used as this parameter, a pressure loss value calculating means for calculating the pressure loss value of the filter, The parameters can be detected by the intake negative pressure detecting means for detecting the intake negative pressure of the internal combustion engine and the intake air amount detecting means for detecting the intake air amount.

[0011]

According to the exhaust gas purification apparatus for an internal combustion engine of the present invention, the particulates in the exhaust gas are collected by the filter F provided in the exhaust gas passage G of the internal combustion engine, and the heating means H heats them at a predetermined time. In the exhaust gas purification device that performs the ignition of the particulates and at the same time supplies the regeneration gas by the regeneration gas supply means and burns this to regenerate the filter, the state parameter of each part of the internal combustion engine by the unburned amount estimation means Is used to fuzzyly infer the unburned amount of particulates in the filter after the filter is regenerated, and the next regeneration time is corrected by the regeneration time correction means according to the estimated unburned amount. As a result, the amount of unburned particulates remaining after the particulate regeneration is correctly determined, excessive collection is avoided, and the temperature is prevented from rising excessively during regeneration, and damage to the filter is prevented.

[0012]

Embodiments of the present invention will be described in detail below with reference to the accompanying drawings. FIG. 2 is an overall configuration diagram of an exhaust emission control device 20 according to an embodiment of the present invention, which is equipped with an electric heater H and includes a particulate filter 5 for collecting particulates in exhaust gas. In FIG. 3, 1 is an intake passage, 3 is a casing for accommodating a particulate filter 5 provided in a part of the exhaust gas passage 2, 4
Is a sealing material, 6 is a secondary air supply passage, 7 is a combustion gas discharge passage, 8 is an exhaust bypass passage bypassing the particulate filter 5, 9 is an air pump for supplying secondary air, 10 is a diesel engine, 11 is a battery , 12 is a voltmeter for measuring the battery voltage, 13 is a heater switch for energizing the electric heater H, 14 is an air cleaner, 1
5 is an air flow meter for detecting the amount of intake air flowing through the intake passage 1, 16 is an air flow meter for measuring the amount of intake air to the air pump 9, 100 is a control circuit, V1 is the exhaust passage 2
Switch valve for switching between the exhaust bypass passage 8 and the exhaust bypass passage 8, V2 is an outlet switch valve provided at the outlet of the exhaust bypass passage 8, V3
Is an opening / closing valve of the combustion gas discharge passage 7, and V4 is an opening / closing valve of the secondary air supply passage 6.

The exhaust gas purification device 20 of this diesel engine is provided with the following sensors. That is, as the sensor for detecting the temperature, the particulate filter 5 is used.
Heater H of the particulate filter 5 and the temperature sensor ST1 provided in the central portion of the end surface side opposite to the heater H of
Temperature sensor ST provided on the outer periphery of the end face side opposite to
2, ST3, a temperature sensor ST4 provided at the center of the filter 5 in the axial direction, a temperature sensor STH for detecting the temperature of the heater H, and a temperature sensor (not shown) for measuring the outside air temperature. Further, as a sensor for measuring the pressure, a pressure sensor SP provided in the intake passage 1 for measuring the suction pressure is used.
0, the pressure sensor SP1 provided in the passage 2 on the exhaust gas inflow side of the particulate filter 5, the pressure sensor SP2 provided in the passage 2 on the exhaust gas outflow side of the particulate filter 5, and the discharge pressure of the air pump 9. There is a pressure sensor SP4 to measure. In addition to this, there are a lever opening sensor (not shown) for detecting the lever opening θ of the fuel injection lever, a rotation speed sensor for detecting the rotation speed Ne of the engine, and the like.

The particulate filter 5 is a honeycomb filter having honeycomb-shaped partition walls made of a porous material, and is generally cylindrical, and has a large number of rectangular parallelepiped passages surrounded by partition walls. Adjacent ones of these passages are closed passages that are alternately plugged with a ceramic blocking material on the exhaust gas inflow side and the exhaust gas outflow side.

The control circuit 100 includes, for example, an interface INa for inputting an analog signal, an interface INd for inputting a digital signal, a converter A / D for converting an analog signal into a digital signal, a central processing unit CPU for performing various arithmetic processes, and a random processor. It is composed of a microcomputer including an access memory RAM, a read-only memory ROM, an output circuit OUT, and a bus line 111 connecting these, but a detailed operation description of the structure is omitted.

The interface INa for inputting an analog signal of the control circuit 100 has pressure detection signals P0 to P4 from the pressure sensors SP0 to SP4 and temperature sensors ST1 to ST.
4, temperature detection signals T1 to T4, heater temperature signal T
H, a temperature detection signal TA from an atmospheric temperature sensor (not shown), a voltage of the battery 11 from the voltmeter 12, flow rate detection signals Ga _and Sa from the air flow meters 15 and 16 _, an engine speed signal from a rotation speed sensor (not shown) Ne, a battery voltage V while the heater is energized, etc. are inputted, and a signal etc. from a key switch (not shown) is inputted to the interface INd for inputting a digital signal. By inputting these data, the control circuit 100 causes the time tmc1, at which the temperatures T1 to T3 are equal to or higher than a predetermined temperature, for example, 600 ° C. or more.
The combustion speed vt is calculated from tmc2, tmc3, and the time from the start of regeneration until the temperatures T1 to T3 reach the peak temperature, and the differential pressure (pressure loss) ΔP across the filter 5 and the K value called the loading K are calculated as follows. It is calculated by the formula.

