JP2000179326A - Particulate filter reclamation control device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To accurately control engine exhaust temperature within a short period of time to a target level during particulate filter reclamation processes. SOLUTION: A particulate filter (DPE) 40 is placed at each of the exhaust ports of all cylinders of a diesel engine 1. An electronic control unit(ECU) 30 of the engine increases exhaust temperature to perform reclamation of DPFs by using any one or more of the following methods: exhaust throttling operation by means of an exhaust throttle valve 37; expansion stroke injection operation in which fuel is injected during an expansion stroke of each cylinder; EGR operation; and, main fuel injection control operation in which the amount of main fuel injected and injection timing for each cylinder are changed. When performing the exhaust throttling operation, the ECU sets a value depending on engine operating conditions for each control amount of the amount of fuel injected during the expansion stroke and injection timing, recirculating exhaust flow rate, and the amount of main fuel injected and injection timing, each different from those when the exhaust throttling operation is not performed.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a particulate filter regeneration control device for controlling a particulate filter regeneration process for collecting particulates in exhaust gas from an internal combustion engine.

[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, various particulate removal means for preventing the release of these particulates to the atmosphere have been proposed.

[0003] As a means for removing particulates, a method has been proposed in which a particulate filter made of, for example, ceramic or non-woven metal fabric is disposed in an exhaust passage of an engine to collect particulates in exhaust gas passing through the filter. I have. When such a particulate filter is used, the amount of particulate collected by the filter increases with the operation of the engine, and the exhaust pressure loss at the filter increases. Therefore, in order to prevent a decrease in engine performance due to an increase in exhaust pressure loss, it is necessary to periodically burn the particulates collected by the filter and regenerate the particulate filter.

In this case, especially in a diesel engine, since the exhaust gas temperature is relatively low, the particulate does not spontaneously ignite except during a considerably high load operation, and some auxiliary means for raising the particulate temperature to the ignition temperature. It is necessary to carry out a reproduction operation using. An example of a particulate filter regeneration control device for performing this type of regeneration operation is disclosed in, for example, JP-A-10-5427.
No. 0 publication.

The apparatus disclosed in the above publication increases the engine fuel injection amount to raise the exhaust gas temperature and performs engine auxiliary equipment such as an alternator in order to regenerate a particulate filter disposed in an exhaust passage of a diesel engine. The load is changed to absorb the increase in the engine output due to the increase in the fuel injection amount. Thus, by suppressing the increase in the engine external output during the particulate filter regeneration processing, it is possible to perform the particulate filter regeneration operation without affecting the engine operability.

[0006]

However, in the apparatus disclosed in JP-A-10-54270, since only the engine output is increased while maintaining the normal operation state, the exhaust gas temperature is controlled accurately to the target temperature. Can be difficult to do. For example, when the apparatus disclosed in the above publication is applied to an automobile engine, the engine speed, the running load, and the like are determined by the vehicle running conditions. In some cases, the exhaust gas temperature cannot be freely set due to the above restriction, and the exhaust gas temperature cannot be controlled to the target temperature. Further, when the exhaust gas temperature is increased by increasing the engine output as in the above-mentioned publication, the rate of increase of the engine output (exhaust gas temperature) is limited, so that the exhaust gas temperature must be raised to the target temperature in a short time. Can be difficult. For this reason, the apparatus disclosed in the above publication has a problem in that the regeneration operation of the particulate filter requires a relatively long time.

SUMMARY OF THE INVENTION In view of the above problems, the present invention provides a particulate filter regeneration control capable of completing a particulate filter regeneration process in a short time by accurately controlling the engine exhaust temperature to a target temperature in a short time. It is intended to provide a device.

[0008]

According to the first aspect of the present invention, there is provided a regeneration control for controlling a regeneration process of a particulate filter for collecting particulates in exhaust gas of an internal combustion engine in accordance with an engine operating state. An exhaust throttle operation for reducing an exhaust flow rate by operating an exhaust throttle valve disposed in an exhaust passage of an internal combustion engine; an expansion stroke injection operation for performing fuel injection during an expansion stroke of each cylinder; and an engine exhaust system. The engine is operated by one or a combination of two or more of an EGR operation for recirculating a part of exhaust gas from the engine to an intake system and a main fuel injection control operation for changing a main fuel injection amount and an injection timing of each cylinder. When performing a particulate filter regeneration process for raising the exhaust gas temperature to burn the particulates collected in the particulate filter and performing the exhaust throttle operation, Determining the manipulated variables of the expansion stroke fuel injection amount and injection timing, the recirculation exhaust flow rate, the main fuel injection amount and the injection timing according to the engine operating state based on a predetermined first relationship; When the exhaust throttle operation is not performed, the particulate filter regeneration processing control device that determines each of the operation amounts based on the engine operating state based on a predetermined second relationship different from the first relationship is provided. Provided.

That is, according to the first aspect of the present invention, when the exhaust throttle for the particulate filter regeneration operation is performed,
The expansion stroke fuel injection amount and the injection timing, the recirculation exhaust flow rate, the main fuel injection amount, the injection timing, etc. according to the engine operating state (for example, engine load, rotation speed, etc.) based on a relationship different from the case where the exhaust throttle is not performed. Is determined. For example, these manipulated variables at the time of performing the exhaust throttling are determined by operating the engine in a state where the exhaust throttling is performed, obtaining a value at which the engine exhaust temperature becomes a target temperature in advance, and determining the engine operating state. The relationship with each operation amount is set as the second relationship. Accordingly, an appropriate operation amount is set based on the engine operating state according to whether or not the exhaust throttle is performed, so that the engine exhaust temperature is controlled to the target temperature in a short time when the regeneration operation is performed. .

