JP2000170521A - Capturing amount calculating method of particulate filter and regenerating method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To accurately calculate the capturing amount of a particulate filter. SOLUTION: Individual particulate filters (DPF) 40 are disposed in the respective cylinder exhaust ports of a diesel engine 1. The electronic control unit(ECU) 30 of the engine calculates a particulate amount PMR generated per unit time from the engine based on an engine load and a revolution speed, and also calculates the rate (capturing efficiency) K1 of those captured by the DPF among particulates generated in the engine. The ECU 30 calculates PMR and K1 for each unit time, and calculates the amount of actually captured particulates by the DPE by integrating the values of PMR×K1. Thus, the amount of particulates captured in the DPE is accurately calculated.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a particulate collection amount calculation method for calculating the amount of particulates collected by a particulate filter for collecting particulates in exhaust gas of an internal combustion engine, and to a particulate filter. The present invention relates to a particulate filter regenerating method for regenerating a particulate filter by burning collected particulates.

[0002]

2. Description of the Related Art The exhaust gas of an internal combustion engine, especially a diesel engine, contains a relatively large amount of exhaust particulates mainly composed of carbon or the like. For this reason, in order to prevent these particulates from being released into the atmosphere, a method has been proposed in which a particulate filter made of, for example, ceramic is disposed in an exhaust passage of an engine to collect particulates in exhaust gas passing through the filter. ing.

When such a particulate filter is used, the amount of particulates collected by the filter together with the operation of the engine (the amount of particulates collected)
And the exhaust pressure loss at the filter increases. If the pressure loss in the filter becomes excessive, the back pressure becomes excessively high, so that the engine performance deteriorates and the fuel efficiency deteriorates. In order to prevent a decrease in engine performance due to an increase in the amount of trapped particulates, it is necessary to reduce the amount of particulates trapped in the filter before the amount of trapped particulates reaches an amount that causes an excessive increase in back pressure. It is necessary to perform a so-called particulate regeneration operation for burning the curates.

In order to properly perform the regeneration operation of the particulate filter, the amount of trapped particulates must be accurately grasped, and the amount of trapped particulates must be reduced before reaching the amount that causes an excessive increase in back pressure as described above. It is necessary to perform a regeneration operation of the particulate filter. Therefore, it is important to accurately estimate the amount of trapped particulates. An example of an apparatus for estimating the amount of trapped particulates and performing a particulate filter regeneration operation when the estimated amount of particulates reaches a predetermined value is disclosed in, for example, JP-A-7-31.
There is one described in Japanese Patent No. 7529.

The device disclosed in the publication detects a differential pressure between the exhaust pressure on the upstream side and the exhaust pressure on the downstream side of a particulate filter disposed in an exhaust passage of a diesel engine, and when the differential pressure reaches a predetermined value, the particulate filter. You are performing a playback operation. Further, in the device disclosed in the publication, the amount of particulates discharged from the engine per unit time is calculated based on the operating state such as the engine load and the number of rotations, and the amount of particulates discharged per unit time is integrated. The amount of particulates collected by the filter is estimated. The device disclosed in the publication further detects the differential pressure when the difference between the particulate collection amount estimated from the differential pressure and the particulate collection amount calculated based on the engine operating state is larger than a predetermined value. It is determined that an abnormality has occurred.

[0006]

The above-mentioned JP-A-7-31
In the apparatus disclosed in Japanese Patent No. 7529, the differential pressure of the particulate filter is detected, and when the differential pressure increases to a predetermined value, the particulate filter regeneration operation is performed. However, the filter differential pressure is not always accurate. And may not correspond. For example, if the particulates are not uniformly collected by the particulate filter for some reason and the distribution of the collected amount occurs on the particulate filter, the filter differential pressure is increased even if the collected amount is relatively large. May be relatively small. Further, even if the distribution of the particulates on the filter is uniform, the differential pressure may differ depending on the form of the particulate layer collected on the filter even if the amount of the collected particulates is the same. In such a case, if the filter differential pressure is small, the back pressure does not increase excessively even if the actual particulate matter trapping amount increases, so that even if the actual trapping amount is large, there is no operational problem. Does not occur. However, in the case where a particulate filter is used in a vehicle engine, the form of retention of the particulate layer collected by the particulate may suddenly change due to vibration during traveling. For this reason, if the trapped amount of particulates is large, the filter may be rapidly clogged due to a change in the particulate retention form during traveling, and the engine may be stalled due to a sudden increase in back pressure. If the regeneration operation is performed by detecting the differential pressure of the filter, such a sudden increase in the back pressure cannot be prevented.

In the apparatus disclosed in Japanese Patent Application Laid-Open No. 7-317529, in order to prevent the above-mentioned problem when the regeneration operation is performed based on the filter pressure difference, the amount of particulates generated in the engine is determined based on the engine operating state. Calculated and accumulated amounts of the generated particulate matter are compared with the detected differential pressure. That is, when the difference between the particulate trapping amount estimated from the engine operating state and the particulate trapping amount calculated from the filter differential pressure is large, the filter differential pressure is reduced to the particulate trapping amount. The filter regeneration operation based on the filter differential pressure is prohibited because it does not correspond accurately, and the regeneration operation is executed every time the particulate collection amount estimated from the engine operation state reaches a predetermined value.

However, in the apparatus disclosed in the publication, the amount of particulates collected is estimated by integrating the amount of particulates generated by the engine calculated from the operating state of the engine. Therefore, the amount of particulates collected must be calculated accurately. There is a problem that can not be. That is, in actual driving,
Not all of the particulates generated in the engine are collected by the particulate filter, and the proportion of the particulate generated by the filter to the amount of generated particulates varies according to the operating state. For this reason, in the apparatus of the above-mentioned publication, it is determined whether or not there is an abnormality in the differential pressure or the regeneration operation is performed based on the inaccurate estimated value of the trapped amount of particulates.

SUMMARY OF THE INVENTION It is an object of the present invention to solve the above-mentioned problem and to provide a method for calculating the amount of trapped particulates, which can accurately estimate the amount of trapped particulates in a filter. Another object of the present invention is to provide a particulate filter regenerating method capable of performing an appropriate particulate filter regenerating operation based on the particulate matter trapping amount estimated as described above. I have.

[0010]

According to the first aspect of the present invention, there is provided a method for calculating a particulate collection amount of a particulate filter for collecting particulates in exhaust gas of an internal combustion engine, comprising: The particulate matter discharge amount of the engine is calculated based on the state, the collection efficiency of the particulate filter is calculated based on the operation state of the engine, and the particulate matter is calculated based on the calculated particulate discharge amount and the collection efficiency. There is provided a particulate collection amount calculation method for calculating the amount of particulates collected by a filter and calculating the particulate collection amount of the particulate filter based on the calculated amount of particulates.

