FR2786529A1 - EXHAUST EMISSION CONTROL DEVICE FOR INTERNAL COMBUSTION ENGINE - Google Patents

Abstract

Device for controlling the exhaust emission of an internal injection engine to reactivate a particulate filter. An engine operating zone is divided into a plurality of zones (I, II, III, IV, V). A means of reactivation is established for each zone. A zone (AFRQ) to which the operating state belongs most frequently is obtained and a zone (ASLCT) in which a reactivation process with a lower fuel consumption rate than the reactivation process established for that zone (AFRQ ) is selected. When an amount of the collected particles (5P) is greater than the upper threshold (SPU), the reactivation of the filter is deactivated when the current operating zone (DOCA) does not correspond to a selected zone (ASLCT). When an operating state changes and a current operating zone (DOCA) matches the selected zone (ASLCT), the filter is reactivated by the corresponding reactivation process (DOCA).

Description

EXHAUST EMISSION CONTROL DEVICE FOR ENGINE
INTERNAL COMBUSTION
The present invention relates to an exhaust emission control device for an internal combustion engine.

 A large quantity of particles composed essentially of carbons or the like is contained in the exhaust of an internal combustion engine. In order to collect these particles and prevent evacuation to the atmosphere, an internal combustion engine having a particulate filter disposed in an engine exhaust passage is known. When an engine running time is prolonged, a quantity of particles collected by the particulate filter is increased, and a backpressure of the engine is increased. Therefore, before the engine back pressure becomes higher than a maximum permissible pressure, it is necessary to remove the collected particles, ie to reactivate a particulate filter.

 As a reaction method such as a particulate, there is known an exhaust emission control device for an internal combustion engine, wherein a burner is disposed in an engine exhaust passage upstream of the exhaust filter. particles, and a temperature of the exhaust that enters the particulate filter is increased, thereby burning the particles (see Japanese Unexamined Patent Application No. 60-47937).

 In addition to using such a burner, in order to increase the temperature of the exhaust that enters the particulate filter, a variety of devices have been proposed including a device for delaying a main fuel injection period in a diesel engine and a method for increasing an amount of EGR (Exhaust Gas Recirculation) gas more significantly than that during normal operation.

 When a burner is used, even if a temperature of the exhaust entering the particulate filter is relatively low, the temperature can be reliably increased to a temperature required to reactivate the particulate filter. However, even when the temperature of the exhaust entering the particulate filter is relatively high, fuel is required for a burner.

 Furthermore, in the process for delaying the main fuel injection period, when the exhaust temperature flowing to a particulate filter is low, the temperature of the particulate filter can not be increased up to a required temperature, and yet, a fuel consumption rate does not increase so much. Accordingly, for example, there is provided both a reactivation method using a burner and a reactivation method using a control for delaying the main fuel injection period. When the temperature of the exhaust entering the particulate filter is low, the particulate filter is reactivated by the reactivation process using the burner. When the temperature of the exhaust entering the particulate filter is high, a fuel consumption rate is reduced by the reactivation process using the main fuel injection timing delay control, thereby making it possible to reliably reactivate a particulate filter.

 That is, a plurality of reactivation processes are provided, and these reactivation methods are selectively used thereby making it possible to reliably reactivate the particulate filter while the energy efficiency is maintained high. However, there has been no description of such a technical concept.

 In order to solve the problem mentioned above, it is an object of the present invention to always use a reactivation means required to reliably reactivate a particulate filter while the energy efficiency is kept very high.

 In order to achieve the above object, according to the present invention, there is provided an exhaust emission control device for an internal combustion engine having a particulate filter for collecting the particles contained in the exhaust gases. exhaust arranged in an exhaust passage of the engine, wherein a plurality of particle filter reactivation means are provided and at least one is selected from the quantity of a plurality of reactivation means based on an internal operating state engine to reactivate particulate filters.

Accordingly, it is possible to always use a reactivation means required to reliably reactivate particulate filters while the energy efficiency is kept very high.

Fig. 1 is an entire view of an internal combustion engine according to the present invention;
Fig. 2 is a view showing zone I to zone V for performing particle filter reactivation control;
Fig. 3 is a timing chart for illustrating the reactivation action of the particulate filter;
Fig. 4 is a flow chart for determining an ASLCT selection area;
Fig. 5 is a flow chart for executing the indicator control;
Fig. 6 is a flow chart for executing the indicator control;
Fig. 7 is a flow chart for executing the particle filter reactivation control;
Fig. 8 is a flow chart for executing the reactivation control of a particulate filter;
Fig. 9 is a flowchart showing a judgment operation of the conditions for initiating the particle filter reactivation control;
Fig. 10 is a flowchart showing a judgment operation of the conditions for stopping the reactivation control of the particulate filter;
Fig. 11 is a flowchart for illustrating an operation for determining each operating variable in the particle filter reactivation control;
Fig. 12 is a flowchart for illustrating an operation of correcting an increased amount of EGR gas in the particle filter reactivation control;
Fig. 13 is a flowchart for illustrating an operation of adjusting an amount of EGR gas in a particle filter reactivation control; and
Fig. 14 is a flowchart for illustrating a control correction operation of an engine air intake amount in the particle filter reactivation control.

 Subsequently, preferred embodiments of the invention will be described with reference to the accompanying drawings.

 Figure 1 shows an example of the application of the present invention to a diesel engine. The present invention is applicable to a spark ignition type motor other than such a diesel engine.

 A main engine body 1 comprises four cylinders N 1, N 2, N 3 and N 4. Each cylinder is connected to an equilibrium tank 3 via an air intake manifold 2. The equilibrium tank 3 is connected to an output portion of a compressor 6c of a positive displacement compressor (for example, an exhaust turbocharger) via an air intake manifold 4 and an intercooler 5. An inlet portion of the compressor 6c is connected to an air filter 8 via an air inlet pipe 7. A throttle of the air inlet gases 10 to be driven by an actuator 9 is disposed inside the intake manifold. air 4 between the equilibrium tank 3 and the intercooler 5. In addition, each cylinder comprises a fuel injection valve 11 for injecting fuel directly into a combustion chamber. Each fuel injection valve 11 is connected to a fuel pump capable of controlling the injection amount via a common fuel pressure storage chamber 12. In a fuel pump 13, the injection quantity is controlled so that the fuel pressure in the fuel pressure accumulation chamber 12 is a target fuel pressure.

 A corresponding branch portion 15 of an exhaust manifold 14 is connected to each cylinder and a particulate filter 16 is housed in each branch portion 15. An aggregation of the exhaust manifold 14 is connected to a portion of the exhaust manifold 14. an exhaust turbine inlet 6t and an exhaust turbocharger 6. An outlet portion of the exhaust turbine 6t is connected to a housing 20 receiving an NOx absorber 19 via an exhaust pipe 18; and the housing 20 is connected to an exhaust pipe 21. In addition, in the exhaust pipe 18 between the exhaust turbine 6t and the NOx adsorbing agent (nitrogen oxide) 19, a reducing agent is ejected to an upstream exhaust flow, and a reducing agent supply valve 22 is arranged to supply a reducing agent to the NOx absorber 19. This reducing agent supply valve 22 is connected to the fuel pressure accumulation chamber 12. In the preferred embodiments, a motor fuel (hydrocarbon) is employed as a reducing agent.

The reducing agent includes, for example, hydrocarbons such as gasoline, isooctane, hexane, heptane, light oil, kerosene, butane and propane, ammonia and urea.

 In addition, the exhaust manifold 14 downstream of the particulate filter 16 and the air inlet manifold 4 downstream of the air inlet throttle valve 10 are mutually connected via a recirculation passage of the exhaust gases. exhaust 23 (hereinafter called EGR) and an EGR control valve 25 to be driven by an actuator 24 is disposed inside the EGR passage 23. Thus, when the EGR passage 23 is provided further upstream than the valve In the case of a reducing agent feed 22, a secondary fuel supplied from the reducing agent supply valve 22 is prevented from returning to the engine air inlet passage together with the EGR gas.

 In addition, the throttle valve 26 to be driven by an actuator 27 is disposed inside the exhaust pipe 18 positioned between the exhaust turbine 6t and the reducing agent supply valve 22. This throttle valve 26 is maintained to be fully open.

 An electronic control unit (ECU) 30 is made up of digital computers and comprises a read only memory (ROM) 32 interconnected via a bidirectional bus 31; a random access memory (RAM) 33, a microprocessor (CPU) 34; a backup RAM (B-RAM) always connected to a power source; an input port 36; and an outlet port 37. A mass flow sensor 38 for detecting an air intake mass flow rate in an air inlet pipe 7. In a fuel pressure accumulation chamber 12, a sensor fuel pressure device 39 for generating an output voltage in proportion to the fuel pressure in the fuel pressure accumulation chamber 12 is disposed. A temperature sensor 40a for generating an output voltage representing a TPF temperature of the particulate filter 16 (an output voltage proportional to a temperature of the exhaust flowing to a particulate filter 16) is disposed at the level of a branch portion 15 of the exhaust manifold 14 disposed downstream of the particulate filter 16.

