DE19957715A1 - Exhaust emission control device for an internal combustion engine - Google Patents

Abstract

The present invention relates to an exhaust gas emission control device for an internal combustion engine for reliably reactivating a particulate filter while largely maintaining energy efficiency. A machine operating area is divided into a plurality of areas (I, II, III, IV, V), and different reactivation devices are set for the respective area from these areas. An area (AFRQ) to which the engine operating state most often belongs is obtained, and an area (ASLCT) in which a reactivation method with a lower fuel consumption rate than that for the area reactivation method (AFRQ) is set is selected. If a quantity of accumulated particles (SP) is larger than an upper limit value (SPU), a reactivation operation of the particle filter is ended if a current operating range (DOCA) does not match the selected range (ASLCT). If an operating state changes and the current operating range (DOCA) matches the selected range (ASLCT), the particle filter is reactivated using a reactivation method set for the current range (DOCA).

Description

PRINCIPLES OF THE INVENTION 1. Field of the Invention

The invention relates to an exhaust gas Control device for an internal combustion engine.

2. Description of the prior art

A large amount of essentially carbon or Such existing particles is one in the exhaust gas Internal combustion engine included. To collect these particles and to prevent emission into the atmosphere has a known internal combustion engine on a particulate filter, which in the machine exhaust system is arranged. Will one Machine operating time extended, then a lot of increases accumulated particles in the particle filter and it enlarges back pressure of the machine. It is therefore necessary remove the accumulated particles, d. H. the Reactivate particle filter before the back pressure of the Machine becomes larger than a permissible maximum pressure. As Process for reactivating such a particle filter is an exhaust emission control device for a Internal combustion engine known, in which a burner in the Engine exhaust system arranged upstream of the particle filter is, and it becomes a temperature of the in the particulate filter flowing exhaust increases, so that the particles burn (reference to Japanese Patent Application Laid-Open No. 60-47937).

In addition to using such a burner and Increase in the temperature of the in the particle filter Incoming exhaust gas were different processes proposed including a delay procedure a main fuel injection period in a diesel engine  and a method of increasing a gas amount exhaust gas recirculation (EGR) in considerable extent beyond normal operation.

If a burner is used, the temperature can can be reliably increased to a temperature which is used for Reactivation of the particle filter is necessary even if the temperature of the flowing into the particle filter Exhaust gas is relatively low. However, it is fuel for a burner is required even if the temperature of the in exhaust gas flowing into the particle filter is relatively high.

On the other hand, in the method of delaying the Main fuel injection period when the temperature of the in exhaust gas flowing in a particulate filter is low, the Particulate filter temperature not required Temperature can be increased, however, a Fuel consumption rate does not increase as much. Therefore there for example, it includes both a reactivation process Using a burner and a reactivation process using the delay control one Main fuel injection period. Is the temperature of the in exhaust gas flowing into the particulate filter low, then the particle filter using the reactivation process below Reactivated use of the burner. Is the temperature of the exhaust gas flowing into the particle filter, then a fuel consumption rate decreased by means of the Reactivation method using a Delay control of the main fuel injection period, so that it is possible to put the particle filter in reactivate reliably.

A large number of reactivation methods are therefore available Available, and these reactivation procedures are described in selectively used, making it possible to use the To reactivate particle filters in a reliable manner, whereby  receive a high degree of economical use of energy becomes. However, there is currently no disclosure of one such a technical concept.

BRIEF DESCRIPTION OF THE INVENTION

To solve the above problem, it is a Object of the present invention, constantly Use reactivation equipment that is required for reliably reactivating a particle filter, whereby energy efficiency is maintained to a high degree.

To achieve the above object according to the present The invention becomes an exhaust emission control device for an internal combustion engine provided with one in one Exhaust system of the machine arranged particle filter for Collect the particles contained in the exhaust gas, whereby a Variety of particle filter reactivation devices is provided, and at least one of the plurality of Reactivation devices based on a Operating state of the internal combustion engine for reactivating Particle filtering is selected. That way it is possible, always a reactivation device for reliable reactivation of particle filters required is to use, energy efficiency to a high degree is maintained.

BRIEF DESCRIPTION OF THE FIGURES

Fig. 1 is an overall view of an internal combustion engine according to the present invention;

Fig. 2 is an illustration of areas I to V to perform a reactivation control of the particulate filter;

Fig. 3 is a timing diagram illustrating the particulate filter reactivation process;

Fig. 4 is a flow chart for determining a selection range ASLCT;

Fig. 5 is a flowchart for performing tag control;

Fig. 6 is a flowchart for performing tag control;

Fig. 7 is a flow chart for performing a reactivation control of the particulate filter;

Fig. 8 is a flow chart for performing a reactivation control of the particulate filter;

Fig. 9 is a flow diagram illustrating an operation of the evaluation conditions for starting the reactivation control of the particulate filter;

Fig. 10 is a flow chart showing an operation of evaluation conditions for terminating the reactivation control of the particulate filter;

Fig. 11 is a flow chart showing an operation for determining each operation variable in the reactivation control of the particulate filter;

Fig. 12 is a flow chart for illustrating an operation of correcting an increased exhaust gas recirculation gas quantity in the reactivation control of the particulate filter;

Fig. 13 is a flow diagram illustrating an operation of the setting of an exhaust gas recirculation gas quantity in the reactivation control of the particulate filter; and

Fig. 14 is a flowchart for explaining a control correction operation is a control Maschinenansaugluftmenge in the reactivation of the particulate filter.

DESCRIPTION OF THE PREFERRED EMBODIMENTS

Preferred embodiments of the present invention with reference to the related Figures described.

Fig. 1 shows an example of applying the present invention to a diesel engine. The invention is applicable to a spark-ignited machine in contrast to the diesel machine.

A main engine block includes four air cylinders # 1, # 2, # 3 and # 4. Each air cylinder is connected to an expansion tank by means of a corresponding intake air branch pipe 2 . The expansion tank is connected to an output region of a compressor 6 c of a supercharger (for example an exhaust gas turbocharger) by means of an air intake duct 4 and an intercooler 5 . An input area of the compressor 6 c is connected to an air cleaner 8 via an intake pipe 7 . An air intake throttle valve 10 , which is driven by an actuator 9 , is arranged within the air intake duct 4 between the expansion tank 3 and the intercooler 5 . Furthermore, each air cylinder has a fuel injection valve 11 for injecting fuel directly into a combustion chamber. Each fuel injection valve 11 is connected to a fuel pump that is able to control the fuel injection quantity via a common fuel pressure collection chamber 12 . The injection quantity is controlled in a fuel pump 13 such that the fuel pressure in the fuel pressure collection chamber 12 assumes a target fuel pressure.

A corresponding branch area 15 of an exhaust manifold 14 is connected to each air cylinder, and a particle filter 16 is arranged in each branch area 15 . Further parts of the exhaust manifold 14 are connected to an input region of an exhaust gas turbine 6 t of an exhaust gas turbocharger 6 ; an input region of the exhaust gas turbine 6 t is connected to a housing 20 , which contains a NOx absorber 19 , by means of an exhaust pipe 18 ; and the housing 20 is connected to an exhaust pipe 21 . In addition, a reducing agent is injected upstream in the exhaust pipe 18 between the exhaust gas turbine 6 t and the NOx (nitrogen oxide) absorbing agent 19 , and a reducing agent supply valve 22 for supplying a reducing agent to the NOx absorber 19 is provided. This reducing agent supply valve 22 is connected to the fuel pressure collection chamber 12 . In the preferred embodiments, engine fuel (hydrocarbons) is used as the reducing agent. The reducing agent includes, for example, hydrocarbons such as gasoline, iso-octane, hexane, heptane, light oil, kerosene, butane and propane, hydrogen, ammonia and urea.

Further, the exhaust manifold 14 downstream of the particulate filter 16 and the air intake passage 4 on the downstream side of the air intake throttle valve 10 are connected to each other via an exhaust gas recirculation passage (hereinafter referred to as EGR) passage 23 , and an EGR control valve 25 which is driven by an actuator 24 , is located within the EGR passage 23 . Thus, when the EGR passage 23 arranged further upstream than the reducing agent supply valve 22, then a fed from the reducing agent supply valve 22 secondary fuel is prevented from being recirculated with the EGR gas to be Maschinenansaugluftdurchlass.

Furthermore, an exhaust gas throttle valve 26 is arranged within the exhaust pipe 18 between the exhaust gas turbine 6 t and the reducing agent supply valve 22 and is driven by an actuator 27 . The exhaust throttle valve 26 is kept in the fully open state.