That is, in the trapping amount calculation method according to the first aspect, the particulate emission amount of the engine is calculated based on the engine operating state. The relationship between the amount of particulate emissions and the operating state of the engine, for example, the relationship between the engine load (fuel injection amount) and the number of revolutions is determined in advance by experiments or the like. The particulate emissions of the engine are calculated by the above, but in actual operation, not all the particulates discharged from the engine are collected by the particulate filter, and some of the particulates in the exhaust gas are filtered. Pass without being captured by Therefore, the amount of particulates actually collected by the particulate filter is a function of the amount of generated particulates and the collection efficiency of the filter. Further, the collection efficiency of the filter is not constant, and the operating state of the engine (eg, the exhaust flow rate, the amount of particulates collected by the filter)
And so on. In the trapping amount calculation method of the present invention, the particulate trapping efficiency of the filter is calculated based on the engine operating state, and the particulate trapping efficiency is actually collected by the particulate filter as a function of the particulate discharge amount and the trapping efficiency of the filter. The amount of particulates to be calculated is calculated. This makes it possible to accurately estimate the actual particulate matter collection amount of the particulate filter.

According to the invention described in claim 2, according to claim 1,
In the calculation method, the amount of the particulates collected by the particulate filter is further calculated at regular time intervals, and the amount of the particulates collected by the particulate filter is calculated by integrating the amount of the collected particulates. Is provided.

That is, in the method of calculating a trapping amount according to a second aspect, the amount of particulates trapped by the particulate filter is calculated at regular time intervals based on the operating state of the engine, and this particulate amount is integrated. The total amount of particulates collected by the particulate filter so far is calculated. For this reason, even when the engine operating state changes, the actual amount of particulates collected by the particulate filter can be accurately estimated.

According to the invention described in claim 3, according to claim 1 of the present invention,
In the calculation method, the amount of particulates burned in the particulate filter is further calculated based on the operating state of the engine, and the calculated trapped amount of particulates is corrected based on the amount of burned particulates. A method for calculating a particulate collection amount is provided. That is, in the trapping amount calculation method according to the third aspect, not only the amount of the particulates newly collected by the particulate filter but also the decrease due to the burning of the amount of the particulates already collected by the filter are considered. The particulates collected by the particulate filter may naturally burn when the engine exhaust temperature rises without performing a special regeneration operation. Therefore, in order to accurately estimate the amount of particulates actually collected in the particulate filter, it is necessary to consider a decrease in the amount of particulates due to combustion. In the present invention, the amount of trapped particulates is calculated based on the method of claim 1, and the amount of particulates combusted in the particulate filter is calculated based on the operating state of the engine (for example, exhaust gas temperature). A correction is made to reduce the amount of trapped particulates of the filter by the amount. This makes it possible to more accurately estimate the particulate collection amount of the particulate filter.

According to the invention described in claim 4, according to claim 1 of the present invention,
A particulate trapping amount is calculated using the calculation method according to any one of claims 3 to 3, and when the particulate trapping amount reaches a predetermined first amount, the amount of particulates in the particulate filter is reduced. A regeneration operation for burning the particulates is performed, and collection of the particulates is restarted after the regeneration operation is completed.If the amount of the particulates burned before the regeneration operation is smaller than a predetermined target combustion amount, the trapping is performed. There is provided a particulate filter regeneration method for performing the regeneration operation when the particulate collection amount reaches a second amount smaller than the first amount after the collection restart.

That is, in the particulate filter regeneration method according to the fourth aspect, when the particulate collection amount of the particulate filter calculated based on any one of the first to third aspects reaches the first amount. A regenerating operation is performed to reduce the amount of particulates in the particulate filter. However, in actual operation, it may be necessary to stop the regeneration operation before the entire amount of the particulates in the particulate filter is burned due to a change in the engine operation state or the like after the start of the regeneration operation. In such a case, since particulates remain in the filter even after the regeneration operation, the filter differential pressure after the resumption of collection becomes higher than when the regeneration operation is completed. For this reason, in such a case, the engine is operated in a state in which the engine exhaust back pressure is high even after the regeneration operation is performed, and there is a possibility that the engine performance is reduced and the fuel efficiency is deteriorated. Therefore, in the present invention, during the regeneration operation, the regeneration operation is stopped before the burning amount of the particulates in the particulate filter reaches the target amount, and the collection is restarted with a certain amount of the particulates remaining in the particulate filter. If so, the next reproduction operation is started without waiting for the amount of particulates to increase to the first collection amount. As a result, the time during which the engine is operated in a state where the exhaust back pressure is high is shortened, so that it is possible to prevent a decrease in engine performance and a deterioration in fuel efficiency.

According to the fifth aspect of the present invention, the amount of particulate emissions of the engine is calculated based on the operating state of the internal combustion engine, and the amount of particulates collected by the particulate filter is calculated based on the amount of particulate emissions. A method for calculating a particulate trapping amount of a particulate filter, wherein the particulate matter emission amount of the engine is corrected based on a recirculated exhaust gas amount recirculated to an engine intake system by an EGR device of the engine. And a method for calculating the trapping amount of the particulate filter, which calculates the trapping amount of the particulate based on the particulate discharge amount.

That is, in the method for calculating the trapping amount according to the fifth aspect, similarly to the first to third aspects, the particulate emission amount of the engine is calculated based on the operating condition such as the load condition of the internal combustion engine. However, in an engine that performs exhaust gas recirculation (EGR), the amount of generated particulates differs depending on the amount of exhaust gas circulated by the EGR even if other engine operating conditions are the same. Therefore, in the present invention, the particulate collection amount is calculated using a value obtained by correcting the particulate generation amount calculated based on the engine operating state based on the recirculated exhaust gas amount (EGR gas amount). This makes it possible to accurately estimate the particulate collection amount of the particulate filter regardless of a change in the EGR gas amount.

According to the sixth aspect of the present invention, the amount of particulate emissions of the engine is calculated based on the operation state of the internal combustion engine, and the amount of particulates collected by the particulate filter is calculated based on the amount of particulate emissions. A particulate matter trapping amount calculation method for calculating the particulate matter amount, wherein the particulate matter emission amount of the engine is corrected based on the engine temperature, and the particulate matter collection amount is calculated based on the corrected particulate matter emission amount. A method for calculating the amount of trapped particulates.

That is, in the trapping amount calculation method according to the sixth aspect, when calculating the trapping amount of particulates based on the operating state of the engine, a correction based on the engine temperature is performed. For example, when the engine temperature is low, E
The GR amount decreases as the engine temperature (for example, cooling water temperature) decreases. When the engine temperature is low, the amount of particulates generated in the combustion chamber tends to decrease. Therefore,
In the present invention, the particulate collection amount is calculated using a value obtained by correcting the particulate generation amount calculated based on the engine operating state based on the engine temperature (for example, engine cooling water temperature). This makes it possible to accurately estimate the particulate collection amount of the particulate filter regardless of a change in the EGR amount due to the engine temperature.

According to a seventh aspect of the present invention, there is provided a method of calculating a particulate collection amount according to the sixth aspect, wherein the correction of the particulate emission amount is performed using a different method according to the engine speed. You. That is, in the trapping amount calculation method according to the seventh aspect, the correction based on the engine temperature according to the sixth aspect is performed by a different method according to the engine speed. For example,
In the high engine speed region, the engine exhaust becomes hot, so the EGR
In some cases, EGR is stopped to ensure the reliability of the device. In such a case, if the amount of collected particulates is corrected based only on the engine temperature, it may not be possible to accurately estimate the amount of collected particulates. Therefore, in the present invention, the correction based on the engine temperature is performed by a different method according to the engine speed, thereby preventing an error in the estimation of the particulate collection amount. To perform the correction by a different method according to the engine speed, for example,
In the case of correcting the particulate trapping amount using a correction coefficient determined according to the engine temperature, a method such as changing the value of the correction coefficient according to the engine speed as well as the engine temperature. Means that correction is performed by

According to the invention described in claim 8, claim 1 is provided.
And calculating a particulate trapping amount by using the calculation method according to any one of claims 3 to 3, and an exhaust throttle that reduces an engine exhaust flow rate when the particulate trapping amount reaches a predetermined amount. A particulate filter regeneration method for performing a regeneration operation of burning particulates in a particulate filter by raising an exhaust gas temperature, wherein at the time of the regeneration operation, the exhaust throttle is stopped, engine exhaust recirculation is stopped, an intake throttle is opened, and fuel is removed. A particulate filter regeneration method for performing at least one of the injection timing retards is provided.