A temperature sensor 40b for generating an output voltage representing a TNA temperature of a NOx absorber 19 (an output voltage proportional to a temperature of the exhaust flowing from the NOx absorber 19) is disposed at an exhaust pipe 21 downstream of the NOx absorber 19. A step quantity sensor 41 generates an output voltage proportional to the amount of step of an accelerator pedal DEP. A mass air flow meter 51 provided in a motor air inlet passage generates an output voltage corresponding to a mass air inlet flow rate.
Ga. The output voltages of these sensors 38, 39, 40a, 40b, 41 and 51 are each inputted to an input port 36 via a corresponding analog / digital converter 42. In addition, a rotational speed sensor 43 for generating an output pulse representing a motor rotation speed is connected to the input port 36. An output port 37 is connected to each fuel injection valve 7, actuators 9,24 and 27, a fuel pump 13 and a reducing agent supply valve 22 via a corresponding driver 44, respectively.

The NOx absorber 19 comprises an alumina as carrier, for example. On this carrier, it is carried at least one selected from the group of alkaline metals such as potassium K, sodium Na, lithium Li and cesium
Cs, alkaline earth metals such as barium Ba and calcium Ca, and rare earth metals such as lanthanum La and yttrium Y, plus noble metals such as platinum Pt, palladium Pd, rhodium Rh and Iridium Ir. When a ratio of a total amount of air supplied in a reducing agent to a total combustion quantity fed into an exhaust passage, a combustion chamber and an inlet passage of Air higher upstream than a position in the engine exhaust passage is called the exhaust air ratio of the exhaust distributing this position, this NOx absorber 19 absorbs the NOx when the air-fuel ratio of the incoming exhaust gas is poor.

When the oxygen concentration in the incoming exhaust is lowered, the NOx absorption and the unloading action to discharge the absorbed NOx is performed.

 In this embodiment, the air-fuel ratio of an air-fuel mixture burned by each cylinder is kept poor during normal operation and accordingly, the NOx in the exhaust to be exhausted from each cylinder is absorbed by 1 '. NOx absorber 19 during normal operation.

However, the NOx absorbing capacity of the NOx absorber 19 is limited and thus it is necessary to discharge the NOx from the NOx absorber 19 before the absorption capacity is saturated. In this embodiment, when an amount of absorption of
NOx obtained from the NOx absorber 19 is larger than a predetermined set amount, a reducing agent is temporarily supplied from the reducing agent supply valve 22 to the NOx absorber 19 so that the
NOx in the NOx absorber 19 is discharged and reduced.

 The exhaust to be removed from the engine contains particles consisting of soot, carbon, soluble organic fraction (SOF), sulfate or the like, and these particles are collected by the particulate filter 16.

However, as the particles collected by the particulate filter 16 are increased in amount, the back pressure is increased. Thus, it is necessary to remove particles from the particulate filter 16, that is, to perform the reactivation action of the particulate filter 16 before the back pressure is increased.

 In this embodiment, a obtained amount of particles collected by the particulate filter 16 is larger than a predetermined upper limit value, the particulate filter 16 is reactivated.

Next, a method for reactivating the particulate filter 16 will be described in detail.

 In this embodiment, as shown in Fig. 2A, a motor operating state area defined by the step amount DEP and the motor rotation speed NE representing a motor load is divided into five I areas. , II, III, IV and V.

 In zone I, a temperature of the exhaust entering the particulate filter 16 is very high.

Thus, even if a temperature increase operation is not performed from the outside, the temperature of the particulate filter 16 becomes larger than the ignition temperature of the particles. As a result, the collected particles start the combustion naturally, the particulate filter 16 is naturally reactivated. Thus, a natural reactivation process in which the particulate filter 16 is naturally reactivated is called the first reactivation process.

 In a zone other than zone I, the particle 16 is not naturally reactivated, thus making it necessary to reactivate the force filter. In this first embodiment of the present invention, a second to fourth forced reactivation process is provided for forcibly reactivating the particulate filter 16.

 The second reactivation method is a method for delaying the main fuel injection period more significantly than during normal operation. When the main fuel injection period is delayed more significantly than during normal operation, the exhaust temperature to be removed from the combustion chamber is increased. As a result, the temperature of the exhaust entering the particulate filter 16 is increased, thereby making it possible to reactivate the particulate filter 16.

 A third reactivation method is a method for increasing a degree of opening DEGR of an EGR control valve 25 more significantly than during normal operation while the secondary fuel injection is performed. In addition to the main fuel injection to be performed around a top dead center, when a second injection of fuel, that is to say, a secondary fuel injection is carried out from a valve d When fuel injection 7 during an expansion treatment or an exhaust air treatment, the temperature of the particulate filter 16 is increased. In addition, at this time, when an increased degree of opening DEGR of the EGR control valve 25 increases the amount of EGR gas, a quantity of fresh air to be supplied into the combustion chamber is decreased. The EGR gases are so hot that the temperature of the exhaust entering the particulate filter 16 can be easily increased.

 Fuel combustion due to secondary fuel injection contributes little to the power of an engine.

 A fourth reactivation method is a method for reducing a DEX opening degree of an exhaust throttle valve 27 more significantly than during normal operation while the secondary fuel injection is performed. When the secondary fuel injection is performed, the temperature of the exhaust entering the particulate filter 16 is increased as described above. In addition, at this moment, when the reduced opening degree DEX of the exhaust throttle valve 27 decreases, an amount of exhaust entering the particulate filter 16, an exhaust flow to be heated is decreased. As a result, the temperature of the exhaust entering the particulate filter 16 can be increased more easily. Here, instead of the exhaust throttle 27, the throttle valve 10 or a degree of opening of both the throttle valve 10 and the throttle valve exhaust gas 27 can be adjusted.

 In the second reactivation process, it is necessary to increase the amount of main fuel injection so as not to cause the lowering of the engine output torque. Its increased amount is small, but the delay value of the main fuel injection period is limited and thus, the temperature of the particulate filter 16 can not be increased significantly and quickly. In the third reactivation process, additional fuel is consumed for secondary fuel injection, but the temperature of the particulate filter 16 can be significantly and rapidly increased. In the fourth reactivation process, it is necessary to increase the amount of main fuel injection so as not to cause the lowering of the engine output torque.

However, an exhaust flow to be heated is decreased and thus the temperature of the particulate filter 16 can be increased more significantly and rapidly than in the third reactivation process. As a result, the fuel consumption rates in the respective reactivation processes are the smallest in the first reactivation process, and are increased more significantly in the second, third and fourth reactivation processes, in order. That is, the temperature increase performance is highest in the fourth reactivation process, and is lower in the third and second reactivation processes, in order.

Considering the fuel consumption rate, the use of the second reactivation process is the most preferable. However, in zones III and IV, since the temperature of the exhaust entering the particulate filter 16 is low, when the second production method is used, the temperature of the particulate filter 16 can not be increased sufficiently. Significantly, when the third reactivation method is used in zone IV, the temperature of the particulate filter 16 can not be increased sufficiently. When the fourth reactivation process is used in zone III, the fuel consumption rate increases. The second reactivation method is used in zone II, the third reactivation method is used in zone III and the fourth reactivation method is used in the zone
IV. A correlation between each zone and the reactivation process to be established is shown in Table 1.

TABLE 1

<tb> Zone <SEP> Process <SEP> of <SEP> Reproduction
<tb><SEP> First <SEP><SEP> Process of <SEP> Reactivation
<tb><SEP> II <SEP> Second <SEP><SEP> Process of <SEP> Reactivation
<tb> III <SEP> Third <SEP><SEP> Process of <SEP> Reactivation
<tb><SEP> IV <SEP> Fourth <SEP><SEP> Process of <SEP> Reactivation
<tb><SEP> V <SEP> (prohibited <SEP> reactivation)
<Tb>
In zone V, the temperature of the exhaust entering the particle filter 16 is very low. As a result, it is very difficult to reactivate the particulate filter 16. In zone IV, the reactivation action of the particulate filter 16 is deactivated.

 It is desirable to select a particle filter reactivation method according to which zones (zone I to zone V) the engine operating state belongs most frequently.

