CN104806327A - Exhaust purification system of internal combustion engine - Google Patents

Abstract

An exhaust purification system of an internal combustion engine comprises a selective reduction type catalyst, a low-pressure EGR (Exhaust Gas Recirculation) mechanism, a supply device and a control unit; the selective reduction type catalyst is arranged in an exhaust channel of the internal combustion engine; the low-pressure EGR mechanism comprises a low-pressure EGR channel and a low-pressure EGR valve; the low-pressure EGR channel is used for serving part of the exhaust flowing in an exhaust channel close to the downstream position in comparison with a turbine of a centrifugal supercharger as the low-pressure EGR gas to be guided into an air inlet channel close to the upstream position in comparison with a compressor; the low-pressure EGR valve is used for changing the channel cross-sectional area of the low-pressure EGR channel; the supply device is used for supplying source compounds of ammonia for the selective reduction type catalyst; the control unit is used for controlling the supply device to supply the source compounds of the ammonia; the supply device can be used for supplying the source compounds of the ammonia for the inside of an exhaust channel of the upstream position of the connecting position of the low-pressure EGR channel. When the low-pressure EGR valve is located in the opened state, the condensed water and gasified matter of the condensed water in a path of the low-pressure EGR gas are neutralized through the source compounds of the ammonia due to the control unit, wherein the source compounds of the ammonia are supplied by the supply device.

Description

The emission control system of internal-combustion engine

The present invention is the divisional application proposed based on the Chinese patent application of the emission control system of application number 200980162798.7, December 8 2009 applying date, denomination of invention internal-combustion engine.

Technical field

The present invention relates to the emission control system of internal-combustion engine, particularly relate to the technology of the corrosion suppressing the parts of air intake system caused by EGR gas.

Background technique

In recent years, there will be a known the low pressure EGR apparatus (LPL-EGR device) in the air inlet of the upstream of a part for the exhaust of the downstream flow of the turbine at centrifugal supercharger importing compressor.In the internal-combustion engine with LPL-EGR device, if the condensed water be present in the path of EGR gas touches EGR gas, then the hydrogen ion exponent (pH) of condensed water declines (Strong oxdiative) sometimes.

Its result, likely above-mentioned condensed water, the vapour of condensed water bring chemical change to the parts such as compressor, interstage cooler.Being directed to this, proposing in the inlet air pathway of swimming on the compressor the technology of the interpolation valve arranged for adding neutralizer (for example, referring to patent documentation 1.)。

Patent documentation 1: Japanese Unexamined Patent Publication 2008-144633 publication

Patent documentation 2: Japanese Unexamined Patent Publication 09-324706 publication

Patent documentation 3: Japanese Unexamined Patent Publication 2009-92005 publication

Patent documentation 4: Japanese Unexamined Patent Publication 2009-85011 publication

Patent documentation 5: Japanese Unexamined Patent Publication 11-82182 publication

Summary of the invention

But, according to above-mentioned prior art, need the new neutralizer that adds to add valve, likely cause the reduction of the increase of parts number of packages, vehicle-mounted property.

The present invention completes in view of above-mentioned actual conditions, the object of the invention is to, provide a kind of can the technology of chemical change of the parts of increase restraint measure in the path of EGR gas of one side suppression component number of packages in the emission control system of internal-combustion engine with low pressure EGR apparatus.

In order to solve the above problems, the present invention have the turbine from centrifugal supercharger downstream inlet air pathway from exhaust passageway to the upstream of compressor import exhaust a part (low pressure EGR gas) low pressure EGR mechanism internal-combustion engine emission control system, use be used for selective reduction type catalyzer supply ammonia derived compound supplier and to low pressure EGR gas path supply ammonia derived compound.

In detail, the emission control system of internal-combustion engine of the present invention comprises:

Selective reduction type catalyzer, it is arranged on the exhaust passageway of internal-combustion engine;

Low pressure EGR mechanism, it has: exhaust passage, a part for the exhaust of flowing in the exhaust passageway downstream of the turbine than centrifugal supercharger is imported as low pressure EGR gas to than compressor inlet air pathway by the upstream; And low pressure EGR valve, the passage sections changing described exhaust passage is amassed;

Supplier, it is the device for the derived compound to described selective reduction type catalyzer supply ammonia, and being configured to can to than the derived compound supplying ammonia in the connection part of described exhaust passage exhaust passageway by the upstream; And

Control unit, it makes described supplier supply the derived compound of ammonia when described low pressure EGR valve is in open mode.

According to this invention, be supplied to inlet air pathway from a part for the derived compound of the ammonia of supplier supply through exhaust passage.Therefore, the derived compound of ammonia is utilized to neutralize the acidic materials (such as the vapour of condensed water, condensed water) in the path (such as exhaust passage, inlet air pathway, compressor, interstage cooler etc.) being present in low pressure EGR gas.

And, supply device, uses the existing device arranged in order to the derived compound of the ammonia as reducing agent is supplied to selective reduction type catalyzer, therefore, can the increase of one side suppression component number of packages, one side suppresses the chemical change of the parts be present in EGR gas path.

The emission control system of internal-combustion engine of the present invention still can comprise acquisition unit, and described acquisition unit obtains the value relevant to the amount of the acidic materials existed in the path of low pressure EGR gas.In this case, control unit is when many by the amount acquired by acquisition unit, many when making the delivery volume of the derived compound of ammonia make a gesture of measuring few.

When adjusting the delivery volume of derived compound of ammonia as described so, the acidic materials be present in low pressure EGR gas path can be neutralized more reliably.Control unit also can make the hydrogen ion exponent of the acidic materials be present in the path of low pressure EGR gas (pH) lower and make the delivery volume of the derived compound of ammonia more.

The emission control system of the internal-combustion engine that the present invention relates to still can comprise the detection unit of the temperature detecting low pressure EGR gas.In this case, control unit can in the temperature detected by detection unit higher than making the delivery volume of the derived compound of ammonia than lower than many during predetermined reference temperature during predetermined reference temperature.Reference temperature mentioned here is such as the lower limit of the temperature field that the derived compound of ammonia can be hydrolyzed.

When the derived compound of ammonia is hydrolyzed, generate as ammonia (NH ₃) compound that like that acid neutralization capacity is high.Therefore, if correspondingly adjust the delivery volume of the derived compound of ammonia with the temperature of low pressure EGR gas, then the derived compound of the ammonia of volume is not supplied when acid neutralization capacity is low.Thus, the consumption of the derived compound of ammonia can be avoided invalidly to increase.

In addition, control unit also can be stopped (stopping the supply of the derived compound of ammonia) lower than making the work of supplier during described reference temperature in the temperature detected by detection unit.In this case, the consumption of the derived compound of ammonia can be suppressed to inferior limit.

The emission control system of the internal-combustion engine that the present invention relates to still can comprise the heating unit of heating low pressure EGR gas.In this case, control unit can make heating unit work when supplying the derived compound of ammonia from supplier.The derived compound of ammonia makes heating unit work in this wise, even if then also can be made to be hydrolyzed when delivery temperature is low.Its result, the chance that neutralization is present in the acidic materials in the path of low pressure EGR gas increases.

When selective reduction type catalyzer is configured in the exhaust passageway of the upstream of the connection part of exhaust passage, heating unit can heat selective reduction type catalyzer, or also can heat the exhaust flowed into before selective reduction type catalyzer.

According to this heating means, except the derived compound of ammonia supplied from supplier, selective reduction type catalyzer can also be heated.Selective reduction type catalyzer has the characteristic of the derived compound being difficult to adsorb ammonia when being exposed in high temperature.

Therefore, if when the derived compound of supplier supply ammonia, heating selective reduction type catalyzer, then from the derived compound of the ammonia of supplier supply roughly all by selective reduction type catalyzer.Its result, easily adjustment flows into the amount of the derived compound of the ammonia of low pressure EGR gas path.

But, also have the situation being adsorbed with the derived compound of ammonia at the moment selective reduction type catalyzer of the derived compound of the path supply ammonia to low pressure EGR gas.If in this case, heating unit heats selective reduction type catalyzer directly or indirectly, then except the derived compound of ammonia supplied from supplier, be also imported into the path of low pressure EGR gas from the derived compound of the ammonia of selective reduction type catalyzer release.Its result, the amount being imported into the derived compound of the ammonia in the path of low pressure EGR gas when heating selective reduction type catalyzer becomes many than when not heating selective reduction type catalyzer.

Therefore, preferably the amount after the amount of the derived compound deducting the ammonia that selective reduction type Catalyst Adsorption is set to from the amount of the derived compound of the ammonia of supplier supply.In this case, the derived compound of the ammonia imported in the path of low pressure EGR gas can be avoided too much, and the amount of the derived compound of the ammonia supplied from supplier can be suppressed to necessary inferior limit.The bed temperature (bed temperature) etc. of the delivery volume of the derived compound of ammonia, selective reduction type catalyzer can be carried out computing as parameter by the amount of the derived compound of the ammonia that selective reduction type catalyzer has adsorbed.

At this, as heating unit, the heater converting electrical energy into heat energy can be used.But, do not have in the system of heater, the derived compound of ammonia can also heated by the following method: make the method that the aperture of intake-air throttle valve reduces; Make the method that the aperture of exhaust shutter reduces; Make the method for the capacity expansion of variable-geometry turbocharger (increasing the aperture of stator blade); Make the method that EGR gas flow increases; Make the method etc. that the ignition timing of the fuel in internal-combustion engine is delayed.

In addition, be configured in the structure in the exhaust passageway of the upstream of the connection part of low pressure EGR gas path at selective reduction type catalyzer, selected reduction catalyst to be hydrolyzed from the derived compound of the ammonia of supplier supply.Therefore, be configured in the structure of the upstream of the connection part of exhaust passage at selective reduction type catalyzer, above-mentioned such heating unit can not be set.

But, do not have in the structure of heating unit, likely selected reduction catalyst to adsorb from the derived compound of the ammonia of supplier supply.Therefore, when the derived compound of the path supply ammonia to low pressure EGR gas, the derived compound of the ammonia needing supply more than the amount of the derived compound of the adsorbable ammonia of selective reduction type catalyzer

Therefore, when needing the derived compound to the path supply ammonia of low pressure EGR gas, control unit can make the derived compound of the ammonia more than the amount of the derived compound of the adsorbable ammonia of selective reduction type catalyzer supply from supplier.

