JPH07189656A - Exhaust emission control device for internal combustion engine - Google Patents

Abstract

PURPOSE:To carry out regenerating treatment accurately by detecting engine operating condition when particulates are collected. CONSTITUTION:An exhaust emission control device 1 for an internal combustion engine 51 is provided with the trapper 11 of particulates, a condition detecting means 21 for detecting collecting condition of the particulates, an operation detecting means 22 for detecting operating condition of the internal combustion engine 51, a temperature raising means 15 for carrying out combustion of the particulates, and a controller 40. In the controller 40, the temperature raising means 15 is operated on the basis of the operation hysteresis of the internal combustion engine 51 during collecting the particulates and present operating condition. The particulates may preferably be separately collected according to operating condition of the internal combustion engine 51.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an exhaust gas purifying apparatus for an internal combustion engine which collects and removes particulates contained in exhaust gas.

[0002]

2. Description of the Related Art Exhaust gas from internal combustion engines such as automobiles, particularly diesel engines, contains exhaust particulates (particulates) containing carbon as a main component, which is a cause of exhaust black smoke. Therefore, a particulate filter made of honeycomb ceramic, wire mesh, or the like is provided in the exhaust passage of the diesel engine, and an exhaust purification device for removing particulates by this filter is provided.

However, with the passage of time, the particulates adhering to the filter cause the filter to become clogged, and as a result, the pressure in the exhaust pipe rises, resulting in a reduction in the output of the engine and a deterioration in the fuel consumption rate. For this reason, a method has been proposed in which clogging of the filter is automatically detected and the collected particulates are burned to regenerate the filter. For example, a method has been proposed in which a valve for restricting intake air is provided upstream of the engine, and the exhaust gas temperature of the engine is raised by restricting the intake air amount, thereby burning particulates (Japanese Patent Laid-Open No. 57-179348).
(See the official gazette).

Further, there has been proposed a method of disposing a warm-up catalytic converter (noble metal oxidation catalytic converter) in the exhaust passage upstream of the filter in order to raise the temperature of the exhaust gas supplied to the particulate filter. (See Japanese Unexamined Patent Publication No. 61-112716). There is also a method in which the filter is separated from the exhaust passage and the particulate is burned by an electric heater or the like to regenerate the filter.

[0005]

However, the method of regenerating the filter in the conventional exhaust gas purification device has the following problems. The conventional exhaust emission control device does not perform proper combustion control according to the engine condition and the properties of the particulates by grasping the operating condition of the engine and the properties of the collected particulates.

The particulates include flame-retardant particulates having a high ignition temperature and good-flammability particulates having a relatively low ignition temperature. However, since the regeneration process is performed uniformly, the ignition temperature of the particulates is raised more than necessary, and unnecessary temperature rising operation that does not reach the ignition temperature is performed.

In the method of narrowing the intake air upstream of the engine to raise the temperature of the exhaust gas, if the intake air of the engine is excessively throttled, the output of the engine is lowered, the fuel consumption rate is deteriorated, and the particulate matter discharged is reduced. There is also the problem that the temperature will rise significantly, and improper temperature raising operations cause such problems.

On the other hand, when the intake throttle is too small,
The exhaust gas temperature rise is insufficient, and the filter cannot be regenerated. In addition, in the method of providing a warm-up catalytic converter upstream of the filter, it is necessary to raise the temperature above a certain value in order to activate the warm-up catalyst. It is necessary to raise the temperature of the engine. In this case as well, unless the control is performed according to the driving situation, the output of the engine will be reduced.

In view of such conventional problems, the present invention is
It is an object of the present invention to provide an exhaust gas purification device for an internal combustion engine, which performs an effective regeneration process suitable for the properties of the collected particulates and the operating condition of the engine and does not reduce the output of the engine. is there.

[0010]

According to the present invention, a trapper with an oxidation catalyst for trapping particulates in exhaust gas, which is provided in an exhaust passage of an internal combustion engine, and a trapped state of particulates trapped by the trapper are detected. Operating means for detecting the operating state of the internal combustion engine, temperature raising means for burning particulates, and operating the temperature raising means,
An exhaust gas purifying apparatus for an internal combustion engine, comprising: a controller for regenerating a trapper, wherein the controller is connected to the operation detecting means, and the flame retardant discharged according to the operation history of the internal combustion engine during particulate collection and concentration. An exhaust gas purifying apparatus for an internal combustion engine, characterized in that the temperature raising means is operated depending on the ratio of the characteristic particulates to the good-burning particulates and the current operating state of the internal combustion engine.