 For example, in the case where an engine operating state belongs to zone II most frequently, when the engine operating state moves to zone IV, it is assumed that a quantity of particles collected is greater than the upper limit. Here, when the particulate filter 16 is reactivated by the fourth reactivation process, the fuel consumption rate increases, which is not preferable. Rather, at this time, the reactivation action of the particulate filter 16 is turned off. Then, when the engine operating state moves (returns) to zone II, the fuel consumption rate can be reduced more significantly by using the second reactivation method. In addition, after the engine operating state has moved to zone I, when a test is made to reactivate the particulate filter using the first reactivation method, the fuel consumption rate can be further reduced more significantly.

 In this embodiment, an AFRQ area to which a motor operating state belongs most frequently, is obtained from areas I to IV based on the engine operating status history, and this AFRQ area. and an area in which a reactivation process with a lower fuel consumption rate than that at which this area is established is selected (subsequently, this area is referred to as the ASLCT selection area). When a collected amount of particles becomes larger than the upper limit threshold, when the engine operating state does not belong to the ASLCT selection area, the reactivation process of the particulate filter 16 is disabled.

Then, when the engine operating state has moved to the ASLCT selection area, the particulate filter 16 is reactivated by the reactivation process set to a zone at which the engine operating state belongs.

 That is, a relationship between the AFRQ area to which the engine operating state most commonly belongs and the ASLCT selection area is shown in Table 2.

TABLE 2

<SEP> AFRQ <SEP> ASLCT
<tb> Zone <SEP> I <SEP> Zone <SEP> I
<tb> Zone <SEP> II <SEP> Zones <SEP> I <SEP> and <SEP> II
<tb> Zone <SEP> III <SEP> Zones <SEP> I, <SEP> II <SEP> and <SEP> I <SEP>
<tb> Zone <SEP> IV <SEP> Zones <SEP> I, <SEP> II, <SEP> III <SEP> and <SEP> IV
<Tb>
Figure 3 shows a timing chart when the area
AFRQ at which the engine operating state most frequently belongs is Zone II (when the ASLCT selection areas are Zones I and II). In the figure, ON indicates that the reactivation action of the particulate filter with each reactivation process is performed and OFF indicates that the above action is stopped.

First, it is assumed that a quantity of collected particles SP is larger than the upper limit threshold value SPU at time "a". At this moment, an area
DOCA to which the engine operating state belongs is zone IV, the reactivation action of the particulate filter 16 is not performed. Then, when the DOCA zone moves to the DOCA zone at time "b", the particle filter reactivation action 16 is initiated by the second reactivation method. After the time has elapsed, when the DOCA zone moves to zone I at time "c", the second reactivation process is stopped and the first reactivation process is executed. When the DOCA zone moves to zone II again at time "d", the second reactivation process is rerun. When a collected amount of particles SP reaches the lower limit threshold SPL at time "e", the second reactivation process is stopped and the reactivation action of the particulate filter is completed.

 In the case where the DOCA zone moves to zone III (i.e., outside the ASLCT selection zone) when the reactivation action of the particulate filter 16 is performed at the time "f "Even if the amount of collected particles SP is greater than the lower limit threshold SPL, the reactivation action of the particulate filter 16 is stopped.

Thus, in this embodiment, an ASLCT selection area is determined based on the operating history of the engine. When the engine operating state belongs to the selection area
ASLCT, the particulate filter 16 is reactivated. Here, in zones I to IV, the particle filters are reactivated, respectively. Accordingly, at least one of the plurality of reactivation methods is selected based on the engine operating state history and the particulate filter 16 is reactivated. In addition, as long as the amount of particles is greater than the upper limit threshold SPU, the reactivation of the particulate filter 16 is started whenever the engine operating state belongs to the selection zone.
ASLCT. Accordingly, a period at which the particulate filter 16 should be reactivated is defined based on the operating history of the engine.

 Meanwhile, as in the fourth reactivation process, for example, it is not preferable to remove a large amount of particles at a time by using the reactivation method having a high fuel consumption rate. In addition, when the upper limit threshold is interrupted by each predetermined time interval.

 First, in step 50, a DOCA zone to which the current engine operating state is determined using a map shown in Fig. 2A. In step 51, it is determined whether the current DOCA zone is the same as the AOLD zone in the previous processing cycle. When DOCA = AOLD, the step goes to step 52 and a counter value CA, representing a time at which an area at which the engine operating state belongs is maintained in the same manner, is incremented by one. Then step 52 goes to step 56. In contrast, when DOCA is different from APLD in step 51, i.e., when the current DOCA moves from the previous AOLD, the step goes to step 53, and it is determined whether or not the AC counter value is better than a certain CAT value. When CA is <CAT, the step jumps to step 55. When CA is> CAT, the step goes to step 54 and the S (AOLD) frequency of the AOLD area is incremented by one. In this case, the AC counter value indicates a time at which the motor operating state is maintained at AOLD. When the engine operating state is maintained at AOLD for a certain period of time or more, the frequency S (AOLD) is increased. In the next step 55, the counter value CA is erased.

 In step 56, the current DOCA field is stored as AOLD. In the next step 57, the highest of the frequencies S (i) (i = I, II, III and IV) is AFRQ. In the next step 58, the selection area ASLCT is determined on the basis of AFRQ.

 In FIG. 5 and FIG. 6, there is shown a subroutine for executing the indicator control.

This routine is executed by a switch at each predetermined time period DLT.

 In step 60, a DOCA area to which the current engine operating state belongs is determined using the map shown in Fig. 2A. In step 61, it is determined whether or not the current DOCA zone is zone I.

When the current DOCA zone is not zone I (DOCA is different from "I"), the step goes to step 62. In step 62, it is determined whether or not an execution indicator XCR reactivation is established. The XCR reactivation execution flag is set when the particle filter 16 should be forcibly reactivated using the second to fourth reactivation methods (XCR = "1"), and if not, the flag is reset, (XCR = "0"). When the XCR reactivation execution flag is reset, the step goes to step 63 and it is determined whether or not an XRD reactivation request flag is set. The XRD reactivation demand indicator is set when the particulate filter 16 should be reactivated (XRD = "1"), and if not, the indicator is reset and (XRD = "0"). When the reactivation request flag XRD is reset, the step goes to step 64, and an amount of dCP particles to be collected by the particle filter 16 per unit of time is calculated. The amount of dCP particles is stored in advance in a ROM 32 as a function of a fuel quantity multiple injected from a fuel injection valve 11, an air inlet flow Ga, a NE motor rotation speed and the particle collection efficiency of the particulate filter 16, for example. In the next step 65, a product (dCP x DLT) of a DLT and dCP interrupt time interval of this routine is multiplied, whereby the amount of particles collected from the particulate filter 16 is calculated (SP = SP + dRP x DLT). In step 66, the upper limit threshold
SPU is calculated on the basis of the AFRQ field to which the engine operating state belongs most frequently. In step 67, it is determined whether or not the amount of SP particles is higher than the SPU upper limit threshold. When SP is <SPU, a processing cycle is complete. When SP is> SPU, the step goes to step 68 and the XRD reactivation request flag is set.

 When the XRD reactivation request flag is set in step 63, step 63 goes to step 69 and it is determined whether or not the current DOCA zone corresponds to the ASLCT selection area. When DOCA is different from ASLCT, the step goes to step 70 and the XCR reactivation execution flag is reset. That is, the reactivation action of the particulate filter 16 is turned off. Then, the step goes to step 64 and further processing of the amount of collected particles SP is performed. In contrast, when DOCA equals ASLCT in step 69, the step goes to step 71 and the XCR reactivation execution flag is set.

That is, the reactivation action of the particulate filter 16 is started.

When the XCR reactivation execution flag is set in step 62, the step goes to step 72 and a quantity of pRP particles to be removed from the particle filter 16 per unit of time is calculated. The amount of pRP particles is stored in advance in the
ROM 32 as a function of a reactivation process, a TFP particulate filter temperature, an air inlet mass flow rate Ga and a motor rotation speed NE, for example. In step 73, a negative value of a product (-dRP x DLT) of DLT and dRP interrupt time intervals of this routine is multiplied, whereby the amount of particles collected SP by the particulate filter 16 is calculated (SP = SP-dRP x DLT). In step 74, it is determined whether or not the amount of particles collected SP by the particulate filter 16 is smaller than the lower limit threshold SPL. When SP is> SPL, a processing cycle is complete. When SP is <SPL, the step goes to step 75 and the XCR reactivation execution flag and the XRD reactivation request flag are reset.

 On the other hand, when the current DOCA zone is zone I (DOCA = "I"), step 61 goes to step 76. In step 76, a quantity of DPD particles to be removed from the particulate filter 16 by unit of time is calculated using the first reactivation method. In the following step 77, as in step 73, the amount of collected particles SP is calculated (SP = SP-dRP x DLT). In step 78, the reactivation execution flag XCR is reset.

