DE10114972A1 - Device for cleaning the exhaust gas of an internal combustion engine - Google Patents

Abstract

An apparatus for purifying the exhaust gas of an internal combustion engine is described, which has a particle filter arranged in the exhaust system, on which the retained particles are oxidized, and a bypass line through which the exhaust gas can bypass the particle filter, the particle filter having a quantity of particles, which can be oxidized and removed depending on the temperature of the particle filter, and if a current exhaust gas condition causes the amount of particles that can be oxidized and removed in the particle filter to be less than a currently required amount of particles that can be oxidized and removed, at least one Part of the exhaust gas is caused to take the detour through the bypass.

Description

BACKGROUND OF THE INVENTION 1. Field of the Invention

The invention relates to a device for cleaning the exhaust gas of a Combustion engine.

2. Description of the prior art

The exhaust gas of an internal combustion engine and in particular a diesel engine contains solid particles that include carbon as the main component. solid fuel Particles are harmful materials, and therefore a particle has been proposed provide filters in the exhaust system to retain the particles before they enter the Atmosphere escape. In such a particle filter, the retained ones have to be retained Particles are burned and disposed of to increase resistance to that To prevent exhaust gas due to clogged meshes.

If during such regeneration of the particle filter the temperature of the part rises above about 600 ° C, they ignite and burn. Usually that is Exhaust gas temperature of a diesel engine, however, significantly lower than 600 ° C, and therefore a heater is needed to heat the particle filter itself.

Japanese Examined Patent Publication No. 7-106290 discloses that when a platinum group metal and an alkaline earth metal oxide lie on the filter, which  Burn particles on the filter and remove them successively at around 400 ° C. 400 ° C is a common temperature for the exhaust gas from a diesel engine.

When the above filter is used, the temperature of the Exhaust gas, however, not always around 400 ° C. It can also have a large amount of feast particles of material are expelled from the engine. Thus, particles that are not can be burned and disposed of every time, settle on the filter.

If a certain amount of particles settles on the filter, it sinks Filters out the ability to burn and remove solid particles so much that the filter cannot regenerate itself. Therefore, if only one such filter is arranged in the exhaust system, relatively quickly to clog the Filter mesh come.

SUMMARY OF THE INVENTION

It is therefore an object of this invention to provide a device for cleaning the To provide exhaust gas from an internal combustion engine, which clogs the mesh of the Particle filter can prevent by particles retained on it.

The invention relates to a device for cleaning the exhaust gas Internal combustion engine according to claim 1.

Preferred embodiments thereof are the subject of claims 2 to 17.

According to this invention, a first device for purifying the exhaust gas of an internal combustion engine, which is arranged in the exhaust system Particle filter on which the retained particles are oxidized, and a Bypass line through which the exhaust gas can bypass the particle filter, wherein the particle filter depending on the temperature of the particle filter be a certain amount of particles can oxidize and eliminate, and if the current  The nature of the exhaust gas leads to the fact that the amount of particles in the particle filter can be oxidized and eliminated, is lower than the currently required particles amount that can be oxidized and disposed of, cause at least part of the exhaust gas is allowed to take the detour via the bypass line.

According to this invention there is provided a second device for purifying the exhaust gas of an internal combustion engine which comprises a particle filter arranged in the exhaust system, on which the retained particles are oxidized, and a bypass line through which the exhaust gas can bypass the particle filter, where the particle filter bears release agent for active oxygen released active oxygen reduction means from the free active oxygen oxidizes the retained particles on the particulate filter, the release agent for the active oxygen NO _x holds, to the NO _x to combine with oxygen when an excess of oxygen present in the environment is, and releases combined NO _x / oxygen, whereby it is broken down to NO _x and active oxygen, when the oxygen concentration of the environment decreases, the particle filter can oxidize and eliminate a certain amount of particles depending on the temperature of the particle filter , and if the instantaneous nature of the exhaust gas leads to the fact that the amount of particles that can be oxidized and eliminated in the particle filter is lower than the currently required amount of particles that can be oxidized and removed is caused to cause at least part of the exhaust gas, the detour to take through the bypass line.

According to this invention, a third device for purifying the exhaust gases of an internal combustion engine, which is arranged in the exhaust system Particle filter on which the retained particles are oxidized, and a Bypass line through which the exhaust gas can bypass the particulate filter includes where with the particle filter depending on the temperature of the particle filter a certain Particle quantity can oxidize and eliminate, and if the amount of injected Fuel is less than a specified amount, causing at least part of the exhaust gas will take the detour via the bypass line.  

According to this invention there is provided a fourth device for purifying the exhaust gas of an internal combustion engine which comprises a particle filter arranged in the exhaust system on which the retained particles are oxidized and a bypass line through which the exhaust gas can bypass the particle filter, where the particle filter containing release agent for active oxygen released active oxygen reduction means from the free active oxygen oxidizes the retained particles on the particulate filter, the release agent for the active oxygen NO _x holds, to the NO _x to combine with oxygen when an excess of oxygen present in the environment is, and releases the combined NO _x / oxygen, so that it is broken down to NO _x and active oxygen, when the oxygen concentration in the environment drops, the particle filter oxidize and eliminate a certain amount of particles depending on the temperature of the particle filter and, if the amount of fuel injected is less than a predetermined amount, at least a portion of the exhaust gas is caused to take the detour through the bypass line.

According to this invention, a fifth device for purifying the exhaust gas of an internal combustion engine, which is arranged in the exhaust system Particle filter on which the retained particles are oxidized, and a Bypass line through which the exhaust gas can bypass the particulate filter includes where with the particle filter depending on the temperature of the particle filter a certain Particle quantity can oxidize and eliminate, and if the temperature of the exhaust gas is lower than a predetermined temperature, causing at least part of the exhaust gas will take the detour through the bypass line.

According to this invention there is provided a sixth device for purifying the exhaust gas of an internal combustion engine, which comprises a particle filter arranged in the exhaust system, on which the retained particles are oxidized, and a bypass line through which the exhaust gas can bypass the particle filter, where the particle filter bears release agent for active oxygen released active oxygen reduction means the retained particles on the particulate active oxygen from the free oxidized, the release agent for the active oxygen NO _x holds, _x to the NO to combine with oxygen when an excess of oxygen in the environment is present , and the combined NO _x / oxygen releases, so that it is broken down to NO _x and active oxygen, when the oxygen concentration in the environment drops, the particle filter depending on the temperature of the particle filter oxidize and remove a certain amount of particles en, and if the temperature of the exhaust gas is lower than a predetermined temperature, at least a portion of the exhaust gas is caused to take the detour through the bypass line.

The invention will become apparent from the description of the preferred embodiments of the Invention, which is given below, together with the accompanying drawings better understood.

BRIEF DESCRIPTION OF THE DRAWINGS

The drawings mean:

Fig. 1 is a schematic vertical sectional view of a four-stroke diesel engine with an exhaust gas purification device according to the invention;

Fig. 2 is an enlarged vertical sectional view of the combustor of Fig. 1;

Fig. 3 is a bottom view of the cylinder head of Fig. 1;

Fig. 4 is an enlarged vertical sectional view of the combustor of Fig. 1;

Fig. 5 is a view showing the relationship between the degree of increase of the intake valve and the exhaust valve and the fuel injection;

Fig. 6 is a view showing the amount of smoke generated, NO _x and the like;

Fig. 7 (A) and 7 (B) are views showing the combustion pressure;

Fig. 8 is a view showing the fuel molecules;

Fig. 9 is a view showing the relationship between the amount of NO _x generated and the EGR rate;

Fig. 10 is a view showing the relationship between the amount of fuel injected and the amount of mixed gas;

Fig. 11 is a view showing the first operating area (I) and the second operating area (II);

Fig. 12 is a view showing the output of the air-fuel ratio sensor.

Fig. 13 is a view showing the opening degree of the throttle valve and the like;

Fig. 14 is a view showing the air-fuel ratio in the first operating area (I);

Fig. 15 (A) is a view showing the target opening degree of the throttle valve.

Fig. 15 (B) is a view showing the target opening degree of the EGR control valve;

Fig. 16 is a view showing the air / fuel ratio in the second operating area (II);

Fig. 17 (A) is a view showing the target opening degree of the throttle valve;

Fig. 17 (B) is a view showing the target opening degree of the EGR control valve;

Fig. 18 is a plan view showing near the changeover portion and the particulate filter in the exhaust system according to an embodiment of the proximity;

Fig. 19 is a side view of Fig. 18;

Fig. 20 is a view showing the other shutoff position of the valve housing in the switching section, which is different from that in Fig. 18;

Fig. 21 is a view showing the central position of the valve housing in the switching section;

Fig. 22 (A) is a front view showing the structure of the particle filter;

Fig. 22 (B) is a sectional side view showing the structure of the particle filter.

Fig. 23 (A) and 23 (B) are views of the particles it clarify the oxidizing activity;

Fig. 24 is a view showing the relationship between the amount of particles that can be oxidized and eliminated and the temperature of the particle filter;

Fig. 25 (A), 25 (B) and 25 (C) are views explaining the operation of Sichabsetzens the particles;

Fig. 26 is a first flow chart for preventing particles from settling on the particle filter;

Fig. 27 is a second flowchart for preventing the particles from settling on the particle filter;

Fig. 28 (A) and 28 (B) are enlarged sectional views of the partition wall of the particle filter;

Fig. 29 is a plan view showing near the changeover portion and the particulate filter in the exhaust system according to another embodiment of the proximity;

Fig. 30 is a plan view showing near the changeover portion and the particulate filter in the exhaust system according to another embodiment of the vicinity.