K = (P1-P2) / P2 During normal particulate collection in exhaust gas, the valves V1 to V4 are controlled to the positions indicated by broken lines, and the exhaust gas discharged from the diesel engine 10 is The particulate filter 5 contained in the casing 3 removes the particulates and discharges them into the atmosphere through a muffler (not shown). On the other hand, when a predetermined amount of particulates is trapped in the particulate filter 5, the control circuit 100 switches the valves V1 to V4 from the positions of broken lines to the positions of solid lines, on / off control of the heater switch 13, and the air pump 9. The flow rate of the secondary air from is controlled. In general, when switching from the particulate trapping operation to the filter 5 regeneration operation is performed when the pressure on the exhaust gas inflow side (upstream side) exceeds the pressure on the exhaust gas outflow side (downstream side) by more than a predetermined value. However, in the present invention, the switching timing is fuzzy inferred from the value of the operating state parameter of the engine described above, which is a main factor, and the unburned amount of the particulates in the filter 5 is inferred. The reproduction time is corrected.

Therefore, next, the unburned amount of the particulates in the filter 5 is determined by using the fuzzy inference by the control circuit 100, and the particulate collection operation according to this determination is switched to the regeneration operation of the filter 5. The control will be described. As a factor for determining the unburned residue in the particulate filter 5 after the regeneration process using fuzzy inference, the present inventor has found that there are the following types depending on what the state parameter during engine operation is to be noted. Found out. (1) Factors related to temperature-T1 at the center of the filter-T2 and T3 at the outer periphery of the filter-T4 of the filter just before regeneration-Temperature TH when the heater is energized-Outside temperature TA-Exhaust temperature TEX (2) Factors related to pressure-Exhaust gas upstream pressure (front pressure) P1 of filter-Exhaust gas downstream pressure (post-pressure) P2 of filter-Suction negative pressure P0-Secondary air discharge pressure P4 of air pump (A / P) 9 (3) Factors related to time-Holding time Tmc1 when the combustion temperature at the center of the filter is 600 ° C or higher-Holding time Tmc2, Tmc3 when the combustion temperature at the outer periphery of the filter is 600 ° C or higher-Collection time tc-Regeneration Time tr (4) Factors related to air flow rate-Intake air amount Ga-Flow rate Sa of the air pump 9 immediately before regeneration Sa (5) Other factors-Engine rotation speed Ne-Lever opening θ-Battery voltage V-Combustion propagation speed v・ Engine cumulative rotation speed ΣNe ・ Collecting mileage Lc ・ Total fuel consumption ΣQ The factors necessary for fuzzy inference are listed above. The main factors are those that can estimate the unburned residue by themselves. It can be divided into a sub-factor that improves the accuracy of estimating the unburned residue and a co-factor that is a supplement that estimates the unburned residue. Then, according to the study of the present inventors, the unburned particulate matter in the filter after regeneration is the same as the above (1).
From (4), when at least one factor in each item was used as the main factor, it was found that fuzzy inference could be performed by combining this main factor with at least one other subfactor.

FIG. 3 is a diagram showing this relationship in the form of a table, in which the main factor is represented by ⊚, the subfactor is represented by ∘, and the supplementary factor is represented by Δ. Controls 1 to 4 described in this figure are sub-factors necessary for determining the amount of unburned fuel when at least one main factor is selected from the above items (1) to (4). It shows the relationship of cofactors. For example,
In the case of control 1, if the filter center temperature T1 and the filter outer peripheral temperature T2 are selected as the main factors, it is shown that the unburned amount of particulates can be estimated by combining with at least one sub-factor indicated by ◯. ..

Therefore, an embodiment of the present invention in which the unburned amount of particulates is estimated by combining the factors shown in FIG. 3 and the regeneration start time is determined will be described. First, an embodiment corresponding to the control 1 of FIG. 3 will be described.
In this embodiment, the filter center temperature T1 and the filter outer peripheral temperature T2 are used as main factors, and the retention time tmc1 at which the filter center is 600 ° C. or more is used as a sub-factor, and the unburned amount of particulates in the filter 5 is calculated. This is a fuzzy estimation, and as a result of this inference, the regeneration timing judgment coefficient such as the differential pressure across the filter 5 (pressure loss) or the loading K (pressure loss divided by the post pressure of the filter) is corrected. is there.