In the emission control system of internal-combustion engine of the present invention, selective reduction type catalyzer also can be configured in the exhaust passageway in the downstream of the connection part of exhaust passage.In this case, because selective reduction type catalyzer becomes the resistance of exhaust, so the exhaust pressure of the upstream of selective reduction type catalyzer uprises.Therefore, it is possible to do not make the aperture of exhaust shutter reduce significantly and to exhaust passage supply ammonia derived compound.Its result, the back pressure acting on internal-combustion engine can not be made to improve significantly and in and low pressure EGR gas path in acidic materials.

Configure in the structure of selective reduction type catalyzer in the exhaust passageway in the downstream of the connection part of exhaust passage, when the upstream of the connection part at exhaust passage also configures catalyzer (such as oxidation catalyst etc.), the pressure loss of this catalyzer is preferably made to be less than the pressure loss of selective reduction type catalyzer.

In addition, be configured in the structure in the exhaust passageway in the downstream of the connection part of exhaust passage at selective reduction type catalyzer, when being provided with the dispersion plate of the derived compound dispersion for making the ammonia from supplier supply in exhaust passageway, this dispersion plate can be configured in the exhaust passageway in the downstream of the connection part of exhaust passage.

In this case, the pressure loss of selective reduction type catalyzer and the pressure loss of dispersion plate can be utilized and improve the exhaust pressure at the connection part place of exhaust passage.Its result, more easily flows into exhaust passage from the derived compound of the ammonia of supplier supply.

Be configured in the structure in the exhaust passageway in the downstream of the connection part of exhaust passage at selective reduction type catalyzer, when the low-pressure EGR gas amount that control unit can flow in described exhaust passage is many, many when making to make a gesture of measuring few from the derived compound of the ammonia of supplier supply.

Compared with time few with amount when the amount of low pressure EGR gas is many, the amount flowing into the derived compound of the ammonia of exhaust passage is many, and the amount flowing into the derived compound of the ammonia of selective reduction type catalyzer is few.Therefore, the derived compound being likely supplied to the ammonia of selective reduction type catalyzer is not enough.

Be directed to this, if supply than the ammonia (NH many when measuring few from supplier when low-pressure EGR gas amount is many ₃), then can avoid the situation of the derived compound deficiency of the ammonia being supplied to selective reduction type catalyzer.Its result, the purifying ability of selective reduction type catalyzer can not be made to reduce make to be present in acidic materials neutralization in the path of low pressure EGR gas.

When applying internal-combustion engine of the present invention and having low pressure EGR mechanism and high pressure EGR mechanism, the emission control system of internal-combustion engine of the present invention also can comprise the arithmetic element of the amount of the derived compound calculating the ammonia flowed in exhaust passage.In this case, control unit can correspondingly revise the flow-rate ratio of low pressure EGR gas and high pressure EGR gas with the operation result of arithmetic element.High pressure EGR mechanism mentioned here is following mechanism, comprise: high pressure EGR passage, for a part for the exhaust of flowing in than the turbine of centrifugal supercharger exhaust passageway by the upstream is imported as high pressure EGR gas to than compressor inlet air pathway downstream; The high pressure EGR valve long-pending with the passage sections changing described high pressure EGR passage.

According to this structure, when the operation result of arithmetic element is less than aim parameter, control unit passes through the aperture of low pressure EGR valve to opening side correction, and the aperture of high pressure EGR valve is revised to closedown side, the EGR gas flow of importing internal-combustion engine (total amount of low pressure EGR and high pressure EGR) can not be made to change and low-pressure EGR gas amount is increased.Its result, can make the amount of the derived compound of the ammonia flowed in exhaust passage be increased to desired value.

On the other hand, when the operation result of arithmetic element is more than aim parameter, control unit by the aperture of low pressure EGR valve being revised to closedown side, and by the aperture of high pressure EGR valve to opening side correction, can not change the EGR gas flow of importing internal-combustion engine and low-pressure EGR gas amount is reduced.Its result, can make the amount of the derived compound of the ammonia flowed in exhaust passage reduce to desired value.

When the DECEL ENLEAN of internal-combustion engine controls to perform, control unit of the present invention also can be implemented that low pressure EGR valve is opened, supply process from the process of the derived compound of supplier supply ammonia.In this case, the combustion regime of internal-combustion engine can not be had influence on and adjust low-pressure EGR gas amount.Therefore, also can not have influence on the combustion regime of internal-combustion engine and adjust the amount of the derived compound of the ammonia flowed in exhaust passage.

During the supply process stated on the implementation, control unit can make the downstream of the connection part being arranged on exhaust passage and exhaust shutter in the exhaust passageway in the downstream of selective reduction type catalyzer is closed.In this case, exhaust passage is flowed to from the derived compound whole amount of the ammonia of supplier supply.Its result, can utilize the derived compound of minimum ammonia that acidic materials are neutralized.And then, the derived compound of ammonia can also be suppressed to be released in air.

In addition, control unit can make when DECEL ENLEAN control terminate after scheduled period import inlet air pathway low-pressure EGR gas amount when implement described supply process than do not implement supply process few.

When not implementing above-mentioned supply process, filled up by air in the path of low pressure EGR gas.In contrast, when implementing above-mentioned supply process, filled up by low pressure EGR gas in the path of low pressure EGR gas.

Therefore, if when implementing above-mentioned supply process, DECEL ENLEAN controls the low-pressure EGR gas amount after terminating and does not implement to supply situation about processing to measure together, then the amount of oxygen likely importing internal-combustion engine is very few.

Thus, if when DECEL ENLEAN control terminate after scheduled period in low-pressure EGR gas amount when implement described supply process than do not implement supply process few, then can avoid importing internal-combustion engine amount of oxygen very few.

The above-mentioned scheduled period be equivalent to low pressure EGR gas in the inlet air pathway in the downstream of the connection part being present in exhaust passage required for new gas (air) removing during (be in other words the downstream of the connection part of exhaust passage inlet air pathway in oxygen concentration rise to needed for predetermined concentration during).The low pressure EGR gas be present in inlet air pathway be removed required during the volume in the path from the connection part of exhaust passage to internal-combustion engine and internal-combustion engine rotational speed (being in other words the gas flow that combustion engine per unit time enters) can be calculated as parameter.

But, after the above-mentioned scheduled period, need to make low-pressure EGR gas amount be increased to amount commonly (not implementing target low-pressure EGR gas flow when above-mentioned supply process), but from exhaust passageway be taken into exhaust passage low pressure EGR gas arrive internal-combustion engine need some times (transportation lag of low pressure EGR gas).Therefore, likely after the scheduled period, the low pressure EGR gas quantity not sufficient of internal-combustion engine is being imported.

Therefore, the emission control system of the internal-combustion engine that the present invention relates to can by the aperture of the high pressure EGR valve after the scheduled period to opening side correction (being greater than the aperture not implementing above-mentioned supply process).

Path due to high pressure EGR gas is shorter than the path of low pressure EGR gas, so the high pressure EGR gas being taken into high pressure EGR passage from exhaust passageway arrives internal-combustion engine early than low pressure EGR gas.Therefore, if by the aperture of the high pressure EGR valve after the scheduled period to opening side correction, then high pressure EGR gas can be utilized to carry out the in shortage of supplementary low pressure EGR gas.

According to the present invention, in the emission control system of internal-combustion engine with low pressure EGR apparatus, can the chemical change of the parts of increase restraint measure in the path of EGR gas of one side suppression component number of packages.

Accompanying drawing explanation

Fig. 1 is the figure of the schematic configuration of the emission control system of the internal-combustion engine represented in the first embodiment.

Fig. 2 is the flow chart of the sour neutralisation treatment program represented in the first embodiment.

Fig. 3 is the figure of the schematic configuration of the emission control system of the internal-combustion engine represented in the second embodiment.

Fig. 4 is the flow chart of the sour neutralisation treatment program represented in the 3rd embodiment.

Fig. 5 is the figure of other structure example of the emission control system of the internal-combustion engine represented in the 3rd embodiment.

Fig. 6 is the figure of the schematic configuration of the emission control system of the internal-combustion engine represented in the 4th embodiment.

Fig. 7 is the flow chart of the sour neutralisation treatment program represented in the 4th embodiment.

Fig. 8 is the figure representing the ammonia saturation capacity of selective reduction type catalyzer and the relation of bed temperature.

Fig. 9 is the flow chart of the sour neutralisation treatment program represented in the 5th embodiment.

Figure 10 is the figure of the schematic configuration of the emission control system of the internal-combustion engine represented in the 6th embodiment.

Figure 11 is the figure representing the bed temperature of selective reduction type catalyzer when performing sour neutralisation treatment in the sixth embodiment and the change of ammonia extent of adsorption.

Figure 12 is the flow chart of the sour neutralisation treatment program represented in the 6th embodiment.

Figure 13 is the flow chart of the sour neutralisation treatment program represented in the 7th embodiment.

Figure 14 is the flow chart of the sour neutralisation treatment program represented in the 8th embodiment.

Figure 15 is the flow chart representing the subroutine that ECU performs in sour neutralisation treatment performs or before performing in the 9th embodiment.

Figure 16 is the first figure of other examples of the subroutine represented in the 9th embodiment.

Figure 17 is the second figure of other examples of the subroutine represented in the 9th embodiment.

Embodiment

Below, with reference to the accompanying drawings the specific embodiment of the present invention is described.The size, material, shape, relative configuration etc. of the structure member recorded in present embodiment unless there are special record, otherwise are not just the meanings technical scope of invention being only defined as these.

< embodiment 1 >

First, according to Fig. 1, Fig. 2, the first embodiment of the present invention is described.Fig. 1 is the figure of the schematic configuration of the emission control system of the internal-combustion engine represented in the present embodiment.

Internal-combustion engine 1 shown in Fig. 1 is the compression-ignition internal combustion engine (diesel engine) of the vehicle traction with 4 cylinders 2.Each cylinder 2 of internal-combustion engine 1 is provided with the Fuelinjection nozzle 3 to this cylinder 2 inner direct fuel.

Internal-combustion engine 1 is connected with intake manifold 5 and gas exhaust manifold 7.Intake manifold 5 is connected with inlet air pathway 4.Gas exhaust manifold 7 is connected with exhaust passageway 6.The compressor 8a of centrifugal supercharger (turbosupercharger) 8 is provided with at inlet air pathway 4.The turbine 8b of turbosupercharger 8 is provided with at exhaust passageway 6.