 Fig. 7 and Fig. 8 show a subprogram for the execution reactivation control. This routine is executed by an interrupt, each predetermined time interval.

 In step 100, it is determined whether or not the XCR reactivation execution flag is set.

When the XCR Reactivation Execution Indicator is set, the step goes to step 101. In step 101, an area
DOCA to which the current engine operating state belongs is determined using the map shown in Fig. 2A. In step 102, it is determined whether or not the current DOCA zone is zone II. When the zone
The current DOCA is zone II (DOCA = "II"), that is to say when the second reactivation method should be executed, the step goes to step 103 and a correction coefficient KT (> 0) the main fuel injection period TMI is calculated. This correction coefficient KT is stored in advance in the ROM 32 as a function of the particle filter temperature TRF, the air inlet mass flow rate Ga and the motor rotation speed NE. In step 104, a secondary fuel injection quantity QSI is set to zero. In step 105, a correction coefficient KEGR of an opening degree
DEGR of an EGR control valve 25 is set to zero. In step 106, a KEX correction coefficient of an opening degree DEX of an exhaust throttle valve 26 is set to zero and the step goes to step 120.

When DOCA is different from "II" in step 102, step 102 goes to step 107 and it is determined whether or not the current DOCA zone is zone III. When the zone
The current DOCA is Zone III (DOCA = "III"), that is, when the third reactivation process should be performed, the step goes to step 108 and the KT correction coefficient of the period TMI main fuel injection is set to zero. In step 109, the amount of secondary fuel injection QSI is calculated. In step 110, a correction coefficient KEGR (<0) of a degree of opening DEGR of the EGR control valve is calculated. These amount of secondary fuel injection
QSI and correction coefficient KEGR are stored in advance in the ROM 32 as a function of the TPF particle filter temperature, the air inlet mass flow rate Ga and the engine rotational speed.
NE, respectively. In step 111, the KEX correction coefficient of an opening degree DEX of the exhaust throttle valve is set to zero, and the step goes to step 120.

In step 107, when DOCA is different from "III", i.e., when the current DOCA zone is zone IV (DOCA = "IV"), and the fourth reactivation method should be performed step 107 goes to step 112 and the correction coefficient KT of the main fuel injection period TMI is set to zero. In step 113, the amount of secondary fuel injection QSI is calculated and in the following step 114, the correction coefficient KEGR of the opening degree DEGR of the EGR control valve is set to zero. In step 115, the correction coefficient KEX (<0) of the degree of opening
DEX of the throttle valve is calculated. The KEX correction coefficient is stored in advance in the ROM 32 as a function of the TPF particle filter temperature, the air inlet mass flow rate Ga and the motor rotation speed NE. Then, the step goes to step 120.

In step 120, a base fuel injection period TMB is calculated and at step 121, the main fuel injection period TMI is calculated from the basic fuel injection period. TMB and correction coefficient KT (TMI = TMB +
KT). In step 122, the base control valve opening degree DEGRB is calculated, and in step 123 the degree of opening of the basic EGR control valve DEGR is calculated from the degree of opening. control valve
Basic EGR DEGRB and correction coefficient KEGR (DEGR = DEGRB + KEGR). In step 124, the throttle opening degree of the DEXB base exhaust gas is calculated and, in step 125, the throttle opening degree of the DEX exhaust gas is calculated from the degree of base throttle valve DEXB and KEX correction coefficient (DEX = DEXB + KEX). The basic main fuel injection period TMB, the degree of opening of the base EGR control valve DEGRB and the degree of throttle opening of the DEX exhaust gases are stored in advance in the ROM 32, respectively, as a function of the air inlet mass flow rate Ga and the motor rotation speed NE, for example.

 In the above embodiment, the particle filter reactivation control is turned on or off based on the engine operating state. However, the reactivation operation can be controlled on the basis of the temperature of the particulate filter.

In the second embodiment of the present invention, even if the engine operating state leaves the reactivation operating zone (zone I to zone
IV) during particle filter reactivation processing, such a reactivation operation is continued as long as the particulate filter temperature meets predetermined operating conditions.

 In this embodiment, a quantity of particles collected by the particulate filter 16 is always monitored. When the amount of collected particles reaches a predetermined amount, and the engine operates at any of the above operating zones II to IV, the reactivation of the particulate filter 16 is started using a reactivation method in accordance with the operating area. The amount of particles collected by the particulate filter 16 can be calculated by detecting the differential pressure between an inlet and an outlet of the particulate filter 16, for example. In this embodiment, the ECU 30 counts or counts a collection amount counter based on the engine operating state, thereby calculating a quantity of collected particles.

 That is, a particle generation amount in a motor is determined as a function of a motor load state (e.g., the fuel injection amount and the rotational speed). In this embodiment, an amount of particles to be discharged per unit time from the engine is experimentally obtained by changing a combination of the amount of engine fuel injection and the rotational speed and operation of an engine. real in advance. Then, the amount is stored in the ECU ROM 30 in the form of a digital table using the fuel injection amount and the rotational speed.

 The ECU 30 calculates a particle generation amount per unit of time from the above numerical table using the engine fuel injection amount and the rotation speed each time period during engine operation. and incrementing the collection counter by a value obtained by multiplying this generation quantity by a predetermined collection rate. In this manner, a collection counter value indicates an amount to be collected by the particulate filter 16 of the particles produced by the engine. On the other hand, when a temperature of the particulate filter 16 is raised in a natural reactivation zone (FIG. 2 and zone I) or by carrying out the reactivation operation, the particles collected by the particulate filter are burned. In this case, a quantity of particles to be burned per unit of time is determined as a function of the temperature of the particulate filter. The ECU 30 performs an operation to increase a value of the collection counter in accordance with the engine particle generation amount as described above; calculates a combustion amount per particle time units collected by the particulate filter from the above numerical table; and decreases the value of the collection counter by the calculated burn amount.

 That is, the ECU 30 increases a value of the collection counter by the amount of particles collected by the particle filter at each predetermined time interval during engine operation.

When the temperature of the particulate filter is raised by changing the engine operating state or performing the reactivation operation, the ECU 30 reduces a value of the collection counter by the amount of particles burned on the particulate filter. In this way, the value of the collection counter accurately indicates a quantity of particles that still exists in the particulate filter 16.

 As described above, in this embodiment, when the engine is operating in zone I, the particle filter reactivation operation is naturally started regardless of the amount of particles collected by the particulate filter. .

When the engine operating area is any of the operating zones II to IV, the reactivation operation is started only if the amount of particles exceeds a predetermined value. In this case, the reactivation operation to be started is the same as an operation according to the operating zone described above. In addition, in the area
II to IV, when the previously mentioned collection counter value is equal to or smaller than a predetermined value while the reactivation operation is performed, the reactivation operation is terminated.

In addition, in this embodiment, as in the first aforementioned embodiment, while the engine is operating in the operating zone I and the combustion of particles continues, for example, in the case where the operating zone changes from zone II to the zone
IV, the reactivation operation does not immediately move to this operating zone II to the zone
IV. That is, even if the operating zone changes from zone I to zone IV, the temperature of the particulate filter is not lowered to a corresponding temperature from zone II to zone IV immediately, the temperature is gradually lowered with a certain period of time. Accordingly, even if the operating state moves from zone I to zone II, while the particle filter temperature is high, it is possible to continue particle combustion sufficiently by performing a gentle increase operation. temperature (for example, retarding the fuel injection with a smaller amount of retardation than during the reactivation operation of zone II). In this case, the combustion of particles is continued by a gentle temperature increase operation, thereby making it possible to suppress an increase in the amount of motor fuel combustion more significantly than when the reactivation operation of the zone It is executed.

Thus, in this embodiment, in the case where one operating state changes to another zone, while the particle combustion is in zone I, while the particle filter temperature is high, the operation of Gentle increase in temperature is achieved so as to continue particle combustion.

 The particle filter used in the present invention is of a separate type, and relatively small with respect to a quantity of collectable particles, but instead a short time is required for reactivation. Thus, even if the operating state moves from zone I to another zone, a probability of completion of reactivation (combustion of all particles) is relatively large that the particle filter temperature is lowered. Therefore, as described above, even if the operating state moves from zone I to another zone, a frequency of completion of particulate filter reactivation by only a gentle increase operation As the temperature becomes high, an increase in the amount of engine fuel combustion for the particulate filter reactivation operation is eliminated.

 On the other hand, when the operating state is changed for zone V (non-reactivation zone) while the particle filter is reactivated in zone II for zone IV, a similar operation is performed. In this case, after the engine operating state has been changed to zone V, a temperature at which the particulate filter temperature can be maintained is ensured for a certain period of time. In this embodiment, in the case where the operating state has moved for a non-reactivation operating zone then the particle filter reactivation operation is performed, the reactivation operation is not performed. canceled immediately when the operating state has moved to the non-reactivation operating zone.