An electronic control unit (ECU) 30 consists of digital computers and comprises a ROM (read-only memory) 32 which is connected by means of a bidirectional bus 31 ; a RAM (read / write memory) 33 , a CPU (microprocessor) 34 ; a B-RAM (backup RAM) that is constantly connected to a power source; an input area 36 ; and an output area 37 . A flow quantity sensor 38 for detecting a flow quantity of the intake air is arranged in an air intake pipe 7 . In a fuel pressure accumulation chamber 12, a fuel pressure sensor 39 is arranged for generating an output voltage proportional to the fuel pressure in the fuel pressure accumulator chamber 12th A temperature sensor 40 a for generating an output voltage to indicate a temperature TPF of the particle filter 16 (an output voltage proportional to a temperature of the exhaust gas flowing into a particle filter 16 ) is arranged in a branching area 15 of the exhaust manifold 14 upstream of the particle filter 16 . A temperature sensor 40 b for generating an output voltage for indicating a temperature TNA of a NOx absorber 19 (an output voltage proportional to a temperature of the exhaust gas flowing into the NOx absorber 19 ) is arranged on an exhaust pipe 21 downstream of the NOx absorber 19 . A step size sensor 41 generates an output voltage proportional to an accelerator step size DEP. An air flow meter 51 is arranged in a machine air intake passage and generates an output voltage corresponding to the air intake flow amount Ga. The output voltage of these sensors 38 , 39 , 40 a, 40 b, 41 and 51 are each input into an input area 36 via corresponding AD converters 42 . Furthermore, a rotational speed sensor 43 for generating an output pulse corresponding to a machine rotational speed is connected to the input region 36 . An output region 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 respective control circuits 44 .

The NOx absorber 19 has, for example, aluminum as a carrier. The carrier carries at least one of the selected elements of alkali 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 lanthanium La and yttrium Y, and noble metals such as platinum Pt, palladium Pd, Rhodium Rh and Iridium Ir. If a ratio of a total amount of air supplied into a reducing agent for an upstream exhaust gas system, a combustion chamber, and an air intake passage more than a position in the engine exhaust system is referred to as an air-fuel ratio of the exhaust gas for distribution in that position, then The NOx absorber 19 absorbs NOx when the air-fuel ratio of the exhaust gas inflow is lean. If the oxygen concentration in the exhaust gas inflow is reduced, a NOx absorption and discharge process is carried out to discharge absorbed NOx.

In this embodiment, the air-fuel ratio of an air-fuel mixture for combustion by each cylinder is maintained at a lean value during normal operation, so that NOx in the exhaust gas discharged from the cylinder therefore during normal operation by the NOx absorber 19 is absorbed.

However, the NOx absorptivity of the NOx absorber 19 is limited and requires NOx to be removed from the NOx absorber 19 before the absorptivity is saturated. In this embodiment, a reducing agent is temporarily supplied to the NOx absorber 19 by the reducing agent supply valve 22 when an NOx absorption amount of the NOx absorber 19 obtained is larger than a predetermined set amount, so that NOx in the NOx absorber 19 is discharged and reduced .

The exhaust gas emitted from the machine includes particles consisting of soot, carbon, soluble organic fractions (SOF), sulfates and the like, and these particles are collected by the particle filter 16 . However, if the amount of the accumulated particles in the particle filter 16 increases, the back pressure is increased. It is therefore necessary to remove the particles from the particle filter 16 , that is to say to carry out a reactivation process of the particle filter 16 before the back pressure is increased.

In this exemplary embodiment, the particle filter 16 is reactivated when the amount of collected particles through the particle filter 16 is greater than a predetermined upper limit value. A method of reactivating the particulate filter 16 will now be described in detail.

In this exemplary embodiment, as shown in FIG. 2A, a machine operating state range, which is defined by the step size DEP and the machine rotational speed NE, for representing a machine load, is divided into five areas I, II, III, IV and V.

In a region I, a temperature of the exhaust gas flowing into the particle filter 16 is very high. Thus, if no temperature increase operation is to be carried out from outside, the temperature of the particle filter 16 becomes higher than the ignition temperature of the particles. The particles thus begin a natural combustion, whereby the particle filter 16 is reactivated in a natural way. Therefore, the natural reactivation method in which the particulate filter 16 is reactivated in a natural manner is called the first reactivation method.

In another area, which is not area I, the particle filter 16 is not reactivated in a natural way, which means that it is necessary to forcibly reactivate the filter. In the first exemplary embodiment of the present invention, the second to fourth forcible reactivation methods are provided for forcibly reactivating the particle filter 16 .

The second reactivation process is a process for significantly delaying the main fuel injection period from normal operation. If the main fuel injection period is significantly delayed from normal operation, the temperature of the exhaust gas discharged from the combustion chamber increases. Therefore, the temperature of the exhaust gas flowing into the particulate filter 16 is increased, whereby it is possible to reactivate the particulate filter 16 .

A third reactivation method is a method for increasing the opening degree DEGR of an EGR control valve 25 to a considerable extent compared to normal operation while the secondary fuel injection is being carried out. In addition to the main fuel injection, which is carried out in the vicinity of the top dead center, the temperature of the particulate filter 16 is increased in the secondary fuel injection, that is to say the implementation of the secondary fuel injection by means of a fuel injection valve 7 during an expansion process or an air ejection process. At this time, when an increased degree of opening DEGR of the EGR control valve 25 increases the amount of EGR gas, an amount of fresh air to be supplied to the combustion chamber is further decreased. The EGR gas is so hot that the temperature of the exhaust gas flowing into the particle filter 16 can be increased in a simple manner.

Combustion due to secondary fuel injection hardly contributes to the machine output.

A fourth reactivation method is a method for reducing an opening degree DEX of an exhaust throttle valve 27 to a greater extent than during normal operation while secondary fuel injection is being performed. If the secondary fuel injection is carried out, then the temperature of the exhaust gas flowing into the particle filter 16 is increased in the manner described above. At this time, when the reduced opening degree DEX of the exhaust throttle valve 27 reduces an exhaust gas amount flowing into the particulate filter 16 , a flow rate of the exhaust gas to be heated is further reduced. Therefore, the temperature of the exhaust gas flowing into the particulate filter 16 can be increased more easily. Here, the intake air throttle valve 10 or an opening degree of both the intake air throttle valve 10 and the exhaust gas throttle valve 27 can be adapted instead of the exhaust gas throttle valve 27 .

In the second reactivation process, it is necessary to increase the main fuel injection quantity so that the engine output torque is not decreased. The increased amount is small, but the degree of retardation of the main fuel injection period is limited, so that the temperature of the particulate filter 16 cannot be increased significantly and quickly. In the third reactivation method, additional fuel is consumed for the secondary fuel injection, but the temperature of the particle filter 16 can be increased considerably and quickly. In the fourth reactivation method, it is necessary to increase the main fuel injection amount so as not to cause the engine output torque to decrease. However, a flow rate of the exhaust gas to be heated is reduced, so that the temperature of the particle filter 16 can be increased considerably and faster than in the third reactivation method. Therefore, the fuel consumption rate in the respective reactivation processes is the lowest in the first reactivation process, and is increased significantly in the second, third and fourth reactivation processes in this order. Here, the temperature raising operation is the most important in the fourth reactivation process, and is lower in the third and second reactivation processes in that order.

Regarding the fuel consumption rate, the use of the second reactivation method is the most advantageous. In regions III and IV, however, the temperature of the particle filter 16 cannot be increased sufficiently because the temperature of the exhaust gas flowing into the particle filter 16 is low when the second reactivation method is used. In the same way, when using the third reactivation method in area IV, the temperature of the particle filter 16 cannot be increased sufficiently. If the fourth reactivation method is used in area III, the fuel consumption rate increases. The second reactivation process is used in area II, the third reactivation process is used in area III and the fourth reactivation process is used in area IV. A correlation between each area and the reactivation process is given in Table 1 below.

TABLE 1

In a region V, the temperature of the exhaust gas flowing into the particle filter 16 is very low. It is therefore very difficult to reactivate the particle filter 16 . A reactivation of the particle filter 16 is suspended in area IV. It is desirable to select a particulate filter reactivation method according to the range (range I to V) to which the engine operating condition most often belongs.