The downstream side of the compressor 8a in inlet air pathway 4 is provided with first segment valve 9.The upstream side of the compressor 8a in inlet air pathway 4 is provided with second section valve 19.The downstream of the compressor 8a in the inlet air pathway 4 and upstream of first segment valve 9 is provided with interstage cooler 40.

The downstream side of the turbine 8b in exhaust passageway 6, the flow direction along exhaust is configured with oxidation catalyst 23, particulate filter 24, selective reduction type catalyzer 26 and exhaust shutter 27 successively from upstream side.Selective reduction type catalyzer 26 is optionally adsorb ammonia (NH ₃) isopolarity molecule and will absorption ammonia (NH ₃) as reducing agent to nitrogen oxide (NOx) catalyzer that reduces and purify in exhaust.

In the exhaust passageway 6 between particulate filter 24 and selective reduction type catalyzer 26, the interpolation valve 25 for supplying reducing agent to above-mentioned selective reduction type catalyzer 26 is installed.As from the reducing agent adding valve 25 supply, the derived compound of the ammonia of liquid, gas or solid can be exemplified.In the present embodiment, use aqueous solution of urea as the reducing agent supplied from interpolation valve 25.Add the mode of execution that valve 25 is the supplieies that the present invention relates to.

Above-mentioned interpolation valve 25 adds aqueous solution of urea when selective reduction type catalyzer 26 is in activated state in exhaust passageway 6.The aqueous solution of urea be added in exhaust passageway 6 is generated ammonia (NH by pyrolysis and hydrolysis in exhaust or in selective reduction type catalyzer 26 ₃).Ammonia (NH generated like this ₃) be adsorbed on selective reduction type catalyzer 26 and the nitrogen oxide (NOx) in exhaust is reduced.Add aqueous solution of urea by interpolation valve 25 to be set to and to implement with the predetermined cycle.

Pressure EGR device 11 and low pressure EGR apparatus 15 is provided with in the air inlet system and exhaust system of internal-combustion engine 1.Pressure EGR device 11 comprises high pressure EGR passage 12, high pressure EGR valve 13 and high pressure cooler for recycled exhaust gas 14.One end of high pressure EGR passage 12 is connected to gas exhaust manifold 7, and its other end is connected to the downstream side of the first segment valve 9 in inlet air pathway 4.

High pressure EGR valve 13 and high pressure cooler for recycled exhaust gas 14 are arranged on high pressure EGR passage 12.The flow of the high pressure EGR gas importing inlet air pathway 4 from gas exhaust manifold 7 through high pressure EGR passage 12 is controlled by high pressure EGR valve 13.

Low pressure EGR apparatus 15 comprises exhaust passage 16, low pressure EGR valve 17 and low pressure EGR cooler 18.One end of exhaust passage 16 is connected to the downstream side of the interpolation valve 25 in exhaust passageway 6 and the upstream side of selective reduction type catalyzer 26, and its other end is connected to the downstream side of the second section valve 19 in inlet air pathway 4 and the upstream side of compressor 8a.

Low pressure EGR valve 17 and low pressure EGR cooler 18 are arranged on exhaust passage 16.The flow of the low pressure EGR gas importing inlet air pathway 4 from exhaust passageway 6 through exhaust passage 16 is controlled by low pressure EGR valve 17.

Electronic control unit (ECU) 20 is provided with in the internal-combustion engine 1 formed as described above.The various sensors such as crankshaft position sensor 21, throttle position switch 22 and exhaust gas temperature sensor 28 are electrically connected with at ECU20.Crankshaft position sensor 21 is sensors of the pivotal position of the output shaft (bent axle) detecting internal-combustion engine 1.Throttle position switch 22 is the sensors of the operation amount (accelerator open degree) detecting gas pedal.Exhaust gas temperature sensor 28 is the sensors of the temperature detecting the exhaust of flowing in exhaust passageway.In the example depicted in figure 1, exhaust gas temperature sensor 28 is configured in particulate filter 24 and adds in the exhaust passageway 6 between valve 25, but also can be configured in the exhaust passageway 6 of the upstream of oxidation catalyst 23, adds in the exhaust passageway 6 in the downstream of valve 25 or in the exhaust passageway 6 in the downstream of selective reduction type catalyzer 26.

In addition, be electrically connected with Fuelinjection nozzle 3, first segment valve 9, second section valve 19 at ECU20, add the various equipment such as valve 25, high pressure EGR valve 13, low pressure EGR valve 17, exhaust shutter 27.ECU20 controls various equipment according to the testing signal of above-mentioned various sensors.

Such as, ECU20, when internal-combustion engine 1 is in running state, carries out the process (hereinafter referred to as " reducing agent adds process ") being supplied to selective reduction type catalyzer 26 as the aqueous solution of urea of reducing agent by periodically making interpolation valve 25 open.Further, ECU20, when low pressure EGR valve 17 is in open mode, opens the process (hereinafter referred to as " sour neutralisation treatment ") carrying out neutralizing the acidic materials be present in the path of low pressure EGR gas by making interpolation valve 25.

Below, the manner of execution of the sour neutralisation treatment in the present embodiment is described.

In the path of low pressure EGR gas, sometimes accumulate condensed water.Sometimes condensed water touches low pressure EGR gas, and the hydrogen ion exponent (pH) of condensed water reduces (Strong oxdiative).If the vapour (acidic materials) of the condensed water that hydrogen ion exponent (pH) is low, condensed water and low pressure EGR gas together flow into compressor 8a, interstage cooler 40 etc., then likely chemical change is brought to compressor 8a, interstage cooler 40.

Be directed to this, add valve 25 if open when low pressure EGR valve 17 opens, then add the part inflow exhaust passage 16 of the aqueous solution of urea exhaust from interpolation valve 25 to.Ammonia (NH is generated by pyrolysis and hydrolysis when aqueous solution of urea is in the exhaust being exposed to high temperature ₃).Ammonia (NH ₃) play a role as the neutralizer of acidic materials.Therefore, as ammonia (NH ₃) when flowing in the path (inlet air pathway 4, compressor 8a and interstage cooler 40) of low pressure EGR gas, be present in acidic materials in the path of low pressure EGR gas by ammonia (NH ₃) neutralization.Its result, can suppress the chemical change of compressor 8a, interstage cooler 40 etc.

And, in the emission control system of the internal-combustion engine of the present embodiment, because selective reduction type catalyzer 26 is configured in the exhaust passageway 6 in the downstream of the connection part of exhaust passage 16, so the exhaust pressure of the upstream extremity of exhaust passage 16 (attachment portion of exhaust passage 16 and exhaust passageway 6) uprises.If the exhaust pressure of the upstream extremity of exhaust passage 16 uprises, then exhaust easily flows to exhaust passage 16 from exhaust passageway 6.Therefore, when low pressure EGR valve 17 is opened, do not need the aperture reducing exhaust shutter 27 significantly.Its result, can rise back pressure when opening low pressure EGR valve 17 and be suppressed to inferior limit.

Then, the execution sequence of the sour neutralisation treatment in the present embodiment is described according to Fig. 2.Fig. 2 is the flow chart representing the control program that ECU20 performs when implementing sour neutralisation treatment.This control program is pre-stored in ROM of ECU20 etc., is periodically performed by ECU20.

In the control program of Fig. 2, first ECU20 performs the process of S101.In S101, ECU20 differentiates whether low pressure EGR valve 17 is in open mode.When being judged as "No" in S101, ECU20 enters S103.In S103, ECU20 controls to add valve 25 as usual.That is, aqueous solution of urea is supplied to selective reduction type catalyzer 26 by making interpolation valve 25 open with predetermined predetermined interval by ECU20.

On the other hand, when being judged as "Yes" in above-mentioned S101, ECU20 enters S102.In S102, ECU20 makes interpolation valve 25 open.Performed the process of S102 by such ECU20, realize the control unit that the present invention relates to.

When performing the process of above-mentioned S102, from add a part that valve 25 adds aqueous solution of urea exhaust on one side by pyrolysis and hydrolysis while flow in exhaust passage 16, remaining aqueous solution of urea by pyrolysis be hydrolyzed while be fed into selective reduction type catalyzer 26.

Flow into the ammonia (NH of exhaust passage 16 ₃) acidic materials be present in the path of low pressure EGR gas are neutralized.Its result, can avoid being configured in the compressor 8a in the path of low pressure EGR gas, interstage cooler 40 contacts with acidic materials and chemical change occurs.

According to the above embodiment described, can suppress to be configured in the chemical change of the equipment in the path of low pressure EGR gas, parts.Further, the interpolation valve 25 for supplying reducing agent to selective reduction type catalyzer 26 can be used as the supplier for supplying neutralizer to the path of low pressure EGR gas, therefore do not need additional new parts.

Thus, can the increase of one side suppression component number of packages, one side suppresses the chemical change of the parts be configured in the path of low pressure EGR gas.

In the present embodiment, describe and add with reducing agent the example processing and separate and implement sour neutralisation treatment, but also reducing agent interpolation process can be made to double as sour neutralisation treatment by allowing the enforcement reducing agent interpolation process when low pressure EGR valve 17 is opened.According to the method, owing to not needing to add with reducing agent to process to separate to implement sour neutralisation treatment, so the simplification of control logic can be sought.

But, if implement reducing agent to add process when low pressure EGR valve 17 is opened, then because a part for reducing agent flows in exhaust passage 16, so the reducing agent being likely supplied to selective reduction type catalyzer 26 is not enough.Therefore, when can implement reducing agent interpolation process when low pressure EGR valve 17 is opened, the adding quantity of reducing agent is increased than enforcement reducing agent adds and processes when low pressure EGR valve 17 is closed.

In addition, in the present embodiment, describe and low pressure EGR valve 17 be in open mode implements sour neutralisation treatment example as condition, but also can be in except open mode except low pressure EGR valve 17, also using the temperature of low pressure EGR gas be that more than reference temperature implements sour neutralisation treatment as condition.Reference temperature mentioned here refers to aqueous solution of urea by equal or slightly higher than the above-mentioned lower limit temperature of the lower limit of the temperature field of pyrolysis and hydrolysis.