According to a second aspect of the present invention, there is provided a regeneration control device for controlling a regeneration process of a particulate filter for collecting particulates in exhaust gas of an internal combustion engine according to an engine operating state. An expansion stroke injection operation for injecting fuel during the expansion stroke of each cylinder of the engine raises the engine exhaust temperature to perform a particulate filter regeneration process for burning the particulates collected in the particulate filter, and an expansion stroke. When performing the EGR operation for recirculating a part of the exhaust gas from the engine exhaust system to the intake system during the execution of the injection operation, the recirculation exhaust flow rate in the EGR operation is reduced as compared with the case where the expansion stroke injection operation is not performed. An apparatus for controlling the regeneration of a particulate filter is provided.

That is, in the second aspect of the present invention, the regeneration process of the particulate filter is performed by performing the expansion stroke injection operation. Fuel injected during the expansion stroke separately from the main fuel injection of each cylinder burns during the cylinder expansion stroke and is discharged from the exhaust port at a high temperature. Therefore, the exhaust temperature rises due to the expansion stroke injection operation. On the other hand, EG
When the R operation is performed, high-temperature exhaust gas is recirculated to the intake system, so that the intake air temperature rises and the exhaust gas temperature rises accordingly. Therefore, if the expansion stroke injection operation and the EGR operation are performed simultaneously, the exhaust gas temperature can be further increased.

By the way, when the expansion stroke injection is performed, the exhaust energy increases due to an increase in the exhaust gas temperature. For this reason,
For example, in an engine having an exhaust supercharger such as a turbocharger, the supercharging performance of the supercharger is increased by the expansion stroke injection operation, and the amount of air taken into the engine is increased. Therefore, in order to raise the exhaust gas temperature to a desired temperature, it is necessary to further increase the fuel injection amount in the expansion stroke injection. Therefore, in the present invention, when the expansion stroke injection operation is performed, an increase in the fuel injection amount is prevented by increasing the flow rate of the recirculated exhaust gas that is recirculated by the EGR operation as compared with a case where the expansion stroke injection operation is not performed. By increasing the recirculation exhaust gas flow rate (EGR gas amount), an increase in the flow rate of fresh air actually sucked into the cylinder is suppressed, so that an increase in the expansion stroke fuel injection amount for increasing the exhaust gas temperature is suppressed. become.

According to a third aspect of the present invention, there is provided a regeneration control device for controlling a regeneration process of a particulate filter for collecting particulates in exhaust gas of an internal combustion engine in accordance with an engine operating state. Engine exhaust is performed by performing one or both of an exhaust throttle operation for reducing an exhaust flow rate by operating an exhaust throttle valve disposed in an exhaust passage of the engine and an expansion stroke injection operation for performing fuel injection during an expansion stroke of each cylinder. When performing a particulate filter regeneration process for raising the temperature to burn the particulates collected in the particulate filter, and performing both the expansion stroke injection operation and the exhaust throttle operation simultaneously, the engine A regeneration control device for a particulate filter for stopping an EGR operation for recirculating a part of exhaust gas from an exhaust system to an intake system It is provided.

That is, according to the third aspect of the invention, the particulate filter is regenerated by one or both of the expansion stroke injection operation and the exhaust throttle operation. For example, by combining the expansion stroke injection with the exhaust throttle operation, the engine output increased by the expansion stroke injection can be offset by the exhaust throttle loss, so that the fuel injection amount of the expansion stroke injection can be suppressed while suppressing the increase in the engine output. Can be increased. However, if the expansion stroke injection operation and the exhaust throttle operation are performed simultaneously, the exhaust pressure may increase significantly due to the increase in exhaust temperature and exhaust throttle loss. In this case, if the EGR operation is performed, the controllability of the EGR gas amount is deteriorated due to an increase in the exhaust pressure. That is, in the case where the EGR gas amount is controlled by a flow control valve (EGR valve) or the like, the EGR gas amount greatly increases even if the valve opening slightly increases when the exhaust pressure increases. Misfire easily occurs due to lack of air.
For this reason, in the present invention, when the expansion stroke injection operation and the exhaust throttle operation are performed simultaneously, the EGR operation is stopped to prevent the engine from misfiring.

According to a fourth aspect of the present invention, there is provided a regeneration control device for controlling a regeneration process of a particulate filter for collecting particulates in exhaust gas of an internal combustion engine in accordance with an engine operating state. Engine exhaust is performed by performing one or both of an exhaust throttle operation for reducing an exhaust flow rate by operating an exhaust throttle valve disposed in an exhaust passage of the engine and an expansion stroke injection operation for performing fuel injection during an expansion stroke of each cylinder. In addition to performing a particulate filter regeneration process for raising the temperature to burn the particulates collected in the particulate filter, performing the expansion stroke injection operation, and further performing the exhaust throttle operation when performing the expansion stroke injection operation The engine target intake air amount is set to different values based on the engine operating state, depending on whether or not the engine is in operation. The engine intake air amount is controlled by controlling one or both of an opening degree of an intake throttle valve arranged in a passage and an opening degree of an EGR valve for controlling an amount of exhaust gas recirculated from the engine exhaust system to the engine intake system. There is provided a regeneration control device for a particulate filter that controls a target intake air amount.

That is, in the invention of claim 4, the target air amount of the engine is set to a different value according to the presence or absence of the expansion stroke injection operation and the presence or absence of the exhaust throttle operation. For this reason, the intake air amount is set to an optimal value in accordance with the engine operating state during the particulate filter regeneration processing by the expansion stroke injection operation and the exhaust throttle operation, and the exhaust gas temperature can be accurately set in a short time. It is possible to raise the temperature.