DESCRIPTION OF THE PREFERRED EMBODIMENT

Fig. 1 is a schematic vertical sectional view of a four-stroke diesel engine with an exhaust gas purification device according to this invention. Fig. 2 is an enlarged vertical sectional view of a combustion chamber of the diesel engine of Fig. 1. Fig. 3 is a bottom view of a cylinder head of the diesel engine of Fig. 1. Figs. 1-3: Reference numeral 1 denotes an engine case, reference numeral 2 denotes a cylinder block , 3 denotes a cylinder head, 4 denotes a piston, 5 a denotes a cavity which is formed on the upper surface of the piston 4 , 5 denotes a combustion chamber which is formed in the cavity 5 a, the Numeral 6 denotes an electrically controlled fuel injector, numeral 7 denotes a pair of intake valves, 8 denotes an intake port, 9 denotes a pair of exhaust valves, and 10 denotes an exhaust port. The suction opening 8 is connected via a corresponding suction pipe 11 with an expansion tank 12 . The expansion tank 12 is connected to an air filter 14 via an intake duct 13 . A throttle valve 16 , which is driven by an electric motor 15 , is arranged in the intake duct 13 . On the other hand, the exhaust opening 10 is connected to an exhaust manifold 17 .

As shown in FIG. 1, an air / fuel ratio sensor 21 is disposed in the exhaust manifold 17 . The exhaust manifold 17 and the expansion tank 12 are connected to one another via an EGR line 22 . An electronically controlled EGR control valve 23 is arranged in the EGR line 22 . An EGR cooler 24 is arranged around the EGR passage 22 to the EGR gas flowing through the EGR passage 22 to cool. In the embodiment of FIG. 1, the engine cooling water is led into the EGR cooler 24 , and therefore the EGR gas is cooled with the engine cooling water.

On the other hand, each fuel injector 6 is connected to the fuel tank, that is, via a fuel supply pipe 25 to a common pressure line (common rail) 26 . Fuel is supplied to the common rail 26 by an electronically controlled variable fuel discharge pump 27 . Fuel that has been supplied to the common rail is supplied to the fuel injector 6 via the fuel supply pipe 25 . A fuel pressure sensor 28 for determining the fuel pressure in the common rail 26 is attached to the common rail 26 . The discharge amount of the fuel pump is controlled on the basis of an output signal from the fuel pressure sensor 28 , so that the fuel pressure in the common rail 26 becomes the target fuel pressure.

Reference numeral 30 denotes an electronic control unit. It consists of a digital computer and is equipped with a ROM (Read Only Memory) 32 , a RAM (Random Access Memory) 33 , a CPU (microprocessor) 34 , an input port 35 and an output port 36 , which are interconnected by a bidirectional Bus 31 are connected. The output signals of the air / fuel sensor 32 and the fuel pressure sensor 28 are each input into the input port 35 via an A / D converter 37 . An engine load sensor 41 is connected to the accelerator pedal 40 , which generates an output voltage that is proportional to the degree of depression (L) of the accelerator pedal 40 . The output signal of the engine load sensor 41 is also given via the A / D converter 37 in the input port 35 . In addition, the output signal of a crank angle sensor 42 , which generates an output pulse each time the crankshaft rotates 30 degrees, for example, is input to the input port 35 . The fuel injector 6 , the electric motor 15 , the EGR control valve 23 and the fuel pump 27 are each connected via a control circuit 38 to the output port 36 in order to be driven on the basis of the input signals.

As shown in FIGS. 2 and 3, the fuel injector 6 in the embodiment of this invention comprises a nozzle with six nozzle openings. Fuel splashes (F) are sprayed from the nozzle openings in a slight downward direction at the same angular intervals against a horizontal plane. As shown in FIG. 3, two fuel splashes (F) of the six fuel splashes (F) are atomized along the lower surface of each exhaust valve 9 . Figs. 2 and 3 show the case where the fuel is injected into the end of the compression stroke. In this case, the fuel splashes (F) reach the edge of the inner surface of the cavity 5 and are then ignited and burned.

Fig. 4 shows the case in which additional fuel is injected from the fuel injector 6 when the degree of increase of the exhaust valves has reached the maximum of the exhaust stroke. That is, Fig. 5 shows the case that the main fuel injection (Qm) is performed near the top compression dead center and then the additional fuel injection (Qa) is performed in the middle stage of the exhaust stroke. In this case, the fuel splashes (F) that move toward the exhaust valves are directed between the screen-like back surface of the exhaust valve 9 and the exhaust port 10 . In other words, two nozzle openings of the six nozzle openings of the fuel injector 6 are shaped such that the fuel splashes (F), when the exhaust valves 9 are opened and the additional fuel injection (Qa) is carried out, between the back surface of the exhaust valve 9 and the exhaust opening 10 be directed. In the embodiment of Fig. 4, this fuel meet splatter (F) on the back surface of the exhaust valve 9 and are of the back surface of the exhaust valve 9 and are reflected back so ge in the exhaust port 10 deflected.

Usually the additional fuel injection (Qa) is not carried out and only the main fuel injection (Qm) is carried out. FIG. 6 shows an example from an experiment that shows the change in the output torque and the amount of smoke, HC, CO and NO _x emitted at the time when the air / fuel ratio A / F (abscissa in FIG. 6) Change in the degree of opening of the throttle valve 16 is changed, and shows the EGR rate at the time of low engine operation. As can be seen from Fig. 6, in this experiment, the EGR rate becomes higher the lower the air / fuel ratio A / F becomes. If the air / fuel ratio is below the stoichiometric air / fuel ratio (almost equal to 14.6), the EGR rate increases to over 65 percent.

When the EGR rate is increased to decrease the air / fuel ratio A / F, as shown in Fig. 6, begins when the EGR rate approaches 40 percent and the air / fuel ratio A / F decreases approximately 30 approaches to increase the amount of smoke produced. Then, when the EGR rate is further increased and the air / fuel ratio A / F is decreased, the amount of smoke generated sharply increases and peaks. Then, as the EGR rate is further increased and the air / fuel ratio A / F is decreased, the amount of smoke generated sharply decreases. When the EGR rate reaches over 65 percent and the air / fuel ratio A / F approaches 15.0, the amount of smoke generated is practically zero. That is, almost no soot is produced. At this point, the output torque of the engine drops slightly and the amount of NO _x generated is significantly reduced. On the other hand, the amounts of HC and CO produced begin to increase at this time.

Fig. 7 (A) shows the changes in the combustion pressure in the combustion chamber 5 when the amount of smoke generated is greatest in the vicinity of an air / fuel ratio A / F of 21. Fig. 7 (B) shows the changes in the combustion pressure in the combustion chamber 5 when the amount of smoke generated in the vicinity of an air / fuel ratio A / F of 18 is practically zero. As is clear from the comparison of FIG. 7 (A) and FIG. 7 (B), the combustion pressure in the case shown in FIG. 7 (B), in which the amount of smoke generated is practically zero, is lower than in FIG Fig. 7 (A) shown case in which the amount of smoke generated is large.

The following can be concluded from the results of the experiment shown in Figs. 6 and 7. Namely, first, when the air / fuel ratio A / F is lower than 15.0 and the amount of smoke generated is practically zero, the amount of NO _x generated drops considerably, as shown in FIG. 6. The fact that the amount of NO _x he produces decreases means that the combustion temperature in the combustion chamber 5 drops. Therefore, it can be said that when almost no soot is produced, the combustion temperature in the combustion chamber 5 decreases. The same can be concluded from FIG. 7. That is, at the stage shown in Fig. 7 (B) where almost no soot is generated, the combustion pressure becomes lower, therefore the combustion temperature in the combustion chamber 5 becomes lower at this time.

Second, when the amount of smoke generated, i.e., the amount of soot produced, becomes practically zero, as shown in Fig. 6, the amount of HC and CO emitted increases. That is, the hydrocarbons are discharged without becoming soot. That is, the straight chain hydrocarbons and aromatic hydrocarbons contained in the fuel and shown in Fig. 8 decompose when their temperature is raised in the state of lack of oxygen, resulting in the formation of a soot precursor. Soot is then produced, which is composed mainly of the solid masses of carbon atoms. In this case, the actual process of soot generation is complicated. How the soot precursor is formed is not clear, but anyway, the hydrocarbons shown in Fig. 8 are converted to soot by the soot precursor. As explained above, therefore, when the amount of soot produced becomes practically zero, the amount of HC and CO discharged increases as shown in Fig. 6, but the HC is a soot precursor at this time or is in a hydrocarbon state before this.

In summary, from these considerations based on the search, which are shown in FIGS. 6 and 7: if the combustion temperature in the combustion chamber 5 is low, the amount of soot produced becomes practically zero. At this time, a soot precursor or a prior hydrocarbon state is emitted from the combustion chamber 5 . More detailed tests and studies have been carried out. As a result, it was recognized that when the temperature of the fuel and gas around the fuel in the combustion chamber 5 is below a certain temperature, the soot-forming process stops halfway, that is, no soot is generated at all, and that, when the temperature of the fuel and gas around the fuel in the combustion chamber 5 rises above the certain temperature, soot is generated.

The temperature of the fuel and gas around the fuel at the time of the growth process of hydrocarbons at the soot precursor stage, that is, the certain temperature above, changes depending on various factors such as the fuel type, the air-fuel ratio and the Compression ratio, so you can not predict exactly, but this certain temperature is closely related to the amount of NO _x generated. Therefore, this certain temperature can be determined to a certain extent from the amount of NO _x generated. That is, the larger the EGR rate, the lower the temperature of the fuel and the gas surrounding it at the time of combustion and the lower the amount of NO _x generated. At the time when the amount of NO _x generated becomes about 10 ppm or less, almost no soot is generated. Therefore, the above certain temperature substantially corresponds to the temperature at the time when the amount of NO _x generated becomes about 10 ppm or less.

Once soot has been produced, it is impossible to clean it by post-treatment using an oxidizing catalyst. In contrast, a soot precursor or a hydrocarbon state before can be easily cleaned by after-treatment with a catalyst having an oxidation function. Therefore, for the purification of exhaust gas, it is extremely effective that the hydrocarbons are emitted from the combustion chamber 5 in the form of a soot precursor or a state before with the reduction in the amount of NO _x generated.