What is most noticeable in the present invention is that the operation detecting means for detecting the operation state of the internal combustion engine is provided and is connected to the controller. Then, the controller operates the temperature raising means according to the ratio of the flame-retardant particulates and the good-burning particulates discharged according to the operation history of the internal combustion engine in the particulate trap concentration and the current operating state of the internal combustion engine. , Play the trapper.

In the above description, the trapper may be composed of a single particulate filter or may be composed of a plurality of particulate filters. Also,
The status detecting means includes, for example, a means for detecting the particulate trapping status by obtaining the ventilation resistance of the particulate filter from the differential pressure between the inlet and outlet of the particulate filter and the ventilation flow rate.

As the temperature raising means, for example, there is one that throttles the intake air of the internal combustion engine to raise the exhaust gas temperature as described above, and the other that raises the temperature by narrowing the exhaust gas,
There are those that change the fuel injection delay angle, those that change the fuel injection amount, and those that raise the temperature by an electric heater.

The trapper is provided with a plurality of particulate collecting portions for separating and collecting the flame-retardant particulates and the good-flammable particulates, and the exhaust gas is exhausted from the plurality of trapping portions. It is preferable to provide a switching means that can lead to different collecting portions, and to form the flow path so that the collecting portion for the flame-retardant particulates is located downstream of the good-burning particulates during regeneration.

That is, since the good-burning particulates can be burned at a low ignition temperature, it is not necessary to operate the temperature raising means excessively. On the other hand, the collection part of the flame-retardant particulates can be located downstream of the collection part of the good-flammable particulates, so that the heat of combustion of the good-flammable particulates is transferred to the downstream side, and the flame-retardant particulates are transferred. This is because it becomes easy to ignite the particulate matter.

Whether the flame-retardant particulates are discharged or the good-burning particulates are discharged can be judged from the operating state of the internal combustion engine. Therefore, the controller outputs the output signal of the operation detecting means. Thus, it is possible to judge the property of the particulates and operate the switching means to separate and collect the particulates in separate collecting portions.

A plurality of collecting portions for separating and collecting particulates having different properties can be formed, for example, on the side of the exhaust ports facing each other of a single particulate filter. That is, the flame-retardant particulates are made to flow in from the first exhaust port of the particulate filter, and the good-flammable particulates are made to flow in from the second exhaust port of the particulate filter (the opposite side of the first exhaust port). . Then, the flame-retardant particulates are deposited on the first exhaust port side, and the good-flammable particulates are deposited on the second exhaust port side, separated and collected. Then, at the time of regeneration, if the ventilation is made to flow from the second exhaust port side toward the first exhaust port side, the collection part of the flame-retardant particulates becomes the collection part of the good-flammable particulates. It can be downstream.

Further, as another method of the plurality of collecting portions for separating and collecting the particulates of different properties, there is a method of using a separate particulate filter, for example. The switching means is composed of a pipe line and a switching valve arranged so that the exhaust gas can be separately guided to the separate particulate filter. Then, at the time of regeneration, the conduit and the like are switched by a switching valve or the like so that the particulate filter in which the flame-retardant particulates are collected is located downstream of the particulate filter in which the good-burning particulates are collected.

[0019]

[Operation and effect] The properties of the particulates discharged from the internal combustion engine differ depending on the operating conditions of the internal combustion engine. For example, the particulate matter discharged when the diesel engine has a high load does not burn unless the SOOT content is high and the temperature is high, but the particulate matter discharged when the medium / low load has a high SOF content and burns at a low temperature.

Since the controller of the present invention can know the operation history of the internal combustion engine at the time of collecting particulates by the output signal of the operation detecting means, it is possible to judge the property of the particulates collected by the trapper. . Therefore, it is possible to perform effective particulate combustion control that is suitable for the properties of the particulates.