That is, in the particulate filter regeneration method according to the present invention, when the amount of trapped particulates increases, the exhaust temperature is raised by the engine exhaust throttle to burn the particulates collected by the particulate filter. By performing the exhaust throttling, the engine exhaust back pressure increases and the engine output decreases. Therefore, even if the engine fuel injection amount is increased, the same engine output can be maintained. In this case, since the engine intake flow rate also decreases, it is necessary to reduce the EGR gas amount according to the decrease in the intake air flow rate. However, in actual operation, the decrease in the EGR gas amount is delayed due to a delay in response of the EGR device, and the amount of the EGR gas becomes excessive at the start of the regeneration operation, causing a sudden change (decrease) in engine output and generation of exhaust smoke.

Therefore, according to the present invention, at the time of performing the regeneration operation, at least one of the stop of the EGR, the opening of the intake throttle, and the retardation of the fuel injection timing is performed simultaneously with the exhaust throttling, thereby preventing a sudden change in the engine output and the occurrence of smoke. are doing. That is, by stopping the EGR at the time of performing the regeneration operation,
A decrease in output due to excessive EGR gas can be prevented. By opening the intake throttle, the intake pipe pressure increases, and the amount of EGR gas flowing into the intake pipe decreases. This prevents the EGR gas from becoming excessive during the regeneration operation. Further, if the fuel injection timing is retarded, the combustion timing in the combustion chamber is delayed, so that the exhaust temperature increases and the engine output decreases. For this reason, even if the degree of the exhaust throttle is reduced (the exhaust flow rate is increased), an increase in the engine output does not occur, and the above-described excessive EGR gas due to a large exhaust throttle is prevented from occurring.

[0025]

Embodiments of the present invention will be described below with reference to the accompanying drawings. FIG. 1 is a diagram showing a schematic configuration of an apparatus when the present invention is applied to an automobile diesel engine. In FIG. 1, reference numeral 1 denotes an automobile internal combustion engine.
In the present embodiment, the engine 1 is a four-cylinder diesel engine,
Each cylinder is provided with an in-cylinder fuel injection valve 111 for injecting fuel directly into the cylinder. Fuel is high pressure fuel injection pump 1
From 13, pressure is fed to a common rail (accumulation chamber) 115 to which each fuel injection valve 111 is connected, and is injected from the common rail into each cylinder by each fuel injection valve 111 at a predetermined timing.

In FIG. 1, reference numeral 21 denotes an intake manifold connecting the intake port of each cylinder to the intake passage 2, and 31 denotes an exhaust manifold connecting the exhaust port of each cylinder to the exhaust passage 3. In the present embodiment, the supercharger 35 for supercharging the engine 1
The exhaust passage 3 is connected to an exhaust inlet of the supercharger 35, and the intake passage 2 is connected to an intake discharge outlet of the supercharger 35. The intake passage 2 is provided with an intercooler 25 for cooling intake air supplied from the supercharger 35 and an intake throttle valve 27. The intake throttle valve 27 is
An appropriate type of actuator 27a, such as a stepper motor or a negative pressure actuator, which operates in response to a signal from the ECU 30, which will be described later, is provided with an opening corresponding to the signal from the ECU 30 to limit the intake flow rate of the engine. In addition, turbocharger 3
An exhaust throttle valve 37 provided with an actuator 37a similar to the intake throttle valve 27 is provided in the exhaust passage 3 on the downstream side of 5, and performs an exhaust throttle by setting an opening in accordance with a signal from the ECU 30.

In FIG. 1, reference numeral 33 denotes an EGR passage which connects the engine exhaust system and the intake system and recirculates part of the engine exhaust to the intake system, and 23 denotes an EGR valve arranged in the EGR passage. E
The GR valve 23 includes an appropriate actuator (not shown) such as a stepper motor and a negative pressure actuator.
An opening degree corresponding to the signal from the engine is taken, and the flow rate of exhaust gas (EGR gas) returned to the intake system through the EGR passage 33 is controlled in accordance with the engine operating state. In this embodiment, the flow rate of exhaust gas (EGR gas amount) recirculated to the engine intake system is controlled by adjusting the opening degree of the EGR valve 23 and the opening degree of the intake throttle valve 27. For example, when the opening degree of the intake throttle valve 27 is reduced, the throttle valve 2
7 The EGR valve 23
Even if the opening degree is the same, the EGR gas amount can be increased.

In this embodiment, the provision of the intake throttle valve 27 enables a relatively large amount of EGR to be performed during engine operation. In the present embodiment, a particulate filter (diesel particulate filter, hereinafter referred to as “DPF”) 40 is provided in an exhaust branch pipe connecting the exhaust manifold 31 to each exhaust port.
The DPF 40 is formed of a heat-resistant porous material such as ceramics, and has a large number of through holes that form an exhaust passage in the axial direction (the exhaust flow direction). Each of these through holes is closed at one of the upstream end and the downstream end in the exhaust flow direction by a plug or the like, and the through holes whose upstream ends are closed and the through holes whose downstream ends are closed alternately adjacent to each other. It is arranged. For this reason, the exhaust gas discharged from the exhaust port of each cylinder flows into the through hole in which the upstream end of each DPF is opened (the downstream end is closed), and passes through the porous partition separating the through holes from each other. Then, the downstream end flows into the open through hole and flows out of the DPF from the downstream end.
Particulates contained in the exhaust gas are collected when the exhaust gas passes through the porous partition.

In this embodiment, the DPF 4 having a relatively small capacity is used.
0 is provided adjacent to the exhaust port of each cylinder,
Because high-temperature exhaust from the cylinder flows directly into the DPF,
The temperature of the PF 40 can be kept high. Further, since each DPF 40 has a small capacity, the amount of particulates that can be collected is small, and it is necessary to set the execution interval of the DPF regeneration operation to be described later relatively short. Over time, the DPF temperature rises and particulate combustion starts. Further, since the amount of collected particulates is small, the combustion of the collected particulates can be completed in a short time, and the time required for the regeneration operation can be reduced. In this embodiment, since a diesel engine is used as the engine 1, the engine exhaust temperature during normal operation is relatively low. In the present embodiment, the so-called separation type DPF in which the small-capacity DPF 40 is disposed at the exhaust port of each cylinder is employed. The regeneration of the DPF 40 can be completed.

In FIG. 1, reference numeral 30 denotes an electronic control unit (ECU) of the engine 1. In the present embodiment, the ECU 30 is a microcomputer having a known configuration including a RAM, a ROM, and a CPU. The ECU 30 performs basic control such as fuel injection control of the engine 1, and also controls the DPF 40 according to an engine operating state by a method described later. Calculation of particulate collection amount and DPF40
And playback operation.

