JP2003155925A - Exhaust emission control device of internal combustion engine - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a technology which estimates that the engine operating condition is suitable for recovering SOx poisoning, and starts the temperature rise of a NOx occluding agent in advance, in an exhaust emission control device of an internal combustion engine with the NOx occluding agent. SOLUTION: The exhaust emission control device comprises the NOx occluding agent to occlude and reduce NOx in the exhaust gas, a sulfur poisoning recovery control means to control the temperature rise of the NOx occluding agent and the sulfur poisoning control means, an execution acceptance/rejection estimating means to estimate whether or not the engine operating condition can perform the sulfur poisoning recovery control by the sulfur poisoning control means. The sulfur poisoning control means controls the temperature rise of the NOx occluding agent when the execution acceptance/rejection estimating means estimates that the engine operating condition can perform the sulfur poisoning recovery control.

Description

Detailed Description of the Invention

[0001]

TECHNICAL FIELD The present invention relates to an exhaust emission control device for an internal combustion engine.

[0002]

2. Description of the Related Art In recent years, internal combustion engines mounted in automobiles,
In particular, diesel engines and lean burn engines that can burn an air-fuel mixture that is in an oxygen excess state (so-called lean air-fuel mixture)
In a gasoline engine, a technique for purifying nitrogen oxides (NOx) contained in exhaust gas of the internal combustion engine is desired.

In response to such demands, a technique for arranging a NOx storage agent in the exhaust system of an internal combustion engine has been proposed. As one of the NOx storage agents, when the oxygen concentration of the inflowing exhaust gas is high, nitrogen oxides (NOx) in the exhaust gas are stored (absorbed, adsorbed), the oxygen concentration of the inflowing exhaust gas decreases, and the reducing agent becomes Nitrogen oxides (NO when stored)
An occlusion reduction type NOx catalyst that reduces x) to nitrogen (N ₂ ) is known.

When the NOx storage reduction catalyst is arranged in the exhaust system of the internal combustion engine, nitrogen oxide (NOx) in the exhaust gas is generated when the internal combustion engine is operated in lean combustion and the air-fuel ratio of the exhaust gas becomes high.
Is stored in the NOx storage reduction catalyst, and when the air-fuel ratio of the exhaust flowing into the NOx storage reduction catalyst becomes low, the nitrogen oxides (NOx) stored in the NOx storage reduction catalyst are nitrogen (N ₂ ). Is reduced to.

By the way, the NOx storage reduction catalyst is a sulfur oxide (S) produced by combustion of sulfur contained in fuel.
Ox) is also stored by the same mechanism as NOx. SOx stored in this way is less likely to be released than NOx,
x Accumulates in the catalyst. This is called sulfur poisoning (SOx poisoning), and the NOx purification rate decreases, so SOx is added at an appropriate time.
It is necessary to perform poisoning recovery processing to recover from poisoning. This poisoning recovery process is performed by passing exhaust gas, which has a reduced oxygen concentration while the NOx catalyst has a high temperature (for example, about 600 to 650 ° C.), to the NOx catalyst.

However, since the temperature of the exhaust gas during the lean burn operation is low, it is difficult to raise the temperature of the catalyst to the temperature required to recover SOx poisoning. In such a case, by adding fuel to the exhaust passage, it is possible to raise the temperature of the catalyst and reduce the oxygen concentration of the exhaust.

As a method of raising the temperature of such a NOx catalyst, an exhaust gas purifying apparatus for an internal combustion engine described in Japanese Patent No. 2845056 has been proposed. The exhaust gas purification device for an internal combustion engine described in this publication is a storage reduction type NO
Considering the amount of reducing agent consumed by reacting with oxygen in the exhaust gas in the x catalyst and the amount of reducing agent required to reduce nitrogen oxides (NOx) stored in the NOx storage reduction catalyst Then, by determining the amount of reducing agent added,
It is intended to prevent the excessive supply or the insufficient supply of the reducing agent and thereby suppress the deterioration of the exhaust emission due to the release of the reducing agent or nitrogen oxide (NOx) into the atmosphere.

[0008]

As described above, SOx
Poisoning recovery is performed by lowering the oxygen concentration in the exhaust gas,
When a reducing agent is added while the internal combustion engine is operating under high load, the reducing agent burns at the NOx storage reduction catalyst and the temperature of the NOx storage reduction catalyst rises, so the heat of the NOx storage reduction catalyst is increased. It may induce deterioration.

Therefore, although the SOx poisoning recovery is performed in the light load region, if the temperature increase control is started from the light load state, the temperature of exhaust gas at that time is low, so that the required temperature is stored. It takes time to raise the temperature of the reduction type NOx catalyst. Furthermore, if the light load state is not maintained, subsequent SOx poisoning recovery will not be performed. Also, SOx
If the temperature raising control of the NOx storage reduction catalyst is started because poisoning has progressed, there is a possibility that a large amount of reducing agent will be consumed before the light load state is entered.

The present invention has been made to solve the above problems, and an object of the present invention is to solve the problems in an exhaust gas purification apparatus for an internal combustion engine, when the engine operating state is SOx.
It is an object of the present invention to provide a technique capable of preliminarily estimating that a state suitable for recovery from poisoning is reached and starting the temperature rise of the NOx storage agent in advance.

[0011]

In order to achieve the above object, the exhaust gas purifying apparatus for an internal combustion engine of the present invention employs the following means. That is, when the air-fuel ratio of the inflowing exhaust gas is lean, which is provided in the exhaust passage of the internal combustion engine capable of lean burn, NO
A NOx storage agent that stores NOx and reduces the stored NOx to N ₂ when the air-fuel ratio of the inflowing exhaust gas is rich, and a sulfur poisoning recovery control that performs temperature increase control and sulfur poisoning recovery control of the NOx storage agent. Means and an executability estimating means for estimating whether or not the engine operating state in which the sulfur poisoning recovery control by the sulfur poisoning recovery control means is feasible is provided, and the sulfur poisoning recovery control means is a sulfur When the execution possibility estimator estimates that the engine operating state in which the poisoning recovery control can be executed becomes
x It is characterized in that the temperature rise of the storage agent is controlled.

The greatest feature of the present invention is that in the exhaust gas purifying apparatus for an internal combustion engine, the executability estimating means estimates that before the operating state is suitable for SOx poisoning recovery, and before the state becomes the light load state. It is to start the temperature rise control.

In the exhaust gas purifying apparatus for an internal combustion engine configured as described above, SOx generated during operation of the internal combustion engine is stored in the NOx storage agent. In this way, the SOx stored in the NOx storage agent is accumulated and inhibits the storage of NOx.
It is necessary to release it from the Ox storage agent. This release includes
First, it is necessary to raise the temperature of the NOx storage agent, and SOx poisoning is recovered after the temperature rise of the NOx storage agent is completed. By the way, SOx poisoning recovery is performed in the light load region,
Since this light load area does not always continue for a long time, N
It is desirable to start the temperature rise of the Ox storage agent before the light load state is reached. By doing so, the SOx poisoning recovery can be performed at the same time when the light load state is achieved, and the chances of performing the SOx poisoning recovery can be increased. However, even if the temperature of the NOx storage agent is raised before the light load state is reached, the SOx poisoning recovery is not performed unless the light load state is reached, and the reducing agent is consumed excessively. Therefore, if the light load state can be estimated before the light load state, the number of times of SOx poisoning recovery can be increased, and the reducing agent consumption amount can be reduced.

In the present invention, the exhaust gas purifying apparatus for an internal combustion engine may include a filter capable of temporarily trapping particulates in exhaust gas, and the NOx storage agent may be carried by the filter.

In the present invention, the exhaust gas purification apparatus for an internal combustion engine includes a navigation system for detecting at least one of a current position of a vehicle and road conditions, and the executability determining means determines sulfur based on information of the navigation system. It is possible to estimate whether or not the engine operating state in which the poisoning recovery control can be executed is achieved.

Nowadays, many vehicles are equipped with a navigation system, and it is possible to know the position and traveling direction of the vehicle. For example, while traveling on a highway, if the vehicle changes its course to the lane that enters the service area by detecting the traveling direction of the vehicle, it is estimated that the vehicle will be driven at a light load thereafter. SOx poisoning recovery can be performed. Therefore, if the temperature rise control of the NOx storage agent is started when the course is changed to a lane entering the service area or the like, SOx poisoning can be recovered even in a short-time light load operation in the service area or the like.

Further, at present, road traffic information can be obtained by FM broadcasting, optical beacons, radio wave beacons and the like. From these information, if the temperature rise control of the NOx storage agent is started when there is a possibility that light load operation may be performed due to traffic congestion or road construction in front of the vehicle, SOx poisoning will occur even in light load operation for a short period of time. It will be possible to recover.

