JP2001303980A - Exhaust emission control device of internal combustion engine - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a technology for rapidly increasing the temperature of a particulate filter when the capacity of the particulate filter for oxidizing and eliminating particulates has to be increased in an exhaust emission control device of an internal combustion engine, fitted with the particulate filter having the function of oxidizing the particulates in exhaust gas. SOLUTION: The exhaust emission control device of the internal combustion engine has such characteristics as follows; when the oxidizing capacity of the particulate filter is put in the nonactive state, the temperature of the exhaust gas flowing into the particulate filter is increased at first, for the purpose of activating the oxidizing capacity of the particulate filter. After that, fuel is supplied to the particulate filter to oxidize by using the oxidizing capacity of the particulate filter and the temperature of the particulate filter is risen by the heat generated above.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a technique for purifying exhaust gas of an internal combustion engine, and more particularly to a technique for purifying fine particles contained in exhaust gas.

[0002]

2. Description of the Related Art In recent years, in an internal combustion engine mounted on an automobile or the like, carbon monoxide (CO), hydrocarbon (HC) and the like contained in the exhaust gas are discharged before the exhaust gas discharged from the internal combustion engine is released into the atmosphere. ), It is required to improve exhaust emissions by purifying or removing harmful gas components such as nitrogen oxides (NOx).

In particular, in a compression ignition type diesel engine using light oil as a fuel, carbon monoxide (CO), hydrocarbon (H
In addition to C), nitrogen oxides (NOx), etc., it is important to purify or remove fine particles called particulate matter (PM: Particulate Matter) such as soot and SOF (Soluble Organic Fraction) contained in exhaust gas. .

For this reason, in a diesel engine, a particulate filter made of a porous base material having a large number of pores having a very small cross-sectional area is arranged in an exhaust passage, and exhaust gas flows through the pores of the particulate filter. By doing
2. Description of the Related Art A method for collecting fine particles in exhaust gas is known.

When the amount of fine particles collected by the particulate filter increases excessively, the cross-sectional area of the exhaust passage in the particulate filter decreases, and the flow of exhaust gas is hindered.

When the flow of exhaust gas is hindered by the particulate filter, the exhaust pressure increases in the exhaust passage upstream of the particulate filter, and the exhaust pressure acts on the internal combustion engine as back pressure.

Therefore, it is necessary to regenerate the particulate filter by purifying the particulates collected by the particulate filter before the amount of the particulates collected by the particulate filter excessively increases.

As a method of regenerating the particulate filter, there is a method of oxidizing the fine particles collected by the particulate filter by setting the inside of the particulate filter to an oxidizing atmosphere.

However, the fine particles are approximately 500 ° C. to 700 ° C.
Because of the ignition and burning at a high temperature of ℃, to oxidize the fine particles collected by the particulate filter, the ambient temperature of the particulate filter is set to 500 ℃ ~ 700 ℃
And the particulate filter must be in an oxygen-excess atmosphere.

However, since the diesel engine performs lean-burn operation with excess air in most of the operating range, the combustion temperature of the air-fuel mixture tends to decrease, and the temperature of the exhaust gas tends to decrease accordingly. Therefore, in a diesel engine, it is difficult to raise the ambient temperature of the particulate filter to 500 ° C. or more using the heat of the exhaust gas.

On the other hand, conventionally, Japanese Patent Publication No. 7-106
No. 290 has proposed a filter for diesel exhaust particles. The filter for diesel exhaust particles described in this publication has a catalyst material containing a mixture of a platinum group metal and an alkaline earth metal oxide supported on a particulate filter, and has a temperature of about 350 ° C.
The ignition and combustion of fine particles can be performed even at a relatively low temperature of about 400 ° C.

[0012]

The catalyst substance carried on the above-mentioned filter for diesel exhaust particles is activated at a predetermined temperature or higher, so that when the temperature is lower than the predetermined temperature, the fine particles in the exhaust gas are sufficiently oxidized. I can't let it.

Further, the above-mentioned catalytic substance has a higher ability to oxidize the fine particles as the temperature increases. Therefore, when a large amount of the fine particles flows into the particulate filter when the temperature of the catalytic substance is low, all the fine particles are oxidized. It becomes difficult.

On the other hand, the exhaust temperature of a diesel engine easily reaches 350 ° C. or more in a high load operation range, but hardly reaches 350 ° C. or more in a low load operation range. Therefore, when the diesel engine is continuously operated at a low load for a long period of time, particularly when the diesel engine is continuously operated at a low load after starting, the purification capacity of the particulate filter is likely to be low, and a large amount of fine particles are generated. It is assumed that they are deposited on the particulate filter without being burned.

If a large amount of fine particles are deposited on the particulate filter, it becomes difficult to burn the fine particles.
Even in the case described above, a large amount of unburned fine particles remains in the particulate filter, and the exhaust passage in the particulate filter may be clogged.

When the exhaust passage in the particulate filter is clogged, the exhaust resistance in the particulate filter increases, and the back pressure acting on the internal combustion engine increases.
The output of the internal combustion engine will be reduced.

That is, by simply arranging a particulate filter having a function of oxidizing particulates in the exhaust passage as in the above-described filter for diesel exhaust particulates, it is possible to efficiently utilize the particulate oxidizing ability of the particulate filter. This may cause clogging of the particulate filter and a decrease in output of the internal combustion engine.

SUMMARY OF THE INVENTION The present invention has been made in view of the various circumstances described above, and is directed to an exhaust gas purifying apparatus for an internal combustion engine having a particulate filter capable of oxidizing fine particles in exhaust gas. When the temperature of the particulate filter is low and the oxidizing ability of the particulate filter is in an inactive state as described above, by providing a technique for quickly raising the temperature of the particulate filter, unnecessary particulates in the particulate filter can be eliminated. An object of the present invention is to prevent accumulation and thereby prevent clogging of a particulate filter and a decrease in output of an internal combustion engine.

[0019]

The present invention employs the following means to solve the above-mentioned problems. That is, an exhaust gas purification device for an internal combustion engine according to the present invention is provided in an exhaust passage of an internal combustion engine, and has a particulate filter capable of oxidizing fine particles contained in exhaust gas, and a particulate filter for raising the temperature of the particulate filter. The fuel supply system further includes a fuel supply unit that supplies fuel to the particulate filter, and an exhaust gas heating unit that raises the temperature of exhaust gas flowing into the particulate filter prior to the operation of the fuel supply unit.

In the exhaust gas purifying apparatus for an internal combustion engine configured as described above, when the temperature of the particulate filter needs to be raised, first, the exhaust temperature raising means raises the temperature of the exhaust gas flowing into the particulate filter. Then, the fuel supply means supplies fuel to the particulate filter.

If it is necessary to raise the temperature of the particulate filter, the fuel is oxidized by using the oxidizing ability of the particulate filter, and the particulate filter is heated by the reaction heat generated when the fuel is oxidized. A method of raising the temperature can be considered.

However, simply supplying the fuel to the particulate filter may supply the fuel in a state where the oxidizing ability of the particulate filter is not sufficiently activated. In such a case, the fuel is oxidized. Since the amount of reaction heat generated when the fuel is oxidized is reduced, it takes time to raise the temperature of the particulate filter.

On the other hand, in the exhaust gas purifying apparatus for an internal combustion engine according to the present invention, when it is necessary to raise the temperature of the particulate filter, the exhaust gas is increased before the fuel supply means supplies the fuel to the particulate filter. The temperature means raises the temperature of the exhaust gas flowing into the particulate filter.

That is, in the exhaust gas purifying apparatus for an internal combustion engine according to the present invention, when it is necessary to raise the temperature of the particulate filter, the exhaust gas flowing into the particulate filter is heated, and then the fuel is supplied to the particulate filter. Was supplied.

When the exhaust gas heated by the exhaust gas heating means flows into the particulate filter, a relatively large amount of heat of the exhaust gas is transmitted to the particulate filter, and the temperature of the particulate filter is raised.

As a result, when the fuel supply means supplies the fuel to the particulate filter, the temperature of the particulate filter becomes relatively high, and the oxidizing ability of the particulate filter is activated.

If fuel is supplied to the particulate filter while the oxidizing ability of the particulate filter is activated, the fuel is easily oxidized, and the reaction heat generated when the fuel is oxidized increases. The temperature of the curated filter rises quickly.

In the exhaust gas purifying apparatus for an internal combustion engine according to the present invention, when the particulate filter carries a noble metal catalyst that is activated at a predetermined temperature or higher, the exhaust gas temperature raising means includes a means for controlling the temperature of the particulate filter to the above value. When the temperature is lower than the predetermined temperature, the temperature of the exhaust gas flowing into the particulate filter is increased, so that when the temperature of the particulate filter becomes equal to or higher than the predetermined temperature, the fuel supply means supplies fuel to the particulate filter. You may.

In the exhaust gas purifying apparatus for an internal combustion engine according to the present invention, when an exhaust throttle valve for reducing an exhaust flow rate in the exhaust passage is provided in an exhaust passage downstream of the particulate filter, the temperature of the exhaust gas is increased. Alternatively, the exhaust gas temperature may be raised by reducing the opening of the exhaust throttle valve.

Here, when the exhaust flow rate in the exhaust passage is reduced by the exhaust throttle valve, the pressure of the exhaust gas increases in the exhaust passage upstream of the exhaust throttle valve, and the exhaust pressure of the cylinder piston in the exhaust stroke increases. This acts on the internal combustion engine as a so-called back pressure that hinders the ascending operation, and the engine speed of the internal combustion engine decreases. On the other hand, in the internal combustion engine, the fuel injection amount is increased to increase the engine speed to a desired target engine speed, so that the amount of fuel burned in each cylinder increases, and the fuel The combustion heat generated when the fuel burns increases, and the calorific value of the exhaust also increases.