When implementing sour neutralisation treatment according to this condition, material (ammonia (NH that can be high using the ability as neutralizer ₃)) be supplied in the path of low pressure EGR gas.Therefore, it is possible to make the acidic materials neutralization be present in the path of low pressure EGR gas more reliably.In addition, the temperature of detected signal value as low pressure EGR gas of exhaust gas temperature sensor 28 can be used.

In addition, in the present embodiment, describe the example periodically implementing sour neutralisation treatment, but also can become below predetermined value for triggering (ト リ ガ) enforcement with the hydrogen ion exponent (pH) being present in the material in the path of low pressure EGR gas.Above-mentioned predetermined value is the value determined according to considering the parts such as compressor 8a, interstage cooler 40 to cause the maximum value of the hydrogen ion exponent of chemical change (pH), such as, be confirmed as the value slightly larger than above-mentioned maximum value.

As the method for hydrogen ion exponent (pH) obtaining the material be present in the path of low pressure EGR gas, the method of the position configuration pH sensor of the easy accumulation condensed water in the path of low pressure EGR gas can be exemplified, according to the operation resume (internal-combustion engine rotational speed of internal-combustion engine 1, fuel injection amount, the aggregate-value of low-pressure EGR gas amount etc.) be the mapping (map) of independent variable, the method that operational model is obtained, according to being the mapping of independent variable with the temperature in the cumulative amount of the nitrogen oxide (NOx) in the path flowing into low pressure EGR gas and low pressure EGR gas path, the method etc. that operational model is obtained.

On the other hand, also can exceed predetermined threshold value with the amount being present in the acidic materials in the path of low pressure EGR gas and implement sour neutralisation treatment for triggering.As the method for amount obtaining the acidic materials be present in the path of low pressure EGR gas, the method that the mapping that can to exemplify according to the temperature in the path of the mapping being independent variable with the operation resume of internal-combustion engine 1 (cumulative amounts of internal-combustion engine rotational speed, fuel injection amount, low pressure EGR gas etc.), method that operational model is obtained, the cumulative amount of nitrogen oxide (NOx) using to flow into exhaust passage 16, low pressure EGR gas etc. be independent variable, operational model are obtained.

< embodiment 2 >

Then, according to Fig. 3, the second embodiment of the present invention is described.At this, the structure different from aforesaid first embodiment is described, to same incomplete structure explanation.

The difference of aforesaid first embodiment and the present embodiment is: in the exhaust passageway 6 of the upstream of selective reduction type catalyzer 26, be provided with the dispersion plate for making from adding aqueous solution of urea that valve 25 supplies and disperseing.

Fig. 3 is the figure of the schematic configuration of the emission control system of the internal-combustion engine represented in the present embodiment.As shown in Figure 3, dispersion plate 29 is configured with in the upstream of selective reduction type catalyzer 26 in the exhaust passageway 6 in the downstream of the connection part of exhaust passage 16.Other structures are identical with aforesaid first embodiment.

In the upstream of selective reduction type catalyzer 26 and when being configured with dispersion plate 29 in the exhaust passageway 6 in the downstream of the connection part of exhaust passage 16, compared with being configured in the situation in the exhaust passageway 6 of the upstream of the connection part of exhaust passage 16 with the situation or dispersion plate 29 that do not arrange dispersion plate 29, the pressure of the upstream extremity of exhaust passage 16 can be improved.

Therefore, when low pressure EGR valve 17 is opened, exhaust (low pressure EGR gas) easily flows into exhaust passage 16 from exhaust passageway 6.Its result, can increase the aperture of the exhaust shutter 27 when low pressure EGR valve 17 is opened.

< embodiment 3 >

Then, according to Fig. 4,5, the third embodiment of the present invention is described.At this, the structure different from aforesaid first embodiment is described, to same incomplete structure explanation.

The difference of aforesaid first embodiment and the present embodiment is: control to implement sour neutralisation treatment when being in executing state in the DECEL ENLEAN of internal-combustion engine 1.

Below, the execution sequence of the sour neutralisation treatment in the present embodiment is described according to Fig. 4.Fig. 4 is the flow chart representing the control program that ECU20 performs when implementing sour neutralisation treatment.This control program is pre-stored in ROM of ECU20 etc., is periodically performed by ECU20.

In the control program of Fig. 4, ECU20 differentiates in S201 the DECEL ENLEAN of internal-combustion engine 1 controls whether to be in execution.When being judged as "No" in S201, ECU20 temporarily terminates this program.And when being judged as "Yes" in S201, ECU20 enters S202.

In S202, ECU20 reads the testing signal (delivery temperature) of exhaust gas temperature sensor 28.Performed the process of S202 by such ECU20, realize the detection unit that the present invention relates to.

Then, ECU20 enters S203, differentiates whether delivery temperature read-out in above-mentioned S202 is more than reference temperature.Reference temperature is can by equal or slightly higher than the above-mentioned lower limit temperature of the lower limit of the temperature range of pyrolysis and hydrolysis with aqueous solution of urea.

When being judged as "No" in above-mentioned S203 (delivery temperature < reference temperature), ECU20 temporarily terminates the execution of this program.And when being judged as "Yes" in above-mentioned S203 (delivery temperature >=reference temperature), ECU20 enters S204.

In S204, ECU20 makes second section valve 19 and exhaust shutter 27 close.Then, ECU20 enters S205, adds the aqueous solution of urea of prearranging quatity from interpolation valve 25.Above-mentioned prearranging quatity is predetermined a certain amount of, is the value determined by utilizing the suitable process of experiment etc. in advance.

In S206, ECU20 differentiates whether the termination condition that DECEL ENLEAN controls is set up.As the termination condition that DECEL ENLEAN controls, can exemplify that internal-combustion engine rotational speed is below predetermined lower limit, the testing signal of throttle position switch 22 (accelerator open degree) is greater than the condition such as zero.

When being judged as "No" in above-mentioned S206, ECU20 performs the process of S206, till the termination condition establishment that DECEL ENLEAN controls.And when being judged as "Yes" in above-mentioned S206, ECU20 enters S207.

In S207, ECU20 makes the aperture of second section valve 19 and exhaust shutter 27 turn back to common aperture.

According to the above embodiment described, owing to all flowing to the path of low pressure EGR gas from the aqueous solution of urea adding valve 25 supply, so easily adjustment is supplied to the amount of the aqueous solution of urea in the path of low pressure EGR gas.Further, can not adsorb ammonia (NH even if be at selective reduction type catalyzer 26 ₃) state under perform sour neutralisation treatment, also can avoid ammonia (NH ₃) be released in air.

When the DECEL ENLEAN of internal-combustion engine 1 controls just in commission, compared with when in internal-combustion engine 1, fuel burns, the temperature step-down of exhaust.Therefore, delivery temperature become more than reference temperature chance, be in other words that the chance implementing sour neutralisation treatment likely reduces.

Therefore, as shown in Figure 5, the downstream of valve 25 can added and the catalyzer 30 of configuration hydrolysis in the exhaust passageway 6 of the upstream of the connection part of exhaust passage 16.In this case, even if when delivery temperature is lower than reference temperature, as long as hydrolyst 30 is in activated state, just sour neutralisation treatment can be implemented.

Hydrolyst also can be configured in exhaust passage 16.But, if configure hydrolyst in exhaust passage 16, then sometimes because the pressure loss of this catalyzer causes exhaust to be difficult to flow into exhaust passage 16 from exhaust passageway 6.In this case, need the aperture reducing exhaust shutter 27, thus the back pressure of internal-combustion engine 1 rises.Therefore, hydrolyst is preferably as the aforementioned configured in as shown in Figure 5 and adds the downstream of valve 25 and in the exhaust passageway 6 of the upstream of exhaust passage 16.

In addition, heating equipment for thermal exhaust also can be set to replace above-mentioned hydrolyst.As heating equipment, the electric heating apparatus converting electrical energy into heat energy can be exemplified.

When performing sour neutralisation treatment as described above, the amount of oxygen likely importing the firing chamber of internal-combustion engine 1 after DECEL ENLEAN control terminates is very few.Further, the carbon dioxide (CO generated due to the hydrolysis of aqueous solution of urea ₂), water (H ₂o) also firing chamber is imported into.Its result, can expect that, after DECEL ENLEAN control just terminates, the combustion stability of internal-combustion engine 1 declines or misfires.

Therefore, it is (following that ECU20 can implement the following processing when performing sour neutralisation treatment when DECEL ENLEAN controls the term of execution, be called " degasification (scavenging) process "): the aperture of the low pressure EGR valve 17 that DECEL ENLEAN was controlled in the scheduled period after terminating is less than target aperture (the target aperture determined by the operating conditions of internal-combustion engine 1), or low pressure EGR valve 17 is closed.

The above-mentioned scheduled period be required till the gas in the inlet air pathway 4 in the downstream of the connection part being present in exhaust passage 16 is eliminated during.The volume in the path of connection part to the firing chamber of internal-combustion engine 1 from exhaust passage 16 and internal-combustion engine rotational speed (gas flow that internal-combustion engine 1 time per unit enters) can be carried out computing as parameter by the scheduled period.

If implement degassing processing as described above, then can avoid after DECEL ENLEAN control terminates, import the firing chamber of internal-combustion engine 1 amount of oxygen deficiency or carbon dioxide (CO ₂), water (H ₂o) amount is too much.Its result, can avoid the situation that the combustion stability of internal-combustion engine 1 after DECEL ENLEAN control terminates declines, situation about misfiring.

After above-mentioned degassing processing terminates, need to make the low-pressure EGR gas amount of the firing chamber of importing internal-combustion engine 1 be increased to aim parameter (aim parameter of the low pressure EGR gas when not implementing sour neutralisation treatment and degassing processing).But the firing chamber arriving internal-combustion engine 1 due to low pressure EGR gas needs some times, so likely import the low pressure EGR gas quantity not sufficient of the firing chamber of internal-combustion engine 1 after degassing processing terminates.When low pressure EGR gas is not enough, the situation likely causing the production of nitrogen oxide (NOx) to increase, combustion noise become large situation.

Be directed to this, the aperture of the high pressure EGR valve 13 after degassing processing can terminate by ECU20 compared with aperture when not performing degassing processing to opening side correction.Reduction value now can be a certain amount of, or also can be the Variable quantity correspondingly changed in shortage with low pressure EGR gas.