[0017]

Embodiments of the present invention will be described below with reference to the accompanying drawings. FIG. 1 is a diagram showing a schematic configuration in a case where the particulate filter regeneration processing control device of the present invention is applied to an automobile diesel engine. FIG.
In the figures, 1 indicates an internal combustion engine for a vehicle. In the present embodiment, the engine 1 is a four-cylinder diesel engine, and each cylinder is provided with an in-cylinder fuel injection valve 111 that injects fuel directly into the cylinder. The fuel is supplied from a high-pressure fuel injection pump 113 to a common rail (accumulator) 1 to which each fuel injection valve 111 is connected.
15 from the common rail.
Accordingly, the fuel is injected into each cylinder 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 outlet of the supercharger 35, and the intake passage 2 is connected to an intake 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.
The opening degree corresponding to the signal from the ECU 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 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. DPF4
Numeral 0 is formed of a heat-resistant porous material such as a ceramic or a metal nonwoven fabric, and has a large number of flow paths that form an exhaust flow path in the axial direction (the exhaust flow direction). Each of these flow paths is closed at one of the upstream end and the downstream end in the exhaust flow direction, and the flow path whose upstream end is closed and the flow path whose downstream end is closed are alternately arranged adjacent to each other. Have been. For this reason, the exhaust gas discharged from the exhaust port of each cylinder flows into the flow path in which the upstream end of each DPF is open (the downstream end is closed), and passes through the porous partition separating the flow paths. Then, the downstream end flows into the open flow path 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 in accordance with the engine operating state as described later. It has a function as a playback processing device that controls playback processing.

To perform these controls, an input port of the ECU 30 receives a signal corresponding to the engine intake air amount from an air flow meter 51 provided in the engine intake passage and a temperature sensor 53 provided in the exhaust manifold 31 at an input port. A signal corresponding to the engine exhaust temperature is input, and a pulse signal is input from the rotation speed sensor 55 disposed near the engine crankshaft (not shown) at every constant rotation angle of the engine crankshaft. Further, in the present embodiment, the ECU
A signal representing the accelerator pedal depression amount (accelerator opening) of the driver is input to an input port 30 from an accelerator opening sensor 57 arranged near an accelerator pedal (not shown) of the engine 1. The ECU 30 converts the output of the air flow meter 51, the output of the accelerator opening sensor 57, and the output of the temperature sensor 53 at predetermined intervals into an A / D conversion of the intake air amount Ga, the accelerator opening ACCP, and the exhaust temperature T in a predetermined area of the RAM of the ECU 30. While storing, the rotation speed sensor 5
The engine speed NE is calculated from the interval of the pulse signal from the step 5 and stored in a predetermined area of the RAM. ECU 30
Calculates the engine basic fuel injection amount and the fuel injection timing based on the accelerator opening ACCP detected by the accelerator opening sensor 57 and the engine speed NE based on a relationship previously stored in the ROM. The fuel injection amount QIJ and the fuel injection timing of the engine are set by adding a correction according to the engine operating state to the amount. 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 a 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 following operation is performed alone or in combination of two or more, thereby increasing the exhaust gas temperature of the engine and regenerating the DPF 40. (A) Retardation of the main fuel injection timing Retarding the fuel injection timing delays the fuel combustion timing in the cylinder, 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 gas temperature rises. Although the exhaust gas temperature rise due to the retard of the main fuel injection timing is relatively small, the increase in engine fuel consumption due to the retard is also relatively small.

(B) Performing EGR When the EGR is performed, high-temperature exhaust gas is drawn into the cylinder. Further, since the amount of low-temperature fresh air sucked into the cylinder decreases in accordance with the EGR gas amount, the exhaust temperature also increases accordingly. In the diesel engine of the present embodiment, EGR is performed in almost all operation regions of the engine even during normal operation, but when performing the regeneration operation of the DPF 40, EGR is performed.
The amount of gas is further increased so that the exhaust gas temperature is made higher than during normal operation. The EGR gas amount is determined by the opening of the EGR valve 23 and the opening of the intake throttle valve 27. If the opening degree of the intake throttle valve 27 is reduced, a negative pressure is generated on the downstream side of the throttle valve. Therefore, even with the same opening degree of the EGR valve 23, the EGR gas amount increases, and a large amount of EGR gas can be returned to the intake system. Become.

(C) Fuel injection during expansion stroke By performing fuel injection during the expansion stroke of each cylinder in addition to main fuel injection, the exhaust temperature rises relatively significantly. Although the fuel injected in the expansion stroke burns in the cylinder, most of the fuel is discharged from the cylinder as high-temperature exhaust gas without being converted into engine output, so that the exhaust gas temperature rises.
The rise width of the exhaust gas temperature changes according to the fuel injection in the expansion stroke injection. Further, in the expansion stroke injection, a part of the combustion energy of the fuel is changed to mechanical work, so that the engine output also increases according to the expansion stroke fuel injection amount. Therefore, when performing the expansion stroke injection, the amount of EGR is increased (reduction of fresh air).
It is preferable to suppress the change in the engine output by performing an exhaust throttle or the like.

(D) Exhaust throttle By closing the exhaust throttle valve 37 to a predetermined opening degree, the exhaust pressure loss at the throttle valve 37 increases and the engine output decreases. Therefore, it is possible to suppress an increase in the engine output when the exhaust throttle is performed to increase the main fuel injection amount or increase the exhaust temperature by performing the expansion stroke fuel injection.
Therefore, by executing the increase of the main fuel injection amount or the injection of the expansion stroke together with the exhaust throttle, it becomes possible to raise the exhaust temperature without greatly deteriorating the operability of the engine. The increase in engine fuel consumption is relatively large.