Therefore, the temperature of the exhaust gas discharged from the internal combustion engine can be raised by reducing the opening degree of the exhaust throttle valve by the exhaust gas temperature raising means. In the exhaust gas purifying apparatus for an internal combustion engine according to the present invention, when the internal combustion engine is provided with a fuel injection valve for directly injecting fuel into each cylinder, the exhaust gas temperature raising means includes the fuel during the expansion stroke of each cylinder. The temperature of the exhaust gas may be increased by injecting the fuel from the injection valve in a secondary manner.

When fuel is injected into the cylinder in the expansion stroke, the fuel is exposed to a high temperature during or immediately after the combustion of the air-fuel mixture and ignites, and burns until just before the end of the expansion stroke of the cylinder. As a result, in the exhaust stroke of each cylinder, high-temperature burned gas immediately after combustion is discharged from the cylinder as exhaust gas, and thus the temperature of the exhaust gas is increased.

In the exhaust gas purifying apparatus for an internal combustion engine according to the present invention, the fuel supply means is provided in an exhaust passage upstream of the particulate filter and adds fuel to exhaust gas flowing through the exhaust passage. Can be exemplified.

In the exhaust gas purifying apparatus for an internal combustion engine according to the present invention, when the internal combustion engine is provided with a fuel injection valve for directly injecting fuel into each cylinder, the fuel injection valve is used during the exhaust stroke of each cylinder. The fuel supply means may be realized by injecting the fuel secondarily.

As the particulate filter according to the present invention, an active oxygen releasing agent that takes in oxygen and retains it in an oxygen-excess atmosphere and releases the retained oxygen as active oxygen when the oxygen concentration decreases. Can be exemplified.

Further, the exhaust gas purifying apparatus for an internal combustion engine according to the present invention, when the internal combustion engine is in a deceleration operation state or when the internal combustion engine is in an operation state other than a high load operation state,
An exhaust flow switching means for switching the flow of the exhaust gas so that at least a part of the exhaust gas bypasses the particulate filter may be further provided.

This is because when the internal combustion engine is in an operation state other than the deceleration operation state or the high load operation state, the temperature of the exhaust gas discharged from the internal combustion engine tends to be low. When flowing into the filter,
This is because the heat of the particulate filter may be taken away by the exhaust gas.

[0038]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS A specific embodiment of an exhaust gas purifying apparatus for an internal combustion engine according to the present invention will be described below with reference to the drawings.

FIG. 1 is a diagram showing a schematic configuration of an internal combustion engine to which the exhaust gas purifying apparatus according to the present invention is applied and an intake / exhaust system thereof. The internal combustion engine 1 shown in FIG. 1 is a compression ignition type diesel engine having four cylinders 2. The internal combustion engine 1 has a fuel injection valve 3 for directly injecting fuel into a combustion chamber of each cylinder 2 and a crankshaft, which is an engine output shaft of the internal combustion engine 1, every time a predetermined angle (for example, 15 °) rotates. A crank position sensor 4 that outputs a pulse signal and a water temperature sensor 5 that outputs an electric signal corresponding to the temperature of cooling water flowing through a water jacket (not shown) of the internal combustion engine 1 are attached.

The above-described fuel injection valve 3 is connected to a pressure storage chamber (common rail) 7 via a fuel pipe 6. The common rail 7 is connected to a fuel pump 9 attached to the fuel tank 8 via a fuel pipe 10 and to the fuel tank 8 via a return pipe 11.

When the fuel pressure in the common rail 7 is lower than a predetermined maximum pressure, the valve is closed at the connection point of the return pipe 11 in the common rail 7 to cut off the conduction between the common rail 7 and the return pipe 11. When the fuel pressure in the common rail 7 becomes equal to or higher than the maximum pressure, a pressure regulating valve 12 is provided which opens to allow conduction between the common rail 7 and the return pipe 11.

A fuel pressure sensor 13 for outputting an electric signal corresponding to the fuel pressure in the common rail 7 is attached to the common rail 7. In the fuel system configured as described above, the fuel pump 9 pumps up the fuel stored in the fuel tank 8 and sends the pumped fuel to the common rail 7 through the fuel pipe 10. At this time, the fuel discharge amount of the fuel pump 9 is feedback-controlled based on the output signal value of the fuel pressure sensor 13 described above.

The fuel supplied from the fuel pump 9 to the common rail 7 is accumulated until the pressure of the fuel reaches a desired target pressure. The fuel accumulated to the target pressure in the common rail 7 is distributed to the fuel injection valve 3 of each cylinder 2 via the fuel pipe 6. Each fuel injection valve 3 opens when a drive current is applied, and injects fuel at the target pressure supplied from the common rail 7 into the combustion chamber of each cylinder 2.

In the fuel system described above, the common rail 7
When the fuel pressure in the chamber becomes higher than the maximum pressure, the pressure regulating valve 1
2 opens. In this case, a part of the fuel stored in the common rail 7 is returned to the fuel tank 8 via the return pipe 11, and the fuel pressure in the common rail 7 is reduced.

Next, an intake branch pipe 14 formed such that a plurality of branch pipes merge into one collecting pipe is connected to the internal combustion engine 1. Each branch pipe of the intake branch pipe 14 communicates with a combustion chamber of each cylinder 2 via an intake port (not shown).
The manifold of the intake branch pipe 14 is connected to the intake pipe 15,
The intake pipe 15 is connected to the air cleaner box 16.

An air flow meter 17 that outputs an electric signal corresponding to the mass of the intake air flowing through the intake pipe 15 is provided immediately downstream of the air cleaner box 16 in the intake pipe 15, and flows through the intake pipe 15. An intake air temperature sensor 18 that outputs an electric signal corresponding to the intake air temperature is attached.

In a portion of the intake pipe 15 downstream of the air flow meter 17, a compressor housing 1 of a centrifugal supercharger (turbocharger) 19 operating by using heat energy of exhaust gas discharged from the internal combustion engine 1 as a driving source.
9a is provided.

An intercooler 20 for cooling fresh air which has been compressed in the compressor housing 19a and has a high temperature is provided at a portion of the intake pipe 15 downstream of the compressor housing 19a.

The above-mentioned intercooler 20 is an air-cooled intercooler that dissipates heat of fresh air by using a traveling wind generated when a vehicle equipped with the internal combustion engine 1 travels. A water-cooled intercooler or the like that lowers the temperature of fresh air by performing heat exchange with cooling water can be exemplified.

An intake throttle valve (throttle valve) 21 for adjusting the flow rate of intake air flowing through the intake pipe 15 is provided at a position downstream of the intercooler 20 in the intake pipe 15. The throttle valve 21 is provided with a throttle actuator 21a for opening and closing the throttle valve 21 and a throttle position sensor 21b for outputting an electric signal corresponding to the opening of the throttle valve 21.

The throttle actuator 21
As a, for example, an electric actuator composed of a stepper motor or the like for driving the opening and closing of the throttle valve 21 in accordance with the magnitude of the applied electric power, or a diaphragm which is displaced in conjunction with the throttle valve 21 and is built-in, A negative pressure actuator or the like that drives the opening and closing of the throttle valve 21 by displacing the diaphragm according to the magnitude of the pressure can be exemplified.

In the intake system configured as described above, fresh air flowing into the air cleaner box 16 is subjected to an air cleaner (not shown) in the air cleaner box 16 to remove dust and dirt from the fresh air. Through the compressor housing 19a of the centrifugal supercharger 19.

The fresh air flowing into the compressor housing 19a is compressed by rotation of a compressor wheel provided inside the compressor housing 19a. Fresh air that has been compressed in the compressor housing 19a and has become high temperature is cooled by the intercooler 20.

The fresh air cooled by the intercooler 20 is guided to the intake branch pipe 14 with the flow rate adjusted by the throttle valve 21 as required. The fresh air guided to the intake branch pipes 14 is distributed from the collecting pipe of the intake branch pipes 14 to the respective branch pipes and guided to the combustion chambers of the respective cylinders 2.

The fresh air distributed to the combustion chamber of each cylinder 2 is compressed by a piston (not shown) and burns using the fuel injected from the fuel injection valve 3 as an ignition source. Next, an exhaust branch pipe 24 formed such that a plurality of branch pipes merge into one collecting pipe is connected to the internal combustion engine 1. Each branch pipe of the exhaust branch pipe 24 communicates with a combustion chamber of each cylinder 2 via an exhaust port (not shown). The collecting pipe of the exhaust branch pipe 24 is connected to an exhaust pipe 25 a via a turbine housing 19 b of the centrifugal supercharger 19.

A portion of the exhaust branch pipe 24 located immediately upstream of the turbine housing 19b and the exhaust pipe 2
In FIG. 5A, a portion located immediately downstream of the turbine housing 19b is connected by a turbine bypass passage 26 that bypasses the turbine housing 19b.

A waste gate valve 27 comprising a valve 27a for opening and closing the turbine bypass passage 26 and an actuator 27b for driving the valve 27a to open and close is attached to the turbine bypass passage 26.

The actuator 27b is connected to the intake pipe 15 located immediately downstream of the compressor housing 19a via a working pressure passage 28. The actuator 27b controls the pressure of fresh air flowing in the intake pipe 15 immediately downstream of the compressor housing 19a. In other words, the valve 27a is opened and closed using the pressure (supercharging pressure) of fresh air compressed in the compressor housing 19a.

Specifically, the actuator 27b holds the valve body 27a at the valve closing position when a pressure less than a predetermined pressure is applied from the intake pipe 15 through the working pressure passage 28, When a pressure equal to or higher than a predetermined pressure is applied through the operating pressure passage 28, the valve 27a is driven to open.

That is, when the supercharging pressure of the intake air by the centrifugal supercharger 19 reaches a predetermined pressure or more, the actuator 27b
The valve body 27a is opened to make the turbine bypass passage 26 conductive, and the flow rate of the exhaust gas flowing into the turbine housing 19b is reduced, so that the supercharging pressure does not exceed the predetermined pressure.