In addition, in the present embodiment, describe and DECEL ENLEAN controlled just in commission to implement as condition the example of sour neutralisation treatment, but also DECEL ENLEAN can be controlled just in commission and the hydrogen ion exponent (pH) being present in the material in the path of low pressure EGR gas for implementing sour neutralisation treatment as condition below predetermined value.In this case, necessary inferior limit can be suppressed to by from the amount of adding the aqueous solution of urea that valve 25 supplies.

< embodiment 4 >

Then, according to Fig. 6 to Fig. 8, the fourth embodiment of the present invention is described.At this, the structure different from aforesaid first embodiment is described, to same incomplete structure explanation.

The difference of aforesaid first embodiment and the present embodiment is, configures selective reduction type catalyzer 26 in the exhaust passageway 6 of the upstream of the connection part of exhaust passage 16.

Fig. 6 is the figure of the schematic configuration of the emission control system of the internal-combustion engine represented in the present embodiment.In figure 6, selective reduction type catalyzer 26 is configured in the upstream of the connection part of exhaust passage 16 and adds in the exhaust passageway 6 in the downstream of valve 25.

If be configured at selective reduction type catalyzer 26 in the structure in the exhaust passageway 6 of the upstream of the connection part of exhaust passage 16 and perform sour neutralisation treatment, then from the ammonia (NH adding valve 25 supply ₃) be adsorbed on selective reduction type catalyzer 26.

But, the adsorbable ammonia (NH of selective reduction type catalyzer 26 ₃) amount limited.Therefore, in the sour neutralisation treatment of the present embodiment, ECU20 controls to add valve 25, makes ammonia (NH more adsorbable than selective reduction type catalyzer 26 ₃) amount (hereinafter referred to as " ammonia saturation capacity ") how ammonia (NH ₃) be fed into selective reduction type catalyzer 26.

Below, the execution sequence of the sour neutralisation treatment in the present embodiment is described according to Fig. 7.Fig. 7 is the flow chart representing the control program that ECU20 performs when implementing sour neutralisation treatment.This control program is pre-stored in ROM of ECU20 etc., is periodically performed by ECU20.

In the control program of Fig. 7, first ECU20 differentiates in S301 whether the executive condition of sour neutralisation treatment is set up.Amount (ionic weight or the molecular weight) Gac of the acid acidic materials of neutralisation treatment executive condition such as in the path being present in low pressure EGR gas exceed threshold value and low pressure EGR valve 17 is in open mode time set up.

As the method for amount Gac obtaining the acidic materials be present in the path of low pressure EGR gas, the method that the mapping that can exemplify the method obtained according to the mapping being independent variable with the operation resume of internal-combustion engine 1 (cumulative amounts of internal-combustion engine rotational speed, fuel injection amount, low pressure EGR gas etc.), operational model or use the temperature in the path of the cumulative amount of the nitrogen oxide (NOx) to flow into exhaust passage 16, low pressure EGR gas etc. to be independent variable, operational model are obtained.By obtaining the amount Gac of acidic materials according to such method ECU20, realize the acquisition unit that the present invention relates to.

When being judged as "No" in above-mentioned S301, ECU20 temporarily terminates the execution of this program.And when being judged as "Yes" in above-mentioned S301, ECU20 enters S302.

In S302, ECU20 starts to carry out the supply of aqueous solution of urea by making interpolation valve 25 open.Now, ECU20 adjusts the delivery volume of aqueous solution of urea, makes the ammonia (NH more than the ammonia saturation capacity of selective reduction type catalyzer 26 ₃) be fed into selective reduction type catalyzer 26.

Fig. 8 is the figure of the relation representing the ammonia saturation capacity of selective reduction type catalyzer 26 and the bed temperature of selective reduction type catalyzer 26.As shown in Figure 8, the ammonia saturation capacity of selective reduction type catalyzer 26 and the bed temperature of this selective reduction type catalyzer 26 correspondingly change.Such as, when selecting the bed temperature of reduction catalyst 26 low, compared with during bed temperature height, the saturated quantitative change of ammonia is many.Therefore, the bed temperature of selective reduction type catalyzer 26 is carried out computing ammonia saturation capacity as parameter by ECU20, controls to add valve 25, makes the ammonia (NH more than ammonia saturation capacity ₃) be fed into selective reduction type catalyzer 26.

If like this more than the ammonia (NH of ammonia saturation capacity ₃) be fed into selective reduction type catalyzer 26, then not by the remaining ammonia (NH selecting reduction catalyst 26 to adsorb ₃) downstream of choice of flow direction reduction catalyst 26.Ammonia (the NH in the downstream of choice of flow direction reduction catalyst 26 ₃) a part and low pressure EGR gas together flow into exhaust passage 16.Flow into the ammonia (NH of exhaust passage 16 ₃) play a role as the neutralizer of the acidic materials be present in the path of low pressure EGR gas.

At this, turn back to the control program of Fig. 7, ECU20 computing in S303 flow into the ammonia (NH of exhaust passage 16 ₃) total amount Gnh3lpl.Specifically, first ECU20 obtains the ammonia (NH flowed out from selective reduction type catalyzer 26 ₃) amount.That is, ECU20 obtains ammonia (NH contained the exhaust of flowing out from selective reduction type catalyzer 26 ₃) concentration C nh3rl.Ammonia (NH contained in exhaust ₃) concentration C nh3rl can obtain according to the mapping being independent variable with the flow velocity of the bed temperature of selective reduction type catalyzer 26, exhaust, operational model, or also can to obtain according to the mapping being independent variable with the flow of exhaust and the checkout value of ammoniacal sensor, operational model.

Then, ECU20 obtains the amount, i.e. the low-pressure EGR gas amount Glpl that flow to the exhaust of exhaust passage 16 from exhaust passageway 6.Low-pressure EGR gas amount Glpl can by the mapping that is independent variable with the operating conditions of internal-combustion engine 1 (entering air quantity, internal-combustion engine rotational speed), the aperture of low pressure EGR valve 17, the aperture of exhaust shutter 27 etc., operational model and obtaining.

ECU20 passes through ammonia (NH ₃) concentration C nh3rl be multiplied with low-pressure EGR gas amount Glpl and calculate the ammonia (NH importing exhaust passage 16 ₃) amount (=Cnh3rl*Glpl).And then ECU20 is by the ammonia (NH to importing exhaust passage 16 ₃) amount carry out integration (adding up) and obtain above-mentioned total amount Gnh3lpl (=Σ (Cnh3rl*Glpl)).

In S304, ECU20 differentiates the acid content quality Gac more than of total amount Gnh3lpl calculated in above-mentioned S303 whether for calculating in above-mentioned S301.When being judged as "No" in S304 (Gnh3lpl < Gac), ECU20 turns back to above-mentioned S303.And when being judged as "Yes" in S304 (Gnh3lpl >=Gac), ECU20 enters S305, makes interpolation valve 25 close.

Then, the calculated value of the acid content quality Gac be present in the path of low pressure EGR gas is reset to zero by ECU20 in S306, terminates the execution of this program.

According to the above embodiment described, even if in the structure of the upstream of the connection part of exhaust passage 16 configuration selective reduction type catalyzer 26, the acidic materials be present in the path of low pressure EGR gas also can be neutralized.Further, according to the present embodiment, owing to adjusting the delivery volume of aqueous solution of urea according to the acid content quality be present in the path of low pressure EGR gas, so necessary inferior limit can be suppressed to the consumption of the aqueous solution of urea of the enforcement of sour neutralisation treatment.

If be configured at selective reduction type catalyzer 26 in the structure in the exhaust passageway 6 of the upstream of the connection part of exhaust passage 16 and implement sour neutralisation treatment, then from the ammonia (NH that selective reduction type catalyzer 26 flows out ₃) a part flow into exhaust passage 16, and the ammonia (NH of remnants ₃) be discharged in air.Therefore, oxidize ammonia (NH will can be used for ₃) catalyzer be configured in the exhaust passageway 6 in the downstream of the connection part of exhaust passage 16.

< embodiment 5 >

Then, according to Fig. 9, the fifth embodiment of the present invention is described.At this, the structure different from aforesaid 4th embodiment is described, to same incomplete structure explanation.

The difference of aforesaid 4th embodiment and the present embodiment is, makes exhaust shutter 27 close when implementing sour neutralisation treatment when DECEL ENLEAN controls the term of execution.

Below, the execution sequence of the sour neutralisation treatment in the present embodiment is described according to Fig. 9.The flow chart of the control program that Fig. 9 performs when being and representing that in the present embodiment, ECU20 implements sour neutralisation treatment.In fig .9, to the same label of marks for treatment be equal to the control program (with reference to Fig. 7) of aforesaid 4th mode of execution.

In the control program of Fig. 9, ECU20 performs the process of S401 after the process performing S302.In S401, ECU20 differentiates whether be that DECEL ENLEAN controls in execution.

When being judged as "Yes" in above-mentioned S401, ECU20 enters S402, second section valve 19 and exhaust shutter 27 is closed, and low pressure EGR valve 17 is opened.If implement sour neutralisation treatment in this state, then from the ammonia (NH that selective reduction type catalyzer 26 flows out ₃) all flow into exhaust passage 16.In other words, the ammonia (NH that can will flow out from selective reduction type catalyzer 26 ₃) all use as neutralizer.Its result, can one side suppress few by the consumption of the aqueous solution of urea of the enforcement with sour neutralisation treatment, one side makes acidic materials neutralize.

In addition, when being judged as "No" in above-mentioned S401, ECU20 enters S403, and the aperture of second section valve 19, exhaust shutter 27 and low pressure EGR valve 17 is controlled the aperture for normal conditions.

In the present embodiment, describe the example also implementing sour neutralisation treatment when not performing DECEL ENLEAN and controlling, but also can be only limitted to implement sour neutralisation treatment when DECEL ENLEAN controls execution.In this case, can the consumption of the aqueous solution of urea of the enforcement with sour neutralisation treatment be suppressed less.

< embodiment 6 >

Then, according to Figure 10 to Figure 12, the sixth embodiment of the present invention is described.At this, the structure different from aforesaid 4th embodiment is described, to same incomplete structure explanation.

The difference of aforesaid 4th embodiment and the present embodiment is, having the heating unit for heating selective reduction type catalyzer 26, making heating unit work in the enforcement of sour neutralisation treatment.

Figure 10 is the figure of the schematic configuration of the emission control system of the internal-combustion engine represented in the present embodiment.In Fig. 10, at selective reduction type catalyzer 26, the heater 260 for heating this selective reduction type catalyzer 26 is installed.Heater 260 is the parts electric energy supplied from storage battery being converted to heat energy and heating selective reduction type catalyzer 26.Other structures are identical with aforesaid 4th embodiment.