For example, if a machine operating condition frequently belongs to area II in a case, then it is assumed that an amount of particles collected is greater than an upper limit when the machine operating condition changes to area IV. If the particle filter 16 is reactivated by means of the fourth reactivation method, the fuel consumption rate increases, which is not desirable. At this point, a reactivation process of the particle filter is therefore suspended. Then, when the engine operating state (goes back) to area II, the fuel consumption rate can be reduced significantly using the second reactivation method. In addition, the fuel consumption rate can be further significantly reduced if an attempt is made to reactivate the particulate filter using the first reactivation method after the engine operating state has transitioned to area I.

In this embodiment, an area AFRQ to which the engine operating state often belongs is obtained from the areas I to IV based on the engine operating state history, and this area AFRQ and an area in which a reactivation method with a fuel consumption rate smaller than that for it Is set, is selected (hereinafter, this area is called the selection area ASLCT). If a quantity of collected particles takes on a greater value than the upper limit value if the machine operating state does not belong to the selected area ASLCT, the reactivation process for the particle filter 16 is suspended. If the machine operating state has then passed to the selection area ASLCT, then the particle filter 16 is reactivated by means of the reactivation method set for an area to which the machine operating state belongs.

Table 2 below shows a relationship between the area AFRQ to which the machine operating state on most often heard, and the selection area ASLCT.  

TABLE 2

FIG. 3 shows a flow chart if the area AFRQ to which the machine operating state most often belongs is area II (if the selection areas ASLCT are area I and II). In the figure, EIN denotes performing a reactivation process of the particulate filter 16 with each reactivation method; and OFF denotes the completion of the above-mentioned processes.

First, it is assumed that an amount of particles SP collected is larger than the upper limit SPU at a time "a". At this time, an area DOCA to which the engine operating state belongs is area IV, and the reactivation process of the particulate filter 16 is not performed. If the area DOCA changes to the area DOCA at time "b", then a reactivation process of the particle filter 16 is started by means of the second reactivation method. After the further lapse of time, when the area DOCA transitions to the area I at time "c", the second reactivation process is ended and the first reactivation process is carried out. If area DOCA again changes to area II at time "d", then the second reactivation process is performed again. If a quantity of the collected particles SP reaches the lower limit value SPL at a time "e", then the second reactivation process is ended and the reactivation process of the particle filter 16 is completed.

In the event that the area DOCA transitions to the area III (ie outside the selection area ASLCT), if the reactivation process of the particle filter 16 is carried out at a time "f", even if the amount of the collected particles SP is greater than the lower limit value SPL , the reactivation process of the particle filter 16 is ended.

Thus, in this embodiment, a selection area ASLCT is determined based on the machine operating history. If the machine operating state belongs to the selection area ASLCT, then the particle filter 16 is reactivated. The particle filters are reactivated in areas I to IV. Therefore, at least one of a variety of reactivation methods is selected based on the machine operating history and the particulate filter 16 is reactivated. Insofar as the amount of collected particles is greater than the upper limit value SPU, the reactivation of the particle filter 16 is also started each time the machine operating state belongs to the selection area ASLCT. Therefore, a period at which the particulate filter 16 is to be reactivated is determined based on the engine operating history.

It is also like the fourth reactivation method for example, not desirable a large amount of Particles at a time using the Reactivation process with a large To remove fuel consumption rate. Furthermore, the upper Limit SPU reduced, then one can be removed Particle quantity reduced in a reactivation process become. In this embodiment, the upper one Limit SPU determined lower than if the  Fuel consumption rate is small if one Reactivation process with a large Fuel consumption rate is carried out. As a result a quantity of particles to be removed in one Reactivation process reduced.

The upper limit SPU is smallest when the range AFRQ, to which the machine operating state most often heard is area IV. The upper limit SPU will larger in the order in which the AFRQ area differs from Area III changes to Area I.

Fig. 4 shows a routine for determining the selection range ASLCT. The routine is executed at predetermined time intervals according to respective interrupts.

First, in step 50, an area DOCA is determined using a map shown in FIG. 2A to which the machine operating state belongs. In step 51 , it is determined whether the current area DOCA is the same area as area AOLD in the previous sequence cycle. If DOCA = AOLD, then a transition is made to step 52 , and a count value CA to indicate a time in which an area to which the machine operating state belongs is likewise maintained increased by one. Then there is a transition from step 52 to step 56 . In comparison, if DOCA ≠ AOLD applies in step 51 , ie if the current area DOAC has changed over to the previous area AOLD, then a transition is made to step 53 and it is determined whether or not the count value CA is greater than a certain value CAT . If CA ≦ CAT applies, a jump is made to step 55 . If CA <CAT applies, a transition is made to step 54 and a frequency S (AOLD) of the area AOLD is counted up by one. In this case, the counter value CA indicates a time at which the machine operating state remains in AOLD. If the machine operating state is maintained in AOLD for a predetermined period of time or longer, the frequency S (AOLD) is increased. In the subsequent step 55 , the count value CA is deleted.

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

In FIGS. 5 and 6 is shown for carrying out a marking control routine. The routine is executed by means of an interrupt after every predetermined time DLT.

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

If area DOCA is not area I (DOCA ≠ "I"), a transition is made to step 62 . In step 62 , it is determined whether or not a reactivation execution flag XCR is set. The reactivation execution flag XCR is set when the particulate filter 16 is to be reactivated using the second to fourth reactivation methods (XCR = "1"), and otherwise the flag is reset (XCR = "0"). If the reactivation execution flag XCR is reset, then a transition is made to step 63 and it is determined whether or not a reactivation request flag XRD is set. The reactivation request flag XRD is set when the particle filter 16 is to be reactivated (XRD = "1"), and otherwise the flag is reset (XRD = "0"). If the reactivation request mark XRD is reset, a transition is made to step 64 and the particle quantity dCP that is to be collected per unit of time by means of the particle filter 16 is calculated. The particle quantity dCP is, for example, stored in advance in a ROM 32 as a function of a number of variables, such as the quantity of fuel injected by means of a fuel injector 11 , an intake air flow rate Ga, an engine rotational speed NE and a particle collection capacity of the particle filter 16 . In the subsequent step 65 , a product (dCP × DLT) of an interrupt time interval DLT and the value dCP of this routine are multiplied, the amount of collected particles SP of the particle filter 16 being calculated (SP = SP + dCP × DLT). In step 66 , the upper limit SPU is calculated based on the range AFRQ to which the machine operating state most often belongs. In step 67 , it is determined whether or not the amount of the collected particles SP is larger than the upper limit value SPU. If SP ≦ SPU applies, the execution cycle is ended. If SP <SPU, then a transition is made to step 68 and the reactivation request flag XRD is set.

If the reactivation request flag XRD was set in step 63 , a transition is made from step 63 to step 69 and it is determined whether the current area DOCA matches the selection area ASLCT or not. If DOCA ≠ ASLCT applies, a transition is made to step 70 and the reactivation execution flag XCR is reset. This means that a reactivation process of the particle filter 16 is switched off. Then there is a transition to step 64 , and an additional procedure is carried out with regard to the amount of the collected particles SP. If, on the other hand, DOCA = ASLCT applies in step 69 , a transition is made to step 61 and the reactivation execution flag XCR is set. The reactivation process of the particle filter 16 is thus started.

If the reactivation execution mark XCR is set in step 62 , a transition is made to step 72 and a quantity of particles dRP to be removed from the particle filter 16 per unit of time is calculated. The particulate amount dRP is stored in the ROM 32 in advance as functions of a reactivation method, for example, a particulate filter temperature TPF, an intake air amount flow rate Ga, and an engine rotation speed NE. In step 73 , a negative product (-dRP × DLT) of an interrupt time interval DLT and the value dRP of this routine are multiplied, the amount of the particles SP collected by means of the particle filter 16 being calculated (SP = SP - dRP × DLT). In step 74 it is determined whether the particle quantity SP collected by means of the particle filter 16 is smaller than the lower limit value SPL. If SP ≧ SPL applies, the execution cycle is ended. If SP <SPL, then a transition is made to step 75 and the reactivation execution flag XCR and the reactivation request flag XRD are reset.

On the other hand, if the current area DOCA is area I (DOCA = "1"), a transition is made from step 61 to step 76 . In step 76 , a particle quantity dPR to be removed from the particle filter 16 per unit of time is calculated using the first reactivation method. In the subsequent step 77 , as in step 73 , the quantity of the particles SP to be collected is calculated (SP = SP - dRP × DLT). In step 78 , the reactivation execution flag XCR is reset.

FIGS. 7 and 8 show a routine for carrying out the reactivation control. This routine is performed according to an interrupt after every predetermined time interval.