The exhaust pipe 25a is provided with a harmful gas component in the exhaust gas, particularly a particulate matter (PM: Part
(i.e., iculate matter). The exhaust gas purification mechanism 29 is connected to an exhaust pipe 25b, and the exhaust pipe 25b is connected downstream to a muffler (not shown). Hereinafter, the exhaust pipe 25a upstream of the exhaust purification mechanism 29 is referred to as an upstream exhaust pipe 25a, and the exhaust pipe 25b downstream of the exhaust purification mechanism 29 is referred to as a downstream exhaust pipe 25a.
b.

A fuel addition nozzle 38 for adding fuel to the exhaust gas flowing through the upstream exhaust pipe 25a is attached to the upstream exhaust pipe 25a. The fuel addition nozzle 38 is connected to the fuel pump 9 via a fuel pipe (not shown), and a part of the fuel discharged from the fuel pump 9 is supplied to the fuel addition nozzle 38. still,
The fuel addition nozzle 38 is a nozzle that opens and injects fuel when a drive current is applied, similarly to the fuel injection valve 3.

An exhaust throttle valve 33 for adjusting the flow rate of the exhaust gas flowing through the downstream exhaust pipe 25b is provided at a portion of the downstream exhaust pipe 25b located immediately downstream of the exhaust purification mechanism 29.
Is attached.

The exhaust throttle valve 33 includes the exhaust throttle valve 3.
An exhaust throttle actuator 34 for opening and closing the opening 3 is mounted. The exhaust throttle actuator 34
Is the exhaust throttle valve 3 using electromagnetic force or negative pressure.
3 is an actuator for opening and closing the actuator 3.

In the exhaust system configured as described above, the burned gas burned in the combustion chamber of each cylinder 2 of the internal combustion engine 1 is discharged to the exhaust branch pipe 24 through the exhaust port of each cylinder 2 and then discharged. From each branch pipe of the exhaust branch pipe 24, it flows into the turbine housing 19b of the centrifugal supercharger 19 through the collecting pipe.

The turbine housing 19 of the centrifugal supercharger 19
When the exhaust gas flows into the turbine housing 19b, the thermal energy of the exhaust gas is converted into rotational energy of a turbine wheel rotatably supported in the turbine housing 19b. The rotational energy of the turbine wheel is transmitted to the compressor wheel of the compressor housing 19a, and the compressor wheel compresses fresh air by the rotational energy transmitted from the turbine wheel.

At this time, when the pressure (supercharging pressure) of the fresh air compressed in the compressor housing 19a rises to a predetermined pressure or higher, the supercharging pressure is increased via the operating pressure passage 28 to the actuator 27b of the waste gate valve 27. And the actuator 27b drives the valve 27a to open.

When the valve body 27a of the waste gate valve 27 is opened, a part of the exhaust gas flowing through the exhaust branch pipe 24 flows to the upstream exhaust pipe 25a via the turbine bypass passage 26, and flows into the turbine housing 19b. Therefore, the heat energy of the exhaust gas flowing into the turbine housing 19b, in other words, the heat energy converted into the rotational energy of the turbine wheel in the turbine housing 19b decreases. As a result, the rotational energy transmitted from the turbine wheel to the compressor wheel decreases, and an excessive increase in the supercharging pressure is suppressed.

The exhaust gas discharged from the turbine housing 19b to the upstream exhaust pipe 25a and the exhaust gas guided from the turbine bypass passage 26 to the upstream exhaust pipe 25a are:
The gas flows into the exhaust gas purification mechanism 29 from the upstream exhaust pipe 25a.
The exhaust gas that has flowed into the exhaust purification mechanism 29 is discharged to the downstream exhaust pipe 25b after purifying or removing fine particles such as soot contained in the exhaust gas, and is discharged to the atmosphere through the downstream exhaust pipe 25b.

The exhaust branch pipe 24 is connected to an exhaust gas recirculation passage (EGR passage) 100.
0 is connected to the intake branch pipe 14. The EGR
An EGR valve 101 that opens and closes an open end of the EGR passage 100 in the intake branch pipe 14 is provided at a connection portion between the passage 100 and the intake branch pipe 14. The EGR
The valve 101 is configured by an electromagnetic valve or the like, and can change an opening degree according to the magnitude of applied power.

In the middle of the EGR passage 100, the EG
An EGR cooler 103 for cooling exhaust gas (hereinafter, referred to as EGR gas) flowing in the R passage 100 is provided.

Two pipes 104 and 105 are connected to the EGR cooler 103, and these two pipes 104 and 105 are connected to each other.
105 is connected to a radiator 106 for radiating the heat of the cooling water of the internal combustion engine 1 to the atmosphere.

One of the two pipes 104, 105 is a pipe for guiding a part of the cooling water cooled in the radiator 106 to the EGR cooler 103, and the other pipe 104. 105 is the E
This is a pipe for guiding the cooling water circulated in the GR cooler 103 to the radiator 106. In the following, the pipe 104 is referred to as a cooling water introduction pipe 104, and the pipe 1
05 is referred to as a cooling water outlet pipe 105.

An opening / closing valve 107 for opening and closing a flow passage in the cooling water outlet pipe 105 is provided in the cooling water outlet pipe 105. The on-off valve 107 is configured by an electromagnetically driven valve or the like that opens when drive power is applied.

The exhaust gas recirculation mechanism (E
In the GR mechanism, when the EGR valve 101 is opened, the EGR
The passage 100 becomes conductive, and a part of the exhaust gas flowing in the exhaust branch pipe 24 passes through the EGR passage 100 and the intake branch pipe 1
It is led to 4.

At this time, when the on-off valve 107 is in the open state, the circulation path connecting the radiator 106, the cooling water introduction pipe 104, the EGR cooler 103, and the cooling water outlet pipe 105 becomes conductive, and is cooled by the radiator 106. The cooled water circulates through the EGR cooler 103. as a result,
In the EGR cooler 103, heat exchange is performed between the EGR gas flowing in the EGR passage 100 and the cooling water circulating in the EGR cooler 103, and the EGR gas is cooled.

The EGR gas recirculated from the exhaust branch pipe 24 to the intake branch pipe 14 through the EGR passage 100 is supplied to the intake branch pipe 1
Each cylinder 2 while mixing with fresh air flowing from the upstream of 4
And the fuel injected from the fuel injection valve 3 is combusted as an ignition source.

Here, the EGR gas contains an inert gas component such as water (H ₂ O) and carbon dioxide (CO ₂ ) which does not burn itself and has endothermic properties, such as water (H ₂ O) and carbon dioxide (CO ₂ ). ing. Therefore, when the EGR gas is contained in the air-fuel mixture, the combustion temperature of the air-fuel mixture is lowered, and the amount of generated nitrogen oxides (NO _x ) is suppressed.

Further, the EGR cooler 103
When the gas is cooled, the temperature of the EGR gas itself decreases, and the volume of the EGR gas decreases.
When the R gas is supplied into the combustion chamber, the ambient temperature in the combustion chamber does not unnecessarily increase, and the amount of fresh air (volume of fresh air) supplied into the combustion chamber is unnecessarily reduced. Absent.

Next, a specific configuration of the exhaust gas purifying mechanism 29 will be described. As shown in FIGS. 2 and 3, the exhaust gas purifying mechanism 29 includes a casing 23 in which a particulate filter 22 having a function of oxidizing fine particles such as soot is loaded. The casing 23 includes a first exhaust passage 76 branched from the upstream exhaust pipe 25a and facing one surface of the particulate filter 22, and a first exhaust passage 76 branched from the upstream exhaust pipe 25a.
A second exhaust passage 77 facing the other surface is formed, and a filter temperature sensor 39 for outputting an electric signal corresponding to the temperature of the particulate filter 22 is attached.

Subsequently, the exhaust gas purifying mechanism 29 is connected to the downstream exhaust pipe 25b from a portion branched from the upstream exhaust pipe 25a to the first and second exhaust passages 76 and 77 without passing through the particulate filter 22. A filter bypass passage 73 for guiding exhaust gas is provided.

First exhaust passage 76 and second exhaust passage 77
An exhaust switching valve 71 is provided at a branch point between the filter and the filter bypass passage 73. The exhaust switching valve 71 includes a valve body 71a driven by an exhaust switching actuator 72 composed of a negative pressure actuator, a stepper motor, or the like, selects the first exhaust passage 76, and switches the first exhaust passage 76 from one side of the particulate filter 22 to the other. The flow of exhaust toward the side (forward flow), the flow of exhaust toward the one side from the other side of the particulate filter 22 by selecting the second exhaust passage 77 (backflow), and the flow of exhaust Exhaust flow bypassing the curated filter (bypass flow)
And can be switched. Thus, the exhaust switching valve 7
1 and the filter bypass passage 73 realize an exhaust flow switching means according to the present invention.

As shown in FIG. 3, the casing 23 containing the particulate filter 22 is disposed right above the filter bypass passage 73, and branches off from the upstream exhaust pipe 25a on both sides of the casing 23. The first exhaust passage 76 and the second exhaust passage 77 are connected. The particulate filter 22 in the casing 23 is formed such that the length in the width direction orthogonal to the length direction is longer than the length in the length direction, assuming that the passage direction of the exhaust gas is the length direction. According to such a configuration, the space required when mounting the exhaust purification mechanism 29 on a vehicle can be reduced.

In the exhaust gas purifying mechanism 29 described above, when the valve body 71a of the exhaust gas switching valve 71 is located at the forward flow position shown by the broken line in FIG. 2, the upstream exhaust pipe 25a and the first exhaust passage 76 are connected. Since the second exhaust passage 77 and the filter bypass passage 73 are electrically connected to each other, the exhaust gas is discharged from the upstream exhaust pipe 25a → the first exhaust passage 76 → the particulate filter 22 → the second exhaust passage 77 → the filter. The air flows in the order of the bypass passage 73 → the downstream exhaust pipe 25b.