The filter center temperature T1, the filter outer peripheral temperature T2, and the holding time t at which the filter center is 600 ° C. or more.
Membership functions for mc1 are shown in FIGS. 4 (a) to 4 (c). The letters shown in this figure are called fuzzy labels and have the following meanings.・ PB (Positive Big) Positive and fairly large ・ PM (Positive Medium) Positive and somewhat large ・ PS (Positive Small) Positive and slightly large ・ Z0 (Zero) standard value ・ NS (Negative Small) Negative and slightly large・ NM (Negative Medium) Negative and somewhat large ・ NB (Negative Big) Negative and considerably large Therefore, when T1 = 650 ° C. in FIG. 4 (a),
It indicates that the probability that the temperature T1 is perceived as Z0 (reference value) is about 50%, and the probability that it is perceived as PS (slightly higher) is about 50%.
Similarly, when T2 = 520 ° C. in FIG. 4 (b), there is a possibility that the temperature T2 is considered to be NS (a little higher), about 80%, and there is a possibility to be considered as Z0 (reference value).
It shows that it is about 0%. Similarly, when tmc1 = 70 sec, there is a 100% possibility that the holding time tmc1 is considered to be Z0 (reference value).

5A and 5B, the filter center temperature T1, the filter outer temperature T2, and the filter center portion are 60
A membership function is shown for the holding time tmc1 which is 0 ° C. or higher and the regeneration timing judgment coefficient “K” for the regeneration status of the particulate filter. That is, FIG. 5 (a)
Is a three-dimensional map in the form of a three-dimensional map based on experience with the three factors of the filter central temperature T1 and the filter outer peripheral temperature T2, and the retention time tmc1 at which the filter central portion is 600 ° C. or more and the regeneration timing determination coefficient “K”. It is a ruled map, and FIG. 5B shows that the retention time tmc1 in FIG.
For example, a map when tmc1 = Z0.

The rule maps shown in FIGS. 5A and 5B will be described in more detail. When the filter center temperature T1 is a little higher, the filter outer temperature T2 is a little lower, and the holding time tmc1 is a reference value when the filter center is 600 ° C. or more, if "K" is increased a little at the time of the next reproduction. It is empirically known that the unburned residue in the filter is reduced and the temperature in the filter does not rise so much. Therefore, the rule maps showing the relationships between the temperatures T1, T2, and the holding time tmc1 and the coefficient “K” based on experience are shown three-dimensionally and two-dimensionally in FIG. 5 (a) and FIG. 5 (b). become.
However, FIGS. 5 (a) and 5 (b) are merely examples, and this rule changes depending on the specifications of the exhaust purification system and the particulate filter.

According to this map, when there is a large amount of unburned particulate matter remaining on the outer peripheral portion of the filter, it is possible to correct the differential pressure ΔP across the filter so as to be slightly larger than the initial set value in consideration of the unburned residue. For example, Figure 4 (a)
As shown in (c), T1 = Z0, T2 = NS, t
When there is a possibility that mc1 = Z0, K = PS according to the rule map of FIG. 5 (b).

FIG. 6 shows the membership function of the reproduction timing judgment coefficient "K". From this figure, FIGS. 5 (a) and 5 (b) are shown.
The fact that the reproduction timing judgment coefficient "K" obtained in step 2 is about 2.2 means that "K" is sensibly increased. Next, a method of obtaining the reproduction timing determination coefficient “K” will be described. Where T1 belongs to Z0 and PS,
Assuming that T2 belongs to NS and Z0, and tmc1 belongs to Z0, the following combinations are possible, and the possible values of the regeneration timing judgment coefficient "K" are required for each case.

(1) T1 = Z0, T2 = NS, tmc1 = Z0 (2) T1 = PS, T2 = NS, tmc1 = Z0 (3) T1 = Z0, T2 = Z0, tmc1 = Z0 (4) T1 = PS, T2 = Z0, tmc1 = Z0 (1) T1 = Z0, T2 = NS, tmc1 = Z0,
From the relationship of the rule map shown in FIG. 5 (b), "K" = P
As shown in FIGS. 7A to 7C, the probability of T1 = Z0 is 50%, the probability of T2 = NS is 80%, and tmc1 =
The probability of Z0 is 100%. At this time, there is a high possibility that K = PS will be tmc1 = Z0 and T2 = NS, but since the possibility that T1 = Z0 is low from the whole, "K" can take PS. Gender will be determined by the likelihood of T1 (50%). Therefore, the possibility of the reproduction timing judgment coefficient "K" is in the area shown in FIG.

(2) T1 = PS, T2 = NS, tmc1 =
In the case of Z0, "K" = PS from the relation of the rule map shown in FIG. 5 (b), and if the possibility is derived by the same method as (1), it becomes 50%. When T1 = Z0, T2 = Z0, tmc1 = Z0 in (3),
From the relationship of the rule map shown in FIG. 5 (b), "K" = Z0
If we derive the possibility with the same method as in (1), it will be 20%.

(4) T1 = PS, T2 = Z0, tmc1 =
In the case of Z0, "K" = Z0 from the relationship of the rule map shown in FIG. 5 (b), and if the possibility is derived by the same method as (1), it becomes 50%. As for the possibility of the reproduction timing judgment coefficient “K” obtained as described above, the maximum possibility that can be taken for each fuzzy label of (1) to (4) is overlapped as shown in FIG. Create a probability distribution of. At this time, the value of "K" becomes the center of gravity of the hatched portion in FIG.