Further, the controller can determine the current exhaust gas temperature and the like based on the current operating state of the internal combustion engine. For example, when the internal combustion engine is operated at low load and low speed rotation, the exhaust gas temperature is low, and when it is operated at high load and high speed rotation, the exhaust gas temperature rises. Therefore, for example, when trying to burn the particulates by increasing the exhaust gas temperature of the engine, the controller determines whether or not the operating state of the internal combustion engine is appropriate for regeneration, and performs appropriate regeneration processing accordingly. You can

Since the trapper in the exhaust gas purifying apparatus of the present invention carries the oxidation catalyst, it also has the function of promoting the combustion of particulates. As described above, according to the present invention, an effective regeneration process suitable for the properties of the collected particulates and the operating condition of the engine is performed, and the internal combustion engine of the internal combustion engine that does not reduce the output of the engine unnecessarily An exhaust emission control device can be provided.

[0023]

【Example】

Embodiment 1 An exhaust emission control device according to an embodiment of the present invention will be described with reference to FIGS.
Will be explained. In this example, as shown in FIG. 1, a trapper 11 with an oxidation catalyst for trapping particulates in the exhaust 81, which is interposed in an exhaust passage 31 of a diesel engine which is an internal combustion engine 51, is trapped by the trapper 11. Situation detecting means 21 for detecting the collected state of particulates
And the operation detecting means 2 for detecting the operation state of the internal combustion engine 51.
2 and temperature raising means 1 for burning particulates
5, an exhaust gas purification device 1 for an internal combustion engine 51 having a controller 40 for operating the temperature raising means 15 and regenerating the trapper 11.

The controller 40 is connected to the operation detecting means 22 and operates the temperature raising means 15 based on the operation history of the internal combustion engine 51 in particulate collection and concentration and the current operating state of the internal combustion engine 51. And the temperature raising means 1
Reference numeral 5 denotes an intake throttle valve 150 provided in the intake passage 32 of the internal combustion engine 51.

Each of these will be described in detail below. The trapper 11 provided in the exhaust passage 31 of the diesel engine
Is a particulate filter 1 carrying an oxidation catalyst.
10 is installed. The particulate filter 110 has a large number of exhaust passages 111 formed by a honeycomb lattice made of a porous material such as ceramic.

Each of the plurality of flow channels 111 has either an inlet or an outlet closed, and a closed inlet and an outlet are alternately arranged in a checkered pattern. . Therefore, the ventilation through the particulate filter 110 flows out through the zigzag path.

A coating layer of γ-alumina or the like is provided on the surface of the channel 111, and Pt, Pd,
An oxidation catalyst such as Cu is supported. The status detection means 21 for detecting the particulate collection status is a differential pressure detector 21 for detecting the pressure difference between the inlet and the outlet of the trapper 11.
1, an engine control ECU 4, and a particulate collection detection program provided in the ECU 4.

The particulate collection detection program is
It is a program that determines the amount of particulates trapped based on the differential pressure of the trapper 11, the engine speed, and the load condition. The engine speed and load status are
It can be known from the driving detecting means 22. The controller 40 is composed of the ECU 4 and a reproduction processing program provided in the ECU.

Next, an outline of regeneration control in the exhaust emission control system of this example will be described. First, the composition and properties of particulates will be described. The combustion temperature of the particulates collected by the particulate filter changes depending on its composition, and most of them are SOF and SOT. And SOF component (component soluble in organic solvent)
The higher the number, the lower the combustion temperature of particulates,
The larger the T content, the higher the particulate combustion temperature.

On the other hand, SOF contained in the particulates
The percentage of minutes generally increases as the engine load decreases, as indicated by the shaded zone in FIG. The reason for this is considered to be that the exhaust temperature is low at low load and a large amount of unburned fuel components are discharged.

The exhaust emission control system of the present embodiment determines the property of particulates (the size of the SOF content) from the operating state of the engine during particulate collection and concentration, and the throttle amount of the throttle valve 150 during regeneration processing is determined by this. Control to change. This is because the exhaust temperature of the engine increases or decreases depending on the size of the throttle.