In the exhaust gas purifying mechanism 29, when the valve body 71a of the exhaust gas switching valve 71 is at the reverse flow position shown by the solid line in FIG.
Since the upstream exhaust pipe 25a and the second exhaust passage 77 conduct, and the first exhaust passage 76 and the filter bypass passage 73 conduct, the exhaust gas flows from the upstream exhaust pipe 25a to the second exhaust pipe 25a. The gas flows in the order of the exhaust passage 77 → the particulate filter 22 → the first exhaust passage 76 → the filter bypass passage 73 → the downstream exhaust pipe 25b.

In the exhaust gas purifying mechanism 29, when the valve body 71a of the exhaust gas switching valve 71 is at the neutral position parallel to the axis of the upstream exhaust pipe 25a as shown in FIG.
5a directly communicates with the filter bypass passage 73,
The exhaust gas flows from the upstream exhaust pipe 25a to the filter bypass passage 73 without passing through the particulate filter 22.
It becomes the bypass flow which flows to. Hereinafter, the neutral position of the valve body 71a is referred to as a bypass flow position.

When the position of the valve body 71a of the exhaust switching valve 71 is alternately switched between the forward flow position and the reverse flow position, the flow of exhaust gas in the exhaust gas purifying mechanism 29 alternates between forward flow and reverse flow. Since fine particles such as soot actively move around in the base material of the particulate filter 22, oxidation of the fine particles is promoted, so that the fine particles are efficiently purified.

FIG. 5A is a view showing an image in the case where exhaust gas is supplied to the particulate filter 22 from only one direction.
And accumulates only on one surface, and hardly moves around, not only causing an increase in exhaust resistance but also hindering the purification of fine particles.

FIG. 5B is a view showing an image in the case where exhaust gas flows from the bidirectional direction to the particulate filter 22. The fine particles are disturbed in both the forward flow direction and the reverse flow direction on both surfaces of the particulate filter 22. Therefore, it moves around on both sides of the particulate filter 22 or inside the base material of the particulate filter 22. As a result, the fine particles are oxidized at substantially the entire active points of the particulate filter 22, so that the accumulation of the fine particles is suppressed, and an increase in exhaust resistance can be avoided.

Here, a specific structure of the particulate filter 22 according to the present embodiment will be described. FIG.
FIGS. 6A and 6B are views showing the structure of the particulate filter 22, FIG. 6A is a front view of the particulate filter 22, and FIG. 6B is a side sectional view of the particulate filter 22.

As shown in FIGS. 6A and 6B, the particulate filter 22 has a first exhaust passage 50 whose one end is closed by a plug 52, and a 5
This is a wall-flow-type filter made of a porous base material in which the second exhaust flow paths 51 closed by 3 are alternately arranged in a honeycomb shape via partition walls 54. In addition, as a base material of the particulate filter 22, cordierite or the like can be exemplified.

In the particulate filter 22 configured as described above, when the flow of exhaust gas is a forward flow, the first
Exhaust that has flowed into the exhaust flow path 50 passes through the pores of the surrounding partition wall 54 as shown by arrows in FIG.
It will flow into the exhaust passage 51.

In the present embodiment, a carrier layer made of alumina or the like is formed on the surface of the partition wall 54 of the particulate filter 22 and on the inner wall surface of the pores of the partition wall 54. A noble metal catalyst and an active oxygen releasing agent are supported.

The above-mentioned noble metal catalyst is a substance having an ability to oxidize fine particles, and examples of such a noble metal catalyst include platinum Pt. The active oxygen releasing agent releases active oxygen and promotes oxidation of the fine particles by the noble metal catalyst.Preferably, when the surroundings of the active oxygen releasing agent are in an oxygen excess atmosphere, oxygen is taken in and held. When the oxygen concentration around the active oxygen releasing agent is reduced, the retained oxygen is released in the form of active oxygen.

As the active oxygen releasing agent as described above,
For example, potassium K, sodium Na, lithium Li,
Alkali metals such as cesium Cs and rubidium Rb;
Examples thereof include those composed of at least one selected from alkaline earth metals such as barium Ba, calcium Ca and strontium Sr, rare earths such as lanthanum La and yttrium Y, and transition metals.

However, the active oxygen releasing agent used in the particulate filter 22 is an alkali metal or alkaline earth metal having a higher ionization tendency than calcium Ca, that is, potassium K, lithium Li, cesium Cs, rubidium Rb, barium Ba. , Strontium Sr or the like is preferable.

This is because calcium Ca is contained in the exhaust gas.
The calcium Ca
Reacts with sulfur oxides on calcium sulfate Ca
SO _FourPrevents the formation of substances that are difficult to decompose, such as
Stop, calcium sulfate CaSO_FourParticipation caused by
This is to prevent the rate filter 22 from being clogged.

Here, platinum P was placed on a carrier made of alumina.
The particulate purification mechanism of the exhaust purification mechanism 29 will be described by taking the particulate filter 22 carrying t and potassium K as an example. The function of the active oxygen releasing agent described below is the same even when an alkali metal other than potassium K, an alkaline earth metal, a rare earth, or a transition metal is used.

In a compression ignition type internal combustion engine such as the internal combustion engine 1 according to the present embodiment, the air-fuel mixture in an excess air state is burned in most of the operating range, so that the exhaust gas discharged from the internal combustion engine 1 is discharged. It will contain a relatively large amount of oxygen. When the air-fuel mixture burns, NO or SO ₂
Is generated, the exhaust gas discharged from the internal combustion engine 1 contains N
O and SO _{2 will} also be included. As a result, exhaust gas containing excess oxygen, NO, and SO ₂ flows into the particulate filter 22.

FIGS. 7A and 7B are schematic views showing enlarged views of the exhaust contact surface of the particulate filter 22. FIG. When the exhaust gas flows into the particulate filter 22, the oxygen O ₂ in the exhaust gas adheres to the surface of the platinum Pt 60 in the form of O ₂ ⁻ or O ²⁻ as shown in FIG. NO in the exhaust gas reacts with O ₂ ⁻ or O ²⁻ on the surface of the platinum Pt 60 to form NO ₂ (2NO + O ₂ → 2NO).
₂ ).

[0102] Then, part of the NO ₂ while being oxidized on the surface of the platinum Pt60 is absorbed in the active oxygen release agent 61, the nitrate ions NO while bonding with the potassium K ₃ ^- in the form of active oxygen release agent It diffuses into 61. At that time, part of the nitrate ions NO ₃ ^- to form potassium nitrate KNO _3.

Also, the SO ₂ contained in the exhaust gas is NO
Is absorbed into the active oxygen releasing agent 61 by the same mechanism as described above. That is, the oxygen O ₂ is O ₂ ^- or platinum P in O ^2- in the form
Since it is attached to the surface of t60, SO _{2 in} the exhaust gas reacts with O ₂ ⁻ or O ²⁻ on the surface of platinum Pt 60 to form SO ₃ .

Subsequently, a part of the SO ₃ is absorbed into the active oxygen releasing agent 61 while being further oxidized on the surface of the platinum Pt 60, and combined with the potassium K to form the active oxygen in the form of sulfate ion SO ₄ ^2−. It diffuses into the release agent 61. At that time, a part of the sulfate ions SO ₄ ^2- forms potassium sulfate K ₂ SO ₄ .

Thus, potassium nitrate KNO ₃ and potassium sulfate K ₂ SO ₄ are formed in the active oxygen releasing agent 61. On the other hand, when the air-fuel mixture burns in the internal combustion engine 1, fine particles mainly composed of carbon C are generated, so that the exhaust gas discharged from the internal combustion engine 1 contains fine particles.

When the exhaust gas containing the fine particles as described above flows into the particulate filter 22, the exhaust gas shown in FIG.
As shown in (2), the fine particles 62 in the exhaust collide and adhere to the surface of the carrier layer, for example, the surface of the active oxygen releasing agent 61.

As described above, the fine particles 62 form the active oxygen releasing agent 6
When it adheres on the surface of No. 1, the oxygen concentration in the contact surface between the active oxygen releasing agent 61 and the fine particles 62 decreases, so that oxygen in the active oxygen releasing agent 61 tends to move toward the contact surface with the fine particles 62. . As a result, the potassium nitrate KNO ₃ formed in the active oxygen releasing agent 61 is decomposed into potassium K, oxygen O and NO, and the oxygen O goes to the contact surface with the fine particles 62, and NO is released from the active oxygen releasing agent 61 Released outside. NO released from the active oxygen releasing agent 61 is oxidized on the platinum Pt on the downstream side, and is absorbed again in the active oxygen releasing agent 61.

At this time, potassium sulfate K ₂ SO ₄ formed in the active oxygen releasing agent 61 also contains potassium K, oxygen O and S
O ₂ is decomposed into O ₂ and the oxygen O is directed toward the contact surface with the fine particles 62, so that SO ₂ is released from the active oxygen releasing agent 61 to the outside. SO released from the active oxygen releasing agent 61
₂ is oxidized on platinum Pt on the downstream side, and is again absorbed in the active oxygen releasing agent 61. However, potassium sulfate K ₂
Since SO ₄ is stable, it is hard to release active oxygen compared to potassium nitrate KNO ₃ .

On the other hand, the oxygen O which moves to the contact surface with the fine particles 62 in the active oxygen releasing agent 61 is made of potassium nitrate K
Since it is oxygen decomposed from compounds such as NO ₃ and potassium sulfate K ₂ SO ₄ , it is in a state where a chemical reaction is likely to occur,
That is, it is in an active state. Such active oxygen is fine particles 6
When the fine particles 62 come into contact with the particles 2, the fine particles 62 are oxidized within a short period of time without emitting a bright flame and completely disappear.

Here, returning to FIG. 1, an electronic control unit (ECU: Electronic Control Uniform) for controlling the internal combustion engine 1 is provided in the internal combustion engine 1 configured as described above.
t) 35 is also provided. The ECU 35 is a unit that controls the operating state of the internal combustion engine 1 according to the operating conditions of the internal combustion engine 1 and the driver's requirements.