To perform these controls, a signal corresponding to the amount of engine intake air from an air flow meter 51 provided in the engine intake passage is provided to an input port of the ECU 30, and an exhaust temperature sensor 53 provided in the exhaust manifold 31. , A signal corresponding to the temperature of exhaust gas flowing into the DPF 40 is input, and a pulse signal is input from the rotational speed sensor 55 disposed near the engine crankshaft (not shown) at every constant rotation angle of the engine crankshaft. ing. Further, in the present embodiment, a signal indicating the accelerator pedal depression amount (accelerator opening) of the driver from the accelerator opening sensor 57 arranged near the accelerator pedal (not shown) of the engine 1 is provided to the input port of the ECU 30; A signal corresponding to the engine cooling water temperature is input from a cooling water temperature sensor 59 arranged in a cooling water jacket of the engine 1. ECU 30
Converts the output of the air flow meter 51, the output of the accelerator opening sensor 57, the output of the exhaust temperature sensor 53 and the output of the cooling water temperature sensor 59 at predetermined intervals, and converts the intake air amount Ga, the accelerator opening ACCP, the exhaust temperature TEX, Cooling water temperature T
The HW is stored in a predetermined area of the RAM of the ECU 30, and the engine speed NE is calculated from the interval of the pulse signal from the rotation speed sensor 55, and is stored in a predetermined area of the RAM. The ECU 30 calculates an engine basic fuel injection amount and a fuel injection timing based on a relationship previously stored in a ROM based on the accelerator opening ACCP detected by the accelerator opening sensor 57 and the engine speed NE. The fuel injection amount Q of the engine is corrected by adding the correction according to the engine operating state to the injection amount.
IJ and fuel injection timing are set. In the present invention, the method for setting the fuel injection amount and the fuel injection timing is not particularly limited, and any of the known methods for a diesel engine can be used.

On the other hand, the output port of the ECU 30 is connected to the fuel injection valve 11 of each cylinder via a fuel injection circuit (not shown) to control the amount and timing of fuel injection into each cylinder.
1, and is connected to a high-pressure fuel pump 113 via a drive circuit (not shown) to control the amount of fuel pumped from the pump 113 to the common rail 115. Also,
The output port of the ECU 30 is further connected to an actuator 27 of the intake throttle valve 27 via a drive circuit (not shown).
a, Actuator 37a of exhaust throttle valve 37 and EGR
The opening degree of the intake throttle valve 27 and the exhaust throttle valve 37 and the EG passing through the EGR valve 23 are connected to the actuator of the valve 23.
The R gas amount is controlled.

Next, the regeneration operation of the DPF 40 in this embodiment will be described. In the present embodiment, the DPF 40 has a different regeneration method depending on the operating state (load state) of the engine.
To play back. FIG. 2 is a diagram showing the area division of the engine operating state (load state) in the present embodiment, in which the vertical axis represents the engine output torque (fuel injection amount QIJ), and the horizontal axis represents the engine speed NE. I have. In this embodiment, the output torque and the number of revolutions are divided into four regions as indicated by I to IV in FIG. 2, and different regeneration operations of the DPF 40 are performed for each region.

The reproduction operation in each area will be described below. (1) Region I (Natural regeneration region) As shown in FIG. 2, the region I is a region near the full load of the engine. In this region, the exhaust gas temperature of the engine also increases according to the load, and the temperature of the DPF 40 becomes equal to or higher than the particulate ignition temperature (for example, 600 ° C.) without performing an auxiliary temperature raising operation. For this reason, when the engine operation state is in the region I, the DPF 40 is naturally regenerated. The DPF regeneration in the region I does not require any special operation for regeneration, so that the fuel consumption of the engine does not increase.

(2) Region II (Fuel Injection Timing Retardation) Region II is a state in which the engine load is lower than in region I.
Since the engine exhaust temperature has also decreased according to the load, the DPF
The temperature is below the ignition temperature of the particulates.
For this reason, the particulate does not start burning naturally, and even during the combustion, the DPF temperature may become lower than the particulate combustion lower limit temperature (for example, 400 ° C.) and the combustion may stop. Therefore, in order to regenerate the DPF, it is necessary to perform a regeneration operation different from the normal operation to raise the DPF temperature. In the present embodiment, in the region II, the exhaust gas temperature is raised by retarding the fuel injection timing to maintain the DPF temperature at a high temperature. When the fuel injection timing is retarded, the combustion timing of fuel in the cylinder is delayed, so that relatively high temperature combustion gas is discharged in the exhaust stroke without sufficiently lowering the temperature in the expansion stroke, and the exhaust temperature rises .
In this load range, the exhaust gas temperature is relatively high even during normal operation, so that the increase in engine fuel consumption is relatively small.

(3) Region III (Expansion stroke injection, EGR
In this region, the exhaust gas temperature in the normal operation is in the region I or II.
Since the temperature becomes lower, it is difficult to raise the exhaust gas temperature to the ignition temperature of particulates only by retarding the fuel injection timing. For this reason, in the region III, in addition to the normal fuel injection (main fuel injection), additional fuel injection (expansion stroke injection) is performed during the expansion stroke of each cylinder, and the EGR valve 2
3, the opening degree of the intake throttle valve 27 is reduced, and the amount of EGR gas introduced into each cylinder is increased. Since the temperature of the EGR gas is high, the intake air temperature of each cylinder of the engine rises, and the fuel injected in the expansion stroke burns, so that the exhaust temperature further rises. In this region, the additional fuel injection is performed during the expansion stroke, so that the fuel consumption of the engine increases more than in region II.

(4) Region IV (combination of expansion stroke injection and exhaust throttling) In region IV, the engine load is small and the exhaust gas temperature is considerably low. In this region, the exhaust gas temperature does not rise to a temperature sufficient for particulate combustion unless the main fuel injection amount and the fuel injection amount of the expansion stroke injection are increased. on the other hand,
Increasing the amount of fuel in the main fuel injection causes an increase in engine output torque. Further, since the engine output also increases due to the combustion of the fuel injected during the expansion stroke, increasing the fuel injection amount of the main fuel injection and the expansion stroke fuel injection will increase the engine output torque. Therefore, in this region, the amount of fuel injection in the main fuel injection and the fuel injection in the expansion stroke is increased, and the exhaust valve throttle 37 is used to reduce the exhaust resistance to suppress the increase in engine output torque.
This makes it possible to regenerate the DPF without greatly deteriorating the operability of the engine. However, the increase in the fuel consumption of the engine becomes larger than that in the regions II and III due to the large increase in the fuel injection amount.

(5) Non-regeneration region In a state where the engine load is lower than the region IV (region V in FIG. 2), the engine exhaust temperature is greatly reduced. Therefore, in each of the above methods, the engine exhaust temperature is increased to the particulate ignition temperature. It becomes difficult. Therefore, in the region V of FIG.
F is not reproduced. That is, in the present embodiment, even when the regeneration operation is being performed in the regions II to IV, the regeneration operation is interrupted when the engine operation state changes to the region IV. In the present embodiment, the ECU 30 constantly calculates the amount of the particulates collected in the DPF 40 by the method described below, so that the amount of the collected particulates reaches a predetermined amount and the engine Operating area I
When the DPF 40 is operated in any one of I to IV, the regeneration of the DPF 40 is started by the regeneration method according to the operation range.