In the present embodiment, the ECU 30 includes the DPF 40
The amount of the collected particulates is constantly monitored, and when the amount of the collected particulates reaches a predetermined amount, one of the regeneration operations (A) to (D) is performed. The regeneration of the DPF 40 is performed by performing one or a combination of two or more. The amount of particulates collected in the DPF 40 can be calculated by, for example, detecting the pressure difference between the inlet and the outlet of the DPF 40,
In the present embodiment, the ECU 30 calculates the collection amount of the particulate by increasing or decreasing the collection amount counter based on the engine operating state.

That is, the amount of particulates generated in the engine is determined by the engine load state (eg, engine fuel injection amount and engine speed). Therefore, in the present embodiment, the actual engine is operated in advance by changing the combination of the engine fuel injection amount and the number of revolutions, and the amount of particulates discharged per unit time from the engine is experimentally obtained. It is stored in the ROM of the ECU 30 in the form of a numerical table using the rotation speed. The ECU 30 calculates the amount of particulates generated per unit time from the numerical value table using the fuel injection amount and the rotation speed of the engine at regular intervals during the operation of the engine,
The collection counter is increased by a value obtained by multiplying the generated amount by a predetermined collection rate. As a result, the value of the collection counter indicates the amount collected by the DPF 40 among the particulates generated by the engine. On the other hand, when the temperature of the DPF 40 rises due to the high load operation of the engine or the execution of the regeneration operation, the particulates trapped in the DPF burn. In this case, the amount of particulates burned per unit time is determined by the exhaust gas temperature. For this reason, in the present embodiment, the relationship between the exhaust gas temperature detected by the exhaust gas temperature sensor 53 and the amount of particulate combustion per unit time in the DPF 40 is experimentally obtained in advance, and a numerical table using the exhaust gas temperature is stored in the ROM of the ECU 30. It is stored in the form of ECU
Numeral 30 performs an operation of increasing the value of the trapping counter in accordance with the amount of particulates generated by the engine as described above, and based on the exhaust gas temperature, the particulates collected in the DPF from the numerical value table per unit time. The combustion amount is calculated, and the value of the trap counter is reduced by the calculated combustion amount.

That is, the ECU 30 increases the value of the collection counter by the amount of particulates collected in the DPF at regular intervals during the operation of the engine, and when the DPF temperature rises due to a change in the engine operation state or execution of the regeneration operation. , The value of the trapping counter is reduced by the amount of particulates burned on the DPF. As a result, the value of the collection counter always accurately represents the amount of particulates present in the DPF 40.

As described above, in the present embodiment, (A)
Since the regeneration process of the DPF 40 is performed by using the methods (A) to (D), it is necessary to control each operation amount such as the fuel injection amount, the injection timing, and the EGR gas amount according to the engine operating conditions and the type of the regeneration operation. Hereinafter, some examples of the control method of these operation amounts will be described. (1) First Embodiment In the present embodiment, when the regeneration operation of the DPF 40 is performed by combining the above-described methods (A) to (D), (D)
Each of the operation amounts (A) to (C) is determined depending on whether or not the exhaust throttle operation is performed.

As described above, when the exhaust throttle is performed, the exhaust pressure loss increases. Therefore, it is possible to greatly increase the main fuel injection amount and the expansion stroke fuel injection amount while suppressing an increase in the engine output. . However, when the exhaust throttle is performed, it is necessary to significantly change other operation amounts according to the exhaust throttle. For example, when the exhaust throttle is performed, the exhaust pressure increases, so that the amount of the EGR gas recirculated to the intake system increases even when the EGR valve 23 has the same opening. In addition, since the exhaust throttle also reduces the engine intake air amount, the EGR gas amount is also set to an optimal value in accordance with the decrease in the intake air amount in order to prevent instability in combustion and reduction in engine output. You need to control. Further, in order to raise the exhaust temperature to an optimum value in a short time, it is necessary to change the fuel injection amount and the injection timing of the main fuel injection, the injection amount and the injection timing of the expansion stroke injection according to the exhaust throttle.

In this embodiment, when the regeneration operation of the DPF 40 is executed, the respective operation amounts such as the fuel injection amount and the injection timing of the main fuel injection, the injection amount of the expansion stroke injection, the injection timing, and the EGR gas amount are changed according to the engine operating state (load state). ) Is determined according to whether or not to perform the exhaust throttle operation as described above, depending on whether or not to perform the exhaust throttle operation even in the same engine operating state (engine load). It is necessary to change the operation amount.
Thus, in the present embodiment, each operation amount is determined from the engine operating state based on a different relationship between when the exhaust throttle is performed and when the exhaust throttle is not performed during the execution of the regeneration operation.

Specifically, in the present embodiment, the engine is operated in advance with changing the load conditions (for example, the fuel injection amount QIJ and the rotational speed NE) to obtain the optimum exhaust gas temperature necessary for the DPF 40 regeneration operation. The operation amounts are obtained, and the respective operation amounts are stored in the ROM of the ECU 30 in the form of a numerical map in the form of FIG. 2 using QIJ and NE as parameters, and the current QIJ, NE and The operation amounts are determined from these values using these numerical maps.These numerical maps include a case where a regeneration operation is performed for each of the exhaust throttles and a case where a regeneration operation is performed for which the exhaust throttle is not performed. Are prepared. In the present embodiment, the optimal operation amount is obtained in each case by determining each operation amount from the numerical maps prepared at the time of performing the regeneration operation, using different maps depending on whether or not the exhaust throttle is performed. Like that.