The ECU 35 is provided in the vehicle compartment in addition to the crank position sensor 4, the water temperature sensor 5, the fuel pressure sensor 13, the air flow meter 17, the intake air temperature sensor 18, the throttle position sensor 21b, and the filter temperature sensor 39. An accelerator position sensor 37 that outputs an electric signal corresponding to the operation amount (accelerator opening) of the accelerator pedal 36 is electrically connected, and the output signals of the above-described sensors are input to the ECU 35.

On the other hand, the ECU 35 includes the fuel injection valve 3, the fuel pump 9, the throttle actuator 21a, the exhaust throttle actuator 34, the fuel addition nozzle 38, the exhaust switching actuator 72, the EGR valve 101, the on-off valve 1
07 and the like are electrically connected, so that the ECU 35 can control each unit described above.

Here, as shown in FIG. 8, the ECU 35 connects the CPs connected to each other by a bidirectional bus 40.
U41, ROM42, RAM43, backup RAM44, input port 45, and output port 46.
A D converter (A / D) 47 is provided.

The input port 45 receives an output signal of a sensor that outputs a digital signal such as the crank position sensor 4 and transmits the output signal to the CPU 41 and the RAM 43 via the bidirectional bus 40. I do.

The input port 45 has an analog signal format such as the water temperature sensor 5, the fuel pressure sensor 13, the air flow meter 17, the intake air temperature sensor 18, the throttle position sensor 21b, the accelerator position sensor 37, the filter temperature sensor 39 and the like. An output signal of a sensor that outputs a signal is input via the A / D 47, and the output signal is transmitted to the CPU 41 or the RAM 43 via the bidirectional bus 40.

The output port 46 includes the fuel injection valve 3, the fuel pump 9, the throttle actuator 21a, the exhaust throttle actuator 34, the fuel addition nozzle 38, the exhaust switching actuator 72, the EGR valve 101, the on-off valve 1
07 and the like via a driving circuit (not shown), and transmits a control signal output from the CPU 41 to each of the above-described units.

The ROM 42 includes a fuel injection control routine for controlling the fuel injection valve 3, a fuel pump control routine for controlling the fuel pump 9, a throttle control routine for controlling the throttle valve 21, and an exhaust throttle valve 3.
Throttle control routine for controlling the EGR valve 1
EGR control routine for controlling valve 01, on-off valve 10
Various application programs, such as an EGR cooling control routine for controlling the exhaust gas control unit 7 and an exhaust gas purification control routine for controlling the exhaust gas purification mechanism 29, are stored.

The ROM 42 stores various control maps in addition to the application programs described above. The control map includes, for example, a fuel injection amount control map indicating a relationship between an operation state of the internal combustion engine 1 and a basic fuel injection amount (basic fuel injection time), and a relation between an operation state of the internal combustion engine 1 and a fuel injection end timing. A fuel injection end timing control map, a common rail pressure control map indicating a relationship between an operating state of the internal combustion engine 1 and a target pressure in the common rail 7, a target pressure in the common rail 7 and a discharge amount of the fuel pump 9 (driving of the fuel pump 9). (Amount of current), a fuel discharge pressure control map showing the relationship between the operating state of the internal combustion engine 1 and the target opening of the throttle valve 21, the operating state of the internal combustion engine 1 and the exhaust throttle valve 33. EGR valve opening control map showing the relationship between the operating state of the internal combustion engine 1 and the target opening of the EGR valve 101, the exhaust throttle opening control map showing the relationship with the target opening of the internal combustion engine 1, Operating conditions and the EGR cooler 10
A cooler operation timing control map showing the relationship with the operation timing of No. 3 (in other words, the opening timing of the on-off valve 107), and exhaust switching showing the relationship between the operating state of the internal combustion engine 1 and the position of the valve element of the exhaust switching valve 71. It is a valve opening control map or the like.

The RAM 43 stores an output signal from each sensor, a calculation result of the CPU 41, and the like. The calculation result is, for example, an engine speed calculated based on a time interval at which the crank position sensor 4 outputs a pulse signal. These data are rewritten to the latest data every time the crank position sensor 4 outputs a pulse signal.

The backup RAM 44 is a nonvolatile memory capable of storing data even after the operation of the internal combustion engine 1 is stopped. The CPU 41 operates in accordance with an application program stored in the ROM 42 to execute fuel injection control, fuel pump control, throttle control, exhaust throttle control, EGR control, and EGR cooling control. Execute purification control.

For example, in the fuel injection control, the CPU 41
First, the amount of fuel injected from the fuel injection valve 3 is determined, and then the timing for injecting fuel from the fuel injection valve 3 is determined. First, when determining the fuel injection amount, the CPU 41
Reads the engine speed and the output signal (accelerator opening) of the accelerator position sensor 37 stored in the RAM 43, and sets the torque required for the internal combustion engine 1 using the accelerator opening and the engine speed as parameters. Is calculated.

At this time, the relationship between the accelerator opening, the engine speed, and the required torque is experimentally obtained in advance, and the relationship between the accelerator opening, the engine speed, and the required torque is represented by a map as R.
You may make it memorize | store in the OM42.

Subsequently, the CPU 41 accesses the fuel injection amount control map in the ROM 42 and calculates a basic fuel injection amount (basic fuel injection time) corresponding to the required torque. The CPU 41 corrects the basic fuel injection time based on the output signal value of the water temperature sensor 5, the output signal value of the air flow meter 17, or the output signal value of the intake air temperature sensor 18, and determines the final fuel injection time. .

Next, when determining the fuel injection timing, C
The PU 41 accesses the fuel injection end timing control map in the ROM 42 and calculates the fuel injection end timing corresponding to the required torque. The CPU 41 calculates the fuel injection start time by subtracting the fuel injection time from the fuel injection end time. C
The PU 41 corrects the fuel injection start timing using the output signal value of the water temperature sensor 5, the output signal value of the air flow meter 17, or the output signal value of the intake air temperature sensor 18 as a parameter, and determines the final fuel injection start timing. .

When the fuel injection start time and the fuel injection timing are determined, the CPU 41 compares the fuel injection start time with the output signal of the crank position sensor 4 and determines whether the output signal of the crank position sensor 4 is the fuel injection start timing. At this time, the application of the driving power to the fuel injection valve 3 is started. The CPU 41 stops applying the driving power to the fuel injection valve 3 when the elapsed time from the start of the application of the driving power to the fuel injection valve 3 reaches the fuel injection time.

In the fuel injection control, when the operating state of the internal combustion engine 1 is an idling operation state, the CPU 41
Is a target idle speed of the internal combustion engine 1 using parameters such as the output signal value of the water temperature sensor 5 and the operating state of accessories that operate using the rotational force of the crankshaft, such as a compressor of a vehicle interior air conditioner. Is calculated. And C
The PU 41 performs feedback control on the fuel injection amount so that the actual idle speed matches the target idle speed.

In the fuel pump control, the CPU 41
Accesses the common rail pressure control map in the ROM 42 and calculates a target pressure corresponding to the engine speed and the accelerator opening. Subsequently, the CPU 41 accesses the fuel discharge pressure control map in the ROM 42, and discharges the fuel pump 9 corresponding to the target pressure (driving current of the fuel pump 9).
Is calculated, and the calculated drive current is applied to the fuel pump 9.

At this time, the CPU 41 applies a voltage to the fuel pump 9 based on a difference between an output signal value of the fuel pressure sensor 13 attached to the common rail 7 (actual fuel pressure in the common rail 7) and the target pressure. Feedback control of the drive current value to be performed is performed.

In the throttle control, the CPU 41
Accesses the throttle opening control map in the ROM 42 and calculates a target throttle opening corresponding to the engine speed and the accelerator opening. The CPU 41 applies a drive current of an amount corresponding to the target throttle opening to the throttle actuator 21a.

Further, the CPU 41 determines the output signal value of the throttle position sensor 21b (actual throttle opening).
The amount of drive current to be applied to the throttle actuator 21a is feedback-controlled based on the difference between the target throttle opening and the target throttle opening.

Further, in the exhaust throttle control, the CPU 41
When the internal combustion engine 1 is in a warm-up operation state after a cold start,
The exhaust throttle actuator 34 is controlled to drive the exhaust throttle valve 33 in the valve closing direction, for example, when the vehicle interior heater is operating. In this case, the load on the internal combustion engine 1 increases, and the fuel injection amount increases accordingly.
As a result, the calorific value of the internal combustion engine 1 increases, the warm-up of the internal combustion engine 1 is promoted, and the heat source of the vehicle interior heater is secured.

In the EGR control, the CPU 41 sets R
The engine speed stored in the AM 43, the output signal of the water temperature sensor 5 (cooling water temperature), the accelerator position sensor 3
7, the output signal (accelerator opening) and the like are read, and it is determined whether or not the execution condition of the EGR control is satisfied.

The above-mentioned EGR control execution conditions are as follows: the coolant temperature is equal to or higher than a predetermined temperature, the internal combustion engine 1 has been continuously operated for a predetermined time or more from the start, and the change amount of the accelerator opening is a positive value. Conditions such as certain conditions can be exemplified.

If it is determined that the EGR control execution condition described above is not satisfied, the CPU 41 controls the EGR valve 101 so as to maintain the EGR valve 101 in the fully closed state. On the other hand, EGR
If it is determined that the control execution condition is satisfied, the CPU
Reference numeral 41 denotes an access to the EGR valve opening control map in the ROM 42 and a target EG corresponding to the engine speed and the accelerator opening.
Calculate the R opening. The CPU 41 applies drive power corresponding to the target EGR opening to the EGR valve 101.

At this time, the CPU 41 performs so-called EGR valve feedback control in which the opening degree of the EGR valve 101 is feedback-controlled using the intake air amount of the internal combustion engine 1 as a parameter.

In the EGR valve feedback control, for example, the CPU 41 determines the target intake air amount of the internal combustion engine 1 using the accelerator opening, the engine speed and the like as parameters.
At this time, the relationship between the accelerator opening, the engine speed, and the target intake air amount may be mapped in advance, and the target intake air amount may be calculated from the map, the accelerator opening, and the engine speed. .