Next, the method for calculating the amount of trapped particulates of the DPF 40 of the present invention and the DP during particulate collection will be described.
An embodiment with the F40 reproducing method will be described. 1. (1) First Embodiment In this embodiment, the amount of particulates generated in the engine per unit time is calculated based on the operating state of the engine, and the amount of particulates generated is calculated based on the calculated amount of generated particulates. The amount of particulates collected in the particulate filter is calculated by multiplying the value obtained by multiplying the particulate filter's collection efficiency determined from the operating state. In addition, the particulate collected by the particulate filter is
When the above-described regeneration operation is performed or when the engine is operated in the above-described operation region I and the exhaust gas temperature rises, it is burned and discharged as CO ₂ together with the exhaust gas. Therefore, when the exhaust gas temperature rises, the amount of particulates collected by the particulate filter decreases. Therefore, in the present embodiment, the particulate collection amount is calculated as a value obtained by subtracting the decrease due to the combustion from the particulate collection amount calculated as described above.

FIG. 3 is a flowchart specifically showing the above-described operation of calculating the amount of trapped particulates in the present embodiment. This operation is performed by a routine executed by the ECU 30 at regular intervals. When the operation of FIG. 3 starts, in step 301, the fuel injection amount QIJ calculated by the fuel injection amount calculation operation separately performed by the ECU 30, the engine speed NE, the exhaust temperature TEX,
The engine intake air amount Ga is read, respectively. here,
As the fuel injection amount QIJ and the engine intake air amount Ga, a value converted into a weight per one engine stroke cycle is read.

Next, at step 303, using the fuel injection amount QIJ and the engine speed read as described above,
From the numerical table stored in the ROM of the ECU 30 in advance, the amount of particulates P generated by the engine per unit time of the engine (here, the time equal to the execution interval of the operation in FIG. 3)
MR is calculated. In the present embodiment, the PMR value is obtained in advance by measuring the amount of particulates generated per unit time when the actual engine is operated while changing the load conditions (the fuel injection amount QIJ and the rotational speed NE). Yes,
It is stored in the ROM of the ECU 30 as a two-dimensional numerical table of the form shown in FIG. 4 using QIJ and NE. In step 303, the particulate generation amount PMR is calculated from the values of QIJ and NE using this numerical table.

Based on the above, step 305 after calculating the PMR
In the DPF 4 based on the intake air amount Ga and the rotational speed NE,
A collection efficiency K1 of 0 is calculated. The collection efficiency K1 of the DPF 40 changes according to the engine exhaust flow velocity. For example, when the engine exhaust flow velocity increases, the amount of exhaust that flows between each DPF 40 and the intake port wall surface increases. For this reason, when the engine exhaust flow velocity increases, the amount of particulates flowing out into the exhaust passage 3 without being collected by the DPF 40 among the particulates in the exhaust gas increases, and the collection efficiency of the DPF 40 decreases. Further, the exhaust flow velocity is determined by the intake air amount Ga and the engine speed NE. Therefore, in the present embodiment, the actual D
The particulate collection efficiency K1 of the DPF 40 was actually measured by changing the conditions of Ga and NE while the PF 40 was mounted on the engine 1, and the result was used as a two-dimensional numerical table in the form of FIG. 5 using Ga and NE. Is stored in the ROM of the ECU 30. In step 305, the value of the trapping efficiency K1 of the DPF 40 is determined from this numerical table based on the values of Ga and NE.

In step 307, the particulate matter amount PMI collected by the DPF 40 per unit time is calculated as PMI = PMR × K1 using the particulate matter generation amount PMR and the DPF collection efficiency K1 calculated as described above. Is done. That is, the PMI indicates the amount of increase in the amount of particulates collected in the DPF 40 per unit time.

Next, at step 309, the amount PMD of the particulate matter trapped by the DPF 40, which burns per unit time, is calculated. The particulate matter collected by the DPF 40 starts burning when the exhaust gas temperature rises due to execution of a regeneration operation or the like. Further, the amount of particulates burned per unit time increases as the exhaust gas temperature TEX increases and as the exhaust flow rate (engine speed) increases. In this embodiment, the PMD value is obtained in advance by measuring the amount of particulate combustion per unit time when the actual engine is operated while changing the exhaust temperature TEX and the rotational speed NE. RO of the ECU 30 as a two-dimensional numerical table of the form shown in FIG.
M. In step 309, the particulate combustion amount PMD is calculated from the values of TEX and NE using this numerical table. PMD represents the amount of decrease in the amount of particulates collected by the DPF 40 per unit time. The PMD value is set to 0 in a region where the exhaust gas temperature is low and particulate combustion does not occur.

In step 311, the particulate matter increase amount PMI and the decrease amount PMD per unit time calculated as described above are respectively added to and subtracted from the value of the particulate matter trapping amount PM of the DPF 40 calculated at the time of executing the previous operation. Thus, the current value of the particulate matter trapping amount PM of the DPF 40 is calculated as PM = PM + PMI-PMD.

If the operation in the above-mentioned region I (natural regeneration region) continues, the value of PM calculated in step 311 may become negative.
In step 5, the operation is terminated after restricting the value of PM to a negative value. By performing the operation shown in FIG. 3, the calculated value of PM accurately represents the amount of particulates currently collected by the DPF 40.

In FIG. 3, in step 305, the trapping efficiency K1 is calculated based only on the engine exhaust flow velocity. However, the trapping efficiency of the DPF 40 itself actually changes according to the trapped particulate amount. . That is, when the particulates accumulate on the filter, the pores of the filter are partially blocked by the particulates and the effective pore diameter is reduced, so that the filter collection efficiency is improved. Therefore, the second trapping efficiency K2 that changes based on the particulate trapping amount is introduced, and the PMI of step 307 is
= PMR × K1 × K2, it is possible to calculate the particulate collection amount more accurately.

In this case, the value of the second trapping efficiency K2 is obtained in advance by operating the DPF 40 while changing the trapping amount PM using actual measurement, and the value of K2 is set as a function of PM. Then, in step 305, the first collection efficiency K1
At the same time, the second collection efficiency K2 is calculated from the above function using the previous value of the particulate collection amount PM, and the PMI value is calculated in step 307 as PMI = PMR ×
What is necessary is just to calculate as K1 * K2.

(2) Second Embodiment Next, the second embodiment of the method for calculating the amount of trapped particulates according to the present invention will be described.
An embodiment will be described. In the present embodiment, the particulate generation amount of the engine is corrected according to the EGR amount of the engine. In the diesel engine 1 of the present embodiment, EGR is performed in almost all operation regions. For this reason, the first
The numerical value table (FIG. 4) used for calculating the particulate generation amount PMR of the engine in the embodiment is also created based on the operation data during the EGR. However, in actual operation, there are cases where EGR cannot be performed even in an operation region where EGR should be performed. For example, when the engine is cold or the like, the combustion becomes unstable. Therefore, when EGR is performed, the engine operation becomes unstable due to the deterioration of the combustion state. For this reason,
Actually, when the engine temperature (cooling water temperature, lubricating oil temperature, etc.) is low, even in the same operation region, the EGR amount is reduced according to the engine temperature compared to after the completion of engine warm-up, thereby stabilizing the engine operation. Is being measured. However, the amount of particulates generated in the engine is closely related to the EGR amount, and when the EGR amount decreases, the particulate amount decreases accordingly. Therefore, even when the EGR amount is reduced at a low engine temperature, the particulate generation amount is calculated based on the data (numerical table in FIG. 4) when the entire amount of EGR after the engine warm-up is introduced. An error occurs in the amount collected. Therefore, in the present embodiment, DP is calculated using a value obtained by correcting the engine particulate generation amount PMR calculated based on FIG. 4 according to the engine temperature (that is, the EGR amount).
The amount of trapped particulates in F40 is calculated.