In order to stop the growth of the hydrocarbons in the pre-soot generation stage, it is now necessary to increase the temperature of the fuel and the gas surrounding it at the time of combustion in the combustion chamber 5 to a temperature below the temperature at which soot is produced reduce. In this case, it has been found that the heat absorbing effect of the gas surrounding the fuel at the time of combustion of the fuel has an extremely great effect in lowering the temperature of the fuel and the gas surrounding it.

This means that if only air surrounds the fuel, the vaporized one rules Fuel immediately with the oxygen in the air and burns. In this case increased the temperature of the air at some distance from the fuel is not so much Only that The temperature around the fuel becomes extremely high locally. That is, at that time the air absorbs the heat of combustion at some distance from the fuel the fuel barely. Since the combustion temperature locally becomes extremely high, generate in this case the unburned hydrocarbons that the heat of combustion on take soot.  

On the other hand, the situation is when a mixed gas consists of a fuel large amount of inert gas and a small amount of air is slightly different. In In this case, the vaporized fuel disperses into the environment and reacts with it the oxygen mixed with the inert gas and burns. In this case the heat of combustion is absorbed by the surrounding inert gas, so that the Combustion temperature no longer increases as much. That is, the combustion temperature can be kept low. That is, the presence of inert gas plays an important role in lowering the combustion temperature. It is possible, the combustion temperature due to the heat absorption effect of the inert gas to keep low.

In this case, in order to lower the temperature of the fuel and the surrounding gas to a temperature below the temperature at which soot is generated, a sufficient amount of inert gas is necessary to absorb a sufficient amount of heat to the Lower temperature. Therefore, as the amount of fuel increases, the amount of inert gas required also increases. Note that the larger the specific heat of the inert gas in this case, the stronger the heat absorbing effect becomes. Therefore, a gas with a high specific heat is preferred as the inert gas. In this connection, it can be said that since CO ₂ and EGR gas have a relatively high specific heat, it is preferable to use EGR gas as the inert gas.

Fig. 9 shows the relationship between the EGR rate and the smoke when EGR gas is used as the inert gas and the degree of cooling of the EGR gas is changed. That is, the curve (A) in Fig. 9 shows the case that the EGR gas is cooled down abge and the temperature of the EGR gas is kept at about 90 ° C, the curve (B) shows the case that the EGR gas is cooled by a compact refrigerator, and the curve (C) shows the case that the EGR gas is not forced-cooled.

When the EGR gas is cooled sharply as shown by curve (A) in Fig. 9, the amount of soot generated peaks when the EGR rate is slightly below 50 percent. In this case, when the EGR rate is increased to over 65 percent or above, almost no soot is produced.

On the other hand, when the EGR gas is cooled slightly, as shown by curve (B) in Fig. 9, the amount of soot produced peaks when the EGR rate is just over 50 percent. In this case, when the EGR rate is increased to over 65 percent, almost no soot is produced.

In addition, when the EGR gas is not forcedly cooled, as shown by the curve (C) in Fig. 9, the amount of soot generated peaks near an EGR rate of 55 percent. In this case, when the EGR rate is increased to over 70 percent, almost no soot is produced.

Note that Fig. 9 shows the amount of smoke generated when the engine load is relatively high. As the engine load becomes smaller, the EGR rate at which the amount of soot generated peaks slightly, and the lower limit EGR rate at which almost no soot is generated also drops slightly. In this way, the lower limit of the EGR rate at which almost no soot is generated changes in accordance with the degree of cooling of the EGR gas or the engine load.

Fig. 10 shows the amount of the mixed gas of EGR gas and air, the proportion of the air in the mixed gas and the proportion of the EGR gas in the mixed gas, which are necessary to determine the temperature of the fuel and the surrounding gas at the time of combustion to make a temperature lower than the temperature at which soot is generated when EGR gas is used as the inert gas. Note that in Fig. 10, the ordinate shows the total amount of the intake gas taken up in the combustion chamber 5 . The broken line (Y) shows the total amount of the intake gas that can be taken into the combustion chamber 5 if no overload is made. The abscissa also shows the required load. (Z1) shows the operating range with low engine load.

Fig. 10: The air content, that is, the amount of air in the mixed gas, shows the amount of air that is required to cause the injected fuel to burn completely constantly. That is, in the case shown in Fig. 10, the ratio of the amount of air and the amount of fuel injected to the stoichiometric air / fuel ratio. On the other hand, in Fig. 10, the proportion of EGR gas, that is, the amount of EGR gas in the mixed gas, shows the minimum amount of EGR gas required to be a temperature from the temperature of the fuel and the gas surrounding it to make it less than the temperature at which soot is produced when the injected fuel is completely burned. This amount of EGR gas, expressed as the EGR rate, is equal to or greater than 55 percent, in the embodiment shown in the figure it is equal to or greater than 70 percent. That is, when the total amount of the intake gas taken in the combustion chamber 5 is made by the solid line (X) in Fig. 10 and the ratio between the amount of air and the amount of EGR gas in the total amount of the intake gas (X) is made to the ratio shown in Fig. 10, the temperature of the fuel and the surrounding gas becomes a temperature below the temperature at which soot is generated, and therefore, soot is no longer generated at all. In addition, the amount of NO _x generated at this time is about 10 ppm or less, and therefore the amount of NO _x generated becomes extremely small.

As the amount of fuel injected increases, the amount of heat generated at the time of combustion increases, so that, in order to maintain the temperature of the fuel and surrounding gas at a temperature below the temperature at which soot is generated, the The amount of heat generated by the EGR gas must be increased. Therefore, as shown in Fig. 10, the amount of EGR gas must be increased as the amount of fuel injected is increased. That is, the amount of EGR gas has to be increased when the required engine load becomes higher.

On the other hand, in the engine load area (Z2) of FIG. 10, the total amount of intake gas (X) required for preventing soot generation exceeds the total amount of intake gas (Y) that can be taken up. Therefore, in this case, in order to provide the total amount of intake gas (X) required for preventing the generation of soot in the combustion chamber 5 , an overload or a compression of both the EGR gas and the absorbed one is required Air or only the EGR gas. If there is no overload or compression of the EGR gas, etc. in the engine load region (Z2), the total amount of the intake gas (X) corresponds to the total amount of the intake gas (Y) that can be taken up. Therefore, in this case, to prevent the soot generation, the amount of air is somewhat reduced to increase the amount of EGR gas, and the fuel is burned at a stage where the air / fuel ratio is rich.

As explained above, Fig. 10 shows the case of burning fuel at the stoichiometric air-fuel ratio. In the low engine load (Z1) operating range shown in FIG. 10, it is possible even if the amount of air is reduced below the amount of air shown in FIG. 10, that is, even if a rich air / fuel ratio is provided to prevent soot generation and cause an amount of NO _x generated to be about 10 ppm or less. In addition, in the low engine load (Z1) operating range shown in FIG. 10, it is possible even if the amount of air is increased beyond the amount of air shown in FIG. 10, that is, for a lean average air / fuel Ratio of 17 to 18 is taken to prevent soot generation and cause an amount of NO _x generated of about 10 ppm or less.

That is, if a rich air-fuel ratio is provided, the fuel is in excess, but since the combustion temperature is lowered to a low temperature, the excess fuel does not convert to soot and therefore no soot is generated. In addition, only an extremely small amount of NO _{x is} generated at this time. On the other hand, when the average air / fuel ratio is lean or when the air / fuel ratio corresponds to the stoichiometric air / fuel ratio, a small amount of soot is generated as the combustion temperature rises, but the combustion temperature becomes low Temperature is lowered, and therefore no soot is produced at all. In addition, an extremely small amount of NO _{x is} generated.

In this way, in the operating range with low engine load (Z1), the air / fuel ratio, i.e. whether it is a rich air / fuel ratio or the stoichiometric air / fuel ratio or an average lean air / fuel ratio, is independent Ratio is present, no soot is produced and the amount of NO _x generated becomes extremely small. Therefore, in view of the improvement in the fuel consumption rate, it can be said that it is preferable to make the average air / fuel ratio lean.

Incidentally, can only if the engine load is relatively low and the The amount of heat generated is low, the temperature of the fuel and the Fuel surrounding gas is reduced below a temperature during combustion become, in which the process of soot growth stops halfway. Therefore in the embodiment of this invention in which the engine load is relatively low is the temperature of the fuel and the gas surrounding the fuel at Combustion reduced to below a temperature at which the process of soot growth stops halfway and therefore a first combustion, d. H. a Low temperature combustion. If the engine load is relatively high, a second combustion, i. H. a normal combustion, as usual. Here, as is clear from the above explanation, the first combustion, i.e. H. the low temperature combustion, a combustion in which the amount of inert gas in the combustion chamber is greater than the most unfavorable amount of inert gas that the maximum amount of soot produced, and therefore no soot is produced at all generated. The second combustion, i. H. the normal combustion is a combustion,  where the amount of inert gas in the combustion chamber is less than the worst Amount of inert gas.

Fig. 11 shows a first operating area (I) in which the first combustion, ie the low-temperature combustion, is carried out, and a second operating area (II) in which the second combustion, ie the normal combustion, is carried out. In FIG. 11, the ordinate (L) shows the degree of depression of the accelerator pedal 40 , ie the engine load required. The abscissa (N) shows the engine speed. In addition, in FIG. 11, X (N) shows a first boundary area between the first operating area (I) and the second operating area (II). Y (N) shows a second border area between the first operating area (I) and the second operating area (II). The decision to change from the first operating area (I) to the second operating area (II) is made on the basis of the first limit area X (N). The decision to switch from the second operating area (II) to the first operating area (I) is made on the basis of the second limit area Y (N).