Instead, the reactivation operation (combination of injection expansion and air inlet treatment and exhaust throttling) is performed. In this way, a probability of completion of particle combustion becomes high and the particulate filter is fully reactivated. In addition, after the engine operating state has entered the zone V, the exhaust temperature is lowered and the particulate filter temperature is lowered. However, in this embodiment, in the case where the particle filter temperature is lowered in such a way that particle combustion can not be maintained using the reactivation method in zone IV only, the operation particle filter reactivation is canceled. As a result, the particulate filter is prevented from producing by significantly increasing the exhaust temperature until the particulate filter temperature has been lowered and an increase in the amount of engine fuel consumption is reduced.

 Fig. 9 and Fig. 10 are flow charts for specifically describing the particle filter reactivation operation in accordance with this embodiment. Fig. 9 shows a judgment operation of the start conditions for the particle filter reactivation operation. Figure 10 shows an operation of judgment of the stopping conditions for the particle filter reactivation operation. The operations shown in Fig. 9 and Fig. 10 are performed by a subroutine to be executed by the ECU at each predetermined time interval.

 In the operation shown in Fig. 9, when the amount of collected particles reaches the upper limit threshold SPU and a motor is operated in any one of the zones II to IV shown in Fig. 2, a reactivation operation forced is started.

 That is, when the operation shown in Fig. 9 is started, a collection amount counter value SP calculated by a collection quantity counter arithmetic operation (not shown) should otherwise be performed at the same time. step 201, the engine fuel injection amount QIJ and the engine rotation speed NE are read, respectively.

 Then, in step 203, it is determined whether or not the reactivation operation of the particle filter 16 is currently performed (particles being burned) based on a value of the parameter RX. Here, the value of the RX parameter indicates a type of reactivation operation executed at this time as will be described later.

 RX = 1 indicates that the natural reactivation operation in zone I (particle combustion) is being performed at this time; and RX = 2 indicates that the forced reactivation operation in zone II (fuel injection timing delay) is executed. In addition, RX = 3 and RX = 4 each indicate that the reactivation operations in zone III and zone IV, respectively (combination of treatment of the expansion process injection and EGR and injection combination of the treatment of expansion and throttling of exhaust / air intake) are performed. Further, RX = 5 indicates that the aforementioned mild temperature increase operation (small fuel injection timing delay) is performed. RX = 0 indicates that particle combustion is not currently being performed.

 When RX is different from 0, in step 203, any reactivation operation is currently performed. There is no need to re-judge the start conditions of the operation, and thus this operation is completed immediately. In addition, when RX = 0, the reactivation operation is not currently performed and thus, the start conditions for performing the reactivation operation are determined in step 205 or later.

 That is, at step 205, it is determined whether or not an engine is currently operating in zone I based on the amount of fuel injection read QIJ and the speed of rotation of the engine. NE engine in step 201.

 When the engine is operating in zone I, the combustion of particles is started without worrying about the current amount of particles collected by the particulate filter 16. Thus, the step goes to step 207 and a value of the parameter RX is set to 1 (while the natural reactivation operation is performed). In addition, in step 205, when the engine is not currently operating in zone I the step goes to step 209 and it is determined whether a quantity of particles collected by the current particulate filter 16 reaches a predetermined value based on a value of the collection counter SP.

 In step 209, when SP <SPU, the quantity of particles collected does not reach a predetermined value. It is not necessary to start the forced reactivation operation again and thus, this operation is immediately completed without the execution of step 211 and following. In addition, in step 209, when SP is> SPU, the amount of particles collected by the particulate filter 16 increases, making it necessary to initiate the reactivation operation. Thus, in steps 211 to 221, a value of the RX parameter is set according to the engine operating area.

That is, in steps 211 to 221, it is determined whether or not the current engine running conditions are in any of the cards II to IV shown in Fig. 2 on the basis of a value between the fuel injection quantity QINJ and the engine rotation speed NE (steps 211, 215 and 219). In the case of any one of these zones, the value of the parameter RX is set to a value of 2 to 4, depending on the zone (steps 313, 317 and 321). Moreover, in step 219, when the current engine operating zone is not zone IV, this indicates that the engine is not currently operating in zone V. Thus, the rigorous reactivation operation of the particles 16 is not realized.

In this case, the value of the RX parameter is not changed (the value of RX = 0 is maintained) and the operation is completed.

 When the value of the parameter RX is set to any one of the operations 2 to 4 shown in FIG. 9, the reactivation operation of the particle filter 16 in accordance with the value of the parameter RX is performed by an additional operation to be executed. by the ECU 30.

 Figure 10 shows a judgment operation of the stop conditions for the reactivation operation in progress. In this operation, as previously described, when the engine operating state changes to another zone in the engine operating zone I during particle combustion, the particle combustion continues by executing an increase operation. soft temperature (RX = 5) until the temperature of the particulate filter 16 has been lowered more significantly than a predetermined temperature. In addition, when the engine operating state changes for zone V (non-reactivation operating zone) while the forced reactivation operation is performed in any of the operating zones II to IV, the continuous forced reactivation operation in the same manner as that in zone IV until the temperature of the particulate filter 16 has been lowered to a temperature at which particle combustion can not be maintained.

In addition, in the case where the receiver of the particulate filter 16 is lowered more significantly than the above temperature after the displacement for the zone V and in the case where the value of the collection meter
SP is equal to or less than a predetermined value during these reactivation operations (for example, in the case where a total quantity of particles collected by the reactivation operation is burned), the value of the parameter RX is set to zero and the forced reactivation operation is stopped.

That is, when this operation is initiated, the values of the collection counter SP, the fuel injection amount QIJ, the engine speed rotation speed NE and the TPF particle filter temperature detected by the temperature sensor 40 yes or no any reactivation operation is currently performed on the basis of the value of the parameter
RX. When RX = 0 in step 303, any reactivation operation (particle combustion) is not currently performed. There is no need to judge the stopping conditions for the reactivation operation and thus, this operation is completed immediately.

 On the other hand, when RX # 0 in step 303, i.e., when RX = 1 to 5, the reactivation operation is currently performed. First, in step 305, it is determined whether or not a motor is currently operated in zone I. When the motor is operating in zone I, the step goes to step 307 and the RX parameter value is set to 1 again. In addition, when an operating zone exits zone I, it is determined whether or not the TPF temperature of the particulate filter 16 is equal to or greater than a predetermined temperature T1 at the next step 309. The temperature T1 corresponds to at a natural ignition temperature of the particles and T1 is set to a value close to 600 C, for example, in this embodiment.

 In step 309, when TPF> T1, the engine operating zone exits zone I. The particle filter temperature is still high, which makes it possible to maintain the combustion of particles by executing an operation. mild increase in temperature. Thus, the step goes to step 311 and the value of parameter RX is set to 5. In this way, the engine fuel injection period is slightly delayed (by a delay value smaller than the reactivation operation in zone II) and the rate of temperature lowering of particulate filter 16 is further reduced. In this way, even in an area other than zone I, it is possible to continue the combustion of particles without performing a forced reactivation operation in zones II to IV while an increase in the amount of fuel combustion of engine is restricted.

In step 309, when the particulate filter temperature is lower than T1, it is determined whether or not the engine operating area is changed for any of the zones II to IV based on QINJ and
NE in the following steps 313 to 321. When the zone is changed to any one of the zones II to IV, the value of the parameter RX is reset to a value according to the zone (any one of II to IV ). In this way, the reactivation operation is subsequently performed according to the engine operating area.

 In step 312, when the engine operating zone exits zone IV, i.e., when the engine is currently operating in zone V, it is determined whether or not a temperature T of the particulate filter 16 is currently lowered more significantly than a predetermined value T2 in the next step 325. T2 is the lowest temperature at which particle combustion can continue, which is set to a value close to 400 C, for example, in this embodiment.

 In step 325, when TPF> T2, the engine operating area is zone V (non-reactivation operating area). The temperature of the particulate filter 16 is not lowered to such a point that particle combustion can not be maintained and thus the step goes to step 323 and the value of the RX parameter is set to 4. From In this way, the forced reactivation operation of zone IV is performed and in zone V also, the rate of temperature decrease of the particulate filter is further reduced and particle combustion continues.

Thus, even if the engine operating zone enters a non-reactivation operating zone, while the temperature of the particulate filter 16 is in a range in which the reactivation operation of the particulate filter continues without being canceled, where the possibility of particle filter reactivation completion becomes high. In addition, at step 425, when TPF <T2, it is difficult to maintain particle combustion in the reactivation operation of zone IV. Thus, the step goes to step 431, the value of parameter RX is set to zero, and the forced reactivation operation is stopped. In this way, a large amount of energy is prevented from being consumed for the temperature increase of the particulate filter and an increase in the amount of fuel consumed by the engine is limited.