FIG. 10 shows a method of obtaining the center of gravity of the possibility distribution of the reproduction timing judgment coefficient "K". Figure 9
The contour of the hatched part of is expressed in the form of a function F (k),
The center of gravity G ₀ is calculated based on the following equation G ₀ = ∫K · F (k) d (k) / ∫F (k) d (k). Then, the reproduction time determination coefficient “K” is corrected by the obtained center of gravity G ₀ .

FIG. 11 is a flow chart showing a procedure for judging the next reproduction time by using the above-mentioned fuzzy inference, which is executed every predetermined time, for example, every 10 ms. In step 101, it is first determined whether or not the engine has just started,
If the engine has just started, the regeneration timing determination value TK is set to the initial value in step 102 and the routine proceeds to step 104. If the engine has not just started, it is determined in step 103 whether the filter is being regenerated. When it is determined in step 103 that the filter is being regenerated, this routine is ended, and when it is determined that the filter is not being regenerated, the routine proceeds to step 104.

In step 104, the engine rotation speed Ne is read, and in the following step 105, the integrated value ΣNe of the engine rotation speed Ne is calculated. And step 10
In No. 6, it is determined whether the engine rotation speed Ne is 1000 rpm or more. When Ne <1000 rpm, this routine is ended, and when Ne ≧ 1000 rpm, the routine proceeds to step 107, where the intake pressure (atmospheric pressure) P0, the filter upstream side pressure. P
1 and the filter downstream side pressure P2 are measured.

At step 108, the value of the loading K for determining the regeneration time of the filter is calculated by the following equation (P1-P2) / (P2-P0), and it is determined whether this value is smaller than the regeneration time judgment value TK. To be judged. And (P1-P2) /
When (P2−P0) ≧ TK, the routine proceeds to step 112, where a filter regeneration start instruction is output and the integrated value ΣNe of the engine rotation speed is cleared. On the other hand, step 10
When (P1−P2) / (P2−P0) <TK in step 8, the routine proceeds to step 109, where the exhaust gas temperature TEX of the engine is measured, and at step 110, it is judged if the exhaust gas temperature is lower than 600 ° C. When TEX <600 ° C., the routine proceeds to step 111, where it is determined whether or not the integrated value ΣNe of the engine speed is equal to or more than a preset integrated reference value NE of the engine speed, and ΣNe
When <NE, this routine is ended, and when ΣNe ≧ NE, the routine proceeds to step 112, where a filter regeneration start instruction is output, and the integrated value ΣNe of the engine speed is cleared. Also, in step 110, TEX ≧ 600 ° C.
If, then the routine proceeds to step 113, where the integrated value Σ of engine speed is
Ne is cleared and this routine ends.

FIG. 12 is a flow chart showing a procedure for fuzzy inferring the unburned residue during filter regeneration and correcting the next regeneration timing judgment. In step 201, it is judged whether or not the filter is being regenerated. If not being regenerated, this routine is ended. If it is being regenerated, the routine proceeds to step 202, where the center temperature T1 of the filter and the outer peripheral temperatures T2 and T3 are measured. Be seen. In the following step 203, the exhaust temperature TEX is 600.
It is determined whether or not the temperature is equal to or higher than ℃, and when TEX ≧ 600 ℃, the routine proceeds to step 204, and the time tmc1 is integrated to step 2
If TEX <600 ° C., the process proceeds to step 205 without proceeding to step 204.

In step 205, it is judged whether or not the regeneration is completed. If it is not completed, this routine is finished, and if it is finished, the routine proceeds to step 206, where the center temperature T1 of the filter and the outer peripheral temperatures T2, T3, And the regeneration time judgment coefficient "K" is fuzzy inferred by the above method using the holding time tmc1 at which the filter temperature is 600 ° C. or higher.
Then, in step 207, it is determined whether or not the inferred reproduction timing determination coefficient "K" is between 1.8 and 2.4. If 1.8≤K≤2.4, the playback timing determination value is determined. T
Reproduction time judgment coefficient “K” that K inferred in step 206
Is replaced with and the routine ends. On the other hand, if 1.8> K or K> 2.4 in step 207, the inferred value in step 206 is regarded as an error and the process proceeds to step 209, the reproduction timing judgment value TK is set to the initial value, and this routine ends. To do.

The specific numbers in FIGS. 11 and 12 described above are given for the sake of convenience, and the numbers differ depending on the individual diesel engine. Next, FIG.
An embodiment corresponding to the control 2 will be described. In this embodiment, the main factor is the ΔP before and after the filter immediately after the end of the reproduction.
(Corresponding to the front pressure P1 and the rear pressure P2 of the filter in FIG. 3) is selected, and the center temperature T1 of the filter is selected as a sub-factor,
The combustion propagation velocity (time) vt during regeneration was selected as a cofactor, and the filter 5 was selected by using these factors.
It is a fuzzy estimation of the unburned amount of particulates in the inside. As a result of this inference, the regeneration timing determination coefficient such as the differential pressure loading K across the filter 5 is corrected.