It is determined in step 100 whether the reactivation execution flag XCR is set or not. If the reactivation execution flag XCR is set, a transition is made to step 101 . In step 101 , an area DOCA to which the machine operating state belongs is determined using the map shown in FIG. 2A. In step 102 , it is determined whether the current area DOCA is area II. If the current area DOCA is area II (DOCA = "II"), ie if the second reactivation process is to be carried out, then a transition is made to step 103 and a correction coefficient KT (<0) of the main fuel injection period TMI is calculated. The correction coefficient KT is stored in advance in the ROM 32 as a function of the particulate filter temperature TRF, the intake air flow rate Ga and the engine rotation speed NE. In step 104 , a secondary fuel injection amount 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 correction coefficient KEX of an opening degree DEX of an exhaust gas throttle valve 26 is set to zero, and a transition is then made to step 120 .

If DOCA ≠ "II" applies in step 102 , a transition is made from step 102 to step 107 , and it is determined whether or not the current area DOCA is area III. If the current area DOCA is area III (DOCA = "III"), ie if the third reactivation process is to be carried out, then a transition is made to step 108 and the correction coefficient KT of the main fuel injection period TMI is set to zero. In step 109 , the secondary fuel injection amount QSI is calculated. In step 110 , a correction coefficient KEGR (<0) of an opening degree DEGR of the EGR control valve is calculated. This secondary fuel injection amount QSI and the correction coefficient KEGR are previously stored in the ROM 32 as functions of the particulate filter temperature TPF, the intake air amount flow rate Ga, and the engine rotation speed NE. In step 111 , the correction coefficient KEX of an opening degree DEX of the exhaust throttle valve is set to zero, and a transition is made to step 120 .

If DOCA ≠ "III" applies in step 107 , ie if the current area DOCA is area IV (DOCA = "IV") and the fourth reactivation method is to be carried out, then a transition takes place from step 107 to step 112 and the correction coefficient KT the main fuel injection period TMI is set to zero. In step 113 , the secondary fuel injection amount QSI is calculated, and in subsequent 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 opening degree DEX of the exhaust throttle valve is calculated. The correction coefficient KEX is stored in advance in the ROM 32 as functions of the particulate filter temperature TPF, the intake air flow rate Ga and the engine rotation speed NE. A transition to step 120 then takes place.

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

In the above embodiment, a Particulate filter reactivation control activated or disabled based on machine operating status. On However, reactivation operations can also be based on the Particle filter temperature can be controlled.

In the second embodiment of the present invention, even if the machine operating status from the Reactivation operating area (areas I to IV) during of a particle filter reactivation process can occur such reactivation operations continue as long as the Particle filter temperature with the predetermined Operating conditions.

In this embodiment, an accumulated amount of particles of the particle filter 16 is constantly monitored. When the amount of the collected particles reaches a predetermined amount and the machine is operating in one of the above operating areas II to IV, the particle filter 16 is reactivated using a reactivation method according to the operating area. The amount of the particles collected by means of the particle filter 16 can be calculated, for example, by detecting a differential pressure between an inlet and an outlet of the particle filter 16 . In this embodiment, the ECU 30 counts up and down a collection amount counter based on the engine operating state, and an amount of the collected particles is calculated.

Thus, an amount of particle generation in a machine is determined depending on an engine load condition (for example, fuel injection amount and engine speed). In this embodiment, an amount of particles to be discharged from the engine during a unit time has been experimentally obtained in advance by changing a combination between the engine fuel injection amount and the engine speed and operating an actual engine in advance. The amount is then stored in the ROM of the ECU 30 in the form of a numerical table using the fuel injection amount and the rotating speed. The ECU 30 calculates a particle generation amount per unit time from the above numerical table using the engine fuel injection amount and the rotational speed after a certain time during the engine operation, and counts up the collection counter by a value obtained by multiplying the generation amount by a predetermined collection rate. In this way, a value of the collection counter indicates a quantity of the particles generated by the machine to be collected by the particle filter 16 . On the other hand, if the temperature of the particle filter 16 has risen in a natural reactivation area ( FIG. 2 and area I) or by carrying out a reactivation operation, the particles collected by means of the particle filter are burned. In this case, a quantity of particles to be burned per unit of time is determined based on the particle filter temperature. The ECU 30 performs an operation of increasing a value of the collection counter depending on the engine particle generation amount as described above; calculates an amount of combustion per unit time of the collected particles through the particle filter from the above numerical table; and decreases the value of the collection counter by the calculated amount of combustion.

The ECU 30 increments a value of the collection counter by the amount of particles collected by the particle filter after every predetermined time interval during the machine operation. If the particle filter temperature has risen due to a change in the operating state or in accordance with carrying out the reactivation operation, the ECU 30 decreases a value of the collection counter by the quantity of particles burned on the particle filter. In this way, the value of the collection counter identifies exactly a quantity of particles that is always present in the particle filter 16 .

According to the above description, in this exemplary embodiment, a particle filter reactivation operation is of course started, regardless of the accumulated particle quantity through the particle filter 16 , when the machine is operated in area I. If the machine is operated in one of the operating areas II to IV, a reactivation operation is only started when the amount of particles exceeds a predetermined value. In this case, the reactivation operation to be started is the same as that in an operation corresponding to the operating range as described above. In areas II to IV, when the value of the above-mentioned collection counter is equal to or less than a predetermined value while a reactivation operation is being performed, the reactivation operation is ended.

In this embodiment in the same way as in the first embodiment also goes to Reactivation operation not in operating area II to IV  immediately above if the machine is in operating area I is operated and particle combustion continues, for example, in the event that the operating range of area II changes to area IV. Even if the Operating area changes from area I to area IV, the Particulate filter temperature is not immediately reduced to a corresponding temperature from area II to the area IV, rather the temperature gradually increases during one predetermined period reduced. Even if the Operating state changes from area I to area II, while the particulate filter temperature is high, it is possible particle combustion in a satisfactory manner to continue by making a gentle Temperature rise operation (e.g. a Fuel injection delay with a smaller amount of Delay than during reactivation operations in the area II). In this case, particle combustion continues through a gentle temperature rise operation, taking it is possible an increase in the Machine fuel consumption to a greater extent suppress as if the area's reactivation operation II is carried out. In this embodiment, a gentle temperature rise operation performed to continue the particle combustion in the event that an operating condition changes to another area while the Particle combustion takes place in area I and during that Particulate filter temperature is high.

The particulate filter used in the present invention is of the separate type and relatively small in the collectible Amount of particles, but a short time to reactivate is required. Even if the operating state of the Area I changes to another area is therefore the Probability of completion of reactivation (Combustion of all particles) relatively large before that Particle filter temperature drops. According to the above  Description, even if the operating state of the area I will change to another area: a frequency of the Completing the particulate filter reactivation by just gentle temperature rise operation big, so that an increase in the machine fuel consumption quantity for Particle filter reactivation is suppressed.

In contrast, when the operating state changes to the area V (Non-activation area) changes during the Particle filter in areas II to IV is reactivated, a similar process is carried out. After the Machine operating state has changed to the area V in this case a temperature at which the Particle filter temperature can be maintained secured for a predetermined period of time. With this Embodiment and in the event that the Operating state for an operating area of the non-activation has changed while a Particulate filter reactivation operation is performed reactivation does not end immediately when the Operating state to the non-reactivation operating area has changed. Rather, the reactivation operation (Combination of expansion plant injection and Intake air and exhaust gas throttling). To this Way becomes a probability of completion of the Particle combustion is large, and the particle filter becomes fully reactivated. After the machine operating state has reached the range V, the exhaust gas temperature is reduced and the particle filter temperature becomes degraded. However, in the present embodiment the particulate filter reactivation operation ends in the case that the particle filter temperature decreases to an extent will that particle combustion will not sustain can be made using only the Reactivation procedure according to area IV. Therefore prevents the particulate filter from being significantly damaged  Increase in the exhaust gas temperature until the Particle filter temperature has decreased, and a Increase in machine fuel consumption prevented.

FIGS. 9 and 10 are flow charts for describing the special reactivation particulate filter operation according to this embodiment. Fig. 9 shows an operation for a review of starting conditions for a particulate filter reactivation operation. Fig. 10 shows the operation for evaluating the termination conditions for the particulate filter reactivation operation. The processes shown in FIGS. 9 and 10 are performed by the ECU 30 after every predetermined time interval by a routine.

In the process according to FIG. 9, an inevitable reactivation operation is started when the quantity of the collected particles 16 reaches the upper limit value SPU and the machine is operated in one of the ranges II to IV according to FIG. 2.