 In addition, when the reactivation operation of any one of RX = 1 to 5 is performed, in the case where the current particle counter value SP smaller than zero in step 327, that is i.e., in the case where a total amount of collected particles is burned, the value of the collection amount counter SP is set to zero and in step 331, the value of the parameter RX is set to zero and the operation of reactivation is stopped.

 In the embodiment above, in order to carry out the second to fourth reactivation processes above, each of the operating variables such as the fuel injection amount, the fuel injection period, the amount of gas EGR can be controlled according to the engine operating state and the type of reactivation process.

 Subsequently, a method for controlling these operating variables will be described.

 In a third embodiment of the present invention, each operation variable is determined according to whether or not the escape throttling operation is implemented.

 When the exhaust throttle is implemented, an exhaust throttle pressure loss is increased, thereby making it possible to significantly increase a main fuel injection amount and a fuel injection amount of treatment expansion (secondary fuel injection amount) while an increase in engine power is limited. However, when the exhaust throttling is implemented, each of the other operating variables must be changed significantly according to the exhaust throttling.

 For example, when exhaust throttling is performed, the exhaust pressure is increased. Thus, even if an opening degree of the EGR valve 25 is not changed, the amount of EGR gas flowing back from an air intake system is increased. In addition, a motor air inlet amount is decreased by the exhaust throttle, thereby causing unstable combustion or lowered engine power. In order to prevent this, it is necessary to control an amount of EGR gas at an optimum value in accordance with a decrease in the amount of air intake. In addition, in order to increase the exhaust temperature to an optimum value in a short time, it is necessary to change the fuel injection amount or the main fuel injection period and the injection quantity or the fuel injection quantity. injection period of the expansion treatment injection according to the exhaust throttling.

 In this embodiment, the fuel injection amount or the main fuel injection period when the reactivation operation of the particulate filter 16 is performed; the amount of injection or injection period of the injection of the expansion treatment; each operating variable EGR gas quantity or the like are determined according to the operating state of the engine (state of charge). However, as described above, even if the operating state (engine load) is not changed depending on whether or not the exhaust throttling is implemented, these operating variables must be changed depending on whether yes or no the throttling operation is implemented. In this embodiment, each operation variable is determined based on a discrete relationship when the escape throttle is implemented or not during execution of the reactivation operation.

 Specifically, the engine operates in advance by changing the loading conditions (for example, fuel injection quantity QIJ and rotation speed NE); each operating variable required to obtain an optimum exhaust temperature for the reactivation operation of the particulate filter 16 is obtained; the respective operating variables are stored in the ECU ROM 30 in the form of a digital map using QIJ and NE as parameters; and each operating variable is determined from current QIJ and NE values during the reactivation operation of the particle filter 16 using these digital maps. Here, the two digital maps are prepared depending on when the reactivation operation to implement the escape throttling was performed and when the reactivation operation was performed without implementing exhaust throttling.

In this embodiment, when the reactivation operation is implemented, each operating variable is determined using different maps depending on whether or not the escape throttle is implemented, thereby to obtain an operating variable. optimal according to the respective case.

 Fig. 11 is a flowchart for specifically illustrating the determination of each operating variable when the aforementioned reactivation operation is implemented in accordance with this embodiment. This operation is performed by a subroutine executed by the ECU 30 at each predetermined time interval.

 In step 401, it is determined whether or not the reactivation operation execution conditions are met. In this embodiment, a quantity of particles collected in the particulate filter 16 during engine operation is always monitored using a collection counter. When a collection counter value increases to a predetermined value, it is determined that the reactivation operation execution conditions are met.

When the particles are burned by performing the reactivation operation or the like, and the value of the collection counter is equal to or less than a predetermined value (for example, close to zero), it is determined that the conditions of Reactivation operation execution is not encountered.

 When the reactivation operation execution conditions are not met in step 401, this operation is complete as it is. In this case, the exhaust throttling operation and the expansion treatment injection are not performed and the main fuel injection amount, the injection period and the amount of EGR gas are determined by the general control operation.

 When the reactivation operation execution conditions are met in step 401, the main fuel injection amount QIJ and the engine rotation speed NE are read in the next step 403. The injection quantity the main fuel QIJ is separately calculated on the basis of the engine rotation speed NE and the acceleration opening degree ACCP.

In this operation, QIJ and NE are used as parameters representing a state of engine operation (a state of charge).

 In step 405, it is determined whether or not the current engine is operated in an area in which the exhaust throttling is to be performed during the reactivation operation from the QIJ and NE readings. The exhaust throttling operation results in a relatively significant increase in fuel consumption. Thus, in this embodiment, the exhaust throttle is implemented only in an operating zone in which the particulate filter 16 can not be reactivated as long as the engine load is relatively low and the exhaust temperature is significantly increased.

 When the exhaust throttle is necessary, a degree of exhaust throttling (degree of opening of the throttle valve 26) is determined from a predetermined relationship based on the state of charge of the engine current (QIJ, NE) at step 407. The degree of opening of the throttle valve can be continuously changed depending on the state of charge of the engine and, however, the degree of opening of the throttle valve. The exhaust is controlled in three stages, fully open, half open (50% of the opening degree) and fully closed in order to simplify the control. In step 407, the opening degree of the throttle valve is set to either full opening or half opening based on the values QIJ and NE.

Step 409 shows an operation of calculating a correction amount (increment) of the main fuel injection amount. At step 409, a correction amount determined based on the values
QIJ and NE from a digital map prepared in advance based on a motor operating result when the exhaust throttling is implemented.

When the exhaust throttling is implemented, it is possible to increase the amount of main fuel injection more significantly than in the case where the exhaust throttling is not implemented. Accordingly, in step 409, an increment of the main fuel injection amount is set to a relatively large value. During the reactivation operation, the actual main fuel injection amount is set to a value obtained by adding a correction amount calculated in step 409 to QIJ.

 In addition, at step 411, the injection timing of the main fuel injection is similarly determined based on the QIJ and NE values from the pre-prepared digital map based on the operating result. engine when the exhaust throttling is implemented.

 In addition, at steps 413, 415 and 417, the fuel injection amount, the injection period and the amount of EGR gas of the expansion treatment injection are determined using the IQJ and NE values, respectively, at from the digital map prepared on the basis of the engine operating result when the exhaust throttling is implemented.

The amount of EGR gas is set to a value smaller than that when the exhaust throttling is not implemented in accordance with the lowering of a fresh air intake amount due to the throttling of exhaust.

 Step 419 shows the control operation for controlling the value of each operating variable to a value established by the above operation. In step 419, an opening degree of the exhaust throttle value 26 is controlled to be an open degree set in step 407. In addition, the opening degree interval of the valve and the fuel injection valve period 11 of each cylinder are set to be the injection period of the main fuel injection amount after correction. Further, in the expansion processing of each cylinder, this interval and this period are set to perform the fuel injection in the amount of the expansion treatment injection and the injection period established in steps 413. and 415. In addition, the degree of opening of the air inlet throttle valve 10 and the degree of opening of the EGR valve 25 are set to those in which the amount of EGR gas set in step 417 is obtained.

 On the other hand, when a motor is operated in an operating zone in which the exhaust throttling is not necessary when the reactivation operation is performed in step 405, the amount of the main fuel injection, the main fuel injection period, the amount of expansion treatment injection and the injection period, and the amount of EGR gas are determined in steps 421 to 429 by a similar operation to that of steps 409 to 417. In this case, each operating variable is determined from the current QIJ and NE values based on the digital map obtained from the engine operating result in which the exhaust throttle n is not implemented in advance in each step. In addition, in step 431, the fuel injection valve, the air inlet throttle valve 11, and the EGR valve 25 are controlled in a manner similar to that in step 419, but the degree of opening of the throttle valve 26 is kept fully open.

 As seen previously, in this embodiment, each operating variable is set according to whether or not the exhaust throttling is implemented, thereby making it possible to obtain a target exhaust temperature precisely in a short time when the exhaust throttling is implemented.

 As actual operation, since an exhaust throttle control delay time 26 is present, a delay time can be produced until the exhaust throttle established during the adjustment of the degree opening of the throttle valve was obtained. Therefore, when the main fuel injection or the expansion treatment injection and the EGR are controlled at their settings in step 419, these operating variables can be changed according to a control speed of the throttle valve. exhaust 26.

 Next, a fourth embodiment of the present invention will be described.

 In this embodiment, the reactivation operation of the particulate filter 16 is performed by the expansion processing injection operation. In addition, in this embodiment, EGR is implemented in almost all operating areas of an engine.