In the present invention, the executability estimating means can estimate whether or not the engine is in an operating state in which the sulfur poisoning recovery control can be executed based on the history of the running state of the vehicle.

In the exhaust gas purifying apparatus for an internal combustion engine configured as described above, the operating state and traveling location of the vehicle are estimated from the traveling history of the vehicle, and NOx is detected when there is a possibility that the operating state will be suitable for SOx poisoning. It is possible to control the temperature rise of the storage agent.

According to the present invention, there is provided climbing state detecting means for detecting that the vehicle is climbing, and the feasibility determining means is provided when the climbing state detecting means detects that the vehicle is climbing. It can be estimated that the sulfur poisoning recovery control becomes feasible.

In the exhaust gas purifying apparatus for an internal combustion engine configured as described above, it is assumed that there is a downhill after an uphill, and the temperature of the NOx storage agent is started to rise from the time when the vehicle is in the uphill state, and the downhill light load Sometimes SOx poisoning recovery control is performed. In this way, compared with the case where the temperature increase control of the NOx storage agent is started after a light load on the downhill, SOx poisoning recovery can be performed earlier and for a longer period of time. It is possible to get many opportunities.

In the present invention, the operating state detecting means for detecting the vehicle speed, the engine speed, the speed reduction ratio and the load, and the vehicle speed, the engine speed and the speed reduction ratio when the vehicle is traveling on a level ground are used. The climbing state detection means is such that the load detected by the driving state detection means is higher than the load calculated by the basic load calculation means by a predetermined value or more for a predetermined time or more. If the vehicle continues, it can be detected that the vehicle is climbing.

The load represented by, for example, the fuel injection amount and the accelerator opening when traveling on a level ground has a substantially constant value if the vehicle speed, engine speed, and reduction ratio are determined. On the other hand, when the vehicle is in an uphill state, the load increases, and therefore, if the vehicle speed, engine speed, and reduction ratio are the same, the fuel injection amount increases and the accelerator opening increases. However, even if the temperature rise control is performed on a short uphill, there is a possibility that the subsequent downhill is also short, and SOx poisoning recovery may not be sufficiently performed. Therefore, in order to perform the temperature increase control only in the case of an uphill which is long to some extent, the temperature of the NOx storage agent is increased when the load higher than the predetermined value continues for the predetermined time or longer. In this way, it becomes possible to suppress unnecessary temperature rise of the NOx storage agent.

[0024]

BEST MODE FOR CARRYING OUT THE INVENTION Specific embodiments of an exhaust gas purification apparatus for an internal combustion engine according to the present invention will be described below with reference to the drawings. Here, the case where the exhaust gas purification apparatus for an internal combustion engine according to the present invention is applied to a diesel engine for driving a vehicle will be described as an example. <First Embodiment> FIG. 1 is a diagram showing a schematic configuration of an engine 1 to which an exhaust emission control device according to the present embodiment is applied and an intake / exhaust system thereof.

The engine 1 shown in FIG. 1 is a water-cooled four-cycle diesel engine having four cylinders 2.

The engine 1 is equipped with a fuel injection valve 3 for directly injecting fuel into the combustion chamber of each cylinder 2. Each fuel injection valve 3 is connected to a pressure accumulator (common rail) 4 that accumulates fuel to a predetermined pressure. A common rail pressure sensor 4a that outputs an electric signal corresponding to the pressure of the fuel in the common rail 4 is attached to the common rail 4.

The common rail 4 communicates with a fuel pump 6 via a fuel supply pipe 5. This fuel pump 6
Is a pump that operates using the rotational torque of the output shaft (crankshaft) of the engine 1 as a drive source. A pump pulley 6a attached to the input shaft of the fuel pump 6 is attached to the output shaft (crankshaft) of the engine 1. The crank pulley 1a is connected to the crank pulley 1a via a belt 7.

In the fuel injection system thus constructed, when the rotational torque of the crankshaft is transmitted to the input shaft of the fuel pump 6, the fuel pump 6 is transmitted from the crankshaft to the input shaft of the fuel pump 6. The fuel is discharged at a pressure according to the rotating torque.

The fuel discharged from the fuel pump 6 is
It is supplied to the common rail 4 through the fuel supply pipe 5, accumulated in the common rail 4 up to a predetermined pressure, and distributed to the fuel injection valve 3 of each cylinder 2. When a drive current is applied to the fuel injection valve 3, the fuel injection valve 3 opens, and as a result, fuel is injected from the fuel injection valve 3 into the cylinder 2.

Next, an intake branch pipe 8 is connected to the engine 1, and each branch pipe of the intake branch pipe 8 communicates with a combustion chamber of each cylinder 2 through an intake port (not shown). There is.

The intake branch pipe 8 is connected to the intake pipe 9,
The intake pipe 9 is connected to the air cleaner box 10. An air flow meter 11 for outputting an electric signal corresponding to the mass of the intake air flowing through the intake pipe 9 and an intake air temperature flowing through the intake pipe 9 are provided in the intake pipe 9 downstream of the air cleaner box 10. The intake air temperature sensor 12 that outputs the electric signal is attached.

An intake throttle valve 13 for adjusting the flow rate of the intake air flowing through the intake pipe 9 is provided at a portion of the intake pipe 9 located immediately upstream of the intake branch pipe 8. The intake throttle valve 13 is provided with an intake throttle actuator 14 configured by a step motor or the like for driving the intake throttle valve 13 to open and close.

The intake pipe 9 located between the air flow meter 11 and the intake throttle valve 13 is provided with a compressor housing 15a of a centrifugal supercharger (turbocharger) 15 which operates using exhaust energy as a drive source. ,
An intercooler 16 for cooling the intake air that has become hot due to being compressed in the compressor housing 15a is provided in the intake pipe 9 downstream of the compressor housing 15a.
Is provided.

In the intake system configured as described above, the intake air flowing into the air cleaner box 10 is cleaned by the filter (not shown) in the air cleaner box 10 to remove dust and the like from the intake air, and then the intake pipe 9 Through the compressor housing 15a.

The intake air flowing into the compressor housing 15a is compressed by the rotation of the compressor wheel installed in the compressor housing 15a. The intake air, which has been compressed in the compressor housing 15a and has reached a high temperature, is cooled by the intercooler 16 and then flows into the intake branch pipe 8 with its flow rate adjusted by the intake throttle valve 13 if necessary. The intake air that has flowed into the intake branch pipe 8 is distributed to the combustion chamber of each cylinder 2 through each branch pipe, and is burned using the fuel injected from the fuel injection valve 3 of each cylinder 2 as an ignition source.

On the other hand, an exhaust branch pipe 18 is connected to the engine 1, and each branch pipe of the exhaust branch pipe 18 communicates with a combustion chamber of each cylinder 2 through an exhaust port (not shown).

The exhaust branch pipe 18 serves as the centrifugal supercharger 15.
Is connected to the turbine housing 15b. The turbine housing 15b is connected to an exhaust pipe 19, and the exhaust pipe 19 is connected downstream to a muffler (not shown).

An occlusion reduction type N is provided in the middle of the exhaust pipe 19.
A particulate filter carrying an Ox catalyst (hereinafter,
Simply called a filter. ) 20 are provided. An exhaust gas temperature sensor 24 that outputs an electric signal corresponding to the temperature of the exhaust gas flowing through the exhaust pipe 19 is attached to the exhaust pipe 19 upstream of the filter 20.

Exhaust pipe 1 downstream of the above-mentioned filter 20
An exhaust throttle valve 21 for adjusting the flow rate of the exhaust gas flowing through the exhaust pipe 19 is provided in the valve 9. This exhaust throttle valve 2
1, an exhaust throttle valve 2 which is composed of a step motor or the like
An exhaust throttle actuator 22 for driving to open and close 1 is attached.

In the exhaust system thus constructed, the air-fuel mixture (burnt gas) burned in each cylinder 2 of the engine 1 is discharged to the exhaust branch pipe 18 through the exhaust port, and then the exhaust branch pipe 18 is exhausted. Turbine housing 15b of centrifugal supercharger 15
Flow into. The exhaust gas flowing into the turbine housing 15b uses the energy of the exhaust gas to rotate the turbine wheel rotatably supported in the turbine housing 15b. At that time, the rotational torque of the turbine wheel is transmitted to the compressor wheel of the compressor housing 15a described above.

The exhaust gas discharged from the turbine housing 15b flows into the filter 20 through the exhaust pipe 19, the particulate matter (hereinafter referred to as PM) in the exhaust gas is collected, and the harmful gas component is removed or. Purified. The exhaust gas, in which the PM is collected by the filter 20 and the harmful gas component is removed or purified, is discharged into the atmosphere through the muffler after the flow rate is adjusted by the exhaust throttle valve 21 as necessary.