Membership functions with respect to the filter center temperature T1, the filter front-rear differential pressure ΔP, and the combustion propagation velocity vt are shown in FIGS. 4 (a), 13 (a), and 13 (b). In addition, FIG.
(a) shows the filter center temperature T1 and the differential pressure across the filter Δ
FIG. 14 (b) shows a three-dimensional rule map in which the relationship between P, the combustion propagation velocity vt, and the regeneration timing judgment coefficient “K” with respect to the regeneration status of the particulate filter is ruled based on experience. 2) shows a two-dimensional rule map when the combustion propagation velocity vt in () is a constant value, for example, vt = PS.

The rule maps of FIGS. 14 (a) and 14 (b) also show the temperature T.
1, the difference thickness ΔP, and the relationship between the combustion propagation velocity vt and the coefficient “K” are ruled based on experience and are three-dimensionally and two-dimensionally expressed. The rules in this rule map are also the exhaust purification system and It changes according to the specifications of the particulate filter. With this map
When the amount of unburned particulates on the outer peripheral portion of the filter is large, the unburned amount can be taken into consideration, and the differential pressure ΔP across the filter can be corrected to be slightly larger than the initial setting value. For example, as shown in FIGS. 4 (a), 13 (a), and 13 (b), the filter center temperature T1 = 620 ° C., the filter front-back differential pressure ΔP
= 20 mmHg, and combustion propagation velocity vt = 420 sec, when T1 = Z0, ΔP = NB, and vt = PS are possible, according to the rule map of FIG. 14 (b), the regeneration timing determination coefficient “K” = It becomes PS.

FIG. 15A shows the membership function of the reproduction timing judgment coefficient "K". Next, a method of obtaining the reproduction timing determination coefficient “K” will be described. Where T
If 1 belongs to Z0 and PS, ΔP belongs to NB, and vt belongs to PS, the following two combinations are possible as the possible values of the regeneration timing judgment coefficient “K”. Can be considered.

(1) T1 = Z0, ΔP = NB, vt = PS (2) T1 = PS, ΔP = NB, vt = PS If T1 = Z0, ΔP = NB, vt = PS of (1), then T
The probability of 1 = Z0 is 80%, and the probability of “K” = PS is 80% from the relationship of the rule map shown in FIG. 14 (b). On the other hand, T2 of (2) = PS, ΔP = N
If B, vt = PS, then T1 = PS is likely 20
%, And there is a 20% chance that “K” = PM from the relationship of the rule map shown in FIG. 14 (b).

As for the possibility of the reproduction timing judgment coefficient "K" obtained as described above, the maximum possibility that can be obtained for each fuzzy label of (1) and (2) is shown in FIG. 15 (a). To create a probability distribution of “K”. At this time, the value of “K” becomes the center of gravity of the hatched portion in FIG. FIG. 15 (b) shows a method of obtaining the center of gravity G ₀ of the possibility distribution of the reproduction timing judgment coefficient “K”.
The contour of the hatched portion in FIG. 15 (b) is represented in the form of a function F (k), and the following equation G ₀ = ∫K · F (k) d (k) / ∫F
The center of gravity G ₀ is calculated based on (k) d (k). Then, the reproduction time determination coefficient “K” is corrected by the obtained center of gravity G ₀ .

The flow chart showing the procedure for determining the next reproduction time using fuzzy inference in this embodiment is exactly the same as that of the first embodiment described with reference to FIG. 11, and therefore its explanation is omitted. FIG. 16 is a flowchart in the present embodiment showing a procedure for fuzzy inferring the unburned residue during filter regeneration and correcting the next regeneration timing judgment.
In step 301, it is judged whether or not the filter is being regenerated. If not being regenerated, this routine is ended. If it is being regenerated, the routine proceeds to step 302, where the center temperature T1 of the filter is measured. In the following step 303, the time vt during which the particulates ignite after the heater is energized and the flame propagates in the filter is measured.

In step 304, it is judged whether or not the regeneration is finished. If it is not finished, this routine is finished, and if it is finished, the routine proceeds to step 305, where the differential pressure ΔP across the filter is measured. Then, the following step 306
, The regeneration timing determination coefficient “K” is calculated using the central temperature T1, the combustion propagation velocity vt, and the differential pressure ΔP across the filter.
Is fuzzy inferred in the manner described above. Then, in step 307, the inferred reproduction timing determination coefficient "K" is 1.8.
And 2.4, it is determined whether 1.8 ≦ K ≦.
In the case of 2.4, the reproduction timing judgment value TK is the step 306.
It is replaced with the reproduction timing judgment coefficient "K" deduced in step 1 and this routine is ended. On the other hand, if 1.8> K or K> 2.4 in step 307, step 30
As the inferred value in 6 is incorrect, the process proceeds to step 309,
The reproduction timing judgment value TK is set to the initial value, and this routine ends. Also in FIG. 16, specific numbers are given for the sake of convenience, and these numbers differ depending on the individual diesel engine.