That is, when the operating state of the engine is the first operating range (I) and the low temperature combustion is carried out and if necessary Engine load (L) the first limit range X (N), which is a function of engine speed (N) exceeds, it is decided that the engine operating range is in the second Operating range (II) changes, and therefore normal combustion is carried out. If the required engine load (L) falls below the second limit range Y (N), which is a function of engine speed (N) decreases, it is decided that the Engine operating range changes to the first operating range (I), and therefore again carried out the low temperature combustion.

Fig. 12 shows the output of the sensor 21 for the air / fuel ratio. As shown in FIG. 12, the output current (I) of the air-fuel ratio sensor 21 changes according to the air-fuel ratio A / F. Accordingly, the air-fuel ratio can be derived from the output current (I) of the air-fuel ratio sensor 21 . The engine operation control in the first operating area (I) and in the second operating area (II) will now be explained schematically with reference to FIG. 13.

Fig. 13 shows the opening degree shows the throttle valve 16, the opening degree of the EGR control valve 23, the EGR rate, the air / fuel ratio, the timing of fuel injection and the amount of injected fuel with respect to the required engine load (L) , As shown in Fig. 13, in the first operating range (I), when the required engine load (L) is low, the throttle valve 16 is gradually opened from the almost fully closed state to the almost half open state, while the required engine load (L ) increases, and the EGR control valve 23 is gradually opened from the almost completely closed state to the fully opened state while the required engine load (L) increases. In the embodiment shown in FIG. 13, an EGR rate of about 70 percent is effected in the first operating range (I) and a slightly lean air / fuel ratio is provided therein.

In other words, in the first operating range (I), the opening degree of the throttle valve 16 and the EGR control valve 23 are controlled so that the EGR rate becomes about 70% and the air / fuel ratio becomes a slightly lean air / fuel ratio becomes. The air-fuel ratio is controlled at the desired air-fuel ratio at this time to correct the opening degree of the EGR control valve 23 based on the output signal of the air-fuel ratio sensor 21 . In the first operating range (Z), the fuel is injected before the compression dead center TDC. In this case, the fuel injection startup timing (θS) is delayed when the required engine load (L) increases, and the fuel injection startup timing (θE) is delayed when the fuel injection startup timing (θS) is delayed.

In idle mode, the throttle valve 16 is closed until it is almost completely closed. At this time, the EGR control valve 23 is also closed to the almost fully closed state. When the throttle valve 16 is closed to the almost fully closed state, the pressure in the combustion chamber 5 is lowered at the initial stage of the compression stroke, and therefore the compression pressure drops. When the compression pressure decreases, the compression performance of the piston 4 decreases, and therefore the vibration of the motor housing 1 decreases. That is, when the engine is idling, the throttle valve 16 is closed until it is almost completely closed, as a result of which the vibration of the motor housing 1 is restricted.

On the other hand, when the engine operating range changes from the first operating range (I) to the second operating range (II), the opening degree of the throttle valve 16 increases in one step from the half-open state to the fully open state. Meanwhile, in the embodiment shown in FIG. 13, the EGR rate suddenly drops from about 70 percent to below 40 percent and the air / fuel ratio increases suddenly. That is, the EGR rate skips the range of the EGR rate ( Fig. 9) in which the large amount of smoke is generated, and therefore no large amount of smoke is generated when the engine operating range from the first operating range (I) to the second operating range (II) replaced.

In the second operating area (II) normal combustion is carried out as usual. This combustion to some extent causes soot and NO _{x to be} generated. However, their thermal efficiency is higher than that of low-temperature combustion. Therefore, when the engine operating range changes from the first operating range (I) to the second operating range (II), the amount of fuel injected decreases in one step, as shown in FIG. 13.

In the second operating area (II), the throttle valve 16 is kept in the fully open state, except in part of it. The opening degree of the EGR control valve 23 gradually decreases as the required engine load (L) increases. In this operating range (II), the EGR rate decreases as the required engine load (L) increases, and the air / fuel ratio decreases as the required engine load (L) increases. However, the air / fuel ratio is made a lean air / fuel ratio even if the required engine load (L) becomes high.

In addition, the second operating area (II) ensures that the start-up time Fuel injection point (θS) near the compression dead center TDC lies.

Fig. 14, the air / fuel ratios A / F showing the first operating region (I). In Fig. 14, the curves labeled A / F = 15.5, A / F = 16, A / F = 17 and A / F = 18 each show the cases where the air / fuel Ratios 15.5, 16, 17 and 18 were. The air / fuel ratio between two of these curves is defined by the proportional allocation. As shown in Fig. 14, in the first operating range (I), the air / fuel ratio is lean, and the leaner the air / fuel ratio, the lower the engine load (L) required.

This means that the amount of heat generated during combustion decreases as the required engine load (L) decreases. Therefore, even if the EGR rate drops as soon as the required engine load (L) decreases, the low temperature combustion can be performed. As the EGR rate drops, the air / fuel ratio becomes high. Therefore, as shown in Fig. 14, the air / fuel ratio A / F increases as the required engine load (L) decreases. The higher the air / fuel ratio, the more the fuel consumption improves. Accordingly, in the present embodiment, the air / fuel ratio A / F increases as the required engine load (L) decreases, so that the air / fuel ratio is made as lean as possible.

A desired degree of opening (ST) of the throttle valve 16 , which is required in order to make the air / fuel ratio to the desired air / fuel ratio, which is shown in FIG. 14, is stored in the ROM 32 of the electronic control unit 32 , wherein it is a function of the required engine load (L) and the engine speed (N), which is shown in Fig. 15 (A). A target opening degree (SE) of the EGR control valve 23 required to make the air-fuel ratio the target air-fuel ratio shown in FIG. 14 is stored in the ROM 32 of the electronic control unit and is a function of the required engine load (L) and engine speed (N) shown in Fig. 15 (B).

Fig. 16 shows aimed air / fuel ratios when the second combustion, ie the normal combustion, is carried out as usual. In Fig. 16, the curves indicated by A / F = 24, A / F = 35, A / F = 45 and A / F = 60 show, respectively, the cases in which the desired air / fuel ratios 24 , 35, 45 and 60. A desired degree of opening (ST) of the throttle valve 16 , which is required to make the air / fuel ratio to the desired air / fuel ratio, is stored in the ROM 32 of the electronic control unit, whereby it is a function of the required engine load (L) and the engine speed (N) shown in Fig. 17 (A). A desired degree of opening (SE) of the EGR control valve 23 , which is required to make the air / fuel ratio to the desired air / fuel ratio, is stored in the ROM 32 of the electronic control unit, wherein it is a function of the engine load required (L) and the engine speed (N) shown in FIG. 17 (B).

Therefore, in the diesel engine of this embodiment, the first combustion, that is, the low temperature combustion, and the second combustion, that is, the normal combustion, alternate due to the degree of depression (L) of the accelerator pedal 40 and the engine speed (N). With each combustion, the opening degrees of the throttle valve 16 and the EGR control valve are controlled based on the records shown in FIGS. 15 and 17.

Fig. 18 is a plan view showing an exhaust gas purifying device, and Fig. 19 is a side view thereof. The device comprises a switching section 71 , which is connected to the downstream exhaust manifold 17 via an exhaust pipe 18 , a particle filter 70 , a first connecting section 72 a for connecting one side of the particle filter 70 to the switching section 71 , a second connecting section 72 b Connect the other side of the particle filter 70 to the switching section 71 , and an exhaust pipe 73 at the downstream switching section 71 . The switching section 71 comprises a valve housing 71 a, which shuts off the flow of the exhaust gas in the alternating area 71 . The valve housing 71 a is driven by a negative pressure drive, a stepper motor or the like. In a shutoff position of the valve housing 71 a communicates the upstream side in the changeover 71 with the first Ver connecting portion 72 a and the downstream side thereof communicates with the second connecting portion 72 b, and thus the exhaust gas from the first side flow of the particulate filter 70 to the second Side as indicated by arrows in FIG. 18.

Fig. 20 shows a further shut-off position of the valve housing 71 a. In this shut-off position, the upstream side in the switching section 71 communicates with the second connecting section 72 b and the downstream side in the switching section 71 communicates with the first connecting section 72 a, and therefore the exhaust gas flows from the second side of the particle filter 70 to the first Side as indicated by arrows in Fig. 20. Therefore, by moving the valve housing 71 a, the direction of the exhaust gas that flows into the particle filter 70 can be reversed, that is, the side of the particle filter on which the exhaust gas flows upward and the side of the particle filter on which the exhaust gas flows downward, can be reversed.

Therefore, this device for purifying the exhaust gas can reverse the side of the particle filter on which the exhaust gas flows upward and the side of the particle filter on which the exhaust gas flows downward by a very simple construction. In addition, the particle filter requires a large opening area to facilitate the introduction of the exhaust gas. In the device, the particle filter with a large opening area can be used without being difficult to attach to the vehicle, as shown in FIGS. 18 and 19.

In addition, Fig. 21 shows an intermediate position of the valve housing 71 a between the two Absperrpositionen. The switchover section 71 is not blocked in the middle position. The exhaust gas does not flow through the particle filter 70 , which has a higher resistance. That is, the exhaust gas bypasses the particulate filter 70 and flows directly into the exhaust pipe as shown by the arrows in FIG. 21. The valve housing 71 a can be set by the stepping motor or the like to any position other than this position. However, the valve housing is usually placed in one of the two shut-off positions and the particle filter is used.