The EGR controls the exhaust of the engine by the EGR valve 23.
Since the exhaust gas returns to the intake system through the above-described process, if the exhaust gas temperature becomes too high, the durability of the EGR system elements such as the EGR valve 23 may be reduced. Therefore, in the high engine speed region where the exhaust gas temperature becomes high, the EGR is stopped to secure the reliability of the EGR system. Therefore, the particulate generation amount PMR calculated based on the numerical table of FIG. 4 is also data based on the operation with the EGR stopped in the region where the engine speed is high. Since EGR is not originally performed in this rotation speed region, it is not necessary to correct the amount of particulates generated even when the engine temperature is low. Therefore, in the present embodiment, the correction coefficient of the particulate generation amount based on the engine temperature is set to a different value for each engine speed. That is, the correction of the particulate generation amount based on the engine temperature is performed by a different method for each engine speed.

FIG. 7 is a flowchart showing a specific operation of the method for calculating the amount of trapped particulates according to the present embodiment. This operation is performed by a routine executed by the ECU 30 at regular intervals (every unit time described above), similarly to the operation of FIG. In the operation of FIG.
Then, the fuel injection amount QIJ, the rotational speed NE, the exhaust temperature TE
The engine coolant temperature THW is read from the coolant temperature sensor 59 in addition to X and the intake air amount Ga. Also, in steps 703 and 705, steps 303 and 3 in FIG.
In the same way as 05, the engine particulate matter PMR
And the first collection efficiency K1 are calculated.

In this embodiment, the collection efficiency K2 based on the particulate collection amount described above in step 707
Is calculated based on the particulate collection amount PM of the DPF 40 calculated at the time of the previous execution of the operation. Further, in steps 709 and 711, a correction coefficient K3 of the particulate generation amount with respect to the EGR amount change is calculated based on the engine cooling water temperature THW. In the present embodiment, the correction coefficient K3
The value of is obtained by measuring the change in the amount of generated particulates by operating the actual engine in advance while changing the cooling water temperature THW, and using the fuel injection amount QIJ and the cooling water temperature THW as shown in FIG. ECU as a two-dimensional numerical table
It is stored in 30 ROMs. Also, as mentioned above,
Whether EGR is performed or not depends on the engine speed.
The numerical table of FIG. 8 is prepared for each rotation speed of the engine. In the operation of this embodiment, a numerical value map (numerical table) for correcting the cooling water temperature corresponding to the current engine speed NE is selected in step 709, and the engine cooling water temperature THW is determined using the map selected in step 711. Correction coefficient K3
Is calculated. Then, in step 713, the particulate matter amount PMI collected by the DPF 40 per unit time
Is calculated as PMI = PMR × K1 × K2 × K3.

Steps 715 to 721 show the same operation as steps 309 to 315 in FIG. That is, also in the present embodiment, the particulate matter trapping amount PM of the DPF 40 is obtained by adding the particulate matter trapping amount PMI per unit time calculated as described above to the trapping amount PM calculated at the time of executing the previous operation. By subtracting the decrease PMD per unit time due to

2. Next, an embodiment of a particulate filter regeneration operation based on the particulate matter collection amount PM of the DPF 40 calculated as described above will be described. (1) First Embodiment In the regeneration operation of the present embodiment, the engine is operating in the above-described regeneration operation executable operation region (regions II to IV in FIG. 2), and the particulate matter trapping amount PM of the DPF 40 is reduced. When the predetermined value PM1 or more is reached, the reproduction operation is executed. The regeneration operation in this case is performed by a method according to the operating range of the engine as described above.

When the entire amount of the particulate matter trapped in the DPF 40 has burned, the regeneration operation is stopped and D
The PF 40 resumes collecting particulates. In addition, if the engine operation state changes during execution of the regeneration operation and the non-regeneration area (FIG. 2, area V) is reached, the regeneration operation is interrupted. . However, when the engine operating state is in the non-regeneration region during the execution of the regeneration operation, the regeneration operation is interrupted before the entire amount of the particulates collected in the DPF 40 burns. The collection of particulates will be resumed with the curates remaining. In this case, since particulates remain in the DPF 40, collection of the particulates is started in a state where the pressure loss of the DPF 40 is higher than when the regeneration operation is completed (the entire amount of the particulates is burned). become. Even in this state, if the particulate collection amount reaches PM1 again and the regeneration operation is performed, the pressure loss of the DPF 40 decreases, but after the regeneration operation is interrupted, the exhaust gas pressure loss is high immediately after the particulate collection is resumed. , The time during which the engine is operated with a high exhaust pressure loss increases, and the fuel efficiency of the engine deteriorates as a whole.

Therefore, in the present embodiment, when the regeneration operation is interrupted and the particulate collection is restarted with a certain amount of particulates remaining in the DPF 40, the start of the next regeneration operation is expedited. ing. In other words, in the present embodiment, the particulate matter collection is normally performed when the amount of collected particulates reaches the first predetermined value PM1, but the previous regeneration operation is interrupted, and the particulate matter of a fixed amount PM0 or more is stored in the DPF 40. When the particulate collection is resumed in the remaining state, the next regeneration operation is started when the particulate collection amount reaches a second predetermined amount PM2 smaller than PM1. As a result, the frequency of operating the engine in a state where the exhaust pressure loss is high is reduced, and problems such as deterioration of fuel efficiency of the engine are prevented.

FIGS. 9 and 10 are flow charts for specifically explaining the reproduction operation of the present embodiment. FIG. 9 shows a reproduction start condition determination operation of the DPF 40, and FIG. 10 shows a reproduction end condition determination operation. ing. 9 and 10 are performed by a routine executed by the ECU 30 at regular intervals. In the regeneration start condition determination operation shown in FIG. 9, the engine operates the DPF 4 shown in regions I to IV in FIG.
The regeneration operation is started when the operation is performed in the regeneration region of 0 and the particulate matter trapping amount PM of the DPF 40 calculated by any of the methods described above is equal to or greater than a predetermined determination value. Here, when the combustion amount of the particulates has reached the target amount at the time of executing the previous regeneration operation and the amount of the particulates remaining in the DPF 40 at the end of the previous regeneration operation is equal to or less than the predetermined value, A relatively large value PM1 is used as the determination value. On the other hand, if the previous regeneration operation was interrupted and the combustion amount of the particulates has not reached the target amount, and if the particulates of the predetermined amount or more remain in the DPF 40 at the end of the regeneration operation, the above determination is made. PM2 smaller than PM1 is used as the value.