When the flow shown in Fig. 9 is started, a value of the collection quantity counter SP calculated by a collection quantity counter calculation process (not shown), which is otherwise performed in step 201 , an engine fuel injection quantity QIJ and an engine rotation speed NE are respectively read.

Then, in step 203, it is determined whether the reactivation operation of the particulate filter 16 is currently ongoing or not (combustion of the particulates) based on a value of the parameter RX. Here, the value of the parameter RX indicates the type of the reactivation operation currently being performed, as will be described later. The specification RX = 1 indicates that the natural reactivation operation is currently carried out in area I (particle combustion); RX = 2 also indicates that an inevitable reactivation operation is carried out in area II (fuel injection period delay). Furthermore, RX = 3 and RX = 4 each indicate that a reactivation operation is carried out in areas III and IV (combination of expansion drain injection and EGR and combination of expansion drain injection and intake air / exhaust gas throttling). Further, RX = 5 indicates that the above-mentioned gentle temperature increasing operation (small fuel injection period lag) is being performed. RX = 0 indicates that no particle combustion is currently taking place.

If RX ≠ 0 in step 203 , a reactivation operation is currently being performed. There is no need to re-evaluate the wake-up operating start conditions, so this process is ended immediately. Furthermore, if RX = 0, then no reactivation operation is currently being performed, so that the starting conditions for performing a reactivation operation are determined in step 205 or the subsequent steps.

Specifically, it is determined in step 205 whether an engine is currently operating in the area I based on the fuel injection amount QIJ read in step 201 and the engine rotation speed NE.

If the machine is operated in area I, particle combustion is started regardless of the current quantity of particles collected by means of the particle filter 16 . The process then proceeds to step 207 and a value of the parameter RX is set to 1 (with the natural reactivation operation being performed). Further, in step 205 , if the machine is not currently operating in area I, a transition is made to step 209 and it is determined there whether an amount of particles collected by the current particle filter 16 reaches a predetermined value based on the value of the collection counter SP .

If SP <SPU applies in step 209 , the quantity of the collected particles does not reach the predetermined value. There is therefore no need to restart the forced reactivation operation, and this process is ended immediately without processing step 211 and the subsequent steps. If SP ≧ SPU also applies in step 209 , then the amount of the collected particles increases through the particle filter 16 , so that it becomes necessary to start the reactivation operation. Thus, in steps 211 to 221, a value of the parameter RX is set depending on the machine operating range.

In steps 211 to 221 , it is determined based on a value between the fuel injection amount QINJ and the engine rotation speed NE (steps 211 , 215 and 219 ) whether the current engine operating conditions are in one of the maps II to IV in FIG. 2. In the case of one of these areas, the value of the parameter RX is set to a value from 2 to 4 depending on the areas (steps 313 , 317 and 321 ). If the machine is not operating in area IV, step 219 also indicates that the machine is not currently operating in area V. Therefore, the particle filter 16 is not necessarily reactivated. In this case, the value of the RX parameter is not changed (the value of RX = 0 is maintained) and the process is ended.

If the value of the parameter RX is set to a value between 2 and 4 by means of the operation shown in FIG. 9, the particle filter 16 is reactivated depending on the value of the parameter RX by an additional operation by means of the ECU 30 .

FIG. 10 shows an operation for evaluating the termination conditions for a reactivation operation performed. In this procedure, as described above, when the machine operating state has changed to another area in the machine operating area I during the particle combustion, the particle combustion is continued by performing a gentle temperature rise operation (RX = 5) until the temperature of the particle filter 16 is higher than a predetermined temperature has been decreased. Furthermore, if the machine operating state changes to an area V (non-activation operating area) while an inevitable reactivation operation is carried out in one of the operating areas II to IV, the inevitable reactivation operation continues in the same manner as in area IV until the temperature of the particle filter 16 reduced to a temperature at which particle combustion can no longer be maintained.

In the case of decreasing the temperature of the particulate filter 16 more than the above temperature after the transition to the area V, and in the event that the value of the collection counter SP is equal to or less than a predetermined value during this reactivation operation (e.g. in FIG In the event that a total of the collected particles are burned by the reactivation process), the value of the parameter RX is set to zero and the inevitable reactivation operation is ended.

If the process is started here, the values of the collection counter SP, the fuel injection quantity QIJ, the engine rotation speed NE and the particle filter temperature TPF, which is detected by means of the temperature sensor 40, are read in step 301 . In step 303 , it is determined based on the value of the parameter RX whether or not a reactivation operation is currently being performed. If RX = 0 in step 303 , then no reactivation operation (particle combustion) is currently being carried out. There is therefore no need to evaluate the termination conditions for the reactivation operation, so that this process is ended immediately.

In contrast, if RX ≠ 0 in step 303 , that is, if RX = 1 to 5, then a reactivation operation is currently being carried out. In step 305 , it is first determined whether the machine is currently operating in area I. If the machine is currently operating in area I, a transition is made to step 307 and the value of the parameter RX is set to 1 again. If an operating range also comes from range I, then in the next step 309 it is determined whether or not the temperature TPF of the particle filter 16 is equal to or greater than a predetermined temperature T1. The temperature T1 corresponds to a natural ignition temperature of the particles, and T1 is set to a value close to 600 ° C, for example in this embodiment.

If TPF ≧ T1 applies in step 309 , the machine operating range moves out of range I. The particle filter temperature is still high, which makes it possible to maintain the particle combustion by performing a gentle temperature increase operation. A transition is made to step 311 and the value of the parameter RX is set to 5. In this way, the engine fuel injection period is slightly delayed (by a delay amount smaller than in the reactivation mode in area II), and the temperature decrease rate of the particulate filter 16 is further reduced. Even in an area that is not area I, it is possible to continue the particle combustion without performing an inevitable reactivation operation in the areas II to IV while suppressing an increase in the amount of engine fuel consumed.

If the particulate filter temperature is lower than T1, it is determined whether the engine operating range has been changed to one of the ranges II to IV based on QINJ and NE in the subsequent steps 313 to 321 . If the range has changed to one of the ranges II to IV, the value of the parameter RX is reset to a value corresponding to the range (a value between 2 and 4). In this way, the reactivation operation is subsequently carried out according to the machine operation area.

In step 321 , it is determined whether a temperature of the particulate filter 16 is currently being decreased more than a predetermined value T2 in the subsequent step 325 when the machine operating area exits the area IV, ie when the machine is currently operating in the area V. T2 denotes the lowest temperature at which the particle combustion can continue, this temperature being set to a value in the vicinity of 400 ° C., for example in the present exemplary embodiment.

In step 325 , the machine operating area is not area V (non-reactivation operating area) if TPF T2 applies. The temperature of the particle filter 16 is not reduced by such an amount that the particle combustion can no longer be maintained, so that a transition takes place to step 323 and the value of the parameter RX is set to 4. In this way, an inevitable reactivation operation of the area IV is carried out, and also in the area V, the particle filter temperature lowering speed is further reduced, and the particle combustion continues. Even if the machine operating area assumes a non-reactivation operating area while the temperature of the particulate filter 16 is within a range in which a particulate filter reactivation operation continues without termination, the possibility of completing the particulate filter reactivation is high. In step 425, under the condition TPF <T2, it is difficult to maintain particle combustion in the region IV reactivation mode. Therefore, a transition is made to step 431 , and the value of the parameter RX is set to zero and an inevitable reactivation operation is ended. This prevents a large amount of energy from being used to raise the temperature of the particulate filter, and thus prevents an increase in the amount of machine fuel consumed.

If a reactivation operation is carried out in accordance with one of the values RX = 1 to 5, in the event that the value of the current particle counter SP is less than zero in step 327 , that is to say in the event that a total amount of the collected particles is burned, the value of the collection quantity counter SP is set to zero, and in step 331 the value of the parameter RX is set to zero and the reactivation operation is ended.

In the above embodiment for performing the above second to fourth reactivation processes, can any of the operational variables like that Fuel injection amount, the fuel injection period, the  EGR gas quantity depending on the machine operating state and the type of reactivation process.

The following is a method for controlling them Operating variables described.

In a third embodiment of the present Invention, each operational variable is determined in dependence whether or not an exhaust gas throttling operation is provided.

If an exhaust gas throttling process is provided, then a Exhaust throttle pressure loss increases, making it possible the main fuel injection quantity and one Expansion fuel injection quantity (Secondary fuel injection quantity) significantly increase, while an increase in machine output is suppressed. However, is an exhaust throttle implemented, then it is required that each of the other operational variables depending on the Exhaust throttling is changed significantly.