Next, the flow of the above control will be described in detail with reference to FIG. First, in step 601, the engine load status is read from the operation detecting means 22 at regular sampling intervals. Then, in step 602, the region 1 in which the engine load T is equal to or greater than the predetermined value T ₀ shown in FIG.
If so, the first counter in the ECU 4 is incremented to a predetermined T
_In the case of area 2 which does not reach ₀ , the second counter is incremented. In FIG. 4, a region 1 is a high load region where flame-retardant particulates are produced, and a region 2 is a low load region where flame-retardant particulates are produced.

Next, at step 603, the differential pressure before and after the trapper 11 is read from the differential pressure detector 211, and the situation detection means 21 calculates the particulate collection amount m as described above. Then, in step 604, it is determined whether or not the collection amount m has reached a preset set value m ₀ (for example, 10 g). When m ₀ is not reached, the above steps 601 to 601 are performed until m ₀ is reached.
604 is repeated, and if m ₀ is reached, step 60
Go to 5.

In the above, as the count number t ₂ of the second counter is large and the count number t ₁ of the first counter is small, the SOF component is large and the particulates have a good flammability. Curates are flame retardant. In the following step 605, the operation detecting means 22 reads the load condition of the engine again to detect which of the regions A to C shown in FIG.

In FIG. 5, a region A is a region not suitable for performing regeneration processing by restricting the intake air of the engine, and a region B.
Indicates a region in which the regeneration process can be performed by restricting the intake air, and a region C indicates a region in which the regeneration process can be executed without restricting the intake air. In addition, the index 1 in the figure shows the maximum engine speed and the maximum load.

The meaning of the areas A to C will be described in more detail. When the engine has a low load and low rotation (area A), the exhaust temperature of the engine is low (for example, 25
(0 ° C. or less), it is difficult to raise the combustion temperature of the particulates even if the intake air is greatly reduced, and the amount of particulates discharged in this operating region is small. Therefore, in this case, the reproduction process is not performed.

In this situation, if the intake air of the engine is throttled, the exhaust temperature T of the engine rises as shown in FIG. 6, but on the other hand, the fuel consumption amount U also increases and the particulate emission amount increases accordingly. However, it is difficult to reproduce the filter well. On the other hand, when the engine is under high load and high rotation (region C in FIG. 5,), the exhaust temperature is high (for example, 400 ° C. or higher) and the combustion temperature of the particulates or higher, so it is not necessary to throttle intake air. Reproduction processing is possible.

When the engine has a medium load and a medium rotation (region B in FIG. 5), the amount of intake air is reduced to
It is possible to regenerate by burning particulates.
Therefore, if it is determined that the region is A in step 606, the intake is not throttled in step 607 and the process returns to step 605 to wait for the condition to be satisfied.

If it is the region C, step 6
In step 09, the throttle is closed and the regeneration process is performed.
If it is determined in step 606 that it is in the region B, the process proceeds to step 608 to calculate an appropriate aperture amount f. A method of determining the aperture amount f in step 608 will be described.

Here, it should be noted that, firstly, as shown in FIG.
As shown in, the size of the aperture is changed according to the characteristics of the particulates. As described above, the combustion temperature of about particulates Waits count t ₁ of the first counter is large high combustion temperature of the particulate as the weights of the count number t ₁ of the first counter is smaller low.

Therefore, in this example, the ratio R of the count number t ₁ of the first counter to the total count number (t ₁ + t ₂ ) of the first and _second counters is calculated, and the solid line f _{3 in} FIG.
As shown in (3), the larger the ratio R, the larger the aperture amount. Conventionally, such a change in the aperture amount has not been performed as shown by a broken line f ₄ in FIG.

Then, in step 610, the throttle valve 150 is operated based on the throttle amount f. Then, in step 611, the trapped amount m of particulates is calculated by the same method as in step 603. Then, in step 612, when the collection amount m is reduced to a predetermined value m ₁ (for example, 0.5 g) or less, step 613
At, the regeneration is completed and the ECU counter is reset. When the collected amount m is m ₁ or more, the process returns to step 605, and the regeneration is continued until the completion condition (m <m ₁ ) is satisfied.