FIG. 3 is a flowchart for specifically explaining the determination of each operation amount at the time of performing the above-described reproduction operation of the present embodiment. This operation is performed by a routine executed by the ECU 30 at regular intervals. When the operation is started in FIG. 3, in step 301, it is determined whether or not the reproduction operation execution condition is satisfied. As described above, in the present embodiment, the ECU 30 constantly monitors the amount of particulates collected by the DPF 40 during operation of the engine using the collection counter. When the value of the collection counter increases to a predetermined value, it is determined that the regeneration operation execution condition has been satisfied, and the particulates burn due to the execution of the regeneration operation and the value of the collection counter is equal to or less than a predetermined value near 0. Is determined, the reproduction operation execution condition is not satisfied.

If the reproduction operation execution condition is not satisfied in step 301, this operation is terminated as it is, and the operation after step 303 is not performed. In this case, the exhaust throttle operation and the expansion stroke injection are not performed, and the main fuel injection amount, the injection timing, and the EGR gas amount are determined by ordinary control. If the regeneration operation execution condition is satisfied in step 301, then in step 303 the main fuel injection amount QI
J and the engine speed NE are read. In the present embodiment, as described above, the main fuel injection amount QIJ is the engine speed N
It is separately calculated based on E and the accelerator opening ACCP. In this operation, QIJ and NE are used as parameters representing the engine operating state (load state).

Next, in step 305, it is determined from the QIJ and NE read as described above whether or not the engine is currently operating in a region where exhaust throttling must be performed during a regeneration operation. Since the exhaust throttle operation causes a relatively large increase in fuel efficiency, in the present embodiment, the exhaust throttle operation is performed only in an operation region where regeneration of the DPF 40 cannot be performed unless the load on the engine is relatively low and the exhaust temperature is significantly increased. Like that.

If the current exhaust throttle is required in step 305, then in step 307, the degree of exhaust throttle (exhaust throttle valve) is determined from a predetermined relationship based on the current engine load condition (QIJ, NE). 37 degrees). The exhaust throttle valve opening may be continuously changed according to the engine load state. However, in this embodiment, the exhaust throttle valve opening is fully opened, half opened (50% opening), Control is performed in three stages of full closing, and in step 307, the exhaust throttle valve opening is set to either full opening or half opening based on the values of QIJ and NE.

Step 309 shows the operation of calculating the correction amount (increase) of the main fuel injection amount. In step 309, a correction amount is determined based on the values of QIJ and NE from a numerical map in the form of FIG. 2 created in advance based on the engine operation result when the exhaust throttle is performed. At the time of performing the exhaust throttling, it is possible to greatly increase the main fuel injection amount as compared with a case where the exhaust throttling is not performed. Accordingly, in step 309, the increase width of the main fuel injection amount is set to a relatively large value. During the regeneration operation, the actual main fuel injection amount is set to QIJ in step 3.
09 is set to a value obtained by adding the correction amount calculated.

Further, in step 311, the injection timing of the main fuel injection is determined from the numerical map of the form shown in FIG. 2 similarly based on the engine operation result when the exhaust throttle is performed.
And NE. Step 3
13, 315, and 317, the fuel injection amount, the injection timing, and the EGR gas amount of the expansion stroke injection are obtained from the numerical maps of the format of FIG. Is determined using the value of It should be noted that the EGR gas amount is set to a smaller value in accordance with a decrease in the fresh air intake amount due to the exhaust throttle than when the exhaust throttle is not performed.

Step 319 shows a control operation for controlling the value of each operation amount to the value set as described above. Step 3
In 19, the opening degree of the exhaust throttle valve 37 is controlled so as to become the opening degree set in step 307. Further, the valve opening period and the valve opening timing of the fuel injection valve 111 of each cylinder are set so as to be the corrected main fuel injection amount and the injection timing, and are set in steps 313 and 315 in the expansion stroke of each cylinder. It is set so as to perform fuel injection at the expansion stroke injection amount and the injection timing. Further, the opening degree of the intake throttle valve 27 and the EGR valve 23
The opening is set to an opening at which the EGR gas amount set in step 317 is obtained. On the other hand, if the engine has been operating in the operating region where the exhaust throttle is not required at the time of executing the regeneration operation in step 305, the main fuel injection amount correction amount and the main fuel injection amount correction amount are determined in steps 321 to 329 by the same operation as in steps 309 to 317. The fuel injection timing, the expansion stroke injection amount and the injection timing, and the EGR gas amount are determined. In this case, in each step, the current QIJ is determined based on a numerical map of the type shown in FIG.
Each operation amount is determined from the values of NE and NE. In step 331, the fuel injection valve, the intake throttle valve 27, and the EGR valve 23 are controlled in the same manner as in step 319, but the exhaust throttle valve 37 is kept fully open.

As described above, in this embodiment, the respective operation amounts are set in accordance with the presence or absence of the execution of the exhaust throttling, so that the target exhaust temperature can be accurately obtained in a short time when the exhaust throttling is performed. It becomes possible. In the actual operation, there is a delay in the operation of the exhaust throttle valve 37, and thus a delay may occur before the exhaust throttle set at the time of adjusting the exhaust throttle valve opening is obtained. For this reason, when controlling the main fuel injection, the expansion stroke injection, and the EGR to the set values in step 319, the operation amounts thereof may be gradually changed in accordance with the operation speed of the exhaust throttle valve 37.

(2) Second Embodiment In this embodiment, the regeneration process of the DPF 40 is performed by the expansion stroke injection operation. Further, as described above, in the engine of the present embodiment, EGR is performed in almost the entire operation range of the engine. When EGR is performed, high-temperature exhaust gas is recirculated to the intake system, and the intake temperature of fresh air decreases, so that the exhaust temperature rises. For this reason, even when the expansion stroke injection operation is performed, E
By continuing the GR operation, the range of increase in the exhaust gas temperature can be increased.