The exhaust branch pipe 18 and the intake branch pipe 8 are exhaust gas recirculation passages (hereinafter referred to as EGR passages) for recirculating a part of the exhaust gas flowing in the exhaust branch pipe 18 to the intake branch pipe 8. )
25 are communicated with each other. In the middle of the EGR passage 25, an exhaust valve (hereinafter, referred to as EG, which is composed of a solenoid valve or the like, flows through the EGR passage 25 according to the magnitude of the applied power.
R gas. ) Flow rate adjustment valve (hereinafter,
Use EGR valve. ) 26 are provided.

In the middle of the EGR passage 25, the EGR valve 26
An EGR cooler 27 that cools the EGR gas flowing through the EGR passage 25 is provided further upstream. A cooling water passage (not shown) is provided in the EGR cooler 27, and a part of the cooling water for cooling the engine 1 circulates.

In the exhaust gas recirculation mechanism constructed as described above, when the EGR valve 26 is opened, the EGR passage 25 is brought into conduction, and a part of the exhaust gas flowing through the exhaust branch pipe 18 is part of the EGR passage 25. To the intake branch pipe 8 via the EGR cooler 27.

At this time, in the EGR cooler 27, heat exchange is performed between the EGR gas flowing in the EGR passage 25 and the cooling water of the engine 1 to cool the EGR gas.

The EGR gas recirculated from the exhaust branch pipe 18 to the intake branch pipe 8 through the EGR passage 25 is introduced into the combustion chamber of each cylinder 2 while being mixed with the fresh air flowing from the upstream side of the intake branch pipe 8. Get burned.

Here, the EGR gas contains an inert gas component such as water (H ₂ O) and carbon dioxide (CO ₂ ) which does not burn by itself and has a high heat capacity. Therefore, when EGR gas is contained in the air-fuel mixture, the combustion temperature of the air-fuel mixture is lowered, and thus nitrogen oxide (NOx)
Is suppressed.

Further, when the EGR gas is cooled in the EGR cooler 27, the temperature of the EGR gas itself is reduced and the volume of the EGR gas is reduced, so that when the EGR gas is supplied into the combustion chamber, the EGR gas is reduced. The ambient temperature of 1 is not unnecessarily increased, and the amount of fresh air (volume of fresh air) supplied into the combustion chamber is not unnecessarily reduced.

Next, the filter 20 according to this embodiment will be described.

FIG. 2 is a sectional view of the filter 20. FIG. 2A is a view showing a cross section in the lateral direction of the filter 20. FIG. 2B is a diagram showing a vertical cross section of the filter 20.

As shown in FIGS. 2A and 2B, the filter 20 is of a so-called wall flow type having a plurality of exhaust flow passages 50 and 51 extending in parallel with each other. These exhaust flow passages are composed of an exhaust inflow passage 50 whose downstream end is closed by a plug 52 and an exhaust outflow passage 51 whose upstream end is closed by a plug 53. The hatched portion in FIG. 2A indicates the plug 53. Therefore, the exhaust inflow passages 50 and the exhaust outflow passages 51 are alternately arranged via the thin partition walls 54. In other words, in the exhaust inflow passage 50 and the exhaust outflow passage 51, each exhaust inflow passage 50 is surrounded by four exhaust outflow passages 51, and each exhaust outflow passage 51 includes four exhaust inflow passages 50.
It is arranged to be surrounded by.

The filter 20 is made of, for example, a porous material such as cordierite, so that the exhaust gas flowing into the exhaust gas inflow passage 50 flows in the surrounding partition wall 54 as shown by the arrow in FIG. 2 (B). It flows out into the adjacent exhaust outflow passage 51.

In the embodiment according to the present invention, each exhaust inflow passage 5
0 and the peripheral wall surface of each exhaust outflow passage 51, that is, each partition wall 54
A carrier layer made of, for example, alumina is formed on both side surfaces of the above and on the inner wall surface of the pores in the partition wall 54, and the occlusion reduction type NOx catalyst is carried on this carrier.

Next, the function of the NOx storage reduction catalyst carried by the filter 20 according to this embodiment will be described.

The filter 20 uses, for example, alumina as a carrier, and potassium (K) and sodium (N) are deposited on the carrier.
a), an alkali metal such as lithium (Li) or cesium (Cs), an alkaline earth such as barium (Ba) or calcium (Ca), and a rare earth such as lanthanum (La) or yttrium (Y). And at least one of them is carried and a noble metal such as platinum (Pt). In the present embodiment, barium (Ba) and platinum (Pt) are supported on a carrier made of alumina, and ceria (Ce ₂ O ₃ ) having an O ₂ storage capacity is further supported.
An NOx storage reduction catalyst was added.

The NOx catalyst thus constructed is
When the exhaust gas flowing into the Ox catalyst has a high oxygen concentration, nitrogen oxides (NOx) in the exhaust gas are stored.

On the other hand, the NOx catalyst releases the stored nitrogen oxides (NOx) when the oxygen concentration of the exhaust gas flowing into the NOx catalyst decreases. At that time, if a reducing component such as hydrocarbon (HC) or carbon monoxide (CO) is present in the exhaust gas, the NOx catalyst converts the nitrogen oxide (NOx) released from the NOx catalyst into nitrogen (N). It can be reduced to ₂ ).

By the way, when the engine 1 is in the lean burn operation, the air-fuel ratio of the exhaust gas discharged from the engine 1 becomes a lean atmosphere and the oxygen concentration of the exhaust gas becomes high.
Nitrogen oxides (NOx) contained in the exhaust gas will be stored in the NOx catalyst, but if the lean burn operation of the engine 1 is continued for a long period of time, the NOx storage capacity of the NOx catalyst will be saturated, and Nitrogen oxides (NOx) are released into the atmosphere without being removed by the NOx catalyst.

In particular, in a diesel engine such as the engine 1, a lean air-fuel ratio mixture is burned in most operating regions, and accordingly, the exhaust air-fuel ratio becomes lean air-fuel ratio in most operating regions. , N of NOx catalyst
Ox storage capacity is easily saturated.

Therefore, when the engine 1 is in the lean burn operation, the concentration of oxygen in the exhaust flowing into the NOx catalyst is lowered and the concentration of the reducing agent is increased before the NOx storage capacity of the NOx catalyst is saturated, and the NOx concentration is increased. It is necessary to reduce the nitrogen oxides (NOx) stored in the catalyst.

As a method of lowering the oxygen concentration in this way, after the fuel addition in the exhaust gas or the amount of EGR gas to be recirculated is increased to increase the soot generation amount to the maximum and then the EGR gas amount is further increased. Although a method such as low temperature combustion for increasing the amount of fuel and changing the fuel injection timing and the number of times into the cylinder 2 can be considered, in the present embodiment, the fuel which is a reducing agent is contained in the exhaust gas flowing through the exhaust pipe 19 upstream of the filter 20. A reducing agent supply mechanism for adding (light oil) is provided, and by adding fuel from the reducing agent supply mechanism to the exhaust gas, the oxygen concentration of the exhaust gas flowing into the filter 20 is reduced and the concentration of the reducing agent is increased. did.

As shown in FIG. 1, the reducing agent supply mechanism is installed so that its injection hole faces the inside of the exhaust branch pipe 18, and is opened by a signal from the ECU 35 to inject fuel. 28, a reducing agent supply path 29 that guides the fuel discharged from the fuel pump 6 to the reducing agent injection valve 28, and a distribution of the fuel in the reducing agent supply path 29 that is provided in the reducing agent supply path 29. And a shutoff valve 31 for shutting off.

In such a reducing agent supply mechanism, the high-pressure fuel discharged from the fuel pump 6 is applied to the reducing agent injection valve 28 via the reducing agent supply passage 29. And ECU3
The reducing agent injection valve 28 is opened by a signal from 5 and fuel as a reducing agent is injected into the exhaust branch pipe 18.

The reducing agent injected from the reducing agent injection valve 28 into the exhaust branch pipe 18 reduces the oxygen concentration of the exhaust gas flowing from the upstream side of the exhaust branch pipe 18.

The thus formed exhaust gas having a low oxygen concentration flows into the filter 20 and reduces the nitrogen oxides (NOx) stored in the filter 20 to nitrogen (N ₂ ).

After that, the reducing agent injection valve 28 is closed by a signal from the ECU 35, and the addition of the reducing agent into the exhaust branch pipe 18 is stopped.