Fig. 22 shows the structure of the particulate filter 70, 22 (A) and Fig. A front view of the particulate filter 70 Fig. 22 (B) is a side sectional view thereof. As shown in these figures, the particulate filter 70 has an elliptical shape and represents, for example, the wall-flow type of a honeycomb structure made of a porous material such as cordierite, and has many axial gaps that are separated by many partitions 54 extend in the axial direction, are separated. In each case one of two neighboring spaces is closed by a closure 53 at the side at which the exhaust gas flows downward, and the other is closed by a closure 53 at the at the side at which the exhaust gas flows upward. Therefore, one of the two adjacent spaces serves as an exhaust gas inflow duct 50 and the other serves as an exhaust gas outflow duct 51 , thereby forcing the exhaust gas to penetrate the partition wall 54 as indicated by arrows in Fig. 22 (B). The particles contained in the exhaust gas are much smaller than the pores of the partition wall 54 , but collide with it and are retained on the surface of the partition wall 54 on the side where the exhaust gas flows upward and on the pore surfaces of the partition wall 54 . Therefore, each partition 54 serves as a trap for retaining the particles. In the present particle filter, in order to oxidize and remove the retained particles, an active oxygen release agent and a noble metal catalyst, which will be explained below, are carried on both sides of the surfaces of the partition 54 and preferably also on the pore surfaces of the partition 54 .

The active oxygen release agent releases active oxygen to the To promote oxidation of the particles and preferably absorbs and holds oxygen back when there is an excess of oxygen in the environment and sets the  retained oxygen is released as active oxygen when the oxygen concentration drops in the area.

Platinum Pt is usually used as the noble metal catalyst. As free at least one element selected from the Alkali metals such as potassium K, sodium Na, lithium Li, cesium Cs and rubidium Rb, alkali earth metals such as barium Ba, calcium Ca and strontium Sr, the rare earth elements such as Lanthan La and Yttrium Y, and the transition metals.

An alkali metal is preferred as the release agent for active oxygen or an alkaline earth metal with an ionization tendency stronger than that of Calcium Ca used, i.e. H. Potassium K, Lithium Li, Cesium Cs, Rubidium Rb, Barium Ba or Strontium Sr.

Next, it will be explained how the part retained on the particle filter Chen through the particle filter, which is such a release agent for active oxygen carried, oxidized and disposed of, referring to the case where Platinum Pt and potassium K can be used. The particles are made in the same way oxidizes and removes, even if another precious metal and another alkali metal, an alkali earth metal, a rare earth metal or a transition metal is used.

In a diesel engine, the combustion usually takes place under a condition of excess air and therefore the exhaust gas contains a large amount of excess air. That is, when the ratio of the air to the fuel introduced into the intake system and the combustion chamber is referred to as an air / fuel ratio of the exhaust gas, the air / fuel ratio is lean. In addition, NO is generated in the combustion chamber and therefore the exhaust gas contains NO. In addition, the fuel contains sulfur S, and sulfur S reacts with the oxygen in the combustion chamber, where it is formed by SO ₂ . Accordingly, the exhaust gas containing excess oxygen, NO and SO _{2 flows} into the side of the particle filter 70 in which the exhaust gas flows upward.

The Fig. 23 (A) and 23 (B) are enlarged views illustrating the surface of the particulate filter 70 with which the exhaust gas comes into contact, schematically. In FIGS. 23 (A) and 23 (B), reference numeral 60 denotes a platinum Pt particles and 61 be distinguished, the releasing agent for active oxygen, potassium K contains.

As described above, the exhaust gas contains a large amount of excess oxygen. When the exhaust gas comes into contact with the exhaust gas contact surface of the particulate filter, oxygen O ₂ adheres on the platinum (Pt) surface in the form of O ₂ ^- or O ^2-, as shown in Figure 23 (A).. On the other hand, NO in the exhaust gas reacts on the surface of platinum Pt with O ₂ ^- or O ^2- , whereby NO ₂ (2NO + O ₂ → 2NO ₂ ) is generated. Next, part of the NO ₂ generated is absorbed in the active oxygen release agent 61 while being oxidized on the platinum Pt and diffuses into the active oxygen release agent 61 in the form of the nitric acid ion NO ₃ ^- while being combined with potassium K. , thereby forming potassium nitrate KNO ₃ as shown in Fig. 23 (A). Therefore, in this embodiment, NO _x contained in the exhaust gas is absorbed in the particulate filter 70 , and the amount thereof released into the atmosphere can be reduced, that is, the active oxygen release agent also serves as NO _x - absorbent.

In addition, the exhaust gas contains SO ₂ as described above, and SO ₂ is also absorbed in the active oxygen release agent 61 due to a mechanism similar to that of the NO case. That is, as described above, oxygen O ₂ in the form of O ₂ ^- or O ^2- adheres to the surface of platinum (Pt), and SO ₃ in the exhaust gas reacts with O ₂ ^- or O ^2- on the surface of platinum ( Pt), producing SO ₃ . Next, part of the generated SO _{3 is} absorbed in the active oxygen release agent 61 while being oxidized on the platinum Pt, and diffuses into the active oxygen release agent 61 in the form of the sulfuric acid ion SO ₄ ^2- while combining it with potassium K. is, whereby potassium sulfate K ₂ SO ₄ ^{- is} formed. Therefore, potassium nitrate KNO ₃ and potassium sulfate K ₂ SO _{4 are} generated in the active oxygen release agent 61 .

The particles in the exhaust gas adhere to the surface of the active oxygen release agent 61 that rests on the particle filter 70 , as shown at 62 in FIG. 23 (B). At this time, the oxygen concentration on the surface of the active oxygen release agent 61 with which the particle 62 is in contact drops. Since the concentration of oxygen falls, a difference arises in the concentration of the release agent for active oxygen 61 having a high oxygen concentration, and therefore tends oxygen release agent for active oxygen 61 to migrate to the surface of the release agent for active oxygen 61, with the particle 62 is in contact. As a result, potassium nitrate KNO ₃ generated in the active oxygen release agent 61 is broken down to potassium K, oxygen O and NO, with oxygen O migrating to the surface of the active oxygen release agent 61 with which the particle 62 is in contact. and NO is emitted to the outside by the active oxygen release agent 61 . Outwardly emitted NO is oxidized to platinum (Pt) on the side of the downward flow and is in turn absorbed in the active oxygen release agent 61 .

At this time, potassium sulfate K ₂ SO ₄ , which was generated in the active oxygen release agent 61, is also broken down to potassium K, oxygen O and SO ₂ , with oxygen O migrating to the surface of the active oxygen release agent 61 with which particle 62 is in contact and SO ₂ is emitted to the outside by the active oxygen release agent. Externally emitted SO ₂ is oxidized on platinum Pt on the side of the downward flow and is again absorbed in the active oxygen release agent 61 . Here, however, the potassium sulfate K ₂ SO ₄ is stable and releases less active oxygen than potassium nitrate KNO ₃ .

On the other hand, the oxygen O which migrates to the surface of the active oxygen release agent 61 with which the particle 62 is in contact is one which has been broken down from such compounds as potassium nitrate KNO ₃ or potassium sulfate K ₂ SO ₄ , Oxygen O that has been broken down from the compound has a high degree of energy and shows a very high activity. Therefore, the oxygen that migrates to the surface of the active oxygen release agent 61 with which the particle 62 is in contact is active oxygen O. As soon as it comes into contact with active oxygen O, the particle 62 is oxidized without generating a flare for a short time, for example a few minutes or a few tens of minutes. In addition, active oxygen for oxidizing the particle 62 is also released when NO and SO ₂ are absorbed in the active oxygen release agent 61 . That is, NO _x can be expected to diffuse into the active oxygen release agent 61 in the form of nitric acid ions NO ₃ ^- while being combined with oxygen atoms and being separated from an oxygen atom, and while active oxygen is being generated. Particles 62 are also oxidized by this active oxygen. In addition, the particles adhering to the particle filter 70 are oxidized not only by active oxygen but also by oxygen contained in the exhaust gas.

The higher the temperature of the particle filter becomes, the more the platinum Pt and the active oxygen release agent 61 are activated. Therefore, the higher the temperature of the particle filter becomes, the larger the amount of the active oxygen O released by the active oxygen release agent 61 per unit time. In addition, the higher the temperature of the particles, the easier the particles are naturally oxidized. Therefore, the amount of particles increases, which can be oxidized and eliminated per unit time without generating a luminous flame on the particle filter, with an increase in the temperature of the particle filter taking place at the same time.

The solid line in Fig. 24 shows the amount of particles (G) that can be oxidized and removed per unit time without generating a glowing flame. In Fig. 24, the abscissa represents the temperature TF of the particle filter. Here, Fig. 24 shows the case that the time unit is 1 second, that is, the amount of particles (G) that can be oxidized and removed per 1 second. However, any time, such as 1 minute, 10 minutes or the like, can be selected as the time unit. For example, in the case where 10 minutes is used as the unit of time, the amount of particles (G) that can be oxidized and removed per unit of time represents the amount of particles (G) that can be oxidized and removed per 10 minutes. In the same case, the amount of particles (G) that can be oxidized and eliminated without generating a luminous flame increases as the temperature of the particle filter 70 increases, as shown in FIG. 24. The amount of particles emitted from the combustion chamber per unit time is called the amount of the emitted particles (M). If the amount of particles (M) emitted is less than the amount of particles (G) that can be oxidized and disposed of, for example, the amount of particles (M) emitted per 1 second is less than the amount of particles (G) per 1 second can be oxidized and removed, or the amount of particles (M) emitted per 10 minutes is less than the amount of particles (G) that can be oxidized and removed per 10 minutes, i.e. in area (I) of Fig . 24 is located, the particles that are emitted from the combustion chamber, all oxidized sequentially and removed, without producing for a short time on the particulate filter a luminous flame.

On the other hand, if the amount of particles (M) emitted is larger than the amount of particles (G) that can be oxidized and disposed of, that is, in the area (II) of Fig. 24, the amount of active oxygen is not sufficient to oxidize and remove all particles one after the other. The Fig. 25 (A) to (C) show how the particles are oxidized in such a case.