However, when the expansion stroke injection is performed, the energy of the exhaust gas increases, so the work of the turbocharger increases in an engine having a turbocharger or the like, and the expansion stroke injection is performed because the supercharging pressure increases. In some cases, the amount of fresh air sucked into the engine may be increased as compared with the case where the engine is not operated.
In order to raise the exhaust gas temperature to a desired temperature with the fresh air flow rate increased, it is necessary to increase the expansion stroke fuel injection amount by an amount corresponding to the fresh air increase amount, and the fuel consumption rate increases. Thus, in the present embodiment, E is added together with the expansion stroke injection.
When performing the GR operation, the EGR gas amount is increased even if the engine load is the same, as compared with the case where the expansion stroke operation is not performed. Thus, an increase in the fresh air flow rate due to the expansion stroke injection is suppressed, and an increase in the fuel consumption rate is prevented.

FIG. 4 is a flow chart for specifically explaining the EGR gas amount control in the regeneration operation. This operation is performed by a routine executed by the ECU 30 at regular intervals. In step 401 of FIG. 4, it is determined whether or not the reproduction operation execution condition is currently satisfied. Step 4
The determination of 01 is made in the same manner as in step 301 of FIG. If the playback operation execution condition is currently satisfied,
Next, at step 403, the engine fuel injection amount QIJ and the engine speed NE are read, and at step 405, it is determined whether or not the engine is currently operating under a load condition in which the regeneration process of the DPF 40 should be performed by the expansion stroke injection. . For example,
In the present embodiment, when the engine is operated in a region where the engine load is high and the exhaust temperature is relatively high, the regeneration of the DPF 40 by the expansion stroke injection is not performed, and the ECU 30 is separately provided.
The regeneration process of the DPF 40 is performed by another method (for example, the main fuel injection timing is retarded) by the other operation executed by.

In step 405, DP is obtained by the expansion stroke injection.
When the regeneration of F40 is performed, next, at step 407, the fuel injection amount and the injection timing in the expansion stroke injection are determined according to the engine load state. In the present embodiment, the optimum expansion stroke fuel injection amount and injection timing for raising the exhaust gas temperature to the target value are obtained in advance for each engine load condition (QIJ, NE) by experiments, and QIJ and NE are set as parameters. As a numerical map in the form of FIG.
In step 407, the QIJ and N
The expansion stroke fuel injection amount and the injection timing are set from this numerical map using the value of E.

Next, at step 409, the EGR correction amount (increase) when the expansion stroke injection operation is performed is calculated. In the present embodiment, the EGR required when the expansion stroke injection is performed
The amount of gas increase is determined in advance by an experiment,
ECU in the form of a numerical map in the form of FIG.
30 are stored in the ROM. In step 409, the EGR correction amount is determined from the values of QIJ and NE using this numerical map.

In step 411, the fuel injection amount and the injection timing of the expansion stroke injection determined as described above are set in the fuel injection circuit, and in step 413, the EGR
The gas amount is increased. As described above, the increase correction of the EGR gas amount is performed by performing one or both operations of increasing the opening degree of the EGR valve 23 and decreasing the opening degree of the intake throttle valve 27. As a result, when the expansion stroke injection operation is performed, the EG is higher than when the expansion stroke injection operation is not performed.
The R gas amount is increased, and an increase in the fuel injection amount of the expansion stroke injection is suppressed.

(3) Third Embodiment In this embodiment, the DPF is performed by performing one or both of the expansion stroke injection operation and the exhaust throttle operation.
40 is reproduced. However, as described above, if both the expansion stroke injection operation and the exhaust throttle operation are performed at the same time, the exhaust pressure greatly increases, and even a small change in the opening degree of the EGR valve 23 greatly changes the EGR gas amount. Therefore, the EGR gas amount becomes excessively large, which may cause a misfire of the engine. Therefore, in the present embodiment, when performing the exhaust throttle operation simultaneously with the expansion stroke injection operation, the EGR valve 23 is fully closed to stop the exhaust gas recirculation, thereby preventing the engine from misfiring.

FIG. 5 is a flowchart specifically illustrating the above-described EGR gas amount control operation of the present embodiment.
5 is performed by a routine executed by the ECU 30 at regular intervals. When the operation starts in FIG. 5, the engine load condition (fuel injection amount QIJ, rotation speed NE) is read in step 501, and in step 503, it is determined whether the regeneration operation execution condition of the DPF 40 is currently satisfied. This determination is made based on the value of the particulate collection counter separately calculated in the same manner as in step 301 in FIG. 3 and step 401 in FIG.

If the regeneration operation execution condition is satisfied in step 503, then in step 505, it is determined whether or not the engine is currently operating in the operation region in which the regeneration process of the DPF 40 is to be performed by the expansion stroke injection operation. Condition (Q
IJ, NE). If the regeneration operation execution condition is not satisfied in step 503, or if the operation region is in the operation region in which the expansion stroke injection is not performed in step 505 (for example, the operation region in which the regeneration operation is performed by retarding the main fuel injection), step 511 is executed. Is executed, and the EGR gas amount is calculated from a numerical map in the form of FIG. 2 during normal operation prepared in advance based on the engine load condition (QIJ, NE). That is, in this case, the EGR gas amount is set to the value during normal operation.

If the engine is operating in the region where the expansion stroke injection operation is to be performed in step 505, then in step 507 the engine is operated in the region where the expansion stroke injection operation and the exhaust throttle operation are to be performed simultaneously. It is determined based on the engine load condition whether or not the engine is being operated. If the exhaust throttle operation is not performed, that is, the DP
If it is the operating range in which the regeneration process of F40 is performed, the process proceeds to step 513, and the EGR gas amount is set based on a numerical map prepared when the expansion stroke injection is performed. Also in the present embodiment, the EGR gas amount is set to a larger value during the expansion stroke injection than during the normal operation.