When EGR is implemented, a high temperature gas is discharged to an air intake system and the exhaust temperature increases as a new amount of air intake is lowered. Accordingly, when the expansion processing injection operation is implemented, the EGR operation continues, making it possible to increase the increment of the exhaust temperature.

 However, when the injection of the expansion treatment is performed, the exhaust energy increases.

Thus, in an engine having a turbocharger, the work of a compressor increases and the compressor pressure increases. For this reason, a quantity of fresh air to be sucked into the engine can be increased more significantly than in the case where the injection of the expansion treatment is not performed.

In order to increase the exhaust temperature to a desired temperature with a new airflow being increased, there appears to be a need to increase the expansion process fuel injection by an amount consistent with the increase in fresh air, resulting in an increase in fuel consumption. In this embodiment, when the expansion treatment injection and the EGR operation are performed, even if the engine load is the same for each, the amount of EGR gas is increased more significantly than in the case where the expansion processing operation is not implemented. In this way, an increase in the fresh air flow rate due to the expansion treatment injection is limited and an increase in the fuel consumption rate is avoided.

 Fig. 12 is a flow chart for specifically illustrating the EGR amount control in the above reactivation operation. This operation is performed by a subroutine executed by the ECU 30 at each predetermined time interval.

At step 501, it is determined whether or not the reactivation operation execution conditions are currently met. Step 501 is performed using the same method as that in step 401 shown in FIG. 11. Commonly, when the reactivation operation execution conditions are met, the amount of engine fuel injection
QIJ and engine rotational speed NE are read in step 503. In step 505, it is determined whether or not the engine is currently operating by the injection of the expansion process under load conditions in which the engine is operating. The reactivation operation of the particulate filter 16 should be performed. For example, when the engine is operating in an area where the engine load is high, and the exhaust temperature is relatively high, the reactivation operation of the particulate filter 16 due to the injection of the expansion treatment is not implemented. Instead, the reactivation operation of the particulate filter 16 using another method (eg, retarding the main fuel injection period or the like) is implemented by another operation to be performed by the ECU 30. .

 When the reactivation operation of the particulate filter 16 is performed by injection of the expansion treatment in step 505, the fuel injection amount and the injection period are determined in accordance with the state of charge. In this embodiment, the amount of expansion processing fuel injection and the optimum injection period for increasing the exhaust temperature to a target value are obtained in accordance with the present invention. test advance, in accordance with each of the engine load conditions (QIJ, NE). These quantity and period are stored in the ECU ROM 30 as a digital map using QIJ and NE as parameters. In step 507, the amount of expansion processing fuel injection and the injection period are established from this digital map using the QIJ and NE values.

 Then, in step 509, the amount of EGR correction (increment) is calculated when the expansion processing injection operation is implemented. In this embodiment, the increment of the EGR gases required when the injection of the expansion processing is implemented is obtained in advance by testing and is stored in the ECU ROM 30 in the form of the digital map using QIJ. and not. At step 509, the EGR correction amount is determined from the QIJ and NE values using this digital map.

In step 511, a fuel injection amount and a determined expansion treatment injection period are set in a fuel injection circuit, and in step 513, the amount of EGR gas is increased. . As previously described, the incremental correction of the amount of the EGR gases is implemented in amount of fresh air any or both of the increase in the degree of opening of the valve
EGR 25 and decreasing the degree of opening of the throttle valve 10. In this way, when the expansion treatment injection operation is implemented, the amount of EGR gas is increased by more significantly than in the case where the operation is not implemented and an increase in the amount of fuel injection of the expansion treatment injection is limited.

 Next, the fifth embodiment of the present invention will be further described.

In this embodiment, the reactivation operation of the particulate filter 16 is performed by performing either the expansion process injection operation, the exhaust throttling operation, or both. However, when both the expansion process injection operation and the exhaust throttle operation are performed simultaneously, the exhaust pressure increases significantly. Even though the degree of opening of the EGR valve 25 is slightly changed, the amount of EGR gas is greatly changed. Thus, the amount of EGR gas is excessively increased and a misfire can be produced. In this embodiment, when the exhaust throttling operation is performed at the same time as the expansion processing injection operation, the valve
EGR 25 is fully closed and the exhaust recirculation is stopped, preventing misfire.

 Fig. 13 is a flow chart for specifically illustrating the above-mentioned EGR gas quantity control operation of this embodiment.

This operation is performed by a subroutine to be executed by the ECU 30 at each predetermined time interval.

 In step 601, the engine load conditions (fuel injection quantity QIJ and rotation speed NE) are read. In step 603, it is determined whether or not the reactivation operation execution conditions of the particle filter 16 are presently encountered. This judgment is made on the basis of the value of the particle collection counter separately calculated in a manner similar to that of step 401 shown in Fig. 11 and step 501 shown in Fig. 12.

 When the reactivation operation execution conditions are found in step 603, in the next step 605, it is determined whether or not the engine is currently operating on the basis of the engine load conditions (QIJ, NE). ) in an operating zone in which the reactivation operation of the particulate filter should be performed by the expansion processing injection operation. When the reactivation operation execution conditions are not met, and when the engine operates in an operating zone in which the injection of the expansion processing is not implemented in step 605 (for example, an operating zone in which the reactivation operation is performed by delaying the main fuel injection), step 611 is performed. Then, the amount of EGR gas is calculated from the digital map during normal operation prepared in advance based on the engine load conditions (QIJ, NE). That is, in this case, the amount of EGR gas is set to a value to be obtained during normal operation.

 Further, when the engine is operating in an area in which the expansion treatment injection operation is to be performed in step 605, it is determined whether or not the engine is operating based on the load conditions of the engine. engine in an area in which the expansion processing injection operation and the exhaust throttling operation should be performed simultaneously at the next step 607. When the exhaust throttling operation is executed , that is to say, in the case of an operating zone in which the reactivation operation of the particulate filter 16 is performed by the charging conditions of the reactivation treatment of the particulate filter 16 is carried out by implementing any one or both the expansion treatment injection operation and the exhaust throttling operation, the target air intake amount (fresh air quantity) of the engine is established to a v different value according to whether or not the expansion processing injection operation is implemented or whether or not the exhaust throttling operation is still implemented when the expansion process injection operation is implemented.

 For example, as described above, when the expansion treatment injection is implemented, compressor pressure increases more significantly than that during normal operation and the amount of air intake increases. In addition, in order to burn fuel injected by the expansion process injection operation and increase the exhaust temperature, a larger amount of air intake than that during normal operation is required. Thus, an optimum air intake amount changes depending on whether or not the expansion processing injection operation is implemented.

 When the exhaust throttling operation is executed simultaneously during the implementation of the expansion process injection operation, as described in the fifth embodiment, the amount of EGR gas is subject to being excessively large, thus making it necessary to reduce the amount of EGR gas more significantly than usual or to stop the EGR operation. In this case, even during the exhaust throttling operation, the amount of air inlet is increased by a decrease in the amount of EGR gas. In addition, an adequate amount of air intake is required to burn a fuel of the incremented injection amount with the implementation of the exhaust throttle and the increase of the exhaust temperature. Accordingly, when the expansion processing injection operation is implemented as well, an optimum air intake amount is changed depending on whether or not the exhaust throttling operation is implemented.

 In this embodiment, with respect to a case of normal operation, (when the expansion processing injection operation is not implemented), a case where only the expansion processing injection operation is implemented and a case where both the expansion process injection operation and the exhaust throttling operation are performed, the engine load conditions (fuel injection quantity QIJ and speed of NE rotation) are changed, the test is performed and an optimum air intake amount (target air intake amount) is obtained. According to one of these respective cases, the optimum air intake amount is stored in the ECU ROM 30 as the digital map using QIJ and NE. Then, a target air intake amount is calculated based on the engine load conditions using the corresponding digital map depending on whether or not the expansion process injection operation is present during the operation of the engine. engine and whether or not the exhaust throttling operation is present.

 In addition, in this embodiment, the degree of opening between the throttle valve 10 and the EGR valve 25 is controlled so that a real amount of engine air inlet is equal to the previously calculated air inlet amount, whereby the air inlet amount is controlled so that the actual engine air inlet amount corresponds to the amount target air intake calculated. Thus, the amount of engine air inlet is controlled at an optimum air intake amount depending on whether or not the expansion processing injection operation is implemented or whether or not the operation Exhaust throttling is implemented, thereby making it possible to prevent the alteration of the exhaust properties due to an excess or a deficiency of a quantity of air intake at the same moment whereas the temperature of the exhaust Exhaust is precisely increased at the target temperature during the implementation of the reactivation operation.

 Fig. 14 is a flow chart for specifically illustrating the above mentioned air intake amount control operation. This operation is performed by a subroutine to be executed by the ECU 30 at each predetermined time interval.