That is, to oxidize in the case where the amount of active oxygen is not sufficient for all the particles, when the particles 62 adhere to the releasing agent for active oxygen 62, only a part of the particles is oxidized, as shown in Fig. 25 (A ), and the other part of the particle that has not been sufficiently oxidized remains on the surface of the particle filter on which the exhaust gas flows upward. If the state of the lack of active oxygen persists, a part of the particles that have not been oxidized remain in succession on the surface of the particle filter on which the exhaust gas flows upward. As a result, the surface of the particulate filter where the exhaust gas flows upward is covered with the remaining ponds 63 as shown in Fig. 25 (B).

The remaining particles 63 are gradually converted into carbon-containing substances that can hardly be oxidized. In addition, when the surface of the particulate filter where the exhaust gas flows upward is covered with the remaining particles 63 , the platinum (Pt) on oxidizing NO and SO ₂ and the active oxygen releasing agent 61 become active oxygen release hindered. The remaining particles 63 can be oxidized gradually over a relatively long period of time. However, as shown in Fig. 25 (C), other particles 64 are attached to the remaining particles 63 one by one, and when the attached particles form a layer, these particles may, even if they are easily oxidizable Particle is not oxidized because these particles are separated from the platinum (Pt) or from the active oxygen release agent. Accordingly, other particles gradually accumulate on these particles 64 . That is, if the state in which the amount of the emitted particles (M) is larger than the amount of the particles (G) that can be oxidized and eliminated, the settled particles form a layer on the particle filter.

Therefore, in the area (I) of Fig. 24, the particles are oxidized and removed without forming a flare for a short time, and in the area (II) of Fig. 24, the deposited particles form a layer on the particle filter. Therefore, the settling of particles on the particle filter can be prevented if the relationship between the amount of emitted particles (M) and the amount of particles that can be oxidized and eliminated (G) is in the range (I). As a result, the pressure loss of the exhaust gas hardly changes in the particle filter and is kept at a minimum pressure loss value that is almost constant. Therefore, the decrease in engine power can be kept as low as possible. However, this is not always done and the particles can settle on the particle filter if nothing is done.

In this embodiment, in order to prevent the particles from settling on the particle filter, the above control unit 30 controls the opening degree of the valve housing 71 a according to a first flow chart shown in FIG. 26. This flowchart is repeated at fixed intervals. At step 101 , a temperature (TF) of the particle filter is determined. In this determination, a temperature sensor is attached to the particle filter and determines the temperature of the particle filter directly. In addition, the temperature of the particle filter can be calculated at fixed time intervals based on the amount of exhaust gas that flows into the particle filter when the engine is started and its temperature. Next, the current operating state of the engine is determined by using the engine load sensor 41 , the crank angle sensor 42 and the like. In the case of the diesel engine of this embodiment, it is also determined which of the two combustion modes has been selected. When the operating state of the engine has been determined, the amount of the exhaust gas, the temperature of the exhaust gas, the oxygen concentration in the exhaust gas, the amount of the emitted particles and the like can be estimated.

Next, at step 103, the currently required amount of particles that can be oxidized and disposed of can be calculated based on the oxygen concentration in the exhaust gas, the amount of the emitted particles, and the like. In addition, the lowest temperature (TFt) of the particle filter that causes this amount of particles to be oxidized and removed is calculated. At step 104 , the amount of temperature change (dTF) of the particulate filter is calculated based on the instantaneous temperature (TF) of the particulate filter, the instantaneous amount of the exhaust gas, the instantaneous temperature of the exhaust gas, and the like.

Next, at step 105, the amount of temperature change (dTF) is added to the current temperature (TF) of the particulate filter and it is determined whether the result is greater than the lowest temperature (TFt). For example, if the instantaneous temperature (TF) of the particulate filter is very high, even if the instantaneous temperature of the exhaust gas is lower than this temperature (TF) so that the temperature of the particulate filter is reduced, the result at step 105 may be positive. If the result at step 105 is positive, no problems arise. Accordingly, the valve housing 71 a remains in a shut-off position and the routine is stopped.

However, if the result at step 105 is negative and nothing is done, the particles settle on the particle filter and become difficult to oxidize and remove. To prevent this, the exhaust gas is caused not to flow through the particle filter, but to bypass it. At step 106 , the amount of redirected exhaust gas is calculated. The lowest temperature (TFt) and the amount of temperature change (dTF) at steps 103 and 104 apply in the event that the total amount of exhaust gas flows into the particle filter. For example, if only half the amount of exhaust gas flows into the particle filter, the amount of emitted particles (M), ie the amount of particles flowing into the particle filter, decreases by half, and therefore the required lowest temperature (TFt) may be lower , In addition, if the temperature of the exhaust gas is lower than the current temperature (TF) of the particle filter, the amount of the temperature change (dTF) becomes a minus value. Their absolute value can be kept small. Therefore, if the temperature of the exhaust gas is lower than the current temperature (TF) of the particulate filter and the result at step 105 is negative without a large difference, the valve housing will be opened to an appropriate degree between the current shut-off position and the central position of step 107 moved. Thus, only the amount of exhaust gas calculated at step 106 is caused to bypass the particulate filter and particulate matter is prevented from settling thereon.

Of course, when the temperature of the exhaust gas is very low, the valve housing 71 a is moved to the central position to prevent the temperature of the particle filter from falling, and therefore the entire exhaust gas is caused to bypass the particle filter. Incidentally, the amount of particles currently required that can be oxidized and eliminated at step 103 is not always the same as the current amount of particles emitted. For example, when fuel is no longer supplied during engine braking and the like, the amount of the emitted particles becomes practically zero. However, at this time, if the required amount of particles that can be oxidized and disposed of becomes zero and the lowest temperature (TFt) drops below 100 ° C (see Fig. 24), so that the temperature of the particle filter actually drops below 100 ° C, the temperature of the particle filter cannot immediately rise the next time the engine accelerates, and therefore not all particles can be oxidized. Accordingly, it is preferred that the required amount of particles that can be oxidized and removed is always above a predetermined amount, that is, the lowest temperature (TFt) of the particle filter does not drop below, for example, 200 ° C.

Incidentally, the amount of the emitted particles increases depending on the operating state of the engine, and thus the result at step 105 is negative. At this time, if a part of the exhaust gas is caused to bypass the particle filter, the amount of the emitted particles, that is, the amount of the particles flowing into the particle filter, can be reduced, and thus the settling of particles on the particle filter be prevented.

Fig. 27 is a second flowchart that is used in place of the first flowchart to prevent particles from settling on the particle filter. This is explained below. This flowchart is repeated at fixed intervals. First, at step 201, it is determined whether the current quantity of injected fuel (TAU) is less than the specified quantity (TAU1). If the result is negative, the amount of fuel injected (TAU) is relatively large and therefore the temperature of the exhaust gas rises. Therefore, since the temperature of the particle filter does not drop much, the valve housing 71 a is kept in a shut-off position and the routine is terminated.

On the other hand, if the result of step 201 is negative, the temperature of the exhaust gas drops below a predetermined temperature. Therefore, when all of the exhaust gas flows through the particulate filter, the temperature of the particulate filter drops considerably, and therefore the amount of particulate that can be oxidized and removed decreases significantly. Accordingly, the amount of the bypassed exhaust gas is calculated so that the lower the temperature of the exhaust gas or the smaller the amount of fuel injected, the larger the amount of exhaust gas that does not flow through the particle filter but bypasses it. At step 203 , the degree of opening of the valve housing 71 a between a shut-off position and the middle position is set based on this amount of the diverted gas.

Therefore, for example during an interruption of the fuel supply, at which makes the temperature of the exhaust gas very low, causes all of the exhaust gas to Bypass particle filter. If the temperature of the exhaust gas is not very low, some of the exhaust gas is caused to bypass the particle filter. Accordingly prevents the temperature of the particle filter from dropping sharply, and therefore the Amount of particles that can be oxidized and eliminated on the particle filter, relative high and particle settling on the particle filter can be prevented.

Of course, in this flowchart, if the result at step 201 is negative, all of the exhaust gas can be made to bypass the particulate filter to prevent the temperature of the particulate filter from lowering with certainty. The control of this flow chart is less precise than that of the first flow chart. However, it is very simple and does not require complicated calculations. In addition, it may be determined at step 201 whether the driver depresses the accelerator pedal instead of determining the amount of fuel injected. At this time, the fuel supply is cut off so that all of the exhaust gas can be caused to bypass the particulate filter. It is also determined, for example, whether the driver releases the accelerator pedal while the car is stopped and the engine is idling at this time, so that the amount of fuel injected is low. Therefore, all or part of the exhaust gas can be caused to bypass the particle filter.

If the exhaust gas is caused by the first or second flowchart, the particle filter to bypass, if the particles on the partition of the particle filter  stay behind, no other particles on the remaining particles since the exhaust gas is diverted. Therefore, the remaining particles of active oxygen released from the active oxygen release agent at the separation wall is released, gradually oxidized and eliminated. The amount of active Oxygen released from active oxygen is limited and therefore it can Active oxygen release agent after active oxygen release, whereby the particles are oxidized and removed, not active oxygen again release if it does not absorb ambient oxygen as above described. When all of the exhaust gas bypasses the filter, the environment becomes the Particle filter partition no new oxygen is supplied and therefore the is off sorbed and released oxygen on the active oxygen release agent inactive due to lack of oxygen. Therefore, the particles left behind may not be fully oxidized and disposed of. In addition, the particles, which has no contact with the active oxygen release agent on the separation Wall of the particle filter have oxidized only with difficulty due to the lack of oxygen become. Accordingly, when the exhaust gas is caused, it is due to the particulate filter bypassing the first or second flowchart, preferably not the whole Exhaust gas is caused to bypass the particle filter so that at least part of the Exhaust gas flows through the particle filter. However, this does not always have to be done become. Thus there is no lack of oxygen in the vicinity of the partition of the Particle filter.