When implementing sour neutralisation treatment in the emission control system of the internal-combustion engine formed like this, ECU20 makes interpolation valve 25 supply aqueous solution of urea, and heater 260 is worked.

In detail, ECU20 obtains the bed temperature of selective reduction type catalyzer 26 when the executive condition of sour neutralisation treatment is set up, decide the desired value (target dose) of ammonia extent of adsorption according to this bed temperature.Target dose is now set to the amount being less than ammonia saturation capacity.

Then, ECU20 makes interpolation valve 25 open according to target dose, and heater 260 is worked.When the bed temperature height of selective reduction type catalyzer 26, compared with time low with bed temperature, ammonia saturation capacity tails off.Therefore, if heat selective reduction type catalyzer 26 by heater 260, then ammonia saturation capacity is lower than target dose.Its result, is supplied to the ammonia (NH of selective reduction type catalyzer 26 ₃) the downstream of a part of choice of flow direction reduction catalyst 26.

At this, the bed temperature of selective reduction type catalyzer 26 when performing sour neutralisation treatment shown in Figure 11 and the change of ammonia extent of adsorption.Solid line in Figure 11 represents ammonia saturation capacity, and single dotted broken line represents that the desired value of ammonia extent of adsorption (is in other words ammonia (NH ₃) target dose).In addition, the bed temperature of selective reduction type catalyzer 26 when the tcat1 in Figure 11 represents that the executive condition of sour neutralisation treatment is set up, tcat2 represents bed temperature when heated selective reduction type catalyzer 26 by heater 260.Further, the ammonia saturation capacity when anh0 in Figure 11 represents that the bed temperature of selective reduction type catalyzer 26 is tcat1, anh1 (< anh0) represents the ammonia (NH in sour neutralisation treatment ₃) target dose, the ammonia saturation capacity (ammonia extent of adsorption) when anh2 (< anh1) represents that the bed temperature of selective reduction type catalyzer 26 rises to tcat2.

As shown in figure 11, when selecting the bed temperature of reduction catalyst 26 to rise to tcat2 from tcat1, ammonia saturation capacity reduces to anh2 from anh0.Because ammonia saturation capacity anh2 is less than target dose anh1, so the ammonia (NH of residual capacity (=anh1-anh2) ₃) exhaust passageway 6 in downstream of choice of flow direction reduction catalyst 26.Flow into the ammonia (NH of the exhaust passageway 6 in the downstream of selective reduction type catalyzer 26 ₃) a part flow to exhaust passage 16, the neutralizer as acidic materials plays a role.

If the heating selective reduction type catalyzer 26 when performing sour neutralisation treatment like this, then do not need the ammonia (NH more than ammonia saturation capacity (setting up ammonia saturation capacity corresponding to the bed temperature in moment with the executive condition of sour neutralisation treatment) ₃) be supplied to selective reduction type catalyzer 26.Its result, can be suppressed to the increase of the consumption of the aqueous solution of urea of the enforcement with sour neutralisation treatment seldom.

In addition, be stopped owing to terminating post-heater 260 in sour neutralisation treatment, so the bed temperature of selective reduction type catalyzer 26 declines.When selecting the bed temperature of reduction catalyst 26 to decline, ammonia saturation capacity increases.Its result, the ammonia adsorptive power of selective reduction type catalyzer 26 produces more than needed, and the downstream to this selective reduction type catalyzer 26 can be avoided to flow out ammonia (NH ₃).

Below, the execution sequence of the sour neutralisation treatment in the present embodiment is described according to the flow chart of Figure 12.Figure 12 is the flow chart representing the control program performed when ECU20 implements sour neutralisation treatment.In fig. 12, same label is had to the marks for treatment be equal to the control program (with reference to Fig. 7) of aforesaid 4th mode of execution.

In the control program of Figure 12, ECU20 performs the process of S501 after performing S302.In S501, ECU20 makes heater 260 work.In the S302 of this program, the such control described in the explanation of ECU20 Figure 11 as the aforementioned adds valve 25, makes the ammonia (NH being supplied to selective reduction type catalyzer 26 ₃) amount (target dose) anh1 be less than ammonia saturation capacity anh0.

ECU20 performs the process of S303 to S305 after the process performing S501.Ammonia (the NH flowed out from selective reduction type catalyzer 26 is asked in S303 ₃) amount when, ECU20 uses bed temperature tcat, target dose anh1 and the as the aforementioned mapping as shown in Figure 11 of current time.That is, ECU20 obtains the ammonia saturation capacity anh corresponding with the bed temperature tcat of current time according to the mapping of Figure 11.Then, ECU20 calculates the ammonia (NH flowed out from selective reduction type catalyzer 26 by deducting ammonia saturation capacity anh from target dose anh1 ₃) amount.

ECU20 performs the process of S502 after the process performing S305.In S502, ECU20 makes heater 260 stop.In this case, because the bed temperature of selective reduction type catalyzer 26 declines, so ammonia saturation capacity increases.Therefore, it is possible to avoid flowing out ammonia (NH from selective reduction type catalyzer 26 after sour neutralisation treatment terminates ₃).

According to the above embodiment described, can the consumption of aqueous solution of urea be suppressed fewer than aforesaid 4th embodiment one side, the acidic materials in one side and in low pressure EGR gas path.

When ECU20 is judged to be "No" in the S304 of above-mentioned control program, if the ammonia extent of adsorption in this moment is less than the residual capacity (=Gac-Gnh3lpl) of acidic materials, then can increase the amount from adding the aqueous solution of urea that valve 25 supplies.In this case, the acidic materials be present in the path of low pressure EGR gas can be neutralized more reliably.

In addition, in the present embodiment, as the mechanism of heating selective reduction type catalyzer 26, exemplified with the heater being arranged on selective reduction type catalyzer 26, but heater also can be configured to convection current enters to select the exhaust of reduction catalyst 26 to heat.

As the additive method realizing heating unit, can at least one in following control be performed by ECU20 and make the temperature of the exhaust of inflow selective reduction type catalyzer 26 increase, that is: the aperture of second section valve 19 be carried out the control revised to closing direction; Make the control of low pressure EGR gas or high pressure EGR gas increment; The aperture of exhaust shutter 27 is carried out the control revised to closing direction; Make the delayed control of the injection timing of Fuelinjection nozzle 3 (making the control that the burning timing of fuel is delayed); And the control of unburned fuel is supplied to oxidation catalyst 23.

When internal-combustion engine 1 has the mechanism opened regularly that can change exhaust valve, can the opening timing advance of exhaust valve be made by ECU20 and make the temperature of the exhaust of inflow selective reduction type catalyzer 26 increase.

When turbosupercharger 8 is variable-geometry turbocharger, can by ECU20, the stator blade aperture of variable-geometry turbocharger be carried out revising to opening direction and make the temperature of the exhaust of inflow selective reduction type catalyzer 26 increase.

< embodiment 7 >

Then, according to Figure 13, the seventh embodiment of the present invention is described.At this, the structure different from aforesaid 6th embodiment is described, to same incomplete structure explanation.

The difference of aforesaid 6th embodiment and the present embodiment is, controls when implementing sour neutralisation treatment in execution, exhaust shutter 27 to be closed in DECEL ENLEAN.

Below, the execution sequence of the sour neutralisation treatment in the present embodiment is described according to Figure 13.Figure 13 is the flow chart representing the control program performed when ECU20 implements sour neutralisation treatment in the present embodiment.In fig. 13, same label is had to the marks for treatment be equal to the control program (with reference to Figure 12) of aforesaid 6th mode of execution.

In the control program of Figure 13, when ECU20 is judged to be "Yes" in S301, before the process performing S302, perform the process of S601 to S603.First, in S601, ECU20 differentiates whether be that DECEL ENLEAN controls in execution.

When being judged to be "Yes" in above-mentioned S601, ECU20 enters S602, second section valve 19 and exhaust shutter 27 is closed, and low pressure EGR valve 17 is opened.If implement sour neutralisation treatment in this state, then from the ammonia (NH that selective reduction type catalyzer 26 flows out ₃) all flow into exhaust passage 16.In other words, the ammonia (NH that can will flow out from selective reduction type catalyzer 26 ₃) all use as neutralizer.Its result, can one side suppress few by the consumption of the aqueous solution of urea of the enforcement with sour neutralisation treatment, one side makes acidic materials neutralize.

In addition, when being judged as "No" in above-mentioned S601, ECU20 enters S603, and the aperture of second section valve 19, exhaust shutter 27 and low pressure EGR valve 17 is controlled the aperture for normal conditions.

In the present embodiment, even if describe the example also implementing sour neutralisation treatment when not performing DECEL ENLEAN and controlling, but also can be only limitted to implement sour neutralisation treatment when performing DECEL ENLEAN control.In this case, can the consumption of the aqueous solution of urea of the enforcement with sour neutralisation treatment be suppressed less.

< embodiment 8 >

Then, according to Figure 14, the eighth embodiment of the present invention is described.At this, the structure different from aforesaid first embodiment is described, to same incomplete structure explanation.

The difference of aforesaid first embodiment and the present embodiment is, when sour neutralisation treatment is implemented and the amount of low pressure EGR gas correspondingly adjust (correction) from the amount of adding the aqueous solution of urea that valve 25 supplies.

Be configured in when performing sour neutralisation treatment in the structure in the exhaust passageway 6 in the downstream of the connection part of exhaust passage 16 at selective reduction type catalyzer 26, flow into exhaust passage 16 from a part of adding the aqueous solution of urea that valve 25 adds, remaining aqueous solution of urea flows into selective reduction type catalyzer 26.

Now, the amount (amount of ammonia) flowing into the aqueous solution of urea of selective reduction type catalyzer 26 changes according to the amount of low pressure EGR gas.That is, when the amount of low pressure EGR gas is many, compared with time few with amount, the quantitative change flowing into the aqueous solution of urea of selective reduction type catalyzer 26 is few.When the amount of the aqueous solution of urea flowing into selective reduction type catalyzer 26 is very few, likely selective reduction type catalyzer 26 can not nitrogen oxide (NOx) completely in purifying exhaust gas.