Further, an embodiment corresponding to the control 3 in FIG. 3 will be described. In this embodiment, intake air pressure P0 (or intake negative pressure Pin) and intake air amount Ga are selected as main factors, and filter temperature T4 immediately before regeneration is selected as a supplementary factor. The amount of unburned particulate matter in the filter 5 is fuzzy estimated. As a result of this inference, the regeneration timing determination coefficient such as the differential pressure loading K across the filter 5 is corrected.

FIG. 1 shows the membership function with respect to the filter temperature T4 immediately before regeneration, the intake air amount Ga, and the intake negative pressure Pin of the engine (atmospheric pressure minus intake air pressure P0).
7 (a)-(c). Further, FIG. 18 (a) shows that the relationship between the filter temperature T4 immediately before regeneration, the intake air amount Ga, the suction negative pressure Pin of the engine, and the regeneration timing judgment coefficient “K” with respect to the regeneration state of the particulate filter is experienced. FIG. 14 (b) shows a three-dimensional rule map based on a rule. The combustion propagation velocity vt in (a) is a constant value, for example, v
The two-dimensional rule map at the time of t = PS is shown.

The rule maps of FIGS. 18 (a) and 18 (b) also show the filter temperature T4, the intake air amount Ga, and the intake negative pressure Pin of the engine Pin.
Is a three-dimensional and two-dimensional expression of the relationship between the coefficient "K" and the coefficient based on experience, and the rules in this rule map also change according to the specifications of the exhaust purification system and the particulate filter. Is. With this map, when there is a large amount of unburned particulates remaining on the outer peripheral portion of the filter, it is possible to correct the differential pressure across the filter ΔP to be slightly larger than the initial set value, taking into consideration the unburned portion. For example, as shown in FIGS. 17A to 17C, filter temperature T4 = 200 ° C., intake air amount Ga =
When there is a possibility of T4 = NS, Ga = NS, Pin = PS at 0.91 and the engine suction negative pressure Pin = 450mmHg, the regeneration timing judgment coefficient “” is determined by the rule map of FIG. 18 (b). K ″ = NS.

FIG. 19A shows the membership function of the reproduction timing judgment coefficient "K". Next, a method of obtaining the reproduction timing determination coefficient “K” will be described. Where G
If a belongs to NS and Z0, T4 belongs to NS, and Pin belongs to PS, the following two combinations are possible as the possible values of the regeneration timing judgment coefficient "K". Can be considered.

(1) Ga = NS, T4 = NS, Pin = PS (2) Ga = Z0, T4 = NS, Pin = PS (1) Ga = NS, T4 = NS, Pin = PS, G =
There is a 55% chance that a = NS, and there is also a 55% chance that “K” = NS from the relationship of the rule map shown in FIG. 18 (b). On the other hand, Ga = Z0, T4 = N in (2)
If S and Pin = PS, there is a possibility that Ga = Z0 is 45.
%, And there is a 45% chance that “K” = Z0 from the relationship of the rule map shown in FIG. 18 (b).

The possibility of the reproduction timing judgment coefficient "K" obtained as described above is the maximum possible for each fuzzy label of (1) and (2) as shown in FIG. 19 (a). To create a probability distribution of “K”. At this time, the value of “K” becomes the center of gravity of the hatched portion in FIG. FIG. 19B shows a method of obtaining the center of gravity G ₀ of the possibility distribution of the reproduction timing judgment coefficient “K”.
The contour of the hatched portion in FIG. 19 (b) is represented in the form of a function F (k), and the following equation G ₀ = ∫K · F (k) d (k) / ∫F
The center of gravity G ₀ is calculated based on (k) d (k). Then, the reproduction time determination coefficient “K” is corrected by the obtained center of gravity G ₀ .

Since the flow chart showing the procedure for judging the next reproduction time using the fuzzy inference in this embodiment is exactly the same as that of the first embodiment described with reference to FIG. 11, its explanation is omitted. FIG. 20 is a flow chart in this embodiment showing a procedure for fuzzy inferring the unburned residue during filter regeneration and correcting the next regeneration timing judgment.
In step 401, it is determined whether or not the filter is being regenerated. If it is not being regenerated, this routine is ended, and if it is being regenerated, the routine proceeds to step 402, where it is determined whether or not it is immediately after the start of the regeneration. If it has just been regenerated, the initial temperature T4 of the filter is measured in step 403 and the process proceeds to step 404. If it has not been regenerated, the process proceeds to step 404 without passing through step 403.