Fig. 29 is a plan view showing a further embodiment of the apparatus for purifying exhaust gas. A difference to the device shown in Fig. 18 is that the oxygen supply units 74 a and 74 b for the oxygen supply with the first connection section 72 a and with the second connection section 74 b are provided. According to this embodiment, if a part of the exhaust gas bypasses the particle filter, as mentioned above, oxygen can be passed into one of the connecting portions 72 a or 72 b, which is on the side where the exhaust gas flows upward. Therefore, the lack of oxygen in the vicinity of the partition of the particulate filter is surely prevented, and therefore the remaining particles on the partition of the particulate filter can be oxidized and removed with certainty while the exhaust gas is bypassed.

Fig. 30 is a plan view showing another embodiment of the exhaust gas purifying device. A difference from the device shown in Fig. 18 is that the reducing agent supply units 75 a and 75 b, which can direct a reducing agent such as fuel into a large area on both sides of the particle filter, are provided. According to this embodiment, when a part of the exhaust gas flows through the particulate filter as mentioned above, the reducing agent can be directed to the side of the particulate filter where the exhaust gas is sucked in. Therefore, the supplied reducing agent is sufficiently burned by the oxidation catalyst platinum (Pt), which rests on the partition of the particle filter, without a lack of oxygen. The heat of combustion therefrom not only increases the temperature in the exhaust gas inlet area of the particle filter, but also the temperature in the exhaust gas outlet area with the exhaust gas flowing through. Therefore, the temperature of the whole particle filter is raised so that the amount of particles that can be oxidized and removed at the partition of the particle filter and thus the particles remaining on the partition of the particle filter can be oxidized and removed with certainty while the exhaust gas is bypassed. In this embodiment, the reducing agent supply units feed the reducing agent directly into the particulate filter, and therefore, no unnecessary reducing agent adhered to the inner wall of the connecting portions 72 a, 72 b and the like is supplied, and the amount of the reducing agent can be minimized become.

In addition, in the first and second flowchart, the exhaust gas that is not by the particle filter flows, temporarily released into the atmosphere. Is at that time however, in the first flow chart, except when the amount of particles emitted at specific engine operating condition is large, the temperature of the exhaust gas usually low, d. H. the amount of fuel injected is low and the amount of emitted particles is low. Therefore, there are no big problems.  

Incidentally, in the wall-flow type particle filter used in this embodiment, the particles collide with the surface of the partition wall 54 where the exhaust gas flows upward and with the surface opposite to the exhaust gas in the pores therein, that is, with one of the trapping surfaces of the partition wall 54 , and are held there. If the amount of active oxygen released from one of the trapping areas is insufficient for the retained particles, all of the retained particles will not be oxidized and removed and some will remain. Although such residual particles are hardly generated according to the first and second flowcharts, particles may remain on one of the trapping surfaces of the partition wall for some reason, as shown in Fig. 28 (A). The valve housing 71 a in the switching section 71 can be in one of the two shut-off positions and therefore the side of the particle filter on which the exhaust gas flows upwards and the side on which the exhaust gas flows downwards can be changed. Therefore, if the valve housing 71 a changes to a different shut-off position after the valve housing 71 a has been moved from one of the shut-off positions to the vicinity of the middle position, the remaining particles and the deposited particles can be oxidized and removed.

Since no other particles settle again on the remaining particles on one of the trapping surfaces of the partition, since the side of the particle filter where the exhaust gas flows upward and the side where the exhaust gas flows downward are reversed, the remaining particles can be gradually replaced by active ones Oxygen released from one of the trapping areas is oxidized and removed. In addition, particularly the particles remaining in the pores in the partition wall are easily broken up into small pieces by the exhaust gas flowing in the opposite direction, as shown in Fig. 28 (B), and mostly migrate through the pore to the side of the downward flow.

Accordingly, many of the particles that have been broken up into small pieces diffuse into the pores of the partition wall and come into direct contact with the active oxygen releasing agent which rests on the pore surface, and are oxidized and removed. Therefore, if the active oxygen release agent is also on the pore surfaces in the partition, the remaining particles can be easily oxidized and removed. On the other trapping surface, which is now on the upstream side, since the exhaust gas flow has been reversed, ie on the surface of the partition 54 where the exhaust gas flows upward and on the surface opposite the exhaust gas in its pores which mainly hits the exhaust gas (from the opposite side of one of the trapping surfaces), the particles in the exhaust gas adhere again and are oxidized and removed by active oxygen released by the active oxygen release agent. In this oxidation, a part of the active oxygen released from the active oxygen release agent on the other trapping area migrates with the exhaust gas to the side of the downward flow, and is caused to cause the particles that are still present despite the reversal of the exhaust gas flow one of the trapping areas, oxide 12647 00070 552 001000280000000200012000285911253600040 0002010114972 00004 12528 and remove.

That is, the remaining particles will be on one of the trapping areas not only exposed to active oxygen released from this trapping area, but also the rest of the active oxygen, which is used for the oxidation and removal of the particles on the other trapping area was used because of the flow of the exhaust gas is reversed. Therefore, if the particles are retained by going off alternately one trapping surface and the other trapping surface of the partition of the Particle filter used to face the particle filter on which the exhaust gas is up flows, and reverse the side where the exhaust gas flows downward, even if some Particles settle as a layer on one of the capture surfaces of the particle filter, When the exhaust gas flow is reversed, active oxygen reaches the deposited ones Particles and there are no particles due to the reverse exhaust gas flow more on the deposited particles, and therefore the deposited particles gradually oxidized and disposed of, and they can be reversed until the next Exhaust gas must be sufficiently oxidized and removed for a certain time. of course is by alternately using one trapping surface and the other trapping area of the partition, the amount of particles retained on each trapping area smaller than with a particle filter, in which always the same trapping area  Traps particles. This facilitates the oxidation and removal of the retained Particles on the trapping surface.

In addition, when the air / fuel ratio of the exhaust gas is made rich, that is, when the oxygen concentration in the exhaust gas is lowered, active oxygen O is suddenly emitted to the outside by the active oxygen release agent 61 . Therefore, the settled particles become those which can easily be oxidized due to the large amount of active oxygen released at one time, and can be oxidized and removed by the latter without a flare.

On the other hand, if the air / fuel ratio is kept lean, the surface of the platinum (Pt) is covered with oxygen, that is, oxygen contamination is caused. When such oxygen contamination is caused, the oxidizing effect on the NO _x by the platinum (Pt) decreases, and therefore the absorption efficiency of the NO _x decreases. Therefore, the amount of active oxygen released from the active oxygen release agent decreases. However, if the air / fuel ratio is made rich, oxygen on the surface of the platinum Pt is consumed and therefore the oxygen contamination ceases. Accordingly, when the air / fuel ratio changes from rich to lean again, the oxidizing effect on the NO _x becomes strong and therefore the efficiency of the absorption increases. Therefore, the amount of active oxygen released by the active oxygen release agent 61 increases .

Therefore, if the air / fuel ratio is kept lean, if the air / fuel ratio changes from lean to rich every now and then, the platinum (Pt) oxygen contamination ceases, and therefore the amount of active released increases Oxygen on when the air / fuel ratio is lean. Therefore, the oxidation process of the particle on the particle filter 70 can be promoted.

In addition, the termination of the oxygen contamination causes the reducing agent to burn and the heat of combustion therefrom increases the temperature of the particle filter. Therefore, the amount of particles that can be oxidized and removed by the particle filter increases, and therefore the deposited particles are more easily oxidized and removed. When the air / fuel ratio is rich in the exhaust gas GE makes, when the side of the upward stream and the side of the down stream of the particulate a reversed from the valve housing 71, or immediately thereafter, the other trapping surface can remain on the no particles or settle release a large amount of active oxygen. Therefore, the larger amount of active oxygen released can oxidize and remove the remaining and deposited particles with greater certainty.

As a method to make the air-fuel ratio rich, for example, the above-mentioned low-temperature combustion can be performed. Of course, when switching from normal combustion to low temperature combustion or before, the side of the particulate filter where the exhaust gas flows upward and the side where the exhaust gas flows downward can be reversed. As mentioned above, the low temperature combustion is carried out on the side with the low engine load, and therefore the low temperature combustion is often carried out immediately after the throttling of the fuel supply during engine braking. Therefore, immediately after the valve housing 71 a has been brought into the central position, low-temperature combustion is often carried out. In addition, by supplying reducing agent through the aforementioned reducing agent supply units, the air / fuel ratio of the exhaust gas can be made rich. In order to make the air / fuel ratio of the exhaust gas rich, only the combustion air / fuel ratio can be made rich. In addition to the main fuel injection in the compression stroke, in the exhaust stroke or in the expansion stroke, the fuel injector can inject fuel into the cylinder (post-injection) or inject fuel into the cylinder (pre-injection). Of course, it is possible that there is no pause between the post-injection or the pre-injection and the main fuel injection. In addition, fuel can be supplied to the exhaust system.

Also, if the side of the particle filter where the exhaust gas flows upward and the side where the exhaust gas flows downward will be reversed even if a large amount of particles settles on one of the trapping surfaces of the particle filter has, the separated particles easily by the reverse exhaust flow into small Smashed pieces. Part of the particles that are not in the pores of the partition can be oxidized and removed is removed by the particle filter. However therefore avoided that the exhaust gas resistance of the particle filter increases more, which a would have harmful effects on vehicle operation, and that the large amount of ab placed particles ignite and burns at once, causing the particle filter would melt due to the heat. In addition, the other capture area of the Particle of the particle filter again hold back particles.