Being directed to this, in the sour neutralisation treatment of the present embodiment, when the amount of low pressure EGR gas is many, compared with time few with amount, making the amount from adding the aqueous solution of urea that valve 25 supplies many.According to this method, even if (when low pressure EGR valve 17 is opened) supplies to give aqueous solution of urea from interpolation valve 25 when sour neutralisation treatment performs, the ammonia (NH of necessary amount also can be supplied to selective reduction type catalyzer 26 ₃).

Below, the execution sequence of the sour neutralisation treatment in the present embodiment is described according to Figure 14.Figure 14 is the flow chart representing the control program performed when ECU20 implements sour neutralisation treatment.In fig. 14, same label is had to the marks for treatment be equal to the control program (with reference to Fig. 2) of aforesaid first embodiment.

In the control program of Figure 14, when ECU20 is judged to be "Yes" in S101, perform the process of S701.In S701, ECU20 calculates when supposing to the addition of the aqueous solution of urea of prearranging quatity from interpolation valve 25 to exhaust, to the ammonia (NH of selective reduction type catalyzer 26 supply ₃) amount anhscr.Can be predetermined a certain amount of at this said prearranging quatity, or also can be the Variable quantity that the amount of the acidic materials in the path being present in low pressure EGR gas, hydrogen ion exponent (pH) are determined as parameter.

Ammonia (the NH of selective reduction type catalyzer 26 is supplied in computing ₃) amount anhscr time, ECU20 is first using from adding the amount of aqueous solution of urea that supplies of valve 25 and the flow Gex of exhaust carrys out ammonia (NH contained in computing exhaust as parameter ₃) concentration.Then, ECU20 obtains the amount, i.e. the low-pressure EGR gas amount Glpl that flow to the exhaust of exhaust passage 16 from exhaust passageway 6.Low-pressure EGR gas amount Glpl can according to using the operating conditions (entering air quantity, internal-combustion engine rotational speed), the aperture of low pressure EGR valve 17, the aperture of exhaust shutter 27 etc. of internal-combustion engine 1 as the mapping of independent variable, operational model and obtaining.

ECU20 deducts low pressure EGF gas flow Glpl from the flow Gex of exhaust and obtains the amount Gscr (=Gex-Glpl) of the exhaust flowing into selective reduction type catalyzer 26.ECU20 passes through amount Gscr and the ammonia (NH of the exhaust by flowing into selective reduction type catalyzer 26 ₃) concentration C nh3rl be multiplied and calculate the ammonia (NH being supplied to selective reduction type catalyzer 26 ₃) amount anhscr (=Cnh3rl*Gscr).

When the above-mentioned such method of employing calculates the ammonia (NH being supplied to selective reduction type catalyzer 26 ₃) amount anhscr time, ECU20 enters S702.In S702, ECU20 differentiates ammonia (NH calculated in above-mentioned S701 ₃) delivery volume anhscr and the difference of desired value anhtrg of ammonia extent of adsorption whether be less than admissible value.

When being judged to be "Yes" in above-mentioned S702, ECU20 enters S102, and the aqueous solution of urea of prearranging quatity is supplied from interpolation valve 25.And when being judged to be "No" in above-mentioned S702, ECU20 enters S703, revise above-mentioned prearranging quatity.Specifically, ECU20 revises above-mentioned prearranging quatity and makes it increase when above-mentioned delivery volume anhscr is less than above-mentioned desired value anhtrg.And make minimizing at above-mentioned delivery volume anhscr more than revising above-mentioned prearranging quatity during above-mentioned desired value anhtrg.

ECU20 enters S102 after the process performing above-mentioned S703, according to prearranging quatity revised in above-mentioned S703, interpolation valve 25 is worked.

According to the above embodiment described, the purifying ability of selective reduction type catalyzer 26 can not be made to reduce perform sour neutralisation treatment.Its result, can not make internal-combustion engine 1 exhaust emission increase and in and low pressure EGR gas path in acidic materials.

< embodiment 9 >

Then, according to Figure 15, the ninth embodiment of the present invention is described.At this, the structure different from aforesaid first embodiment is described, to same incomplete structure explanation.

The difference of aforesaid first embodiment and the present embodiment is, when implementing sour neutralisation treatment, with the ammonia (NH flowing into exhaust passage 16 ₃) amount correspondingly adjust the flow-rate ratio of low pressure EGR gas and high pressure EGR gas.

Assuming that following situation: when the flow of low pressure EGR gas is few or when the flow of low pressure EGR gas is zero (only high pressure EGR institution staff), be difficult to the ammonia (NH of the amount conformed to the amount of the acidic materials be present in low pressure EGR gas path ₃) be supplied to low pressure EGR gas path.

On the other hand, assuming that following situation: when the flow of low pressure EGR gas is many or when only low pressure EGR gas works (when high pressure EGR gas amount is zero), relative to the amount of the acidic materials be present in low pressure EGR gas path, ammonia (NH ₃) delivery volume too much.Particularly be configured in the structure in the exhaust passageway 6 in the downstream of the connection part of exhaust passage 16 at selective reduction type catalyzer 26, to supply the ammonia (NH of desired amount to selective reduction type catalyzer 26 ₃), then be probably supplied to the ammonia (NH of exhaust passage 16 ₃) too much.

Be directed to this, in the sour neutralisation treatment of the present embodiment, ECU20 is at the ammonia (NH supplied to exhaust passage 16 ₃) quantity not sufficient time, revise low pressure EGR gas make it increase relative to the flow-rate ratio of high pressure EGR gas.In this case, the EGR gas flow (total amount of low-pressure EGR gas amount and high pressure EGR gas amount) importing internal-combustion engine 1 can not be changed and make to be supplied to the ammonia (NH in low pressure EGR gas path ₃) increment.

On the other hand, at the ammonia (NH supplied to exhaust passage 16 ₃) amount too much time, revise low pressure EGR gas make it reduce relative to the flow-rate ratio of high pressure EGR gas.In this case, the EGR gas flow importing internal-combustion engine 1 can not be changed and reduce the ammonia (NH being supplied to low pressure EGR gas path ₃).

Below, the execution sequence of the sour neutralisation treatment in the present embodiment is described according to Figure 15.Figure 15 is the flow chart representing the subroutine that ECU20 performs in sour neutralisation treatment performs or before performing.

In the subroutine of Figure 15, ECU20 first in S801 computing low-pressure EGR gas amount relative to the ratio α (=(low-pressure EGR gas amount)/(total EGR gas flow)) of total EGR gas flow (summation of high pressure EGR gas amount and low-pressure EGR gas amount).

In S802, ECU20 computing is present in the amount Gac of the acidic materials in the path of low pressure EGR gas.Acid content quality Gac can adopt the method same with aforesaid 4th embodiment to obtain.

In S803, ECU20 carrys out according to the ratio α calculated in above-mentioned S801 the ammonia (NH that computing flows into exhaust passage 16 ₃) amount Ghn3lpl.When the subroutine of Figure 15 performs before sour neutralisation treatment performs, ECU20 hypothesis with the addition of the aqueous solution of urea of prearranging quatity from interpolation valve 25 and carries out above-mentioned computing.

In S804, the acid content quality Gac that ECU20 computing calculates in above-mentioned S802 and the ammonia (NH calculated in above-mentioned S803 ₃) the difference △ G (=Ghn3lpl-Gac) of amount Ghn3lpl.

In S805, ECU20 computing is for revising the reduction value △ C of low-pressure EGR gas amount relative to the ratio α of total EGR gas flow.Reduction value △ C can be predetermined a certain amount of, or also can be the absolute value of the poor △ G being set to calculate in above-mentioned S804 large time than the Variable quantity of value large time little.

In S806, ECU20 differentiates whether the poor △ G calculated in above-mentioned S804 is greater than zero.When being judged as "Yes" in S806 (△ G > 0), ECU20 enters S807.In S807, ECU20 revises low-pressure EGR gas amount by deducting above-mentioned reduction value △ C from ratio α calculated in above-mentioned S801 makes it reduce relative to the ratio α of total EGR gas flow.In this case, increase high pressure EGR gas amount, and reduce low-pressure EGR gas amount.Its result, does not change total EGR gas flow and reduces the ammonia (NH being supplied to exhaust passage 16 ₃) amount.

On the other hand, when being judged to be "No" in above-mentioned S806 (△ G≤0), ECU20 enters S808, differentiates whether above-mentioned △ G is less than zero.When being judged to be "Yes" in S808 (△ G < 0), ECU20 enters S809.In S809, revise low-pressure EGR gas amount by being added with ratio α calculated in above-mentioned S801 by above-mentioned reduction value △ C and make it increase relative to the ratio α of total EGR gas flow.In this case, reduce high pressure EGR gas amount, and increase low-pressure EGR gas amount.Its result, does not change the ammonia (NH of total EGR gas flow and exhaust passage 16 of increasing supply ₃) amount.

When being judged as "No" in above-mentioned S808 (△ G=0), ECU20 terminates the execution of this program.

According to the above embodiment described, even if when when low pressure EGR mechanism is in off position, (low pressure EGR valve 17 is in the situation of closed condition), low-pressure EGR gas amount are low relative to the flow-rate ratio of high pressure EGR gas amount, also can in and acidic materials in low pressure EGR gas path.

But, suppose, in the operation area of the operation area of only high pressure EGR institution staff, high pressure EGR mechanism and these both sides of low pressure EGR mechanism work, when increasing the ratio α of low-pressure EGR gas amount, to cause due to the decline of compression end temperature misfiring.

Therefore, can using import the firing chamber of internal-combustion engine 1 the temperature of gas higher than lower limit as condition, the ratio α revising low-pressure EGR gas amount makes it increase.In this case, as long as ECU20 is according to the ratio α of subroutine correction low-pressure EGR gas amount as shown in Figure 16.

The difference of the subroutine of aforesaid Figure 15 and the subroutine of Figure 16 is, when being judged as "Yes" in S808, (△ G < 0) performs the process of S901.In S901, ECU20 differentiates whether the temperature Tin of the gas of the firing chamber importing internal-combustion engine 1 is more than lower limit temperature Tinlt.

At this, as the temperature Tin of the gas of the firing chamber of importing internal-combustion engine 1, the temperature (temperature in such as intake manifold 5) of the gas in the inlet air pathway 4 in the downstream of the connection part of high pressure EGR passage 12 can be used.Temperature in intake manifold 5 can be measured by temperature transducer.In addition, the temperature in intake manifold 5 also can use air inflow, intake temperature, high pressure EGR gas amount, high pressure EGR gas temperature, low-pressure EGR gas amount, low pressure EGR gas temperature etc. as the mapping of independent variable, operational model and obtaining.