If, for example, exhaust gas throttling is carried out, the exhaust gas pressure is increased. Even if the opening degree of the EGR valve 25 is not changed, the amount of EGR gas flowing back through an air intake system is increased. An engine intake air amount is reduced by exhaust gas throttling, causing unstable combustion or lower engine output. To prevent these effects, it is necessary to control an EGR gas amount to an optimal value depending on a reduced amount of intake air. In order to increase the exhaust gas temperature to an optimum value within a short time, it is necessary to change the fuel injection amount or the injection period of the main fuel injection or the fuel amount or fuel period of the expansion drain injection depending on the exhaust gas throttling.

In this embodiment, the fuel injection amount or the injection period of the main fuel injection is provided in the reactivation operation of the particulate filter 16 ; the injection amount or the injection period of the expansion drain injection; each operational variable of the EGR gas amount or the like is determined depending on the engine operating condition (load condition). However, even if the operating state (engine load) does not change depending on whether exhaust gas throttling is provided or not, as described above, it is necessary to change these operating variables depending on whether exhaust gas throttling operation is provided or not. In this embodiment, each operation variable is determined based on a discrete relationship if exhaust gas throttling is provided or not while performing a wake-up operation.

Specifically, the engine is operated in advance by changing the load conditions (for example, fuel injection amount QIJ and rotational speed NE); any operating variable that requires an optimal exhaust temperature for a reactivation operation of the particulate filter 16 is obtained; the respective operating variables are stored in the ROM of the ECU 30 in the form of a numerical map using the quantities QIJ and NE as parameters; and each operation variable is determined from the current values QIJ and NE during the reactivation operation of the particulate filter 16 using this numerical map. Here, two numerical maps are provided depending on whether a reactivation operation was carried out to take account of exhaust gas throttling or whether a reactivation operation was carried out without taking exhaust gas throttling into account. In this embodiment, when a reactivation operation is provided, each operation variable is determined using different maps depending on whether exhaust gas throttling is provided or not, whereby optimal operation variables are obtained depending on the respective operation cases.

Fig. 11 shows a flow chart for illustrating the determination of each particular operational variables, when the reactivation operation described above is provided according to this embodiment. The process is carried out by means of a routine that is processed by the ECU 30 after every predetermined time interval.

In step 401 , it is determined whether or not the execution conditions for a wake-up operation are met. In this embodiment, a quantity of particles collected by the particle filter 16 during machine operation is continuously monitored using a collection counter. When a value of the collection counter rises to a predetermined value, it is determined that the wake-up operation execution conditions are satisfied. If the particles are burned by performing a wake-up operation or the like, and the value of the collection counter is equal to or less than a predetermined value (for example, near zero), it is determined that the wake-up operation execution conditions are not met.

If the reactivation operation execution conditions in step 401 are not met, then this flow is ended in the current state. In this case, exhaust throttle operation and expansion drain injection are not performed, and the main fuel injection amount, the injection period, and the EGR gas amount are determined by a general control operation.

If the reactivation operation execution conditions according to step 401 are met, then the main fuel injection quantity QIJ and the engine rotation speed NE are read in the subsequent step 403 . The main fuel injection amount QIJ is calculated separately based on the engine rotation speed NE and the acceleration opening degree ACCP. In this process, the quantities QIJ and NE are used as parameters to represent a machine operating state (a load state).

In a step 405 , it is determined from the read variables QIJ and NE whether the engine is currently being operated in an area in which exhaust gas throttling is required to carry out the reactivation operation. Exhaust throttle operation requires a relatively large increase in fuel consumption. Thus, in this exemplary embodiment, exhaust gas throttling is only provided in an operating range in which the particle filter 16 cannot be reactivated as long as the machine load is relatively low and the exhaust gas temperature is increased considerably.

If exhaust throttling is required, the degree of exhaust throttling (opening degree of the exhaust throttle valve 26 ) is determined from a predetermined relationship based on the engine load state (QIJ, NE) in step 407 . The opening degree of the exhaust gas throttle valve can be changed continuously depending on the machine load state, and in particular the opening degree of the exhaust gas throttle valve is controlled on three levels in order to achieve simplified control, i.e. to full opening, half opening (50% opening degree) and the fully closed state. In step 407 , the opening degree of the exhaust throttle valve is set to either the fully open or half open state based on the values of QIJ and NE.

Step 409 shows a calculation process of a correction amount (enlargement) of the main fuel injection amount. In step 409 , the correction amount is determined based on the values of QIJ and NE from a numerical map that was formed in advance based on the engine operating results when exhaust gas throttling is provided. If exhaust gas throttling is provided, it is possible to increase the main fuel injection quantity to a greater extent than in the event that exhaust gas throttling is not provided. Therefore, in step 409, an increase in 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 the QIJ value.

Further, in step 411, the injection period of the main fuel injection is determined in the same way based on the values of QIJ and NE from the numerical map that was formed in advance based on the engine operating results when implementing exhaust throttling.

In steps 413 , 415, and 417 , the fuel injection amount, the injection period, and the EGR gas amount of an expansion drain injection are determined using the values of QIJ and NE from the numerical map that was formed based on the engine operating results in consideration of exhaust throttling. The EGR gas amount is set to a value smaller than that when exhaust gas throttling is not provided in accordance with a decrease in a fresh air intake amount due to the exhaust gas throttling.

Step 419 shows a control flow for controlling the value of each operation variable to a value set by the above-described flow. In step 419 , an opening degree of the exhaust gas throttle valve 26 is controlled such that an opening degree set in step 407 is achieved. Further, the valve opening degree interval and the period of the fuel injection valve 11 of each air cylinder are set so that the injection period of the main fuel injection amount is reached after the correction. In the expansion course of each air cylinder, this interval and period are further set so that fuel injection is performed with the expansion course injection amount and the injection period as set in steps 413 and 415 . Furthermore, the opening degree of the air intake throttle valve 10 and the opening degree of the EGR valve 25 are set such that the EGR gas amount set in step 417 is obtained.

On the other hand, if an engine is operated in an operating range in which exhaust throttling is not required in the reactivation operation according to step 405 , the main fuel injection amount correction amount, the main fuel injection period, the expansion drain injection amount and the injection period and the EGR gas amount in steps 421 to 429 are the same as determined in steps 409 through 417 . In this case, each operation variable in each step is determined from the current values of QIJ and NE based on the numerical map obtained in advance from the engine operation results for which no exhaust gas throttling is provided. In step 431 , the fuel injection valve, the air intake throttle valve 11 and the EGR valve 25 are controlled in the same manner as in step 419 , but the degree of opening of the exhaust gas throttle valve 26 is kept in the fully open state.

As described above, each Operating variable in this embodiment in Depends on whether exhaust gas throttling is provided or not, it being possible to have a Target exhaust temperature in a precise manner within a short To get time if exhaust gas throttling is provided.

In actual operation, a delay time may be formed until the exhaust throttle set during the adjustment of the exhaust throttle valve opening degree is obtained because there is an actuation delay time of the exhaust throttle valve 26 . If the main fuel injection or the expansion drain injection and EGR are controlled with regard to their settings in step 419 , these operating variables can be changed depending on an actuation speed of the exhaust throttle valve 26 .

A fourth embodiment of FIG described the present invention.

In this exemplary embodiment, a reactivation operation of a particle filter 16 is carried out by means of an expansion drain injection operation. Furthermore, in this exemplary embodiment, exhaust gas recirculation EGR is provided in almost all operating areas of a machine. If an EGR is provided, a high temperature gas is returned to the air intake system and the exhaust gas temperature rises because a fresh amount of intake air is reduced. If an expansion drain injection operation is provided, EGR operation is continued, whereby it is possible to increase the increase in the exhaust gas temperature.

If an expansion drain injection is performed, then however, the exhaust gas energy increases. In one with one Turbocharger-equipped machine therefore increases performance of the supercharger and the supercharging pressure also increases. Therefore can increase the amount of fresh air drawn in by the machine increase than in the event that a Expansion drain injection is not performed. For Increase the exhaust gas temperature to a desired one Temperature with the increased fresh air flow rate there is a need to enlarge the Expansion drain fuel injection amount by an amount in Dependence on the fresh air rise, causing an increase the fuel consumption rate occurs. With this Embodiment becomes the EGR gas amount in a stronger manner enlarged than in the case that no expansion drain operation is provided when an expansion drain injection and EGR operation can be performed even if the Machine loads are identical to each other. To this There is an increase in a fresh air flow rate suppressed due to the expansion drain injection, and it will increase the rate of fuel consumption prevented.