In the present embodiment, the fuel is injected into the exhaust gas to add the fuel, but instead of this, the low temperature combustion may be performed, and the expansion stroke of the engine 1 and the exhaust gas may be changed. Sub-injection in which fuel is injected from the fuel injection valve 3 may be performed during a stroke or the like.

The engine 1 configured as described above is provided with an electronic control unit (ECU) 35 for controlling the engine 1. The ECU 35 is a unit that controls the operating state of the engine 1 in accordance with the operating conditions of the engine 1 and the driver's request.

The ECU 35 includes the common rail pressure sensor 4
a, an air flow meter 11, an intake air temperature sensor 12, an intake pipe pressure sensor 17, an exhaust gas temperature sensor 24, a crank position sensor 33, a water temperature sensor 34, an accelerator opening sensor 36, and other various sensors are connected via electrical wiring. Output signals of the various sensors are input to the ECU 35.

On the other hand, the ECU 35 has a fuel injection valve 3, an intake throttle actuator 14, an exhaust throttle actuator 22, a reducing agent injection valve 28, an EGR valve 26, and a shutoff valve 31.
Etc. are connected via electrical wiring, and the above-mentioned parts are connected to the ECU.
35 can be controlled.

Here, the ECU 35, as shown in FIG. 3, is connected to each other by a bidirectional bus 350, C
The input port 356 includes a PU 351, a ROM 352, a RAM 353, a backup RAM 354, an input port 356, and an output port 357.
And an A / D converter (A / D) 355 connected to.

The input port 356 inputs the output signals of a sensor that outputs a digital signal format signal such as the crank position sensor 33, and outputs those output signals to C.
It is transmitted to the PU 351 and the RAM 353.

The input port 356 is used for the common rail pressure sensor 4a, the air flow meter 11, and the intake air temperature sensor 1.
2, such as the intake pipe pressure sensor 17, the exhaust gas temperature sensor 24, the water temperature sensor 34, the accelerator opening sensor 36, etc., which are input through the A / D 355 of a sensor that outputs a signal in an analog signal format, and output signals thereof CPU351 and RA
Send to M353.

The output port 357 is connected to the fuel injection valve 3,
Intake throttle actuator 14, exhaust throttle actuator 22, EGR valve 26, reducing agent injection valve 28, shutoff valve 3
1 and the like via electric wiring, and outputs control signals output from the CPU 351 to the fuel injection valve 3, the intake throttle actuator 14, the exhaust throttle actuator 2 described above.
2, to the EGR valve 26, the reducing agent injection valve 28, or the shutoff valve 31.

The ROM 352 includes a fuel injection control routine for controlling the fuel injection valve 3, an intake throttle control routine for controlling the intake throttle valve 13, an exhaust throttle control routine for controlling the exhaust throttle valve 21, and an EGR valve. 26, an EGR control routine for controlling 26, a NOx purification control routine for adding a reducing agent to the filter 20 to reduce the stored NOx, a poisoning elimination control routine for eliminating SOx poisoning of the filter 20, and a trap for the filter 20. An application program such as a PM combustion control routine for burning and removing the collected PM is stored.

The ROM 352 stores various control maps in addition to the above application programs. The control map is, for example, a fuel injection amount control map showing the relationship between the operating state of the engine 1 and the basic fuel injection amount (basic fuel injection time), and the fuel showing the relationship between the operating state of the engine 1 and the basic fuel injection timing. Injection timing control map,
An intake throttle valve opening control map showing the relationship between the operating state of the engine 1 and the target opening degree of the intake throttle valve 13, and an exhaust throttle valve opening map showing the relationship between the operating state of the engine 1 and the target opening degree of the exhaust throttle valve 21. Control map, engine 1 operating status and EGR
An EGR valve opening control map showing the relationship with the target opening of the valve 26, a reducing agent addition control map showing the relationship between the operating state of the engine 1 and the target addition of the reducing agent (or the target air-fuel ratio of the exhaust gas), It is a reducing agent injection valve control map and the like showing the relationship between the target addition amount of the reducing agent and the valve opening time of the reducing agent injection valve 28.

The RAM 353 stores the output signal from each sensor, the calculation result of the CPU 351 and the like. The calculation result is, for example, the engine speed calculated based on the time interval at which the crank position sensor 33 outputs a pulse signal. These data are rewritten to the latest data each time the crank position sensor 33 outputs a pulse signal.

The backup RAM 354 is a non-volatile memory capable of storing data even after the engine 1 is stopped.

The CPU 351 operates according to the application program stored in the ROM 352 to control the fuel injection valve, the intake throttle control, the exhaust throttle control, E
GR control, NOx purification control, poisoning elimination control, PM combustion control, etc. are executed.

For example, in the NOx purification control, the CPU 35
1 executes so-called rich spike control in which the oxygen concentration in the exhaust gas flowing into the filter 20 is reduced in a spike-like (short time) manner in a relatively short cycle.

In the rich spike control, the CPU 351
Determines whether the rich spike control execution condition is satisfied every predetermined period. As the rich spike control execution condition, for example, the filter 20 is in an active state, the output signal value (exhaust temperature) of the exhaust temperature sensor 24 is equal to or lower than a predetermined upper limit value, poisoning elimination control is not executed, Examples of such conditions are as follows.

When it is determined that the rich spike control execution condition as described above is satisfied, the CPU 351
Controls the reducing agent injection valve 28 so that the reducing agent injection valve 28 injects fuel as the reducing agent in a spike manner to temporarily change the air-fuel ratio of the exhaust gas flowing into the filter 20 to a predetermined target rich air-fuel ratio. And

Specifically, the CPU 351 has the RAM 35.
Engine speed, accelerator opening sensor 3 stored in 3
6 output signal (accelerator opening), air flow meter 11
Output signal value (intake air amount), output signal of the air-fuel ratio sensor, fuel injection amount, and the like.

The CPU 351 accesses the reducing agent addition amount control map of the ROM 352 by using the engine speed, the accelerator opening, the intake air amount, and the fuel injection amount as parameters, and sets the exhaust air-fuel ratio to the preset target air-fuel ratio. The amount of addition of the reducing agent (target amount of addition) required to obtain the fuel ratio is calculated.

Subsequently, the CPU 351 accesses the reducing agent injection valve control map of the ROM 352 using the target addition amount as a parameter, and the reducing agent necessary for injecting the target addition amount of the reducing agent from the reducing agent injection valve 28. The valve opening time (target valve opening time) of the injection valve 28 is calculated.

When the target opening time of the reducing agent injection valve 28 is calculated, the CPU 351 opens the reducing agent injection valve 28.

The CPU 351 closes the reducing agent injection valve 28 when the target opening time elapses from the time when the reducing agent injection valve 28 is opened.

When the reducing agent injection valve 28 is opened for the target opening time in this way, the target addition amount of fuel is injected from the reducing agent injection valve 28 into the exhaust branch pipe 18. Then, the reducing agent injected from the reducing agent injection valve 28 mixes with the exhaust gas that has flowed from the upstream side of the exhaust branch pipe 18 to form an air-fuel mixture having a target air-fuel ratio, and then flows into the filter 20.

As a result, the air-fuel ratio of the exhaust gas flowing into the filter 20 is such that the oxygen concentration changes in a relatively short cycle, so that the filter 20 stores and reduces nitrogen oxide (NOx). It will repeat alternately in a short cycle.

Next, in the poisoning elimination control, the CPU 351
Will perform a poisoning elimination process in order to eliminate the poisoning due to the oxide of the filter 20.

Here, sulfur (S) is used as the fuel for the engine 1.
When such a fuel is burned in the engine 1, sulfur oxides (SOx) such as sulfur dioxide (SO ₂ ) and sulfur trioxide (SO ₃ ) are generated.

Sulfur oxide (SOx) flows into the filter 20 together with the exhaust gas and is stored in the filter 20 by the same mechanism as nitrogen oxide (NOx).

Specifically, when the oxygen concentration of the exhaust gas flowing into the filter 20 is high, the sulfur oxides (S) such as sulfur dioxide (SO ₂ ) and sulfur trioxide (SO ₃ ) in the inflowing exhaust gas are included.
Ox) is oxidized on the surface of platinum (Pt) and stored in the filter 20 in the form of sulfate ions (SO ₄ ²⁻ ). Furthermore,
The sulfate ions (SO ₄ ²⁻ ) stored in the filter 20 are
Sulfate (BaS) combined with barium oxide (BaO)
O ₄ ) is formed.

By the way, the sulfate (BaSO ₄ ) is more stable than barium nitrate (Ba (NO ₃ ) ₂ ) and hard to decompose, and is decomposed even when the oxygen concentration of the exhaust gas flowing into the filter 20 becomes low. Instead, they remain in the filter 20.