Thus, when the regeneration operation is interrupted due to a change in the engine operation state or the like and the particulate collection is restarted in a state where the pressure loss of the DPF 40 is large, the regeneration operation is performed early. In addition, the frequency of operating the engine in a state where the exhaust pressure loss is large is reduced. When the operation in FIG. 9 starts, in step 901 the fuel injection amount QIJ, the engine speed NE, and the particulate collection amount P of the DPF 40 calculated by the operation in FIG. 3 or FIG.
M is read. Then, in step 903, it is determined based on the map of FIG. 2 whether the engine is currently operating in the non-regeneration region (region V in FIG. 2) based on the fuel injection amount QIJ and the rotational speed NE read as described above. If the vehicle is operating in the non-regeneration region, the value of the regeneration operation execution flag XR is set to 0 in step 905, and the operation is terminated. When the value of the reproduction operation execution flag XR is set to 0, the above-described reproduction operation is not executed, and when the reproduction operation is being executed, the reproduction operation is stopped.

On the other hand, if the current engine operation area is not the non-regeneration area in step 903, that is, if the engine is currently operating in the regeneration execution area from I to IV in FIG.
Next, at step 907, it is determined whether or not the reproduction is currently being executed (that is, whether or not the value of the flag XR is set to 1). If the reproduction operation is currently being executed, there is no need to determine whether or not the reproduction operation needs to be newly started, so this operation is immediately terminated, and the value of the flag XR is kept at 1.

If it is determined in step 907 that the reproducing operation is not currently being executed, it is determined in steps 909 to 913 whether or not the reproducing operation needs to be started this time. That is,
In step 909, it is determined based on the value of the flag XC whether or not the amount of particulates in the DPF 40 has been sufficiently reduced by the execution of the previous regeneration operation. The flag XC is a flag indicating whether or not the previous reproduction operation has been completed.
XC = 1 when the playback operation is completed by the operation of
When the reproduction operation is interrupted, XC = 0 is set.

If XC = 1 in step 909, that is, if the particulates have been sufficiently burned during the previous regeneration operation and the collection of the particulates has started from a state where the exhaust pressure loss is small, the following process is performed. Step 9
11, the current particulate matter collection amount PM of the DPF 40
Is determined to have increased to a first predetermined value PM1,
If PM ≧ PM1, the regeneration operation needs to be started, so the process proceeds to step 915, where the value of the regeneration operation execution flag XR is set to 1. The value of the flag XR is 1
Is set in the engine operating region I shown in FIG. 2 by a routine (not shown) separately executed by the ECU 30.
The reproduction operation described above is executed according to the steps IV to IV. (If the engine operation state is in the region I (natural regeneration region), the normal operation in the region I is continued without performing any special regeneration operation even if the value of the flag XR is set to 1. On the other hand, if XC ≠ 1 in step 909, that is, it means that the previous regeneration operation of the DPF 40 has been interrupted, and particulate collection has been resumed in a state of high exhaust pressure loss. I have. Therefore, in this case, since the operation is not performed in a state where the exhaust pressure loss is small after the completion of the regeneration operation, there is a possibility that the engine fuel efficiency and the like are deteriorated as a whole. Therefore, in this case, in step 913, the current particulate matter trapping amount PM is set to the second predetermined value PM.
2 (PM2 <PM1) is determined, and PM
If .gtoreq.PM2, the value of the flag XR is set to 1 in step 915, and the reproduction operation is started.

Next, the reproduction end determination operation shown in FIG. 10 will be described. In this operation, when the engine operation state enters the non-regeneration region (region V in FIG. 2) during execution of the regeneration operation,
When the entire amount of the particulate matter trapped in the PF 40 has burned, the regeneration operation being executed is ended. If the amount of particulates remaining in the DPF 40 at the end of the regeneration operation is smaller than the predetermined value PM0, the value of the regeneration operation completion flag XC is set to 1 and the particulates of PM0 or more remain. If there is, the value of the reproduction operation completion flag XC is set to 0.

That is, when this operation starts, FIG.
In step 1001, the current value of the particulate trapping amount PM is read, and in step 1003, the current DP is collected.
Whether or not the reproduction operation of F40 is being performed is determined based on the value of the flag XR. If XR ≠ 1 in step 1003, that is, if the reproduction operation is not currently being executed, it is not necessary to determine whether or not the reproduction operation needs to be ended, so this operation ends immediately. Also, the reproduction operation is currently being executed (X
If R = 1), steps 1005 to 1009 are executed next. If the particulate matter amount PM currently held in the DPF 40 is smaller than the predetermined value PM0, the value of the regeneration operation completion flag XC is changed. Set to 1, PM
Is greater than or equal to PM0, the value of the flag XC is set to 0. Accordingly, for example, when the regeneration operation is interrupted due to a change in the engine operation state (XR in step 905 in FIG. 9)
Is set to 0), the value of XC indicates whether or not the amount of particulate at the time of interruption is smaller than PM0.

Steps 1011 and 1013 represent a regeneration ending operation when the regeneration operation is completely performed, that is, when the entire amount of the particulates in the DPF 40 is completely burned. That is, in step 1011, the current D
It is determined whether or not the residual particulate amount PM in the PF 40 has become 0. If PM ≦ 0, the value of the flag XR is set to 0 in step 1013, and the reproduction operation ends. If PM> 0, this operation ends without changing the value of the flag XR. This allows
As long as the operating state of the engine does not enter the non-regeneration region (region V) in FIG. 2, the regeneration operation is continued until the entire amount of the particulates in the DPF 40 is burned.

(2) Second Embodiment In each of the above-described embodiments, as the particulate filter regeneration method when the engine is operated in the region IV, the expansion stroke injection and the main fuel injection are performed to increase the engine output. The use of the exhaust throttle in combination to suppress the increase in the torque has been described above. However, when the exhaust throttling is performed, the engine output torque may be temporarily reduced at the start of the regeneration operation to cause a torque shock. That is, when the exhaust throttle is performed, the engine intake air amount also decreases. Therefore, it is necessary to reduce the EGR amount in accordance with the decrease in the intake air amount. However, EGR
Since the response speed of the valve 23 is considerably slower than the speed at which the amount of intake air is reduced by the exhaust throttle, when the exhaust throttle valve 37 is operated, the amount of EGR gas temporarily supplied to the engine may become excessive. For this reason, the combustion state may be temporarily deteriorated during the execution of the exhaust throttling, causing a drop in the engine output torque, the occurrence of exhaust smoke, and the like. Therefore, in the present embodiment, a decrease in the engine output and the occurrence of exhaust smoke when the regeneration operation is performed by the exhaust throttle are prevented by the following method.

(A) Stopping EGR Normally, the EGR valve 23 performs feedback control based on the difference between the target opening and the actual opening. The larger the difference between the target opening and the actual opening, the larger the EGR valve. The operating speed of the valve 23 increases. Therefore, when the EGR is stopped when the exhaust throttle is performed (that is, the target opening of the EGR valve is set to 0), the EG
The operating speed of the R valve increases, and the actual decreasing speed of the EGR amount increases. Therefore, by stopping the EGR at the same time as the exhaust throttle, the amount of the EGR gas actually recirculated to the intake system can be rapidly reduced. As a result, it is possible to prevent a temporary excessive EGR from being caused by the exhaust throttle, and it is possible to suppress a temporary decrease in engine output and generation of smoke.