 In step 701, the engine load conditions (QIJ fuel injection amount and NE rotation speed) are read. In step 703, it is determined whether or not the expansion process injection operation is currently performed, i.e., whether or not the reactivation operation of the particulate filter 16 is currently running. At this time, when the expansion processing injection operation is not executed, i.e., when the normal operation is currently in progress, the step goes to the next step 707. Next, a target air intake amount is set from the values QIJ and NE read at step 701 using a normal operation board of the digital maps stored in the ECU ROM 30. At step 709, the degree of opening between the air inlet throttle valve 10 and the EGR valve 25 is adjusted in accordance with the set target air intake amount.

 When the expansion process injection operation is implemented in step 703, it is determined whether or not the expansion process injection operation and the exhaust throttling operation are currently implemented in the next step 705.

When only the expansion processing injection operation is implemented, the target air intake amount is established based on the digital map during the implementation of the expansion processing injection operation stored in the ECU ROM 30 at step 707. In step 709, the degree of opening between the air inlet throttle valve 10 and the EGR control valve 23 is adjusted in accordance with the amount of target air inlet.

 On the other hand, when both the expansion process injection operation and the exhaust throttling operation are implemented in step 705, the target air intake amount is set on the digital map base when both the expansion processing injection operation and the exhaust throttling operation are implemented from the digital map stored in the ROM of the ECU 30 to the next. step 715.

In step 717, the degree of opening between the air inlet gas valve 10 and the EGR control valve 23 is adjusted according to the amount of target air inlet.

In this embodiment, in each operating condition (normal operation, implementation of the expansion processing injection operation and implementation of both the expansion processing injection operation and the exhaust throttling operation), a combination of the opening degree of the throttle valve 10 and the EGR valve 25 required to establish the amount of engine air at an inlet amount target air under each engine load condition is obtained in advance by testing, and is stored in the ECU ROM 30 in the form of these digital maps shown in Figure 2 using
QIJ and NE at each respective operating condition.

In steps 709 and 717, the opening degrees of the air inlet throttle valve 10 and the EGR valve 25 are set based on the values QIJ and NE read in step 601 using a condition card. corresponding operation of these digital maps.

 By performing the operation shown in Fig. 14, an air intake amount is set to an optimal target air inlet amount depending on whether or not the expansion processing injection operation is implemented. and whether or not the escape throttling operation is further implemented when the expansion processing injection operation is implemented.

 In the previously described embodiment, a fuel for heating the particulate filter is provided using the secondary fuel injection for the purpose of reactivating the particulate filter. However, an additional fuel injection valve is disposed in an exhaust passage upstream of the particulate filter 16 and the heating fuel can be supplied from this additional fuel injection valve. Moreover, in this embodiment, the opening degree of the throttle valve 26 is controlled, thereby controlling a flow rate of the exhaust which enters the particulate filter 16. However, the flow rate can be controlled by controlling the degree of opening of the air inlet throttle valve 10 disposed in the engine air inlet passage.

 In addition, the forced reactivation method of the particulate filter 16 includes: disposing an electric heater on the particulate filter 16 to directly heat the particulate filter 16; the use of a burner; changing a fuel ratio of the air-fuel mixture to be burned in an engine fuel combustion chamber for a "rich" side more significant than that during normal operation; or the delay of an ignition period in a spark ignition type internal combustion engine more significantly than that during normal operation.

Claims (14)

 An exhaust emission control device for an internal combustion engine (1) having a particulate filter (16) for collecting particles contained in the exhaust gas disposed in an engine exhaust passage ( 14,15) of the engine, the device characterized by the fact that it comprises  a plurality of reactivation means for reactivating the particulate filter (16), wherein  at least one is selected from the plurality of reactivation means on the basis of an operating state of the engine (1) so that the particulate filter (16) is reactivated by the selected reactivation means.  An exhaust emission control device according to claim 1, characterized in that the selected reactivation means is determined on the basis of a history of an operating state of the engine (1).  Exhaust emission control device according to claim 1, characterized in that:  an operating state of the engine (1) is divided into a plurality of zones (I, II, III, IV), the reactivation means being assigned separately to each of the operational zones and  the particulate filter (16) is reactivated when an operating state of the engine belongs to a zone in which the selected reactivation means is assigned.  4. Exhaust emission control device according to claim 1, characterized in that each of the plurality of reactivation means has an energy efficiency and a temperature increase performance which are different from each other .  Exhaust emission control device according to claim 1, characterized in that:  a motor operating state (1) is divided into a plurality of zones (I, II, III, IV, V);  at least one zone is selected from the plurality of zones based on a history of an engine operating state; and  the particulate filter (16) is reactivated when the operating state of the engine belongs to the selected zone.  An exhaust emission control apparatus according to claim 5, further characterized in that it comprises means for determining the amount of particles (SP) collected in the particulate filter (16), wherein the particle filter (16) is reactivated when the amount of particles (SP) is larger than a predetermined amount (SPU).  7. exhaust emission control device according to claim 6, characterized in that the predetermined amount is changed according to the selected area or the selected reactivation means.  Exhaust emission control device according to claim 1, characterized in that the plurality of reactivation means comprises:  delay reactivation means for delaying the main fuel injection period more significantly than during normal operation; and  secondary injection EGR reactivation means for effecting secondary fuel injection for engine expansion treatment or exhaust treatment and increasing an amount of EGR gas more significantly than that of normal operation, in which  the particulate filter (16) is reactivated by the delay reactivation means when a motor load is higher than a predetermined load, and  the particulate filter (16) is reactivated by the secondary injection EGR reactivation means when the engine load is lower than the predetermined load.  An exhaust emission control apparatus according to claim 1, further characterized in that it comprises exhaust flow control means for controlling a flow rate of the exhaust gas entering the filter. particles (16), wherein  the plurality of reactivation means comprises:  secondary EGR reactivation means for performing secondary fuel injection for engine expansion treatment or exhaust treatment and increasing the amount of EGR gas more significantly than in normal operation; and  secondary injection exhaust amount reactivation means for performing secondary fuel injection for engine expansion treatment or exhaust treatment and decreasing an exhaust flow rate which enters the particulate filter in a manner such that more significant than in normal operation,  the particulate filter (16) is reactivated by the secondary injection EGR reactivation means when a motor load is higher than a predetermined load, and  the particulate filter (16) is reactivated by the secondary injection exhaust amount reactivation means when the engine load is lower than the predetermined load.  Exhaust emission control device according to claim 1, characterized in that it further comprises:  temperature sensing means (40a) for detecting a temperature of a particulate filter; and  reactivation control means for performing the reactivation operation of the particulate filter (16) when an internal combustion engine (1) is operating in a predetermined operating zone, wherein  the reactivation control means continues the reactivation operation in the case where a temperature of the particulate filter (16) satisfies the predetermined temperature conditions when an operating state of the internal combustion engine is out of the operating zone during reactivation of the particulate filter.  An exhaust emission control apparatus according to claim 1, wherein the plurality of reactivation means increases an engine exhaust temperature by at least one operation selected from the group consisting of:  an exhaust throttling operation for reducing an exhaust flow by operating an exhaust throttle (26) disposed in an engine exhaust passage (18);  an expansion treatment injection operation for performing fuel injection in an expansion process of a rectangular cylinder of an engine;  an EGR control operation for recirculating a portion of the exhaust from the engine exhaust system to an exhaust system; and  a main fuel injection control operation for changing the main fuel injection amount and the injection period of each engine cylinder,  in which  each of the operating variables such as the amount of expansion treatment fuel injection, the expansion treatment fuel injection treatment, the recirculation exhaust flow rate, the main fuel injection amount and the main fuel injection period is determined on the basis of a first predetermined relationship according to an operating state of the engine when the exhaust throttling operation is performed, and  each of the operating variables is determined on the basis of a second predetermined relationship according to a motor operating state which is different from the first relationship, when the exhaust throttling operation is not performed.  An exhaust emission control device according to claim 11, characterized in that the recirculation exhaust rate is increased more significantly than when the expansion treatment injection operation is not carried out. executed when the EGR command operation is implemented during execution of the expansion process injection operation.  An exhaust emission control device according to claim 11, characterized in that the EGR operation is stopped when both the expansion processing injection operation and the throttling operation are completed. Escapes are implemented.  An exhaust emission control device according to claim 11, characterized in that the target air intake amount is set on the basis of the operating state of the engine according to whether or not the operation of expansion processing injection is implemented, or whether or not the exhaust throttling operation is implemented, and  at least one of an opening degree of an air inlet throttle (10) disposed in an engine air intake passage and an opening degree of the intake amount EGR motor air is controlled, thereby controlling an amount of engine air inlet to the target air intake amount.