Sulfate (BaS) in the filter 20
As the amount of O ₄ ) increases, the nitrogen oxides (N
Barium oxide (B) that can participate in the storage of Ox)
Since the amount of aO) decreases, so-called SOx poisoning occurs in which the NOx storage capacity of the filter 20 decreases.

As a method of eliminating SOx poisoning of the filter 20, the ambient temperature of the filter 20 is raised to a high temperature range of about 600 to 650 ° C. and the oxygen concentration of the exhaust gas flowing into the filter 20 is lowered. ,
Barium sulfate (BaSO) stored in the filter 20
₄₎ the SO ₃ ^- and SO ₄ ^- and pyrolyzed, followed by SO ₃ ^- and SO ₄
^- it can be exemplified a method of reducing the ^- is reacted with a hydrocarbon in the exhaust gas (HC) and carbon monoxide (CO) gaseous SO ₂ and.

Therefore, in the poisoning elimination processing according to the present embodiment, the CPU 351 first executes the catalyst temperature raising control for raising the bed temperature of the filter 20, and then lowers the oxygen concentration of the exhaust gas flowing into the filter 20. I did it.

In the catalyst temperature raising control, the CPU 351 may, for example, inject fuel secondarily from the fuel injection valve 3 and add fuel from the reducing agent injection valve 28 into the exhaust gas during the expansion stroke of each cylinder 2. Alternatively, those unburned fuel components may be oxidized in the filter 20, and the heat generated during the oxidation may raise the bed temperature of the filter 20.

However, if the temperature of the filter 20 rises excessively,
Since the heat deterioration of the filter 20 may be induced, it is preferable that the secondary injection fuel amount and the additional fuel amount be feedback-controlled based on the output signal value of the exhaust temperature sensor 24.

When the bed temperature of the filter 20 rises to a high temperature range of about 600 ° C. to 650 ° C. due to the catalyst temperature raising process as described above, the CPU 351 causes the reducing agent injection to reduce the oxygen concentration of the exhaust gas flowing into the filter 20. Fuel is injected from the valve 28.

When excessive fuel is injected from the reducing agent injection valve 28, those fuels burn rapidly in the filter 20 and the filter 20 overheats, or excessive fuel injected from the reducing agent injection valve 28 is injected. Since the filter 20 may be unnecessarily cooled by the fuel, the CPU 351 controls the reducing agent injection valve 28 based on the output signal of the air-fuel ratio sensor (not shown).
It is preferable to feedback control the fuel injection amount from.

When the poisoning elimination processing is executed in this way,
When the bed temperature of the filter 20 is high, the oxygen concentration of the exhaust gas flowing into the filter 20 becomes low, so that barium sulfate (BaSO ₄ ) stored in the filter 20 is thermally decomposed into SO ₃ ⁻ and SO ₄ ^−. The SO ₃ ⁻ and SO ₄ ⁻ react with hydrocarbons (HC) and carbon monoxide (CO) in the exhaust gas and are reduced, whereby SOx poisoning of the filter 20 is eliminated.

Even if the temperature raising control is performed, the SOx poisoning recovery is not performed unless the engine 1 is subsequently operated in the light load region. Then, the temperature of the filter 20 decreases, and it is necessary to perform the temperature increase control again in order to recover the SOx poisoning. As described above, if SOx poisoning recovery is not performed, the amount of added fuel increases and fuel consumption deteriorates.

Therefore, in the present embodiment, based on the information obtained from the navigation system mounted on the vehicle, this is estimated before the light load operation is performed and the filter 2 is used.
A temperature rise control of 0 is performed.

FIG. 4 is a schematic configuration diagram of the navigation system used in this embodiment.

Here, the navigation system used in the present embodiment is equipped with a satellite receiving antenna 96 for receiving signals from a plurality of artificial satellites arranged in outer space at an altitude of about 20,000 km. Navigation computer 9 based on signals received at 96
0 is a system for calculating the current position. A speed sensor 97 that outputs a vehicle speed signal, a gyro sensor 98 that detects an angular velocity of the vehicle, a display unit 92 that displays a map display and the position of the vehicle, and road information is received and demodulated and output to the navigation computer 90. A road traffic information system computer 91 and the like are connected.

The navigation computer 90 calculates the own vehicle position from the signal from the satellite receiving antenna 96,
Further, the vehicle position is determined by combining the self-contained navigation that detects the moving distance and the traveling direction based on the signals from the speed sensor 97, the gyro sensor 98 and the like. Then, the position of the vehicle is compared with the map data to correct the vehicle so that it is on the road.

Further, the road traffic information system computer 91 uses the FM radio antenna 95 for receiving radio waves from the FM broadcasting station, the radio wave beacon installed on the side of the road, and the traffic congestion information and traffic regulations sent from the optical beacon. It is provided with a radio wave beacon receiving antenna 93 and an optical beacon receiving antenna 94 capable of receiving road traffic information. The signal received by each antenna includes traffic jam information, construction information, traffic regulation information, and the like. The road traffic information system computer 91 demodulates the signal received by each antenna and transfers it to the navigation computer 90.
The navigation computer 90 receiving this signal
Display unit 9 processes each signal and displays road traffic information
Display on 2.

Thus, the navigation system makes it possible to obtain the vehicle position and road traffic information.

Next, a method of determining the start of the filter temperature raising control according to this embodiment will be described.

As described above, the SOx poisoning recovery control is performed when the load is light. Therefore, while driving on the highway,
x Poisoning recovery control is rarely performed. However, when traveling on the highway for a long time, the amount of SOx absorbed increases,
SOx poisoning recovery may be required. Here, since the light load operation may be performed even on the expressway, the SOx poisoning recovery control can be performed in such a case. For example, when a vehicle enters a service area or a parking area, is running on an interchange, passes through a checkpoint or toll gate with temporary stoppage, or is driving on a road during traffic jams or under construction. Is likely to be done.

Further, when the vehicle is traveling in the suburbs, it is operated in a relatively high load region. Therefore, the greater the number of traffic lights and intersections, the higher the probability that light load operation with temporary stop will be performed. In addition, the number of vehicles increases as the distance to the urban area increases, and light-duty driving increases.

Furthermore, in the city area, the traffic volume of vehicles is large,
In addition, since there are many signals, it is often operated with a light load. Further, in urban areas, there is a large difference in traffic volume between commuting hours, daytime, and nighttime, and there is a high possibility that driving will be performed in a light load area, especially during commuting hours because of the large traffic volume. On the other hand, there is a large difference in traffic volume between the case of a metropolitan area and the case of not so, and a large city is often driven with a light load.

As described above, the possibility that the light load operation is performed greatly differs depending on the place where the vehicle is traveling, the time zone, the route, the vehicle speed, and the like. In the present embodiment, the temperature rise control of the filter 20 is started when the possibility of becoming a light load state becomes high.

Next, the flow of temperature raising control according to this embodiment will be described.

FIG. 5 is a flow chart showing the flow of temperature raising control according to the present embodiment.

In step S101, it is determined whether or not SOx poisoning recovery control needs to be performed. The determination condition can be determined based on the amount of fuel added, an output signal from a NOx sensor (not shown), the traveling distance of the vehicle, and the like.
Since the NOx storage reduction catalyst supported on the filter 20 is poisoned by the sulfur component in the fuel, the amount of fuel added is stored in the RAM 353, and when the amount of fuel added reaches a predetermined amount, SOx is stored. It may be used as a start condition for poisoning recovery control. In addition, if SOx poisoning progresses, NOx storage reduction type
The amount of NOx stored in the catalyst decreases, and the amount of NOx flowing downstream of the filter 20 increases. Therefore, a NOx sensor (not shown) may be provided downstream of the filter 20, the output signal thereof may be monitored, and the condition for starting the SOx poisoning recovery control may be set when the NOx distribution amount exceeds a predetermined amount. Further, when the vehicle travel distance becomes equal to or greater than a predetermined value, it is necessary to recover the SOx poisoning, and this time may be set as the start condition of the SOx poisoning recovery control.

If an affirmative decision is made in step S101, the operation proceeds to step S102, while if a negative decision is made, this routine is ended.

In step S102, the current position is read. The ECU 35 accesses the navigation computer 90 and reads the current position. It should be noted that in the present embodiment, whether or not the temperature raising control of the filter 20 can be executed is determined by classifying the vehicle position into three types: expressway, suburbs, and urban areas. Here, the map data may be classified in advance into three types of expressways, suburbs, and urban areas, and the position of the vehicle may be read.

In step S103, it is determined whether or not the current vehicle position is on the highway. The CPU 351 determines whether or not the current position is on the highway based on the map data. When a positive determination is made, step S10
4, the process proceeds to step S106 if a negative determination is made.