On the other hand, if it is determined in step 507 that the engine is currently operating in the region where both the expansion stroke injection operation and the exhaust throttle operation are to be performed, the process proceeds to step 509, and
The EGR control valve 23 is fully closed, and the EGR operation is stopped. This prevents the engine from misfiring due to the deterioration of the controllability of the EGR gas amount. (4) Fourth Embodiment In the present embodiment, as in the third embodiment, the regeneration process of the DPF 40 is performed by performing one or both of the expansion stroke injection operation and the exhaust throttle operation. Then, the target intake air amount (new air amount) of the engine is set to a different value depending on whether the expansion stroke injection operation is performed, and when the expansion stroke injection operation is performed, further depending on whether the exhaust throttle operation is performed.

For example, as described above, when the expansion stroke injection is performed, the supercharging pressure increases compared to the normal operation, so that the intake air amount increases. Further, in order to raise the exhaust gas temperature by burning the fuel injected by the expansion stroke injection, a larger intake air amount is required than during normal operation. For this reason, the optimum intake air amount changes depending on whether or not the expansion stroke injection operation is performed.

When the exhaust throttle operation is performed simultaneously during the expansion stroke injection, the EGR gas amount tends to be excessive as described in the third embodiment. Operation must be stopped. In this case, even during the operation of the exhaust throttle, the intake air amount increases by the decrease of the EGR gas amount. Further, in order to raise the exhaust gas temperature by burning the increased injection amount of fuel together with the execution of the exhaust throttle, an appropriate amount of intake air is required. For this reason, even when the expansion stroke injection operation is performed, the optimum intake air amount changes depending on whether the exhaust throttle operation is performed.

In this embodiment, during normal operation (when the expansion stroke injection operation is not performed), when only the expansion stroke injection operation is performed, and when both the expansion stroke injection operation and the exhaust throttle operation are performed, Experiments are performed in advance by changing the load conditions of the engine (fuel injection amount QIJ, rotation speed NE) to determine the optimal intake air amount (target intake air amount), and FIG. 2 using QIJ and NE in each case. Is stored in the ROM of the ECU 30 as a numerical map of the form:
Then, the target intake air amount is calculated based on the engine load condition by using a corresponding numerical map according to the presence or absence of the expansion stroke injection operation and the presence or absence of the exhaust throttle operation during engine operation.

Further, in this embodiment, the opening degree of the intake throttle valve 27 and the opening degree of the EGR valve 23 are adjusted so that the actual engine intake air amount becomes the target intake air amount calculated as described above. The intake air amount is controlled so that the engine intake air amount matches the target intake air amount calculated above. In this way, by controlling the engine intake air amount to the optimal target intake air amount in accordance with the presence or absence of the expansion stroke injection operation and the presence or absence of the exhaust throttle operation, the exhaust temperature can be accurately and quickly reduced during the regeneration operation. While the temperature is raised to the target temperature, it is possible to prevent deterioration of the exhaust properties due to excess or deficiency of the intake air amount.

FIG. 6 is a flowchart specifically illustrating the above-described intake air amount control operation of the present embodiment. This operation is performed by a routine executed by the ECU 30 at regular intervals. In the operation of FIG.
At 1, engine load conditions (fuel injection amount QIJ, rotation speed NE)
Is read, and in step 603, it is determined whether or not the expansion stroke injection operation is currently being performed, that is, whether or not the regeneration operation of the DPF 40 is currently being performed.

If the expansion stroke injection is not currently being executed, that is, if the normal operation is currently being performed, then step 60 is executed.
7, the program proceeds to step 601 using the map for normal operation among the numerical maps stored in the ROM of the ECU 30 in advance.
The target intake air amount is set from the values of QIJ and NE read in step (1). Then, in step 609, the opening degree of the intake throttle valve 27 and the EGR valve 23 is adjusted according to the set target intake air amount.

If it is determined in step 603 that the expansion stroke injection operation is currently being performed, it is determined in step 605 whether the exhaust throttle operation is currently being performed together with the expansion stroke injection. If only the operation is being performed, in step 611, the target intake air amount is set based on the numerical map during the execution of the expansion stroke injection stored in the ROM of the ECU 30. In step 613, the intake throttle valve 27 is set in accordance with the target intake air amount. And the opening degree of the EGR control valve 23 is adjusted.

On the other hand, if both the expansion stroke injection operation and the exhaust throttle operation are performed in step 605, the expansion stroke injection operation and the exhaust throttle operation of the numerical map stored in the ROM of the ECU 30 are performed in step 615. The target intake air amount is set based on the numerical map in the case of performing both of them, and in step 617, the opening degree of the intake throttle valve 27 and the EGR control valve 23 is adjusted according to the target intake air amount.

In the present embodiment, each operating condition (normal operation,
(When the expansion stroke injection operation is performed, and when both the expansion stroke injection operation and the exhaust throttle operation are performed), the opening degree of the intake throttle valve 27 required to bring the engine intake air amount to the target intake air amount under each engine load condition. The combination with the opening degree of the EGR valve 23 is obtained in advance by an experiment, and QIJ and NE are determined for each operating condition.
Are stored in the ROM of the ECU 30 in the form of a numerical map in the form of FIG. Steps 609, 613, 6
In step 17, the intake throttle valve 27 opening degree and E based on the values of QIJ and NE read in step 601 using the maps of the corresponding operating conditions among these numerical maps.
The GR valve 23 opening is set.

By executing the operation of FIG. 6, the optimum target intake air amount is determined according to whether or not the expansion stroke injection operation is performed, and according to whether or not the exhaust throttle operation is performed when the expansion stroke injection operation is performed. It will be set to the amount of air.