As described above, in this example, the proper regeneration process is performed in accordance with the characteristics of the collected particulates and the current operating condition of the engine. Therefore, the exhaust gas purification device can be regenerated without performing an inappropriate intake throttling operation or an excessive intake throttling operation. It also maintains a good fuel economy and does not inappropriately reduce engine output. As described above, according to this example, it is possible to reduce the output of the engine by adapting to the properties of the collected particulates and performing effective regeneration processing that is compatible with the current engine condition. It is possible to provide an exhaust emission control device for an internal combustion engine that does not have the above.

Embodiment 2 As shown in FIG. 8, this embodiment is another embodiment in which the regeneration treatment method is slightly changed in Embodiment 1 when the engine is operated at a low load for a long time. That is, as shown in FIG. 8, when the engine is operated with a low load for a long time, the normal throttle amount f _{1 is changed} to the throttle amount f ₂ for a fixed time (for example, 5 minutes) at the beginning of the regeneration process. The exhaust gas is increased to a high temperature (for example, about 600 ° C.), and thereafter, the throttle amount f ₁ is restored to the same as in the first embodiment.

When the engine is operated under a low load, particulates containing a large amount of SOF are generated, and the surface of the oxidation catalyst is covered with this SOF, which causes a problem of deterioration of catalytic performance. For this reason, it becomes difficult to burn the particulates, but the SOF component on the catalyst surface is burned to restore the catalyst ability by raising the exhaust temperature for the first fixed time as in this example. be able to. Others are the same as those in the first embodiment.

Third Embodiment In this embodiment, as shown in FIG. 9, in the first or second embodiment, the regions 1 and 2 shown in FIG. 4 are divided into four regions 3 to 6 and the control shown in FIG. Step 602 in the flow
The counter of the ECU4 in 2 was increased from 2 to 4,
This is another embodiment in which the algorithm of step 608 for calculating the aperture amount f is changed.

That is, in this example, the operating conditions of the engine at the time of particulate collection are divided into four sections in FIG. 9, and these are individually counted by the four counters of the ECU 4 (step 602 in FIG. 3). In this way, the operating history of the engine at the time of particulate collection can be grasped in more detail.

Then, the aperture amount f during reproduction (see FIG. 3,
Step 608) is calculated by the following equation. f = at ₃ + bt ₄ + ct ₅ + dt ₆ (1) In the above, a, b, c and d are constants such that a <b <c <d, and t _{3 to} t ₆ are It is the count number counted by the counter corresponding to the area of FIG. 9 indicated by each subscript 3 to 6. That is, since the larger the subscript is, the stronger the flame retardancy of the particulates is, the weights (a to d) for calculating the aperture amount are increased.

As described above, by more finely grasping the operation history at the time of collecting particulates,
The properties of the particulates can be grasped more accurately, which enables more appropriate regeneration processing. The algorithm of the above formula (1) is only an example, and it is possible to brush up to a more appropriate formula by accumulating data. Others are the same as those in the first and second embodiments.

Embodiment 4 As shown in FIG. 10, this embodiment is another embodiment in which the intake throttle valve of the temperature raising means 15 is changed to the exhaust throttle valve 160 in the first, second or third embodiment. Here is an example. That is,
In the present example, the exhaust gas temperature is raised by throttling the engine displacement with the exhaust throttle valve 160 downstream of the trapper 11. Others are the same as those in the first and second embodiments.

Fifth Embodiment In this embodiment, as shown in FIGS. 11 and 12, in the first, second or third embodiment, the temperature raising means is the fuel injection increasing device 17 (FIG. 11) and the intake air intake This is another embodiment in which the throttle amount f is replaced with the fuel injection increase amount f (FIG. 12). That is, in this example, the exhaust temperature of the engine is changed by changing the fuel injection amount by the fuel injection increasing device 17. Then, as shown in steps 614 to 617 of the control flow chart of FIG.
The amount of increase in fuel injection is controlled instead of the throttle amount f (steps 607 to 610 in FIG. 3). Others are the same as those in the first, second or third embodiment.