In step 404, it is judged whether or not the regeneration is completed. If it is not completed, this routine is finished. If it is finished, the routine proceeds to step 405, where the engine speed Ne, the lever opening of the fuel injection device are opened. θ, intake air pressure P0,
And the intake air amount Ga is measured. Then, in the following step 406, the regeneration timing determination coefficient "K" is fuzzy inferred by the above-described method using the rotation speed Ne, the lever opening θ, the intake air pressure P0, and the intake air amount Ga. Then, in step 407, it is determined whether or not the inferred reproduction timing determination coefficient "K" is between 1.8 and 2.4,
If 1.8 ≦ K ≦ 2.4, the reproduction timing judgment value TK is replaced with the reproduction timing judgment coefficient “K” inferred in step 406, and this routine is ended. On the other hand, step 4
If 1.8> K or K> 2.4 in 07,
Inferred value in step 406 is incorrect and step 4
In step 09, the reproduction timing judgment value TK is set to the initial value, and this routine ends. Also in FIG. 20, specific numbers are given for the sake of convenience, and these numbers differ depending on the individual diesel engine.

Although the three embodiments have been described above, it is possible to infer the unburned amount of particulates after completion of filter regeneration in addition to these embodiments, and as described with reference to FIG. The unburned amount of particulates can be fuzzy inferred by combining factors with subfactors or cofactors. The membership functions of each factor shown in FIG. 3 are shown in FIGS. 21 to 23 for reference. Here, FIGS. 21A to 21D show the outside air temperature Ta, the heater temperature TH, and the discharge pressure P of the air pump, respectively.
a, the membership function of the pre-filter pressure P1 is shown in FIG.
2 (a) to (d) are the battery voltage V, the discharge flow rate Sa of the air pump immediately before the end of the regeneration, and the engine integrated rotational speed ΣN, respectively.
e, the membership function of the total fuel consumption ΣQ is shown in FIG.
3 (a) to 3 (c) show membership functions of the traveling distance Lc during collection, the collection time tc, and the time tmc2 or tmc3 when the temperature during regeneration of the outer peripheral portion of the filter is 600 ° C. or higher.

The value of the membership function shown above changes depending on the model of the diesel engine and the structure of the particulate filter system, and the values shown in the embodiments are merely examples. ..

[0053]

As described above, according to the present invention,
The amount of unburned particulates remaining after the particulate filter is regenerated is accurately determined by fuzzy inference, and the particulate filter is prevented from being excessively collected by finely compensating the regeneration timing correction. There is an effect that it is possible to prevent the particulate filter from being damaged by overheating.

[Brief description of drawings]

FIG. 1 is a configuration diagram showing a principle configuration of an exhaust gas purification apparatus for an internal combustion engine according to the present invention.

FIG. 2 is a system diagram showing an overall configuration of an embodiment of an exhaust emission control device for an internal combustion engine of the present invention.

FIG. 3 is a diagram showing, in the form of a table, the relationship between factors necessary for fuzzy inference and combinations of these factors that can estimate the unburned residue of particulates.

4A is a diagram showing a membership function with respect to a filter center temperature, FIG. 4B is a diagram showing a membership function with respect to a filter outer temperature, and FIG.
It is a figure which shows the membership function with respect to the above holding time.

FIG. 5 (a) is a filter center temperature and a filter outer temperature,
And a holding time of 600 ° C or more at the center of the filter
A map diagram in which the relationship between two factors and the regeneration time judgment coefficient is ruled in the form of a three-dimensional map based on experience. (B) shows the relationship between the regeneration center judgment coefficient and the two factors of the filter center temperature and the filter outer temperature. It is a map figure which made into a rule in the form of a two-dimensional map based on experience.

FIG. 6 is a diagram showing a membership function of a reproduction timing judgment coefficient.

7A is a diagram showing a possibility that the filter center temperature in the membership function of the filter center temperature is Z0 = 50%, and FIG. 7B is a filter outer temperature of the filter outer temperature in the membership function NS = 80. Figure showing the probability of%,
(c) is a diagram showing a possibility that the retention time in the membership function of the retention time at which the central portion of the filter is 600 ° C. or higher is Z0 = 100%.

8 is a region diagram showing the possibility of a regeneration timing judgment coefficient when there is a possibility that the filter temperature is PS = 50% in FIG. 7. FIG.

9 is a region diagram showing the possibility of a reproduction timing determination coefficient when all the possibilities in FIG. 7 are combined.

FIG. 10 is a diagram showing a method of obtaining the center of gravity of the possibility distribution of the reproduction timing determination coefficient.

FIG. 11 is a flowchart showing a procedure for determining the next reproduction time using fuzzy inference according to the present invention.

FIG. 12 is a flowchart showing a procedure in the first embodiment for fuzzy inferring an unburned residue during filter regeneration and correcting the next regeneration timing determination.

13A is a diagram showing a membership function with respect to a differential pressure across a filter, and FIG. 13B is a diagram showing a membership function with respect to a combustion propagation velocity.

FIG. 14 (a) is a map diagram in which the relationship between the three factors of the filter center temperature, the filter differential pressure across the filter, and the combustion propagation velocity, and the regeneration timing determination coefficient is ruled in the form of a three-dimensional map based on experience. (b) is a map diagram in which the relationship between the two factors of the filter center temperature and the differential pressure before and after the filter and the regeneration timing determination coefficient is ruled in the form of a two-dimensional map based on experience.