When the target intake air amount is determined by the above procedure, the CPU 41 reads out the output signal value (actual intake air amount) of the air flow meter 17 stored in the RAM 43, and reads the actual intake air amount and the target intake air amount. Compare with air volume.

If the actual intake air amount is smaller than the target intake air amount, the CPU 41 sets the EGR valve 1
01 is closed by a predetermined amount. In this case, the EGR passage 100
The amount of EGR gas flowing into the intake branch pipe 14 from the engine decreases, and accordingly, the amount of EGR gas drawn into the cylinder 2 of the internal combustion engine 1 decreases. As a result, the amount of fresh air sucked into the cylinder 2 of the internal combustion engine 1 increases by an amount corresponding to the decrease in the EGR gas.

On the other hand, when the actual intake air amount is larger than the target intake air amount, the CPU 41 opens the EGR valve 101 by a predetermined amount. In this case, the amount of EGR gas flowing into the intake branch pipe 14 from the EGR passage 100 increases, and accordingly, the amount of EGR gas drawn into the cylinder 2 of the internal combustion engine 1 increases. As a result, the amount of fresh air sucked into the cylinder 2 of the internal combustion engine 1 decreases by an amount corresponding to the increase in the EGR gas.

When it is necessary to increase the EGR gas amount, if the EGR valve 101 is already in the fully opened state, the CP
U41 controls the throttle actuator 21a to close the throttle valve 21 by a predetermined opening degree. In this case, the intake branch pipe 14 located downstream of the throttle valve 21
In this case, the degree of the negative pressure of the intake pipe negative pressure increases, so that the amount of EGR gas sucked from the EGR passage 100 into the intake branch pipe 14 increases.

The predetermined amount may be a fixed value that is determined in advance, or may be a variable value that is changed in accordance with a deviation between the actual intake air amount and the target intake air amount. .

The EGR cooling control is a control executed when the EGR control is in an execution state. This EGR
In the cooling control, the CPU 41 opens the on-off valve 107 and sets the radiator 1 when the EGR cooling condition is satisfied.
A part of the cooling water cooled in 06 is circulated to the EGR cooler 103, thereby cooling the EGR gas flowing through the EGR passage 100.

The above-mentioned EGR cooling conditions are as follows: the output signal value (cooling water temperature) of the water temperature sensor 5 is equal to or higher than a predetermined temperature; the engine speed is equal to or higher than a predetermined speed; Conditions such as certain conditions can be exemplified.

Further, in the exhaust gas purification control, the CPU 41
The exhaust switching actuator 72 is controlled so that the particulate filter removing function of the particulate filter 22 is used efficiently.

Since the noble metal catalyst and the active oxygen releasing agent carried on the particulate filter 22 become active as the ambient temperature of the particulate filter 22 increases, the active oxygen O which the active oxygen releasing agent can release per unit time becomes active. The amount increases as the ambient temperature of the particulate filter 22 increases. Accordingly, the amount of fine particles that can be removed by oxidation in the particulate filter 22 without emitting bright flame per unit time also increases as the ambient temperature of the particulate filter 22 increases.

FIG. 9 is a graph showing the relationship between the amount of oxidizable particles that can be oxidized and removed without emitting luminous flame per unit time and the bed temperature TF of the particulate filter 22. Assuming that the amount of fine particles discharged from the internal combustion engine 1 per unit time is the discharged fine particle amount M, when the discharged fine particle amount M is smaller than the oxidizable and removable fine particles G, that is, in the region I in FIG. All of the fine particles thus obtained are oxidized and removed in the particulate filter 22 without emitting a bright flame.

On the other hand, when the amount M of discharged fine particles is larger than the amount G of fine particles that can be removed by oxidation, that is, in the region II in FIG.
In order to oxidize and remove all of the fine particles discharged from the internal combustion engine 1 by the particulate filter 22, the amount of active oxygen is insufficient.

When the amount of active oxygen is insufficient for the amount of fine particles flowing into the particulate filter 22,
As shown in FIG. 10A, when the fine particles 62 adhere to the active oxygen releasing agent 61, only a part of the fine particles 62 is oxidized, and the finely oxidized fine particles remain on the carrier layer. Next, when the state of the shortage of the active oxygen amount continues, the fine particles that have not been oxidized one after another remain on the carrier layer, and as a result, as shown in FIG.
The surface of the carrier layer is covered with the residual fine particle portion 63.

Residual fine particle portion 63 covering the surface of the carrier layer
Is gradually transformed into a carbon material that is difficult to oxidize,
It becomes easy to remain on the particulate filter 22 as it is. Further, when the surface of the carrier layer is covered with the residual fine particle portion 63, the oxidizing action of NO and SO ₂ by platinum Pt and the releasing action of active oxygen by the active oxygen releasing agent 61 are suppressed.

As a result, as shown in FIG.
Another fine particle 64 is deposited one after another on the residual fine particle portion 63, and as a result, the fine particles are deposited in a layered manner. When the fine particles are deposited in a layered manner on the surface of the carrier layer, the fine particles are separated from the platinum Pt or the active oxygen releasing agent. It is not oxidized, and further fine particles are deposited on the fine particles.

Therefore, in the exhaust gas purification control of the present embodiment, the CPU 41
The exhaust switching actuator 72 of the exhaust gas purifying mechanism 29 is controlled in order to remove the fine particles deposited on the particulate filter 22 or prevent the fine particles from being deposited on the particulate filter 22.

Specifically, the CPU 41 operates the exhaust switching valve 7
The exhaust switching actuator 72 is controlled so that the position of one valve body 71a is alternately switched between a forward flow position and a backward flow position. The exhaust gas switching actuator 72 reverses the flow of exhaust gas to the particulate filter 22 (reverse flow from forward flow to reverse flow or reverse flow to reverse flow).
1, the upstream and downstream sides of the particulate filter 22 are reversed, and the active oxygen releasing agent in the portion downstream of the particulate filter 22 prior to the switching releases the active oxygen O due to the attachment of the fine particles. The fine particles are released and the fine particles are oxidized and removed by the active oxygen O. Further, a part of the active oxygen O released from the active oxygen releasing agent moves to the downstream side of the particulate filter 22 together with the exhaust gas,
The fine particles deposited here are removed by oxidation.

Further, when the exhaust gas switching actuator 72 drives the exhaust gas switching valve 71 to reverse the flow of exhaust gas to the particulate filter 22, fine particles are disturbed on both surfaces of the particulate filter 22 in the forward flow direction and the reverse flow direction. The particles move around on both sides of the particulate filter 22 or inside the base material, and are oxidized at almost all active points of the particulate filter 22.

Therefore, if the flow of the exhaust gas is reversed by the exhaust gas switching valve 71 at the time when the particulates start to accumulate on the particulate filter 22, the particulates can be completely oxidized and removed from the particulate filter 22,
Particulate filter 22 caused by accumulation of fine particles
Can be prevented from being clogged.

When particulates accumulate on the particulate filter 22, the CPU 41 lowers the oxygen concentration around the active oxygen releasing agent by temporarily making the air-fuel ratio of the exhaust gas rich. The active oxygen releasing agent from almost the entire area of the particulate filter 22
May be released.

The particulate filter 22
The noble metal catalyst and active oxygen releasing agent composed of platinum Pt and potassium K supported on the metal can be activated at a predetermined temperature or higher to oxidize and remove fine particles. If it is less than
It becomes difficult to sufficiently oxidize and remove the fine particles contained in the exhaust gas.

For example, the amount of fine particles that can be oxidized and removed without emitting luminous flame per unit time in the particulate filter 22 is determined by the temperature (T.sub.T) of the particulate filter 22 as described in FIG.
The temperature (TF) of the particulate filter 22 increases at a predetermined temperature (for example, 150 ° C.).
When the temperature is lower than (° C.), the value becomes substantially zero.

As described above, the particulate filter 22
When the amount of fine particles that can be removed by oxidation becomes substantially zero, the exhaust switching valve 7
Even if the flow of the exhaust gas flowing into the particulate filter 22 is reversed by 1, it is assumed that the oxidizing action of the fine particles by the active oxygen is not obtained and the fine particles are deposited on the carrier layer in a layered manner.

Therefore, when the temperature of the particulate filter 22 is lower than the predetermined temperature, it is necessary to quickly raise the temperature of the particulate filter 22 to the predetermined temperature or higher.

In contrast, the particulate filter 2
By supplying the unburned fuel component to the particulate filter 22 when the temperature of the fuel cell 2 is lower than the predetermined temperature,
It is conceivable that the unburned fuel component is oxidized by using the oxidizing ability of the noble metal catalyst, and the temperature of the particulate filter 22 is increased by the reaction heat generated at that time.

However, when the precious metal catalyst is in an inactive state when the unburned fuel component is supplied to the particulate filter 22, the unburned fuel component is not sufficiently oxidized, and the temperature of the particulate filter 22 rises. There is a risk of slowness.

Therefore, in the present embodiment, the CPU 41
When the temperature of the particulate filter 22 is lower than the predetermined temperature and the noble metal catalyst of the particulate filter 22 is in an inactive state, the noble metal catalyst is quickly activated and then the unburned fuel is transferred to the particulate filter 22. Supply the components, and the particulate filter 2
The particulate filter temperature raising control for raising the temperature of No. 2 to a predetermined temperature or more immediately is executed.

Hereinafter, the particulate filter temperature raising control according to the present embodiment will be specifically described. In the particulate filter temperature raising control, the CPU 41
A particulate filter temperature raising control routine as shown in FIG. The particulate filter temperature raising control routine is a routine stored in the ROM 42 in advance, and is executed at predetermined time intervals (for example, every time the crank position sensor 4 outputs a pulse signal).
1 is a routine that is repeatedly executed.