In step S104, information is read from the navigation system. The information read at this time is whether or not the route has been changed to a service area, a parking area, or an interchange, and whether or not there is a ticket inspection station, toll gate, traffic jam, road construction, etc. in the traveling direction.

In step S105, it is determined whether or not the temperature raising control of the filter 20 is started. Step S104
If the route is changed to a service area, parking area, or interchange based on the information of the navigation system read in, or if there is a checkpoint, tollgate, traffic jam, construction, etc. within the predetermined range of the vehicle traveling direction. The temperature rise control of the filter 20 is started.

If an affirmative decision is made in step S105, the operation proceeds to step S111, while if a negative decision is made, the operation proceeds to step S112.

In step S106, it is determined whether or not the current vehicle position is in the suburbs. The CPU 351 determines whether or not the current position is in the suburbs based on the map data. If an affirmative determination is made, the process proceeds to step S107, while if a negative determination is made, the process proceeds to step S109.

In step S107, information is read from the navigation system. At this time, what is read is whether or not there are traffic lights, intersections, and the like in the traveling direction of the vehicle, whether or not the current vehicle position is around the city area, and the like.

In step S108, it is determined whether or not the temperature raising control of the filter 20 is started. Step S107
When there is a signal, an intersection, or the like within a predetermined range in the vehicle traveling direction based on the information of the navigation system read by, the temperature rise control of the filter 20 is started when the current vehicle position is around the city.

If an affirmative decision is made in step S108, the operation proceeds to step S111, while if a negative decision is made, the operation proceeds to step S112.

In step S109, information is read from the navigation system. The information read at this time is the interval between intersections in the vehicle traveling direction, the speed of the vehicle, the current time, or whether or not it is a metropolitan area.

In step S110, it is determined whether or not the temperature raising control of the filter 20 is started. Step S109
When the interval between the intersections in the vehicle traveling direction is within a predetermined interval based on the navigation system information read by, the vehicle speed of the vehicle is less than or equal to a predetermined value, and when the current time corresponds to the commuting time zone, the filter 20 The temperature rise control is started. These predetermined values can be changed depending on whether or not it is a metropolitan area.

In step S111, the temperature rise control of the filter 20 is performed, and then the SOx poisoning recovery control is performed when shifting to the light load operation.

In step S112, the temperature rise control is prohibited and the present routine ends.

In this way, it is possible to determine whether or not the temperature raising control can be executed.

Here, the conventional temperature raising control is executed when SOx of a predetermined amount or more is stored in the NOx catalyst.
However, if the light load operation is not performed thereafter, the SOx poisoning recovery control is not performed, and it is necessary to raise the temperature again and the fuel consumption amount is increased.

On the other hand, in the exhaust gas purification apparatus for an internal combustion engine according to the present embodiment, the temperature rise control is performed only when the light load operation is likely to be performed, so that the fuel consumption amount can be reduced. .

As described above, in the exhaust gas purification device for an internal combustion engine according to the present embodiment, it is possible to reduce the fuel consumption amount associated with the filter temperature raising control and improve the fuel consumption. <Second Embodiment> This embodiment is different from the first embodiment in the following points.

In the first embodiment, execution determination of the temperature rise control of the filter 20 is made based on the information from the navigation system, but in the present embodiment, the determination is made from the traveling history of the vehicle.

Although the present embodiment is different from the first embodiment in that the navigation system is not used, the basic configuration of the engine 1 and other hardware to which the present invention is applied is the same as that of the first embodiment. The description is omitted because it is the same as that of the first embodiment.

In the present embodiment, the place where the vehicle is currently traveling is estimated from the traveling history of the vehicle, and it is determined whether or not the temperature raising control is performed based on the estimated place. In the present embodiment, the traveling locations of the vehicles are classified into three types: expressways, suburbs, and other urban areas. Here, the vehicle speed is high while traveling on the highway, and that state continues for a long time. In addition, while traveling in the suburbs, the vehicle speed is faster than in urban areas, and moreover, the state continues for a longer time.

Therefore, in the present embodiment, the current position of the vehicle is estimated based on the average speed of the vehicle and its duration.

Next, the flow of the temperature increase control execution determination method according to this embodiment will be described.

FIG. 6 is a flow chart showing the flow of the temperature increase control execution determination method according to the present embodiment.

In step S201, it is determined whether it is necessary to perform SOx poisoning recovery control. The determination condition can be determined based on the amount of fuel added, an output signal from a NOx sensor (not shown), the traveling distance of the vehicle, and the like.
Since the NOx storage reduction catalyst supported on the filter 20 is poisoned by the sulfur component in the fuel, the amount of fuel added is stored in the RAM 353, and when the amount of fuel added reaches a predetermined amount, SOx is stored. It may be used as a start condition for poisoning recovery control. In addition, if SOx poisoning progresses, NOx storage reduction type
The amount of NOx stored in the catalyst decreases, and the amount of NOx flowing downstream of the filter 20 increases. Therefore, a NOx sensor (not shown) may be provided downstream of the filter 20, the output signal thereof may be monitored, and the condition for starting the SOx poisoning recovery control may be set when the NOx distribution amount exceeds a predetermined amount. Further, when the vehicle travel distance becomes equal to or greater than a predetermined value, it is necessary to recover the SOx poisoning, and this time may be set as the start condition of the SOx poisoning recovery control.

If an affirmative judgment is made in step S201, the routine proceeds to step S202, while if a negative judgment is made, this routine is ended.

In step S202, the traveling conditions of the vehicle are read. It is the history of speed that is read. The vehicle speed is obtained based on the pulse transmitted by the speed sensor (not shown). The CPU 351 reads the speed history for the past 5 minutes stored in the RAM 353.

In step S203, the traveling mode is determined. Here, it is assumed that the vehicle is traveling on an expressway when the average vehicle speed of 70 km / h or more continues for 5 minutes or more.
If the SOx poisoning recovery control is performed in such a case, the temperature of the filter 20 becomes too high, which causes thermal deterioration of the filter 20. Therefore, the SOx poisoning recovery control is not performed while traveling on the highway.

If an affirmative decision is made in step S203, the operation proceeds to step S207, while if a negative decision is made, the operation proceeds to step S204.

At step S204, the average vehicle speed is 50 km / h.
It is determined whether the above state has continued for 3 minutes or more. Here, it is assumed that the vehicle is traveling on a road in the suburbs when the average vehicle speed of 50 km / h or more continues for 3 minutes or more. In such a case, there is a possibility of shifting to light load operation, and at this time, the temperature rise control of the filter 20 can be performed.

If an affirmative decision is made in step S204, the operation proceeds to step S205, while if a negative decision is made, the operation proceeds to step S210.

In step S205, the engine speed and the accelerator opening are read. CPU351 is RA
By accessing M353, the output signals of the crank position sensor 33 and the accelerator opening sensor 36 are read.

In step S206, it is determined whether or not it is in the idle state. The CPU 351 determines that the engine is in the idle state when the engine speed is equal to or lower than a predetermined idle engine speed and the accelerator opening is fully closed.

If an affirmative decision is made in step S206, the operation proceeds to step S210, while if a negative decision is made, the operation proceeds to step S208.

In step S207, the current vehicle speed is 40
It is judged whether or not it is less than km / h. When the vehicle speed becomes 40 km / h or less when traveling on a highway, a determination is made to immediately start the temperature rise control. This is because in such a situation, the opportunity for the temperature rise control may be lost unless the temperature rise control is immediately performed.

If an affirmative decision is made in step S207, the operation proceeds to step S210, while if a negative decision is made, the operation proceeds to step S208.

In step S208, the congestion information of the highway radio which transmits the congestion information of the expressway via the radio is read.

In step S209, it is determined whether or not there is traffic jam in the traveling direction. Determine the distance to the traffic jam point,
The traffic jam information is used to start the temperature rise control when approaching the traffic jam.

If an affirmative decision is made in step S209, the operation proceeds to step S210, while if a negative decision is made, the operation proceeds to step S211.

In step S210, the temperature rise control of the filter 20 is performed, and then the SOx poisoning recovery control is performed when shifting to the light load operation.

In step S211, the temperature raising control is prohibited and the present routine ends.

In this way, it is possible to determine the conditions for executing the temperature raising control.

Here, the conventional temperature raising control is executed when SOx of a predetermined amount or more is stored in the NOx catalyst.
However, if the light load operation is not performed thereafter, the SOx poisoning recovery control is not performed and the temperature rise is required again, which causes the deterioration of fuel efficiency.