Fig. 12 shows a flowchart for specifically illustrating the control of the amount of EGR gas in the previous reactivation operation. This process is carried out by the ECU 30 every predetermined time intervals by means of a routine.

In step 501 , it is determined whether the wake-up operation execution conditions are currently satisfied. At this time, step 501 is performed using the same method as in step 401 of FIG. 11. If the wake-up operation execution conditions are currently satisfied, then in step 403 the engine fuel injection amount QIJ and the engine rotation speed NE are read. It is determined in step 505 whether the engine is currently being operated by means of an expansion drain injection under load conditions in which the particle filter 16 is to be reactivated. For example, if the machine is operated in an area in which the machine load is high and the exhaust gas temperature is relatively high, a reactivation process of the particle filter 16 as a result of the expansion process injection is not provided. Rather, a reactivation operation of the particulate filter 16 is provided using another method (for example, the main fuel injection period delay or the like), the other process being processed by the ECU 30 .

If the particle filter 16 is reactivated by an expansion drain injection in step 505 , the fuel injection quantity and the injection period are determined in accordance with the next step 507 as a function of the engine load state. In this embodiment, the expansion drain fuel injection amount and the injection period, which are optimal for raising the exhaust gas temperature to a target value, are obtained in advance by means of a test according to the engine operating conditions (QIJ, NE). This quantity and period are stored in the ROM of the ECU 30 in the form of a numerical map using the quantities QIJ and NE as parameters. In step 507 , the expansion fuel injection amount and the injection period are set using the values of QIJ and NE according to this numerical map.

In step 511 , the fuel injection amount and the injection period of the determined expansion process are set in a fuel injection circuit, and in step 513 , the EGR gas amount is increased. As described above, an increase in the EGR gas amount is provided by performing either an increase in the degree of opening of the EGR valve 25 or a decrease in the degree of opening of the air intake throttle valve 10 or both. In this way, when an expansion drain injection operation is provided, the EGR gas amount is increased more than when this operation is not provided, and an increase in the fuel injection amount of the expansion drain injection is prevented.

A fifth embodiment of FIG described the present invention.

In this embodiment, a reactivation operation of the particulate filter 16 is performed by performing either an expansion drain injection operation or an exhaust gas throttle operation, or both. However, if both the expansion drain injection operation and the exhaust gas throttle operation are carried out at the same time, the exhaust gas pressure rises considerably. Even if the opening degree of the EGR valve 25 is changed slightly, the amount of EGR gas changes significantly. Therefore, the amount of EGR gas is increased excessively so that misfires can occur. In this embodiment, the EGR valve 25 is completely closed and exhaust gas recirculation is stopped to prevent misfire when an exhaust throttle operation is performed simultaneously with the expansion drain injection operation.

Fig. 13 is a flowchart for specifically illustrating the above-mentioned EGR gas quantity control operation of this embodiment. This process is always performed at predetermined time intervals as a routine using the ECU 30 .

In step 601 , the engine load conditions (fuel injection amount QIJ and rotational speed NE) are read. It is further determined in step 603 whether or not the reactivation operation execution conditions for the particulate filter 16 are currently satisfied. This evaluation is made on the basis of the value of the particle collection counter, which was calculated separately in a manner as in step 401 in FIG. 11 and step 501 in FIG. 12.

If the wake-up operation execution conditions are met in step 603 , then in subsequent step 605 it is determined based on the engine load conditions (QIJ, NE) whether the engine is currently operating in an operating range in which the particulate filter 16 is to be woken up by performing an expansion drain injection operation. If the wake-up operation execution conditions are not yet met and the engine is operating in an operating area where expansion drain injection is not provided according to step 605 (e.g., in an operating area where the wake-up operation is effected by delaying the main fuel injection) then step 611 is processed . Then the EGR gas amount during normal operation is calculated from the numerical map previously formed on the basis of the engine load conditions (QIJ, NE). In this case, the EGR gas amount is set to a value obtained during normal operation.

Furthermore, if the engine is operated in an area in which an expansion drain injection operation is to be carried out according to step 605 , it is determined on the basis of the engine load conditions whether the engine is operated in an area in which the expansion drain injection operation and the exhaust gas throttle operation are carried out simultaneously according to step 607 become. If an exhaust gas throttle operation is carried out, that is to say in the case of an operating range in which the particle filter 16 is only reactivated by the expansion drain load conditions, a transition is made to step 611 . Then, the EGR gas amount is set based on the numerical map previously formed when the expansion drain injection is provided. In this embodiment, too, the EGR gas amount is set to a value larger than that during normal operation when an expansion drain injection is provided.

On the other hand, if the machine is operated in an area in which both the expansion process injection operation and the exhaust gas throttle operation are to be carried out in accordance with step 607 , a transition is made to step 609 . Then, the EGR control valve 23 is completely closed and the EGR operation is ended. In this way, misfire generation due to deteriorated control properties of the EGR gas amount is prevented.

A sixth embodiment of FIG described the present invention.  

In this embodiment, the target intake air amount (fresh air amount) of the engine is set to a different value depending on whether or not an expansion drain injection operation is provided or whether an exhaust gas throttle operation is further provided if the expansion drain injection operation is provided if the reactivation operation of the particulate filter 16 is performed by implementing either the expansion drain injection mode or the exhaust throttle mode, or both.

If an expansion drain injection is provided, then can for example as described above Supercharger pressure rise more than in normal operation, and this increases the amount of intake air. Furthermore, the Combustion of a fuel using a Expansion drain injection mode was injected, and for Increasing the exhaust gas temperature a larger amount of intake air required than in normal operation. So one changes optimal intake air volume depending on whether a Expansion drain injection operation is provided or not.

If an exhaust throttle operation occurs simultaneously during the Expansion drain injection operation performed as in fifth embodiment is described, then the EGR exhaust gas amount become excessively large, which makes it is necessary to increase the amount of EGR gas more than usual reduce or stop EGR operation. In this case the intake air volume is reduced by reducing the EGR Gas quantity also increased during exhaust throttle operation. It an adequate amount of intake air is also required Combustion of an amount of fuel injected by the provided exhaust gas throttling is increased and the Exhaust gas temperature is increased. Is therefore also a Expansion drain injection mode is provided, then one  optimal intake air volume changed depending on whether an exhaust gas throttling operation is provided or not.

Regarding a case of normal operation (when an expansion drain injection mode is not provided), a case where only an E 07677 00070 552 001000280000000200012000285910756600040 0002019957715 00004 07558x expansion drain injection mode is provided, and a case where both the expansion drain injection mode and the exhaust gas mode are provided In this embodiment, the engine load conditions (fuel injection amount QIJ and rotational speed NE) are changed, a check is made, and an optimal intake air amount (target intake air amount) is obtained. Depending on the case of the above cases, the optimum intake air amount is stored in the ROM of the ECU 30 using the quantities QIJ and NE as a numerical map. Then, a target intake air amount is calculated based on the engine load conditions using the corresponding numerical map depending on whether or not there is an expansion drain injection operation during the operation of the engine and whether or not there is an exhaust throttle operation.

Further, in this embodiment, the degree of opening between the intake air throttle valve 10 and the EGR valve 25 is controlled such that an actual engine intake air amount is equal to the target intake air amount calculated above, and the intake air amount is controlled so that the actual engine intake air amount matches the calculated target intake air amount. Thus, the engine intake air amount is controlled to an optimal intake air amount depending on whether an expansion drain injection operation is provided or not or whether an exhaust gas throttling operation is provided or not, so that it is possible to prevent deterioration of the exhaust gas characteristics due to an excessive decrease in an intake air amount at the same time while the exhaust gas temperature is increased exactly to the target temperature during the intended reactivation process.

FIG. 14 is a flowchart specifically illustrating the intake air amount control process mentioned above. This procedure is processed by the ECU 30 after every predetermined time interval by means of a routine.

In step 701 , the engine load conditions (fuel injection amount QIJ and rotational speed NE) are read. It is then determined in step 703 whether an expansion drain injection operation is currently being performed, that is, whether a reactivation operation of the particulate filter 16 is currently being performed or not. If an expansion sequence injection operation is not currently being carried out, ie if normal operation is currently taking place, then a transition to the subsequent step 707 takes place . Then, a target intake air amount is set from the values QIJ and NE read in step 701 using a normal operation map of the numerical maps stored in the ROM of the ECU 30 . In step 709 , the degree of opening between the intake air throttle valve 10 and the EGR valve 25 is adjusted depending on the set target intake air quantity.