Incidentally, when SO ₃ is present, calcium (Ca) forms calcium sulfate (CaSO ₄ ) in the exhaust gas in the form of ash. To prevent clogging of the meshes of the particle filter by calcium sulfate CaSO ₄ , an alkali metal or an alkaline earth metal with a stronger tendency to ionize than calcium (Ca), for example potassium (K), can be used as a release agent for active oxygen 61 . Therefore, SO ₃ diffused into the active oxygen release agent 61 is combined with potassium (K), thereby forming potassium sulfate (K ₂ SO ₄ ), and therefore calcium (Ca) is not combined with SO ₃ but permeates it Partition walls of the particle filter. Accordingly, the mesh of the particle filter is not clogged with ash. Therefore, it is desirable to use an alkali metal or an alkaline earth metal with a tendency to ionize stronger than calcium (Ca) as the release agent for active oxygen 61 , for example potassium (K), lithium (Li), cesium (Cs), rubidium (Rb), Barium (Ba) or Strontium (Sr).

Even if only a noble metal such as platinum (Pt) rests on the particle filter, active oxygen can be released from the NO ₂ or SO ₃ , which is held on the surface of platinum (Pt). In this case, however, a curve representing the amount of particles that can be oxidized and removed (G) is slightly shifted to the right compared to the fixed curve shown in FIG. 24. Cerium can also be used as a release agent for active oxygen. The cerium absorbs oxygen when the oxygen concentration is high (Ce ₂ O ₃ → 2CeO ₂ ) and releases active oxygen when the oxygen concentration decreases (2CeO ₂ → Ce ₂ O ₃ ). Therefore, in order to oxidize and remove the particles, the air / fuel ratio of the exhaust gas must be made rich at regular or irregular intervals. Instead of cerium, iron (Fe) or tin (Sn) can be used as a release agent for active oxygen.

It is also possible to use a NO _x absorbent for cleaning NO _x as a release agent for active oxygen. In this case, the air / fuel ratio of the exhaust gas must be made rich at least at times in order to release and reduce the absorbed NO _x and SO _x . It is desirable to make the air-fuel ratio rich after reversing the upstream side and the downstream side.

Therefore, it is desirable that the upstream side and the Ab reverse flow of the particle filter are reversed. This limits the present one However, invention is not. Some or all of the exhaust gas may be induced bypassing the particle filter using a bypass line the side of the particle filter where the current is directed upwards with the side where the current is directed downwards, can communicate as required. Moreover can the diesel engine of this embodiment between the low temperature combustion and normal combustion. This limits the present one Not invention. Of course, the present invention can also be applied to a diesel engine be used, which only carries out the normal combustion, or on an Otto motor that emits solid particles.

In this embodiment, the particle filter itself carries the active oxygen release agent and active oxygen released from the active oxygen release agent oxidizes and removes the particles. However, this does not limit the present invention. For example, a particle oxidation material, such as active oxygen and NO ₂ , which acts just like active oxygen, can be released by a particle filter or a material resting thereon, or can flow into the particle filter from outside. In the event that the particle oxidizing material flows into the outside of the particle filter, when the first trapping surface and the second trapping surface of the partition are used alternately to retain the particles, a trapping surface which is now on the side can be used , where the exhaust gas flows downward, no more particles settle on the remaining particles and the remaining particles are completely oxidized and removed after a certain time. During this period, the other trapping area can retain the particles and the retained particles are oxidized and removed by the particle oxidizing material on the other trapping area. Thus, the same effects as mentioned above can be achieved. Of course, in this case, when the temperature of the particle filter rises, the temperature of the particles themselves increases, and therefore their oxidation and removal can be facilitated.

Although the invention be with reference to specific embodiments thereof It should be understood that numerous modifications have been made by a person skilled in the art of which can be carried out without departing from the basic idea and framework of the Er deviate.

Claims (17)

1. An apparatus for purifying the exhaust gas of an internal combustion engine, comprising a particle filter arranged in the exhaust system, on which the retained Particles are oxidized, and a bypass line through which the exhaust gas Particle filter can handle, the particle filter a lot of particles which oxidizes and ent depending on the temperature of the particle filter can be removed, and if a current exhaust gas condition causes the Amount of particles that can be oxidized and removed in the particle filter is smaller than a currently required amount of particles that oxidize and ent can be removed, at least part of the exhaust gas is caused, the detour to take through the diversion. 2. Device for cleaning the exhaust gas of an internal combustion engine according to An claim 1, wherein the particle filter is a release agent for active oxygen and active oxygen released from the active acid release agent was released, the retained particle on the particle filter oxidized. 3. Device for cleaning the exhaust gas of an internal combustion engine according to An claim 2, wherein the active oxygen release agent takes up oxygen and holds when there is an excess of oxygen in the environment, and the captured oxygen releases as active oxygen when the oxygen concentration in the area decreases. 4. An apparatus for purifying the exhaust gas of an internal combustion engine, comprising a particle filter arranged in the exhaust system, on which the retained particles are oxidized, and a bypass line through which the exhaust gas can bypass the particle filter, the particle filter carrying an active oxygen release agent, active oxygen that was released from the release agent for active oxygen, which retained particles oxidized on the particulate filter, holding the release agent for active oxygen NO _x to the NO _x to combine with oxygen when an excess oxygen exists in the surroundings, and combined _NOx / Releases oxygen so that it is broken down to NO _x and active oxygen when the oxygen concentration in the environment drops, the particle filter has an amount of particles that can be oxidized and removed depending on the temperature of the particle filter, and when a current exhaust gas condition causes the amount of particles that can be oxidized and removed in the particle filter to be less than a currently required amount of particles that can be oxidized and removed, causing at least a portion of the exhaust gas to take the bypass route. 5. An apparatus for purifying the exhaust gas of an internal combustion engine, comprising a particle filter arranged in the exhaust system, on which the retained Particles are oxidized, and a bypass line through which the exhaust gas Particle filter can bypass, the particle filter depending on the tem temperature of the particle filter oxidize and ent a certain amount of particles and if an amount of fuel injected is less than one fixed amount, at least part of the exhaust gas is caused to take the detour to take through the bypass line. 6. Device for cleaning the exhaust gas of an internal combustion engine according to An claim 5, wherein the particle filter is a release agent for active oxygen carries, and active oxygen from the active oxygen release agent was released, the retained particles oxidized on the particle filter. 7. Device for cleaning the exhaust gas of an internal combustion engine according to An claim 6, wherein the active oxygen release agent takes up oxygen and holds when there is an excess of oxygen in the environment, and the  captured oxygen releases as active oxygen when the oxygen concentration in the area decreases. 8. An apparatus for purifying the exhaust gas of an internal combustion engine, comprising a particle filter arranged in the exhaust system, on which the retained particles are oxidized, and a bypass line through which the exhaust gas can bypass the particle filter, the particle filter carrying a release agent for active oxygen, active oxygen that was released from the release agent for active oxygen, the retained particle filter on the particle oxidizes, holding the release agent for active oxygen NO _x to the NO _x to combine with oxygen when an excess of oxygen in order gebung present in the, and the combined NO _x / releases oxygen to be broken down into NO _x and active oxygen when the oxygen concentration in the environment drops, the particle filter has an amount of particles that can be oxidized and removed depending on the temperature of the particle filter, and when the amount on injected Fuel is less than a predetermined amount, at least a portion of the exhaust gas is caused to take the detour through the bypass line. 9. Device for cleaning the exhaust gas of an internal combustion engine after a of claims 5-8, wherein when the engine is idling it is determined that an amount of fuel injected is less than the specified amount. 10. Device for cleaning the exhaust gas of an internal combustion engine after a of claims 5-8, wherein when the fuel supply is cut off, it is determined that an amount of fuel injected is smaller than that set amount. 11. Device for cleaning the exhaust gas of an internal combustion engine after a of claims 5-8, wherein when the brake pedal is depressed, determines  becomes that an amount of fuel injected is smaller than the specified one Quantity. 12. Apparatus for purifying the exhaust gas of an internal combustion engine, comprising a particle filter arranged in the exhaust system, on which the retained Particles are oxidized, and a bypass line through which the exhaust gas Particle filter can handle, the particle filter a lot of particles which oxidizes and ent depending on the temperature of the particle filter can be removed, and if a temperature of the exhaust gas is lower than one specified temperature, at least part of the exhaust gas is caused to to take away through the bypass line. 13. Device for cleaning the exhaust gas of an internal combustion engine according to An claim 12, wherein the particle filter is a release agent for active oxygen carries, and active oxygen from the active oxygen release agent was released, the retained particles oxidized on the particle filter. 14. Device for cleaning the exhaust gas of an internal combustion engine according to An claim 13, wherein the active oxygen release agent is oxygen takes and holds when there is an excess of oxygen in the environment, and releases the trapped oxygen as active oxygen when the oxygen concentration in the area decreases. 15. An apparatus for cleaning the exhaust gas of an internal combustion engine, comprising a particle filter arranged in the exhaust system, on which the retained particles are oxidized, and a bypass line through which the exhaust gas can bypass the particle filter, the particle filter carrying a release agent for active oxygen, active oxygen that was released from the release agent for active oxygen retained ponds on the particulate filter is oxidized, holding the release agent for active oxygen NO _{x, x} to the NO to combine with oxygen when an excess oxygen exists in the surroundings, and combined _NOx / oxygen releases, whereby it is broken down into active oxygen and NO _x , when the oxygen concentration in the environment decreases, the particle filter has an amount of particles that can be oxidized and removed depending on the temperature of the particle filter, and when an exhaust gas temperature is lower t as a set temperature, at least part of the exhaust gas is caused to take the detour through the bypass line. 16. Device for cleaning the exhaust gas of an internal combustion engine after a of claims 1-15, wherein when causing at least part of the exhaust gas will take the detour through the bypass line, oxygen into the Particle filter is passed. 17. Device for cleaning the exhaust gas of an internal combustion engine after a of claims 1-15, wherein the particle filter has an oxidizing ability, and if at least part of the exhaust gas is caused to take the detour through the Bypass line to take a reducing agent the particle filter is fed.