[0065]

According to the present invention, the particulate filter regeneration process is completed in a short time by precisely controlling the engine exhaust temperature to the target temperature in a short time when performing the particulate filter regeneration operation. This has a common effect that can be performed.

[Brief description of the drawings]

FIG. 1 is a diagram showing a schematic configuration when a particulate filter regeneration processing control device of the present invention is applied to an automobile diesel engine.

FIG. 2 is a diagram showing an example of a format of a numerical map.

FIG. 3 is a flowchart illustrating an operation of determining each operation amount in a particulate filter regeneration process.

FIG. 4 shows E in a particulate filter regeneration process.
It is a flowchart explaining the increase correction operation of GR gas amount.

FIG. 5 shows E in a particulate filter regeneration process.
It is a flowchart explaining the setting operation of the GR gas amount.

FIG. 6 is a flowchart illustrating a control operation of an engine intake air amount in a particulate filter regeneration process.

[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

──────────────────────────────────────────────────続 き Continued on the front page (51) Int.Cl. ⁷ Identification code FI Theme coat ゛ (Reference) F02D 21/08 301 F02D 21/08 301B 41/04 360 41/04 360Z 41/40 41/40 C 43 / 00 301 43/00 301H 301J 301N 301T 301Z 301K F02M 25/07 550 F02M 25/07 550A 550C 570 570D 570J F-term (reference) 3G062 AA01 AA05 BA05 BA06 CA06 EA05 EA11 BA01 GA05 GA01 BA10 BA20 BA24 DA05 EB08 FA07 FA10 FA33 3G090 AA02 BA01 CA00 CB25 DA00 DA12 DA18 EA04 EA06 3G092 AA02 AA17 BB01 BB06 DC03 DC09 DC10 DC12 DC14 DG06 DG08 EA01 EA13 EA14 EA17 FA18 HA01Z HA06X HA06BZHBZH01B01 HA13 JA24 LA00 LB13 MA11 MA18 P A01Z PD11Z PE01Z PF03Z

Claims (4)

[Claims] 1. A regeneration control device for controlling a regeneration process of a particulate filter for collecting particulates in exhaust gas of an internal combustion engine according to an engine operating state, comprising: an exhaust throttle disposed in an exhaust passage of the internal combustion engine. Exhaust throttle operation to reduce exhaust flow rate by operating a valve, expansion stroke injection operation to inject fuel during the expansion stroke of each cylinder, and EGR operation to recirculate part of exhaust gas from the engine exhaust system to the intake system And the engine exhaust temperature is increased by one or a combination of two or more main fuel injection control operations for changing the main fuel injection amount and the injection timing of each cylinder, and the fuel is collected in the particulate filter. Along with performing a particulate filter regeneration process for burning particulates, when performing the exhaust throttle operation, the expansion stroke fuel injection amount and injection timing, The respective operation amounts of the circulating exhaust flow rate, the main fuel injection amount, and the injection timing are determined according to the engine operating state based on a predetermined first relationship, and when the exhaust throttle operation is not performed, the respective operation amounts are determined. Is determined in accordance with the engine operating state based on a predetermined second relationship different from the first relationship. 2. A regeneration control device for controlling regeneration of a particulate filter for trapping particulates in exhaust gas of an internal combustion engine according to an engine operating state, wherein the regeneration process is performed during an expansion stroke of each cylinder of the internal combustion engine. In addition to performing a particulate filter regeneration process of raising the engine exhaust temperature by an expansion stroke injection operation for performing fuel injection and burning the particulates collected in the particulate filter, the engine exhaust system is operated during the expansion stroke injection operation. When the EGR operation for recirculating a part of the exhaust gas to the intake system is performed, the regeneration control of the particulate filter for increasing the recirculated exhaust flow rate in the EGR operation is performed as compared with the case where the expansion stroke injection operation is not performed. apparatus. 3. A regeneration control device for controlling regeneration of a particulate filter for collecting particulates in exhaust gas of an internal combustion engine according to an engine operating state, comprising: an exhaust throttle disposed in an exhaust passage of the internal combustion engine. The exhaust gas temperature is increased by operating one or both of an exhaust throttle operation for reducing the exhaust flow rate by operating a valve and an expansion stroke injection operation for injecting fuel during an expansion stroke of each cylinder to increase the engine exhaust temperature and thereby reduce the amount of exhaust gas in the particulate filter. When performing the particulate filter regeneration process for burning the particulates collected in the engine and simultaneously performing both the expansion stroke injection operation and the exhaust throttle operation, the exhaust gas is discharged from the engine exhaust system to the intake system. A regeneration control device for a particulate filter for stopping an EGR operation for recirculating the part. 4. A regeneration control device for controlling regeneration of a particulate filter for collecting particulates in exhaust gas of an internal combustion engine according to an engine operating state, comprising: an exhaust throttle disposed in an exhaust passage of the internal combustion engine. The exhaust gas temperature is increased by operating one or both of an exhaust throttle operation for reducing the exhaust flow rate by operating a valve and an expansion stroke injection operation for injecting fuel during an expansion stroke of each cylinder to increase the engine exhaust temperature and thereby reduce the amount of exhaust gas in the particulate filter. A particulate filter regeneration process for burning the particulates collected in the engine is performed, and the engine target is determined according to whether or not the expansion stroke injection operation is performed and whether or not the exhaust throttle operation is further performed when the expansion stroke injection operation is performed. The intake air flow rate is set to different values based on the engine operating condition, and the intake throttle valve located in the engine intake passage E for controlling the amount of exhaust gas recirculated to the engine intake system from the opening and the exhaust system
A particulate filter regeneration control device for controlling one or both of the degree of opening of a GR valve to control the engine intake air amount to the target intake air amount.