On the other hand, in the exhaust gas purifying apparatus for an internal combustion engine according to the present embodiment, the temperature rise control is performed only when the light load operation is likely to be performed, so that the fuel consumption amount can be reduced. Becomes

As described above, in the exhaust gas purification device for an internal combustion engine according to the present embodiment, the fuel consumption amount associated with the filter temperature raising control can be reduced and the fuel consumption can be improved. <Third Embodiment> This embodiment is different from the first embodiment in the following points.

In the first embodiment, the execution determination of the temperature raising control of the filter 20 is made based on the information from the navigation system, but in the present embodiment, the determination is made from the driving state of the vehicle.

Although the present embodiment is different from the first embodiment in that the navigation system is not used, the basic configuration of the engine 1 and other hardware to which the present invention is applied is the same as that of the first embodiment. The description is omitted because it is the same as that of the first embodiment.

In the present embodiment, the temperature rise control is performed when the vehicle is traveling uphill. Here, the load is low when the vehicle is traveling on a flat ground, and is high when the vehicle is traveling uphill. When the SOx poisoning recovery control is performed when the load is high, the catalyst overheats and induces thermal deterioration, so it is difficult to perform the SOx poisoning recovery control on the uphill. On the other hand, on a downhill, the load becomes low and deceleration may occur, so the operating state is suitable for SOx poisoning recovery control.

However, if the temperature of the catalyst is raised and the SOx poisoning recovery is carried out after the vehicle has entered the downhill, the load becomes high during that time, and there is a risk that the opportunity for SOx poisoning recovery will be lost. Further, even if the temperature rise of the catalyst is completed while traveling on a downhill, there is a possibility that the SOx poisoning recovery time is shortened and the recovery may not be performed sufficiently.

Therefore, in the present embodiment, temperature rising control for SOx poisoning recovery is started while the vehicle is traveling uphill. Here, if the vehicle is traveling on level ground, the vehicle speed,
When the engine speed and the reduction ratio (shift position) are determined, the load (for example, fuel injection amount, accelerator opening) is determined as a predetermined value. This load can be obtained in advance by experiments or the like and made into a map. On the other hand, the load actually applied to the engine can be detected by, for example, actually measuring the fuel injection amount and the accelerator opening. Therefore, the vehicle speed,
By actually detecting the engine speed, the reduction ratio (shift position), and the load, it is determined whether or not the load detected at that time is higher than the load during flatland traveling (the load determined by the map), If the actual load is higher than the load during flatland traveling, it can be determined that the vehicle is traveling uphill, for example.

However, there is a situation in which the load on the engine becomes high in addition to the uphill road, and even if the uphill road is actually running, if the uphill road is short, the effect will be obtained even if the temperature rise control is performed. Is small. Therefore, in the present embodiment, the temperature of the catalyst is raised when the load condition of a predetermined value or more continues for a predetermined time or more.

Next, the flow of the temperature increase control execution determination method according to this embodiment will be described.

FIG. 7 is a flow chart showing the flow of the temperature increase control execution determination method according to the present embodiment.

At step S301, S of the filter 20
It is determined whether or not Ox poisoning recovery control needs to be performed.
The determination condition can be determined based on the amount of fuel added, an output signal from a NOx sensor (not shown), the traveling distance of the vehicle, and the like. Since the NOx storage reduction catalyst supported on the filter 20 is poisoned by the sulfur component in the fuel, the amount of fuel added is stored in the RAM 353, and when the amount of fuel added reaches a predetermined amount, SOx is stored. It may be used as a start condition for poisoning recovery control. Further, when SOx poisoning proceeds, the amount of NOx stored in the NOx storage reduction catalyst decreases, and the amount of NOx flowing downstream of the filter 20 increases. Therefore,
A NOx sensor (not shown) may be provided downstream of the filter 20, the output signal thereof may be monitored, and the condition for starting the SOx poisoning recovery control may be set when the amount of NOx flowing exceeds a predetermined amount. Further, when the vehicle travel distance becomes equal to or greater than a predetermined value, it is necessary to recover the SOx poisoning, and this time may be set as the start condition of the SOx poisoning recovery control.

If an affirmative judgment is made in step S301, the routine proceeds to step S302, while if a negative judgment is made, this routine is ended.

In step S302, PM combustion control is executed and PM regeneration of the filter 20 is performed. Here, the filter 20 in a state in which PM is accumulated to recover SOx poisoning
When rich air-fuel ratio exhaust gas is supplied to the
Rapidly burns and the filter 20 overheats. This overheating induces thermal deterioration of the filter 20 and causes a reduction in NOx reduction ability. Therefore, in the present embodiment,
The PM regeneration of the filter 20 is performed before the SOx poisoning recovery control.

The PM regeneration is performed by the catalyst temperature rise control. At this time, the temperature of the filter 20 may be detected and feedback control based on the temperature of the filter 20 may be performed.

In step S303, it is determined whether PM regeneration is completed. For the determination, for example, the filter 20
Is provided with a reducing agent for a predetermined time, or a differential pressure sensor (not shown) for measuring the pressure difference between the exhaust gas upstream and downstream of the filter 20 is provided, and the amount of PM remaining in the filter 20 is estimated based on this output signal. May be. Besides, for example, it is possible to determine the residual amount of PM based on the decrease in the front pressure of the filter 20 (back pressure upstream of the filter 20) or the intake air amount.

If an affirmative decision is made in step S303, the operation proceeds to step S304, while if a negative decision is made, the operation returns to step S302.

In step S304, it is determined whether the vehicle is traveling uphill. Specifically, it is determined by the uphill determination logic in step S401 and subsequent steps, which will be described later.

If an affirmative decision is made in step S304, the operation proceeds to step S305, while if a negative decision is made, the operation returns to step S304.

In step S305, temperature raising control for SOx poisoning recovery is executed.

In step S306, it is determined whether the temperature of the filter 20 is within the predetermined temperature range. The range of the predetermined temperature is a temperature higher than the temperature required for SOx poisoning recovery and lower than the temperature at which thermal deterioration occurs, for example, 600 to 650 ° C.

The temperature of the filter 20 is measured by the exhaust temperature sensor 2
4 or can be obtained by a temperature sensor that directly measures the bed temperature of the filter 20.

If an affirmative decision is made in step S306, the operation proceeds to step S307, while if a negative decision is made, the operation returns to step S305.

In step S307, it is determined whether or not the vehicle is traveling downhill or is decelerating. The CPU 351 determines that the vehicle is in the light load state because the accelerator opening is smaller than the predetermined opening or the fuel injection amount is equal to or smaller than the predetermined opening. Further, it may be determined whether or not the vehicle is traveling downhill as it is determined in step S304 whether or not the vehicle is traveling uphill.

In step S308, SOx poisoning recovery control is started. The SOx poisoning recovery control is a low temperature combustion that further increases the EGR gas amount after the fuel addition in the exhaust gas or the recirculated EGR gas amount is increased to increase the soot generation amount to the maximum (Patent No. No. 3116876), secondary injection is performed by injecting fuel again during the expansion stroke after main injection for injecting fuel for engine output.

At step S309, it is judged if the SOx poisoning recovery is completed. As a determination condition, a NOx sensor (not shown) may be provided downstream of the filter 20, the output signal thereof may be monitored, and the SOx poisoning recovery may be completed when the amount of NOx flowing becomes a predetermined amount or less. Furthermore, whether or not the SOx poisoning recovery has been performed for a predetermined time may be used as the determination condition.

If an affirmative decision is made in step S309, this routine is terminated, while if a negative decision is made, the routine returns to step S308, and the SOx poisoning recovery control is continued.

In this way, it is possible to raise the temperature of the filter 20 while traveling on an uphill and to recover SOx poisoning in the subsequent downhill or decelerated state.

Next, the uphill determination logic according to this embodiment will be described.

FIG. 8 is a flowchart showing the flow of the uphill determination logic according to this embodiment.

In step S401, the engine operating state is detected. The detected operating states are the engine speed (the output signal of the crank position sensor 33), the vehicle speed, the shift position, and the load (the output signal of the accelerator opening sensor or the fuel injection amount). Here, the shift position is obtained by a shift position sensor (not shown) provided on the transmission (not shown). Further, the vehicle speed is obtained by a speed sensor (not shown) provided in the transmission.

In step S402, step S401
It is determined whether or not the actual load q read in is larger than a value obtained by adding a predetermined value to the load qstd calculated by a map previously obtained from the engine speed, the vehicle speed, and the shift position.

Here, the predetermined value is, for example, a value of 20% of the load qstd calculated by the map.

If an affirmative decision is made in step S402, the operation proceeds to step S403, while if a negative decision is made, the operation returns to step S401.

In step S403, step S402
It is determined whether or not the operating state determined in step 2 has continued for a predetermined time or longer.