In the particulate filter temperature raising control routine, the CPU 41 first determines in step S1101 that R
The output signal value of the filter temperature sensor 39 (the bed temperature of the particulate filter 22) stored in the AM 43 is input.

In S1102, the CPU 41 executes the processing in S1.
It is determined whether or not the filter temperature input at 101 is higher than a predetermined temperature: T1. The aforementioned predetermined temperature: T1 is a temperature at which the noble metal catalyst (in this case, platinum Pt) supported on the particulate filter 22 is activated.

If it is determined in S1102 that the filter temperature is higher than the predetermined temperature T1, the CPU 4
In step S1103, the process proceeds to step S1103. In S1103, the CPU 41
Determines whether the filter temperature input in S1101 is higher than a predetermined temperature: T2. The above-mentioned predetermined temperature: T2 is the activation temperature of the active oxygen releasing agent, or the amount of fine particles that can be oxidized and removed by the particulate filter 22 per unit time (the amount G of oxidizable particles) per unit time from the internal combustion engine 1 per unit time. The temperature is substantially equal to the amount of discharged fine particles (the amount M of discharged fine particles).

If it is determined in S1103 that the filter temperature is higher than the predetermined temperature T2, the CPU 4
No. 1 considers that the noble metal catalyst and the active oxygen releasing agent of the particulate filter 22 are already in the active state,
Go to 04.

At S1104, the CPU 41 determines whether or not the fuel addition control is being executed to increase the bed temperature of the particulate filter 22. If it is determined in S1104 that the fuel addition control is not in the execution state, the CPU 41 determines that the execution of the fuel addition control has already been completed, and once ends the execution of this routine.

If it is determined in S1104 that the fuel addition control is being executed, the CPU 41 proceeds to S11.
In step 05, the application of the drive current to the fuel addition nozzle 38 is stopped, the execution of the fuel addition control is terminated, and the execution of this routine is terminated.

On the other hand, if it is determined in S1102 that the temperature of the particulate filter 22 is equal to or lower than the predetermined temperature: T1, the CPU 41 determines that the noble metal catalyst and the active oxygen releasing agent of the particulate filter 22 are in an inactive state. It proceeds to S1106.

In S1106, the CPU 41 controls the exhaust throttle actuator 34 to reduce the opening of the exhaust throttle valve 33 by a predetermined opening. In this case, since the opening degree of the exhaust throttle valve 33 is reduced, the flow rate of exhaust gas passing through the exhaust throttle valve 33 in the downstream exhaust pipe 25b is reduced. 29,
The exhaust pressure in the exhaust passage including the upstream exhaust pipe 25a and the exhaust branch pipe 24 increases.

The exhaust pressure thus increased acts on the internal combustion engine 1 as so-called back pressure, which prevents the piston (not shown) of the cylinder 2 in the exhaust stroke from rising in the exhaust stroke of the internal combustion engine 1, and acts on the internal combustion engine 1. The rotation speed decreases. On the other hand, the CPU 41 increases and corrects the fuel injection amount in the separate fuel injection control so that the engine speed matches the target speed.

As a result, the amount of fuel burned in each cylinder of the internal combustion engine 1 increases, and accordingly, the combustion heat generated when the fuel burns increases, thereby increasing the amount of heat of the exhaust gas. Become.

Here, returning to the particulate filter temperature raising control routine of FIG. 11, the CPU 41 executes the aforementioned S1.
After executing the process in step 106, the process advances to step S1107 to determine whether the operation state of the internal combustion engine 1 is in the deceleration operation state.

As a method for determining whether or not the operation state of the internal combustion engine 1 is in the deceleration operation state, the accelerator opening is zero and the vehicle speed is not zero, or the vehicle speed is not zero and the brake pedal is not operated. A method of determining that the operating state of the internal combustion engine 1 is in the decelerating operation state when a condition such as the operation amount is not zero is satisfied can be exemplified.

If it is determined in step S1107 that the operation state of the internal combustion engine 1 is not in the deceleration operation state, the CPU 4
1 proceeds to S1108, where the valve body 71a of the exhaust switching valve 71
The exhaust switching actuator 72 is controlled to drive the exhaust gas to the forward flow position or the backward flow position, so that the exhaust gas flows through the particulate filter 22.

In this case, high-temperature exhaust gas discharged from the internal combustion engine 1 flows into the particulate filter 22, and a relatively large amount of heat of the exhaust gas is transmitted to the particulate filter 22, and the particulate filter 22 Temperature rises.

When it is determined in S1107 that the operating state of the internal combustion engine 1 is in the decelerating operating state,
The CPU 41 proceeds to S1109, and controls the exhaust switching actuator 72 to drive the valve body 71a of the exhaust switching valve 71 to the bypass flow position.

In this case, the exhaust gas discharged from the internal combustion engine 1 flows bypassing the particulate filter 22. This is because when the internal combustion engine 1 is in the deceleration operation state, fuel injection is prohibited and combustion is not performed in each cylinder 2, so extremely low temperature exhaust is discharged from the internal combustion engine 1,
Such a cryogenic exhaust gas is used as a particulate filter 2
2, the temperature of the particulate filter 22 may not only rise but also fall.

When the operating state of the internal combustion engine 1 is in an operating state other than the acceleration operating state, the temperature of the exhaust gas tends to be low. Even when the first operation state is an operation state other than the acceleration operation state, the exhaust switching actuator 72 may be controlled so that the exhaust gas flows bypassing the particulate filter 22.

The CPU 41 executes the processing in S1108 or S1108 described above.
When the processing of 1109 is completed, the execution of the present routine is temporarily terminated, and after a lapse of a predetermined time, the present routine is executed again.

When the CPU 41 executes this routine again, if the temperature of the particulate filter 22 is still equal to or lower than the predetermined temperature: T1, the CPU 41 determines in S1102 that the filter temperature is equal to or lower than the predetermined temperature: T1. , S1106 to S1109 are continuously executed.

If the temperature of the particulate filter 22 rises to a temperature range higher than the predetermined temperature T1 and lower than the predetermined temperature T2 by continuously executing the exhaust throttle control in S1106 to S1109, the CPU 41 sets
In S1102, it is determined that the filter temperature is higher than the predetermined temperature: T1, then, in S1103, it is determined that the filter temperature is equal to or lower than the predetermined temperature: T2, and the process proceeds to S1110.

At S1110, the CPU 41 determines whether or not the exhaust throttle control is being executed. This S111
If it is determined that the exhaust throttle control is in the execution state at 0, the CPU 41 proceeds to S1111 and proceeds to S1111.
The exhaust throttle actuator 34 is controlled to return the opening of No. 3 to the normal opening.

When it is determined in step S1110 that the exhaust throttle control is not in the execution state, or in step S1111.
When the processing of step S111 is completed, the CPU 41 proceeds to step S111.
Proceeding to 2, it is determined whether or not the operation state of the internal combustion engine 1 is in the deceleration operation state.

If it is determined in step S1112 that the operation state of the internal combustion engine 1 is not in the deceleration operation state, the CPU 4
1 proceeds to S1113, and the valve body 71a of the exhaust switching valve 71
The exhaust switching actuator 72 is controlled to drive the exhaust gas to the forward flow position or the backward flow position, so that the exhaust gas flows through the particulate filter 22.

Subsequently, the CPU 41 proceeds to S1114, applies a drive current to the fuel addition nozzle 38, and starts execution of fuel addition control. In this case, the fuel addition nozzle 38
The fuel is injected into the exhaust gas flowing in the upstream exhaust pipe 25a upstream of the particulate filter 22, in other words, into the exhaust gas flowing into the particulate filter 22.

The fuel injected from the fuel addition nozzle 38 flows into the particulate filter 22 together with the exhaust gas flowing in the upstream exhaust pipe 25a. At this time, since the noble metal catalyst of the particulate filter 22 is already active, the fuel contained in the exhaust gas is oxidized by the noble metal catalyst.

As a result, a relatively large amount of heat generated when the fuel is oxidized causes the particulate filter 22
Rapidly rises in temperature. By the way, S1
If it is determined in 112 that the operation state of the internal combustion engine 1 is in the deceleration operation state, the CPU 41 proceeds to S1115 and controls the exhaust switching actuator 72 to drive the valve body 71a of the exhaust switching valve 71 to the bypass flow position. Then, the cryogenic exhaust gas is prevented from flowing into the particulate filter 22, and the application of the driving current to the fuel addition nozzle 38 is stopped to interrupt the execution of the fuel addition control.

The CPU 41 determines whether S1114 or S1
When the processing of 1115 is completed, the execution of the present routine is temporarily terminated, and after a predetermined time has elapsed, the present routine is executed again.

When the CPU 41 executes this routine again, if the temperature of the particulate filter 22 is still equal to or lower than the predetermined temperature: T2, the CPU 41 determines in S1103 that the filter temperature is equal to or lower than the predetermined temperature: T2. , S1110 to S1115 are continuously executed.

When the fuel addition control in S1110 to S1115 is continuously performed, the temperature of the particulate filter 22 becomes higher than the predetermined temperature: T2,
U41 determines in S1103 that the filter temperature is higher than the predetermined temperature: T2, and ends the execution of the fuel addition control in S1104 to S1105.

When the CPU 41 executes the particulate filter temperature raising control routine, the exhaust gas temperature raising means and the fuel supply means according to the present invention are realized, and the temperature of the particulate filter 22 is lower than a predetermined temperature.
In addition, when the noble metal catalyst of the particulate filter 22 is in an inactive state, the unburned fuel component is supplied to the particulate filter 22 after activating the noble metal catalyst promptly.
2 can be quickly raised to a temperature range higher than a predetermined temperature: T2.