Above-mentioned lower limit temperature Tinlt is the minimum temperature of the temperature range that can not misfire or the temperature slightly higher than above-mentioned minimum temperature, is determined by utilizing the suitable operation of experiment etc. in advance.

When ECU20 is judged as "Yes" in above-mentioned S901, (Tin >=Tinlt) enters S809, and the ratio α revising low-pressure EGR gas amount makes it increase.But, when being judged as "No" in above-mentioned S901 (Tin < Tinlt), not revising the ratio α of low-pressure EGR gas amount and terminate the execution of this program.

According to subroutine as shown in Figure 16, the ratio α being only limitted to revise when can avoid the generation misfired low-pressure EGR gas amount makes it increase.Therefore, it is possible to avoid the drive performance of the internal-combustion engine 1 caused by the execution of sour neutralisation treatment to reduce.

In addition, when also can be judged as "No" in above-mentioned S901 (Tin < Tinlt), one side is controlled to low pressure EGR gas and walks around the flowing of low pressure EGR cooler 18 ground, or be controlled to high pressure EGR gas and walk around the flowing of high pressure cooler for recycled exhaust gas 14 ground, one side revises ratio α makes it increase.In addition, also simultaneously can be improved the temperature of low pressure EGR gas and high pressure EGR gas by adjustment fuel injection timing, one side revises ratio α makes it increase.

On the other hand, suppose in the operation area of the operation area of only low pressure EGR institution staff, high pressure EGR mechanism and these both sides of low pressure EGR mechanism work, when reducing ratio α (the increasing high pressure EGR gas amount) of low-pressure EGR gas amount, parts (such as high pressure EGR valve 13) in high pressure EGR gas path are overheated, or the situation of premature firing of fuel occurs due to the rising of compression end temperature.

Therefore, can using the temperature of high pressure EGR gas lower than CLV ceiling limit value as condition, revise the ratio α of low-pressure EGR gas amount and make it reduce.In this case, ECU20 is according to the ratio α of subroutine correction low-pressure EGR gas amount as shown in Figure 17.

The difference of the subroutine of aforesaid Figure 15 and the subroutine of Figure 17 is, when being judged as "Yes" in S806, (△ G > 0) performs the process of S1001.In S1001, ECU20 differentiates whether the temperature Thv of high pressure EGR gas is below upper limiting temperature Thvlt.

At this, as the temperature Thv of high pressure EGR gas, the temperature of the high pressure EGR gas near high pressure EGR valve 13 can be used.High pressure EGR gas temperature near high pressure EGR valve 13 can be measured by temperature transducer, also can carry out computing according to the running state of internal-combustion engine 1 (internal-combustion engine rotational speed, fuel injection amount).

Above-mentioned upper limiting temperature Thvlt is the maximum temperature of the temperature range that high pressure EGR valve 13 etc. can not be overheated and can avoids the temperature of the lower side in the maximum temperature of the temperature range of the premature firing of fuel or the temperature slightly lower than this temperature, is determined by utilizing the suitable operation of experiment etc. in advance.

When ECU20 is judged as "Yes" in above-mentioned S1001, (Thv≤Thvlt) enters S807, and the ratio α revising low-pressure EGR gas amount makes it reduce.But, when being judged as "No" in above-mentioned S1001 (Thv > Thvlt), not revising the ratio α of low-pressure EGR gas amount and terminate the execution of this program.

According to subroutine as shown in Figure 17, be only limitted to can avoid being configured in that the parts in the path of high pressure EGR gas are overheated, revise the ratio α of low-pressure EGR gas amount in the premature firing situation of fuel and make it reduce.Therefore, it is possible to avoid the deterioration of the parts caused by the execution of sour neutralisation treatment, the drive performance reduction of internal-combustion engine 1.

In addition, when also can be judged as "No" in above-mentioned S1001 (Thv > Thclt), one side makes the low-pressure EGR gas amount via low pressure EGR cooler 18 increase, or make the high pressure EGR gas amount via high pressure cooler for recycled exhaust gas 14 increase, one side revises ratio α makes it reduce.In addition, also can simultaneously by adjustment fuel injection timing, the temperature of low pressure EGR gas and high pressure EGR gas be declined, one side revises ratio α makes it reduce.

In the aforesaid embodiment of the 1st, 2,4 to 8, describe the example applying the present invention to the internal-combustion engine with low pressure EGR mechanism and high pressure EGR mechanism, but also can be applied to the internal-combustion engine without high pressure EGR mechanism.

Label declaration

1 internal-combustion engine

2 cylinders

3 Fuelinjection nozzles

4 inlet air pathways

5 intake manifold

6 exhaust passageways

7 gas exhaust manifolds

8 turbosupercharger

8a compressor

8b turbine

9 first segment valves

11 pressure EGR device

12 high pressure EGR passage

13 high pressure EGR valve

14 high pressure coolers for recycled exhaust gas

15 low pressure EGR apparatus

16 exhaust passage

17 low pressure EGR valves

18 low pressure EGR coolers

19 second section valves

21 crankshaft position sensors

22 throttle position switchs

23 oxidation catalysts

24 particulate filters

25 add valve

26 selective reduction type catalyzer

27 exhaust shutters

28 exhaust gas temperature sensors

29 dispersion plates

30 hydrolysts

40 interstage coolers

260 heaters

Claims (13)

1. an emission control system for internal-combustion engine, is characterized in that, comprising:

Low pressure EGR mechanism, it has: exhaust passage, a part for the exhaust of flowing in the exhaust passageway downstream of the turbine than centrifugal supercharger is imported as low pressure EGR gas to than compressor inlet air pathway by the upstream; And low pressure EGR valve, the passage sections changing described exhaust passage is amassed;

Selective reduction type catalyzer, it is configured in the connection part exhaust passageway downstream than described exhaust passage;

Supplier, it is the device for the derived compound to described selective reduction type catalyzer supply ammonia, and being configured to can to than the derived compound supplying ammonia in the connection part of described exhaust passage exhaust passageway by the upstream; And

Control unit, it makes described supplier supply the derived compound of ammonia when described low pressure EGR valve is in open mode, than many when measuring few the low-pressure EGR gas amount making the derived compound of the ammonia supplied from described supplier flow when described exhaust passage is many.

2. the emission control system of internal-combustion engine according to claim 1, is characterized in that,

Also comprise acquisition unit, described acquisition unit obtains the value relevant to the amount of the acidic materials existed in the path of low pressure EGR gas,

Described control unit makes the derived compound of the ammonia supplied from described supplier when many by the amount acquired by described acquisition unit than many when measuring few.

3. the emission control system of internal-combustion engine according to claim 1 and 2, is characterized in that,

Also comprise the detection unit of the temperature detecting low pressure EGR gas,

Described control unit make the amount of the derived compound of the ammonia supplied from described supplier when the temperature detected by described detection unit higher than predetermined reference temperature than when lower than many when reference temperature.

4. the emission control system of the internal-combustion engine according to any one in claims 1 to 3, is characterized in that,

Also comprise the heating unit that low pressure EGR gas is heated,

Described control unit makes described heating unit work when making described supplier supply the derived compound of ammonia.

5. the emission control system of internal-combustion engine according to claim 4, is characterized in that,

Described heating unit heats the exhaust flowed into before described selective reduction type catalyzer.

6. the emission control system of internal-combustion engine according to claim 1, is characterized in that,

Also comprise dispersion plate, described dispersion plate be arranged on than described exhaust passage connection part downstream and exhaust passageway more by the upstream than described selective reduction type catalyzer, the derived compound of the ammonia supplied from described supplier is disperseed.

7. the emission control system of internal-combustion engine according to claim 1, is characterized in that, also comprises:

High pressure EGR mechanism, it has: high pressure EGR passage, for a part for the exhaust of flowing in than the turbine of described centrifugal supercharger exhaust passageway by the upstream being imported as high pressure EGR gas to than compressor inlet air pathway downstream; The high pressure EGR valve long-pending with the passage sections changing described high pressure EGR passage; And

Arithmetic element, the amount of the derived compound of the ammonia that its computing is flowed in described exhaust passage,

The operation result correction low pressure EGR gas of described control unit according to described arithmetic element and the flow-rate ratio of high pressure EGR gas.

8. the emission control system of internal-combustion engine according to claim 7, is characterized in that,

When the operation result of described arithmetic element is less than aim parameter, described control unit by the aperture of described low pressure EGR valve to opening side correction, and by the aperture of described high pressure EGR valve to closedown side revise.

9. the emission control system of internal-combustion engine according to claim 7, is characterized in that,

When the operation result of described arithmetic element is more than aim parameter, the aperture of described low pressure EGR valve is revised to closedown side by described control unit, and by the aperture of described high pressure EGR valve to opening side correction.

10. the emission control system of internal-combustion engine according to claim 1, is characterized in that,

Described control unit is enforcement supply process when the DECEL ENLEAN of internal-combustion engine controls to perform, and described supply process is the process of the derived compound described low pressure EGR valve being opened, makes described supplier supply ammonia.

The emission control system of 11. internal-combustion engines according to claim 10, is characterized in that,

Also comprise exhaust shutter, described exhaust shutter is arranged on connection part than described exhaust passage downstream and than described selective reduction type catalyzer exhaust passageway downstream, and the passage sections changing exhaust passageway is amassed,

Described control unit makes described exhaust shutter close when implementing described supply process.

The emission control system of 12. internal-combustion engines according to claim 10, is characterized in that,

Described control unit make when DECEL ENLEAN control terminate after scheduled period import inlet air pathway low-pressure EGR gas amount when implement described supply process than do not implement described supply process few.

The emission control system of 13. internal-combustion engines according to claim 12, is characterized in that,

Also comprise high pressure EGR mechanism, described high pressure EGR mechanism has: high pressure EGR passage, and it is for importing a part for the exhaust of flowing in than the turbine of described centrifugal supercharger exhaust passageway by the upstream to than compressor inlet air pathway downstream as high pressure EGR gas; The high pressure EGR valve long-pending with the passage sections changing described high pressure EGR passage,

Described control unit after have passed through the described scheduled period by the aperture of described high pressure EGR valve to opening side correction.