Here, the predetermined time is, for example, 30 seconds. In this way, the condition for continuation for a predetermined time or more is to eliminate fluctuations in the load caused by factors other than uphill,
Also, on a short uphill, it becomes difficult to sufficiently raise the temperature of the filter 20 and subsequently recover SOx poisoning.

If an affirmative decision is made in step S403, the operation proceeds to step S404, while if a negative decision is made, the operation returns to step S401.

In step S404, it is determined that the road is uphill.

In this way, it is possible to determine whether or not the vehicle is traveling uphill. Further, similarly, it is possible to determine whether or not the vehicle is traveling on a downhill. In this case, the load q in step S402 is
It is possible to determine whether the load is smaller than a value obtained by adding a predetermined value to the load qstd determined by the engine speed, the vehicle speed, and the shift position.

Here, the conventional temperature rise control is executed when SOx of a predetermined amount or more is stored in the NOx catalyst.
However, if the light load operation is not performed thereafter, the SOx poisoning recovery control is not performed and the temperature rise is required again, which causes the deterioration of fuel efficiency.

On the other hand, in the exhaust gas purifying apparatus for an internal combustion engine according to the present embodiment, the temperature rise control is performed during uphill traveling, which is likely to be followed by a light load operation, so that the fuel consumption amount is reduced. It becomes possible.

As described above, in the exhaust gas purifying apparatus for the internal combustion engine according to the present embodiment, the fuel consumption amount associated with the filter temperature raising control can be reduced and the fuel consumption can be improved.

[0202]

In the exhaust gas purifying apparatus for an internal combustion engine according to the present invention, it is possible to estimate that before the engine operating condition required for SOx poisoning recovery control is reached and perform the temperature rise control of the filter in advance. . Therefore, unnecessary temperature rise control can be reduced, and fuel consumption can be improved. Further, SOx poisoning recovery is possible even in a light load state for a short time.

[Brief description of drawings]

FIG. 1 is a schematic configuration diagram showing an engine to which an exhaust gas purification apparatus for an internal combustion engine according to an embodiment of the present invention is applied and an intake / exhaust system thereof.

FIG. 2A is a diagram showing a lateral cross section of a particulate filter. (B) is a figure which shows the longitudinal cross section of a particulate filter.

FIG. 3 is a block diagram showing an internal configuration of an ECU.

FIG. 4 is a schematic configuration diagram of a navigation system used in the first embodiment.

FIG. 5 is a flowchart showing a temperature increase control execution determination flow according to the first embodiment.

FIG. 6 is a flowchart showing a temperature increase control execution determination flow according to the second embodiment.

FIG. 7 is a flowchart showing a flow of a temperature increase control execution determination method according to a third embodiment.

FIG. 8 is a flowchart showing a flow of an uphill determination logic according to the third embodiment.

[Explanation of symbols]

1 ... Engine 1a: Crank pulley 2 ... Cylinder 3 ... Fuel injection valve 4 ... Common rail 4a ... Common rail pressure sensor 5 ... Fuel supply pipe 6 ... Fuel pump 6a ... Pump pulley 8 ... Intake branch pipe 9 ... Intake pipe 18 ... Exhaust branch pipe 19 ... Exhaust pipe 20 ... Particulate filter 21 ... Exhaust throttle valve 24 ... Exhaust gas temperature sensor 25 ... EGR passage 26 ... EGR valve 27 ... EGR cooler 28 ... Reducing agent injection valve 29 ... Reductant supply path 31 ... Shut-off valve 33 ... Crank position sensor 34 ... Water temperature sensor 35 ... ECU 36 ... Accelerator opening sensor 90 ... Navigation computer 91: Road traffic information computer 92 ... Display 93 ... Radio beacon receiving antenna 94 ... Optical beacon receiving antenna 95 ... FM radio antenna 96 ... Satellite signal receiving antenna 97 ... Speed sensor 98: Gyro sensor

─────────────────────────────────────────────────── ─── Continuation of front page (51) Int.Cl. ⁷ Identification code FI theme code (reference) F01N 3/24 F01N 3/24 R 3/28 301 3/28 301C 301P F02D 41/04 360 F02D 41/04 360A 45/00 314 45/00 314Z (72) Inventor Shinobu Ishiyama 1 Toyota Town, Toyota City, Aichi Prefecture Toyota Motor Co., Ltd. (72) Inventor Naofumi Kumada 1 Toyota Town, Toyota City, Aichi Prefecture Toyota Motor Corporation Stock Company (72) Inventor Masaaki Kobayashi 1 Toyota Town, Toyota City, Aichi Prefecture Toyota Motor Co., Ltd. (72) Inventor Daisuke Shibata 1 Toyota Town, Toyota City, Aichi Prefecture Toyota Motor Co., Ltd. (72) Inventor Oha Takahiro 1 Toyota Town, Toyota City, Aichi Prefecture Toyota Motor Corporation (72) Inventor Akihiko Negami Toyota City, Aichi Prefecture Toyota Town No. 1 Toyota Motor Co., Ltd. F term (reference) 3G084 AA01 AA03 AA04 BA05 BA08 BA09 BA13 BA15 BA19 BA20 BA24 DA10 DA27 EB22 FA02 FA05 FA07 FA10 FA11 FA12 FA20 FA26 FA27 FA33 3G090 AA03 BA01 CA01 CB25 DA01 DA09 DA10 DA12 DA14 DA14 DA14 DA14 DA19 DA20 3G091 AA02 AA10 AA11 AA18 AB06 AB13 BA00 BA04 BA11 BA14 BA32 BA33 CA13 CA18 CB02 CB03 CB07 CB08 DA01 DA02 DB10 EA01 EA05 EA06 EA07 EA15 EA16 HA16 HA06H06B06 HA06B05 HA06 FC14 HA05 FC06 HA14 FC05 HA14 FC05 FC14 HA05 FC06 FC14 HA05 FC06 FC14 HA05 FC02 FC04 HA14 FC05 FC14 HA05 FC04 HA05 FC06 HA14 FC05 HA06 FC14 HA13 JA15 JA24 JA25 JB09 LB11 MA01 MA11 MA18 MA26 NA06 NA07 NA08 NE01 NE06 NE11 NE12 NE13 NE15 PA01B PA01Z PA07B PA07Z PA10B PA10Z PA16B PA16Z PD11B PD11Z PE01B PE01Z PE08B PE08Z PF01B PF01Z PF03B PF03

Claims (6)

[Claims] 1. NOx provided in an exhaust passage of an internal combustion engine capable of lean burn, and when the air-fuel ratio of the inflowing exhaust gas is lean.
A NOx storage agent that stores NOx and reduces the stored NOx to N ₂ when the air-fuel ratio of the inflowing exhaust gas is rich; and a sulfur poisoning recovery control means that performs temperature increase control and sulfur poisoning recovery control of the NOx storage agent. And an executability estimating means for estimating whether or not the sulfur poisoning recovery control means is in an engine operating state in which the sulfur poisoning recovery control is executable, and the sulfur poisoning recovery control means is a sulfur poisoning recovery control means. An exhaust emission control device for an internal combustion engine, which performs temperature increase control of the NOx occluding agent when the executability estimating means estimates that an engine operating state in which poison recovery control can be performed is made. 2. The exhaust gas purification apparatus for an internal combustion engine comprises a filter capable of temporarily trapping particulate matter in exhaust gas, and the NOx storage agent is carried by the filter. Exhaust gas purification device for internal combustion engine. 3. The exhaust gas purification apparatus for an internal combustion engine comprises a navigation system for detecting at least one of a current position of a vehicle and road conditions, and the executability estimating means recovers sulfur poisoning based on information of the navigation system. The exhaust gas purification device for an internal combustion engine according to claim 1 or 2, wherein it is estimated whether or not the control is in an executable engine operating state. 4. The execution feasibility estimating means estimates whether or not an engine operating state in which sulfur poisoning recovery control can be executed is made based on a history of a running state of a vehicle. 2. An exhaust emission control device for an internal combustion engine according to 2. 5. An uphill state detecting means for detecting that the vehicle is in an uphill state, wherein the executability estimating means is sulfur poisoning when the uphill state detecting means detects that the vehicle is in an uphill state. The exhaust emission control device for an internal combustion engine according to claim 1 or 2, wherein it is estimated that the recovery control can be executed. 6. A load is calculated from an operating state detecting means for detecting a vehicle speed, an engine speed, a reduction ratio and a load, and a vehicle speed, an engine speed and a reduction ratio when the vehicle is traveling on a flat ground. When the load detected by the driving state detection means is higher than the load calculated by the basic load calculation means by a predetermined value or more for a predetermined time or more. The exhaust emission control device for an internal combustion engine according to claim 5, wherein it is detected that the vehicle is in an uphill condition.