FIG. 15 (a) is a region diagram showing the possibility of a regeneration timing judgment coefficient when the possibilities of three factors, that is, the filter center temperature, the differential pressure across the filter, and the combustion propagation speed are combined,
(b) is a diagram showing a method of obtaining the center of gravity of the possibility distribution of the reproduction timing judgment coefficient in (a).

FIG. 16 is a flowchart showing a procedure in a second embodiment for fuzzy inferring an unburned residue during filter regeneration and correcting the next regeneration timing determination.

17A is a diagram showing a membership function with respect to a filter temperature immediately before regeneration, FIG. 17B is a diagram showing a membership function with respect to an intake air amount, and FIG. 17C is a membership function with respect to an engine suction negative pressure. It is a figure.

FIG. 18 (a) is a map in which the relationship between the three factors of the filter temperature immediately before regeneration, the intake air amount, and the engine suction negative pressure, and the regeneration timing determination coefficient is ruled in the form of a three-dimensional map based on experience. FIG. 6B is a map diagram in which the relationship between the two factors of the filter temperature immediately before the regeneration and the intake air amount and the regeneration timing determination coefficient is ruled in the form of a two-dimensional map based on experience.

FIG. 19 (a) is a region diagram showing the possibility of a regeneration timing judgment coefficient when the possibilities of three factors of the filter temperature immediately before regeneration, the intake air amount, and the engine suction negative pressure are combined,
(b) is a diagram showing a method of obtaining the center of gravity of the possibility distribution of the reproduction timing judgment coefficient in (a).

FIG. 20 is a flow chart showing a procedure in a third embodiment for fuzzy inferring an unburned residue during filter regeneration and correcting the next regeneration timing judgment.

21A is a diagram showing a membership function of outside air temperature, FIG. 21B is a heater temperature, FIG. 21C is a discharge pressure of an air pump, and FIG.

22 (a) is a battery voltage, FIG. 22 (b) is a discharge flow rate of an air pump immediately before the end of regeneration, FIG.
FIG. 4 is a diagram showing a membership function of the total fuel consumption ΣQ.

FIG. 23 (a) is the traveling distance at the time of collection, (b) is the collection time,
(c) is a diagram showing a membership function at a time when the temperature during regeneration of the outer peripheral portion of the filter is 600 ° C. or higher.

[Explanation of symbols]

 1 ... Intake passage 2 ... Exhaust gas passage 3 ... Casing 5 ... Particulate filter 6 ... Secondary air supply passage 7 ... Combustion gas discharge passage 8 ... Bypass passage 9 ... Air pump 10 ... Diesel engine 11 ... Battery 12 ... Voltmeter 13 ... Heater switch 15, 16 ... Air flow meter 20 ... Exhaust gas purification device 100 according to one embodiment of the present invention 100 ... Control circuit H ... Electric heater SP0-SP3 ... Pressure sensor ST1-ST4, STH ... Temperature sensor V1-V4 ... Valve

Claims (7)

[Claims] 1. A particulate filter in an exhaust gas passage of an internal combustion engine for collecting particulates in the exhaust gas,
In an exhaust gas purification device that performs heating by a heating means at a predetermined time to ignite particulates and at the same time supplies regeneration gas by the regeneration gas supply means and burns the regeneration gas to regenerate a filter, Based on the state parameter, an unburned amount estimation means for fuzzy inferring the unburned amount of particulates in the filter after the filter regeneration, and a regeneration time correction means for correcting the next regeneration time according to the estimated unburned amount, An exhaust gas purification device for an internal combustion engine, characterized in that: 2. The state parameter is a parameter capable of estimating the unburned particulate matter by itself,
The exhaust gas purification device for an internal combustion engine according to claim 1, wherein the exhaust gas purification device is detected during filter regeneration. 3. The means for detecting the state parameter comprises: a filter center temperature detecting means for detecting a temperature of a center portion of the filter; and an outer peripheral temperature detecting means for detecting a temperature of an outer peripheral portion of the filter. The exhaust gas purification device for an internal combustion engine according to claim 2, wherein 4. The means for detecting the state parameter further includes a time period in which the temperature of the central portion of the filter is equal to or higher than a predetermined temperature, and the temperature of an outer peripheral portion of the filter is equal to or higher than a predetermined temperature. The exhaust gas purifying apparatus for an internal combustion engine according to claim 3, further comprising: a predetermined temperature duration detecting means for detecting a duration of time when the engine has been operated. 5. The state parameter is a parameter capable of estimating the unburned residue of particulates by itself,
The exhaust gas purification device for an internal combustion engine according to claim 1, wherein the exhaust gas purification device is detected when collecting particulates immediately after filter regeneration. 6. The means for detecting the state parameter comprises:
The exhaust gas purifying apparatus for an internal combustion engine according to claim 2, which is a pressure loss value calculating means for calculating a pressure loss value of the filter. 7. The means for detecting the state parameter is an intake negative pressure detecting means for detecting an intake negative pressure of the internal combustion engine, and an intake air amount detecting means for detecting an intake air amount of the internal combustion engine. The exhaust gas purification device for an internal combustion engine according to claim 2, wherein