(B) Opening of the intake throttle When the intake throttle is opened, the negative pressure generated in the intake system downstream of the throttle valve is eliminated, and the pressure of the intake system increases. Therefore, even if the opening degree of the EGR valve 23 is the same, the amount of the EGR gas actually recirculated to the intake system decreases. Therefore, by fully opening the intake throttle valve 27 simultaneously with the exhaust throttle, the EGR
The gas amount can be rapidly reduced. This allows
Temporary excess EGR due to the exhaust throttle can be prevented from occurring, and a temporary decrease in engine output and generation of smoke can be suppressed.

(C) Retardation of Fuel Injection Timing In the region IV, the expansion stroke fuel injection is performed in addition to the main fuel injection. However, if the main fuel injection timing is further retarded, the combustion timing in the cylinder as a whole is delayed. Therefore, the engine output torque decreases. Further, since the amount of burned gas discharged without performing work in the cylinder increases, the exhaust gas temperature rises. Therefore, by retarding the main fuel injection timing, it is possible to sufficiently suppress the increase in the engine output and raise the temperature of the exhaust even if the degree of the exhaust throttle is reduced. In this case, the degree of reduction of the EGR amount is small because the degree of the exhaust throttle is small, and excessive EGR does not occur even when the reduction speed of the EGR amount is slow. Therefore, by temporarily retarding the main fuel injection timing together with the exhaust throttle, it is possible to suppress a temporary decrease in engine output and the occurrence of smoke.

Although the above methods (A), (B), and (C) are effective even if used alone, the engine can be more reliably determined by simultaneously executing two or more of these methods. It is possible to prevent the output from temporarily lowering and the occurrence of smoke.

[0070]

According to the particulate collection amount calculation methods of the first to third and fifth to seventh aspects, it is possible to accurately estimate the amount of the particulate collected by the particulate filter. Further, according to the particulate filter regeneration method of the present invention, it is possible to perform an appropriate particulate filter regeneration operation based on the amount of trapped particulates, and the engine is operated in a state where the pressure loss of the particulate filter is high. It is possible to reduce the time taken.

Further, according to the particulate filter regeneration method of the present invention, when the particulate filter is regenerated using the exhaust throttle, it is possible to effectively suppress the fluctuation of the engine output torque and the generation of exhaust smoke. It becomes possible.

[Brief description of the drawings]

FIG. 1 is a diagram showing a schematic configuration of an embodiment in which an apparatus for implementing a particulate trapped amount calculation method and a particulate filter regeneration method of the present invention is applied to an automobile diesel engine.

FIG. 2 is a map showing an operation region in which a particulate filter regeneration operation of the engine of FIG. 1 is performed.

FIG. 3 is a flowchart illustrating one embodiment of a method for calculating a particulate trapping amount of a particulate filter.

FIG. 4 is a diagram showing a format of a numerical value table used in the trapping amount calculation method of FIG. 3;

FIG. 5 is a diagram showing a format of a numerical value table used in the trapping amount calculation method of FIG. 3;

6 is a diagram showing a format of a numerical value table used in the trapping amount calculation method of FIG. 3;

FIG. 7 is a flowchart illustrating another embodiment of the method for calculating the amount of trapped particulates in the particulate filter, which is different from FIG. 3;

8 is a diagram showing a format of a numerical value table used in the trapping amount calculation method of FIG. 7;

FIG. 9 is a flowchart illustrating an example of a particulate filter regeneration operation start condition determination operation.

FIG. 10 is a flowchart illustrating an example of a stop condition determination operation of a particulate filter regeneration operation.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 ... Diesel engine 111 ... In-cylinder fuel injection valve 27 ... Intake throttle valve 30 ... Electronic control unit (ECU) 3 ... Exhaust passage 31 ... Exhaust manifold 37 ... Exhaust throttle valve 33 ... EGR passage 23 ... EGR valve 40 ... Particulate filter (DPF) 53 ... Exhaust temperature sensor 59 ... Cooling water temperature sensor

Continued on the front page F term (reference) 3G062 AA01 BA05 BA06 CA06 DA01 EA04 EA11 ED09 GA01 GA06 GA08 GA09 3G090 AA02 AA04 BA01 CA02 CB25 DA12 DA14 DA18 DA20 DB06 DB07 DB10 EA04 EA06 EA07 3G301 HA02 HA13 JA21 KA06 MA23 NC PA17Z PD11Z PE01Z PE08Z

Claims (8)

[Claims] 1. A method for calculating a particulate collection amount of a particulate filter that collects particulates in exhaust gas of an internal combustion engine, comprising calculating an amount of particulate emissions of the engine based on an operation state of the engine. The collection efficiency of the particulate filter is calculated based on the operating state of the engine, and the amount of the particulate collected by the particulate filter is calculated based on the calculated particulate discharge amount and the collection efficiency. A particulate collection amount calculation method for calculating a particulate collection amount of a particulate filter based on the calculated amount of particulates. 2. The calculation method according to claim 1, further comprising: calculating the amount of particulates collected by said particulate filter at regular time intervals; and integrating the amount of said collected particulates. A method for calculating the amount of trapped particulates, which calculates the amount of trapped particulates in a filter. 3. The calculating method according to claim 1, further comprising: calculating an amount of particulates burned in the particulate filter based on an operation state of the engine; and calculating the calculated particulate matter collection amount. A method for calculating the amount of trapped particulates, which is corrected based on the amount of curate. 4. One of claims 1 to 3
The particulate collection amount is calculated using the calculation method described in the section, and a regeneration operation for burning the particulates in the particulate filter is performed when the particulate collection amount reaches a predetermined first amount. When the collection of particulates is restarted after the end of the regeneration operation, and the amount of the particulates burned before the end of the regeneration operation is smaller than a predetermined target combustion amount, the collection amount of the particulates after the restart of the collection. A particulate filter regeneration method in which the regeneration operation is performed when the value reaches a second amount smaller than the first amount. 5. A particulate filter of a particulate filter for calculating a particulate emission amount of an engine based on an operation state of an internal combustion engine and calculating a particulate collection amount of the particulate filter based on the particulate emission amount. A collecting amount calculating method, wherein a particulate emission amount of the engine is corrected based on a recirculated exhaust gas amount recirculated to an engine intake system by an EGR device of the engine, and the particulate emission amount is corrected based on the corrected particulate emission amount. A particulate collection amount calculation method for calculating a particulate collection amount. 6. A particulate filter which calculates a particulate emission amount of the engine based on an operation state of the internal combustion engine and calculates a particulate collection amount of the particulate filter based on the particulate emission amount. A method for calculating the amount of particulates, wherein the amount of particulates discharged from the engine is corrected based on an engine temperature, and the amount of collected particulates is calculated based on the corrected amount of particulates discharged. 7. The method according to claim 6, wherein the correction of the particulate discharge amount is performed by using a different method according to the engine speed. 8. Any one of claims 1 to 3
The particulate trapping amount is calculated by using the calculation method described in the paragraph, and when the particulate trapping amount reaches a predetermined amount, the exhaust gas temperature is raised by an exhaust throttle that reduces the engine exhaust flow rate to increase the particulate filter. A particulate filter regeneration method for performing a regeneration operation for burning particulates in the engine, wherein at least one of stop of engine exhaust recirculation together with the exhaust throttle, opening of an intake throttle, and retarding of fuel injection timing during the regeneration operation. Execute the particulate filter regeneration method.