If an expansion drain injection operation is provided according to step 703 , then it is determined whether the expansion drain injection operation and the exhaust gas throttling operation according to the subsequent step 705 are currently provided. If only the expansion drain injection mode is provided, the target intake air amount is set in step 707 based on the numerical map stored in the ROM of the ECU 30 during the implementation of the expansion drain injection mode. In step 709, the opening degree between the intake air throttle valve 10 and the EGR control valve 23 are adjusted depending on the target intake air quantity.

On the other hand, if both the expansion drain injection operation and the exhaust gas throttling operation are provided in step 705 , then the target intake air amount is set in step 715 based on a numerical map stored in the ROM of the ECU 30 if both the expansion drain injection operation and the exhaust gas throttling operation are provided. In step 717, the opening degree between the intake air throttle valve 10 and the EGR control valve 23 is adjusted depending on the target intake air quantity.

In this embodiment, for each operating condition (normal operating condition, implementation of the expansion drain injection operation, and implementation of both the expansion drain injection operation and the exhaust gas throttling operation), a combination between the opening degrees of the intake air throttle valve 10 and the EGR valve 25 required to adjust the engine intake air amount to a target intake air amount obtained by tests in advance under each engine load condition and stored in the ROM of the ECU 30 in the form of these numerical maps shown in FIG. 2 using the quantities QIJ and NE for all respective operating conditions. In steps 709 and 717 , the opening degrees of the intake air throttle valve 10 and the EGR valve 25 are set on the basis of the values QIJ and NE read in step 601 using a map of the relevant operating conditions of this numerical map.

In carrying out the process of FIG. 14 is an intake air quantity to an optimum target intake air quantity in response to set whether an expansion flow injection operation is provided or not and whether an exhaust throttling operation is further provided or, if the expansion flow injection operation is not provided.

In the above-described embodiment, fuel for heating the particulate filter is supplied using the secondary fuel injection for the purpose of reactivating the particulate filter. However, an additional fuel injection valve is provided in the exhaust system upstream of the particle filter 16 , and the heating fuel can be supplied by means of this additional fuel injection valve. Furthermore, in this exemplary embodiment, an opening degree of the exhaust gas throttle valve 26 can be controlled, so that the exhaust gas flow rate flowing into the particle filter 16 is controlled. However, the flow rate can also be controlled by controlling the degree of opening of the intake air throttle valve 10 disposed in the engine air intake passage.

Furthermore, the inevitable reactivation method of the particle filter 16 includes the arrangement of an electrical heating device on the particle filter 16 for direct heating of the particle filter 16 ; the use of a burner; the change in the fuel ratio of the air-fuel mixture for combustion in the combustion chamber of the engine towards the "rich" side to a greater extent than during normal operation; or the delay in the ignition period in spark-ignited internal combustion engines to a greater extent than in normal operation.

Claims (14)

1. Exhaust emission control device for an internal combustion engine ( 1 ) with a particle filter ( 16 ) arranged in an engine exhaust system ( 14 , 15 ) of the machine for collecting particles contained in an exhaust gas,
marked by
a plurality of reactivation devices for reactivating the particle filter ( 16 ), wherein
at least one of the plurality of reactivation devices is selected on the basis of an operating state of the machine ( 1 ), so that the particle filter ( 16 ) is reactivated by means of the selected reactivation device. 2. Exhaust emission control device according to claim 1, characterized in that the selected reactivation device is determined on the basis of a history of the operating state of the machine ( 1 ). 3. Exhaust emission control device according to claim 1, characterized in that
the operating state of the machine ( 1 ) is divided into a plurality of areas (I, II, III, IV), the reactivation device being assigned separately for each of the operating areas, and
the particle filter ( 16 ) is reactivated when an operating state of the machine belongs to an area to which the selected reactivation device is assigned. 4. Exhaust emission control device according to claim 1, characterized in that the multitude of Reactivation features related to Have energy efficiency and temperature increase that are different from each other. 5. Exhaust emission control device according to claim 1, characterized in that
an operating state of the machine ( 1 ) is divided into a plurality of areas (I, II, III, IV, V),
at least one area is selected from the plurality of areas based on a history of an operating state of the machine, and
the particle filter ( 16 ) is reactivated when an operating state of the machine belongs to the selected area. 6. Exhaust emission control device according to claim 5, characterized by a device for determining a particle quantity (SP) accumulated in the particle filter ( 16 ), the particle filter ( 16 ) being reactivated when the particle quantity (SP) is greater than a predetermined quantity (SPU) is. 7. The exhaust emission control device according to claim 6. characterized in that the predetermined amount in Depends on the selected area or the selected reactivation device is changed. 8. Exhaust emission control device according to claim 1, characterized in that the plurality of reactivation devices comprises:
delay reactivation means for delaying the main fuel injection period more than normal operation, and
a secondary injection EGR reactivation device for performing a secondary fuel injection in an engine expansion process or an exhaust gas operation and increasing an amount of EGR gas to a greater extent compared to the normal operation, wherein
the particulate filter ( 16 ) is reactivated by the delay reactivation device when an engine load is greater than a predetermined load, and
the particulate filter ( 16 ) is reactivated using the secondary injection EGR reactivation device when the engine load is lower than the predetermined load. 9. The exhaust gas emission control device according to claim 1, further characterized by an exhaust gas flow rate control device for controlling a flow rate of an exhaust gas flowing into the particle filter ( 16 ), the plurality of reactivation devices comprising:
a secondary EGR reactivation device for performing a secondary fuel injection in an engine expansion process and an exhaust gas operation and increasing an amount of EGR gas to a greater extent compared to normal operation, and
a secondary injection exhaust gas amount reactivation device for performing a secondary fuel injection in an engine expansion process or an exhaust gas operation and reducing an exhaust gas flow rate flowing into the particle filter to a greater extent compared to normal operation, wherein
the particulate filter ( 16 ) is reactivated by the secondary injection EGR reactivation device when an engine load is higher than a predetermined load, and
the particulate filter ( 16 ) is reactivated by the secondary injection exhaust gas amount reactivation device when the engine load is lower than the predetermined load. 10. The exhaust emission control device according to claim 1, further characterized by
a temperature detection device ( 40 a) for detecting a temperature of a particle filter, and
a reactivation control device for carrying out a reactivation operation of the particle filter ( 16 ) when an internal combustion engine ( 1 ) is operated in a predetermined operating range, wherein
the reactivation control device continues the reactivation operation in the event that a temperature of the particle filter ( 16 ) fulfills predetermined temperature conditions if an operating state of the internal combustion engine lies outside the operating range during the particle reactivation. 11. The exhaust emission control device according to claim 1, wherein the plurality of reactivation devices raise an engine exhaust temperature by at least one operation from the following group of possibilities:
an exhaust gas throttling operation for reducing an exhaust gas flow rate by actuating an exhaust gas throttle valve ( 26 ) arranged in a machine exhaust gas system ( 18 ),
an expansion drain injection operation for performing a fuel injection during an expansion drain of a right-angle air cylinder of a machine,
EGR control operation for recirculating part of the exhaust gas of the engine exhaust system to an exhaust system, and
a main fuel injection control operation for changing the main fuel injection amount and injection period for each air cylinder of the engine, wherein
each of the operation variables such as the expansion drain fuel injection amount, the expansion drain fuel injection drain, the recirculating exhaust gas flow rate, the main fuel injection amount, and the main fuel injection period are determined based on a first relationship, the relationship being predetermined depending on the engine operating condition when the exhaust throttling operation is performed, and
each operation variable is determined based on a second relationship that is predetermined depending on the engine operating condition and that is different from the first relationship when the exhaust throttle operation is not performed. 12. The exhaust emission control device according to claim 11. characterized in that the circulating again Exhaust gas flow rate is increased to a greater extent Compared to the case that the Expansion drain injection operation not performed when an EGR control operation is implemented while performing the Expansion drain injection operation. 13. The exhaust emission control device according to claim 11. characterized in that the EGR operation is ended, when both the expansion drain injection operation and the exhaust gas throttling operation are also provided. 14. The exhaust emission control device according to claim 11, characterized in that the target intake air amount is set based on the engine operating state depending on whether the expansion drain injection operation is provided or not and whether the exhaust gas throttling operation is provided or not, and
at least one of the degrees of opening of an intake air throttle valve ( 10 ) arranged in an engine intake air duct and the EGR engine intake air amount is controlled, whereby the engine intake air amount is controlled to a desired intake air amount.