Therefore, according to the exhaust gas purifying apparatus for an internal combustion engine according to the present embodiment, even when the temperature of the particulate filter 22 is extremely low, for example, immediately after the internal combustion engine 1 is cold started, the present invention is not limited thereto. Since it is possible to raise the temperature of the particulate filter 22 to a desired temperature range in an extremely short time, it is possible to suppress the accumulation of fine particles on the carrier of the particulate filter 22, and Particulate filter 2 caused by accumulation of fine particles
It is possible to prevent the output of the internal combustion engine 1 from decreasing due to the clogging of the second filter and the clogging of the particulate filter 22. In the present embodiment, an example has been described in which the exhaust throttle valve 33 is used as a method of increasing the temperature of exhaust gas to activate the noble metal catalyst of the particulate filter 22, but the fuel injection of the cylinder 2 during the expansion stroke is performed. The temperature of the exhaust gas may be increased by injecting fuel from the valve 3 and burning the auxiliary fuel in the cylinder.

When fuel is secondarily injected into the cylinder 2 during the expansion stroke in the internal combustion engine 1, the fuel is exposed to a high temperature during or immediately after the combustion of the air-fuel mixture and ignited. Will be burned to just before the end of the expansion stroke.
As a result, in the exhaust stroke of each cylinder 2, high-temperature burned gas immediately after combustion is exhausted from the cylinder as exhaust gas.
Thus, the temperature of the exhaust increases.

Therefore, by injecting fuel from the fuel injection valve 3 of the cylinder 2 during the expansion stroke in the internal combustion engine 1, high-temperature exhaust gas can flow into the particulate filter 22, and The noble metal catalyst of the filter 22 is exposed to the high-temperature exhaust gas and is quickly activated.

Further, in this embodiment, after the noble metal catalyst of the particulate filter 22 is activated, fuel is supplied from the fuel addition nozzle 38 to the particulate filter 22 to increase the temperature of the particulate filter 22. However, in the case of an internal combustion engine that does not include the fuel addition nozzle 38, after activating the noble metal of the particulate filter 22, the fuel injection valve 3 of the cylinder in the exhaust stroke is operated to make the unburned fuel unburned. May be caused to flow into the particulate filter 22.

[0197]

In the exhaust gas purifying apparatus for an internal combustion engine according to the present invention, when the temperature of the particulate filter having the function of oxidizing the particulates in the exhaust gas is increased, the temperature of the exhaust gas flowing into the particulate filter is increased. Later, fuel will be supplied to the particulate filter.

In this case, the particulate filter is
First, the temperature is raised by receiving a relatively large amount of heat of the exhaust gas. This activates the oxidizing function of the particulate filter. When fuel is supplied to the particulate filter, the fuel is oxidized by the oxidizing function of the particulate filter.

As a result, the particulate filter
The temperature rises rapidly due to the heat generated when the fuel oxidizes,
Accordingly, the oxidizing ability of the particulate filter is quickly activated.

Therefore, according to the exhaust gas purifying apparatus for an internal combustion engine according to the present invention, when the oxidizing ability of the particulate filter is in an inactive state, the oxidizing ability of the particulate filter can be quickly activated. Therefore, it is possible to suppress unnecessary accumulation of fine particles in the particulate filter, thereby preventing the particulate filter from being clogged and the output of the internal combustion engine from being reduced due to the clogging.

In the exhaust gas purifying apparatus for an internal combustion engine according to the present invention, when the internal combustion engine is in a deceleration operation state or when the internal combustion engine is in an operation state other than a high load operation state, at least a part of the exhaust gas is exhausted. When exhaust gas switching means for switching the flow of exhaust gas so as to bypass the particulate filter is provided, the internal combustion engine in an operating state other than the deceleration operation state or the high load operation state during the temperature rise of the particulate filter. Since the discharged low-temperature exhaust gas does not flow into the particulate filter, the temperature rise of the particulate filter is not hindered.

[Brief description of the drawings]

FIG. 1 is a diagram showing a schematic configuration of an internal combustion engine to which an exhaust gas purification device according to an embodiment is applied.

FIG. 2 is a horizontal sectional view showing a configuration of an exhaust gas purification mechanism.

FIG. 3 is a side view showing a configuration of an exhaust gas purification mechanism.

FIG. 4 is a diagram for explaining the operation of an exhaust gas switching valve.

5A is an image showing a state in which fine particles are deposited on a filter substrate. FIG. 5B is an image showing a state in which fine particles are disturbed by forward / backward flow of exhaust gas.

FIG. 6 is a diagram showing a configuration of a particulate filter.

FIG. 7 is a conceptual diagram showing an oxidizing action of fine particles in a particulate filter.

FIG. 8 is a block diagram showing an internal configuration of an ECU.

FIG. 9 is a diagram showing the relationship between the amount of particulates that can be removed by oxidation of the particulate filter and the temperature of the particulate filter.

FIG. 10 is a conceptual diagram showing the action of depositing fine particles in a particulate filter.

FIG. 11 is a flowchart illustrating a particulate filter temperature raising control routine;

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 ... Internal combustion engine 2 ... Cylinder 3 ... Fuel injection valve 14 ... Intake branch pipe 15 ... Intake pipe 17 ... Air flow meter 18 ... Intake air temperature sensor 19 ... Centrifugal supercharger 19a Compressor housing 19b Turbine housing 20 Intercooler 21 Throttle valve (intake throttle valve) 22 Particulate filter 23 Casing 24 Exhaust branch Pipe 29: Exhaust purification mechanism 33: Exhaust throttle valve 34: Exhaust throttle actuator 38: Fuel addition nozzle 39: Filter temperature sensor 71: Exhaust switching valve 72: Exhaust switching Actuator 73 Filter bypass passage 76 First exhaust passage 77 Second exhaust passage 100 EGR valve

──────────────────────────────────────────────────続 き Continued on the front page (51) Int.Cl. ⁷ Identification symbol FI theme coat ゛ (Reference) F01N 3/02 321 F01N 3/24 E 4D048 3/36 B 3/24 F02D 41/38 B 3/36 43 / 00301J F02D 41/38 301T 43/00 301 301Z 301W 45/00 310R B01D 53/36 ZAB 45/00 310 103C F term (reference) 3G065 AA01 AA03 AA04 AA09 AA10 CA12 DA04 DA06 DA15 FA12 GA00 GA05 GA08 GA09 GA10 GA27 GA41 GA46 HA21 HA22 JA04 JA09 JA11 KA02 3G084 AA01 BA00 BA05 BA13 BA15 BA19 BA24 CA06 DA00 DA10 EA11 FA00 FA02 FA07 FA10 3G090 AA03 BA01 CA00 CB00 CB24 CB25 DA00 DA09 DA14 DB01 DB06 DB07 EA05 EA06 A11A13 AA13A11 AA13A11 CB02 CB03 DB10 DC01 EA01 EA05 EA07 EA08 EA09 EA15 EA22 FA01 FA14 FA19 GB01Y GB02Y GB03Y GB04Y GB05W GB17 X HA14 HB03 HB05 HB06 3G301 HA02 HA06 HA11 HA13 JA24 KA01 KA09 KA16 LB11 MA11 MA18 MA23 NA08 NC04 ND04 ND07 PA01Z PA10Z PA11Z PB03Z PB05Z PB08Z PE01Z PE03Z PE08Z PF03Z PG00BAX BA14BA02 BA14BA02 BA14BA02 DA05 DA06 DA10 DA13

Claims (8)

[Claims] 1. A particulate filter provided in an exhaust passage of an internal combustion engine and capable of oxidizing fine particles contained in exhaust gas, and a fuel for supplying fuel to the particulate filter to raise the temperature of the particulate filter. An exhaust gas purifying apparatus for an internal combustion engine, comprising: a supply unit; and an exhaust temperature raising unit that raises the temperature of exhaust gas flowing into the particulate filter prior to the operation of the fuel supply unit. 2. The particulate filter supports a noble metal catalyst that is activated at a predetermined temperature or higher, and the exhaust gas temperature increasing means is configured to: when the temperature of the particulate filter is lower than the predetermined temperature, The fuel supply means increases the temperature of the exhaust gas flowing into the filter, and adds the fuel to the particulate filter after the temperature of the particulate filter becomes equal to or higher than the predetermined temperature. An exhaust gas purifying apparatus for an internal combustion engine according to claim 1. 3. An exhaust throttle valve provided in an exhaust passage downstream of the particulate filter to reduce an exhaust flow rate in the exhaust passage, wherein the exhaust gas heating means narrows an opening of the exhaust throttle valve. 2. The exhaust gas purifying apparatus for an internal combustion engine according to claim 1, wherein the temperature of the exhaust gas is increased by the operation. 4. A fuel injection valve for injecting fuel directly into each cylinder of the internal combustion engine, wherein the exhaust gas heating means injects fuel from the fuel injection valve in a secondary stroke during each cylinder expansion stroke. The exhaust gas purifying apparatus for an internal combustion engine according to claim 1, wherein the temperature of the exhaust gas is increased by causing the temperature of the exhaust gas to rise. 5. The fuel supply device according to claim 1, wherein the fuel supply means is a fuel addition device provided in an exhaust passage upstream of the particulate filter and adding fuel to exhaust flowing in the exhaust passage. An exhaust gas purifying apparatus for an internal combustion engine according to claim 1. 6. A fuel injection valve for directly injecting fuel into each cylinder of the internal combustion engine, wherein the fuel supply means injects fuel from the fuel injection valve during an exhaust stroke of each cylinder. 2. The exhaust gas purifying apparatus for an internal combustion engine according to claim 1, wherein fuel is supplied to the particulate filter. 7. The particulate filter carries an active oxygen releasing agent that takes in and holds oxygen in an oxygen-excess atmosphere and releases the held oxygen as active oxygen when the oxygen concentration decreases. The exhaust gas purifying apparatus for an internal combustion engine according to any one of claims 1 to 6, wherein: 8. When the internal combustion engine is in a deceleration operation state or when the internal combustion engine is in an operation state other than a high load operation state, at least a part of the exhaust gas bypasses the particulate filter. The exhaust gas purifying apparatus for an internal combustion engine according to any one of claims 1 to 7, further comprising exhaust flow switching means for switching a flow.