Embodiment 6 In this embodiment, as shown in FIG. 13 and FIG. 14, in the embodiment 1, embodiment 2 or embodiment 3, the temperature raising means of FIG. FIG. 13) is another embodiment in which the injection retard angle amount is used instead of the throttle amount in FIG. 3 (FIG. 14). That is, in this example, steps 621 to 621 in FIG.
As indicated by 624, the fuel injection delay amount is controlled in place of the throttle amount (FIG. 3, steps 607 to 610, FIG. 12, steps 614 to 617) in the first to third embodiments.
Others are the same as those in the first or second embodiment.

Embodiment 7 In this embodiment, as shown in FIG. 15, in the embodiment 1, embodiment 2 or embodiment 3, the temperature raising means 15 is constituted by the intake throttle valve 150 of the engine and the fuel injection retardation device 17. One more
Two examples. As shown in FIG. 16 instead of FIG. 5, the current engine operating conditions are D, E, E ′, F.
Are divided into four areas, and the control mode is changed corresponding to each of the areas D to F.

That is, as shown in FIG.
At 6, it is determined whether the operating state of the engine is in any one of the regions D to F, and the control is performed as follows according to the determination.
If it is in the region D, it is judged to be unsuitable for the regeneration process as in the region C (FIG. 5), the process proceeds to step 627, and the temperature raising means 15 is not operated (corresponding to step 607 in FIG. 13). If it is in region F, go to step 630,
In this case, as in the area C (FIG. 5), the temperature raising means 15
Similarly, the temperature raising means 15 is not operated because it can be regenerated even if it is not operated (corresponding to step 609 in FIG. 3).

Then, in the areas E and E ', the temperature raising means 15 is operated to perform the regeneration process. First, in the case of the E'region where the load is relatively medium and high, the routine proceeds to step 632, where the fuel injection retardation device 17 is operated to raise the temperature. The amount of temperature rise when the fuel injection is retarded is smaller than that at the time of throttle reduction of the intake air, but the deterioration of fuel consumption and the like is small, so that the region E'of relatively high temperature is
Then, only the injection retardation is performed.

In the case of the medium and low load E region, since it is necessary to increase the temperature rise amount, the routine proceeds to step 633, where both the fuel injection retardation device 17 and the throttle valve 150 are operated to raise the temperature. To do. Other control flows are the same as those in FIG. 3 of the first embodiment. Other than that, it is the same as the first, second, and third embodiments.

Embodiment 8 In this embodiment, as shown in FIGS. 17 and 18, the fuel injection retardation device is replaced with the fuel injection increasing device 18 in the seventh embodiment.
Is another example. That is, as shown in FIG. 17, the operation of the temperature raising means of FIG. 19 (steps 632, 63
The retarding device (retarding amount) in 3) is changed to the increasing device 18 (injection amount increasing) (steps 628, 629). Others are the same as in the seventh embodiment.

Example 9 In this example, the flame-retardant particulates and the good-burning particulates are separated and collected as in Example 1 or Example 2,
This is another embodiment in which the flame-retardant particulate trap portion is located downstream of the good-flammable particulate trap portion for regeneration treatment.

That is, as shown in FIG. 20, the trapper 11
Has a plurality of traps 115, 116 for separately collecting the flame-retardant particulates and the good-flammable particulates, and the exhaust 81 is provided with the different traps 115, 116.
Has a switching means 32 for the exhaust passage 31 leading to the exhaust passage 31 and operates the switching means 32 at the time of regeneration of the trapper 11 to collect the flame-retardant particulates 115.
Can be located downstream of the good flammable particulate collecting portion 116.
0 is the switching means 32 so that the exhaust gas 81 is introduced into the separate collecting portions 115 and 116 according to the operating state of the internal combustion engine 51.
Is operated to collect the flame-retardant particulate collecting portion 115 and the good-flame particulate collecting portion 116.
A flow passage is formed so as to be located downstream of the.

Then, the two collecting parts 115, 116
Is formed on the side of the exhaust ports 117 and 118 facing each other in the single particulate filter 110, and the switching means 32 is provided with the particulate filter 110.
Valve 320 for reversing the inlet of the exhaust 81 to the
Is.

A supplementary explanation will be added to the above. As shown in FIG. 20, a first exhaust pipe 31 connected to the engine is provided downstream of the internal combustion engine 51 (diesel engine).
1, the switching valve 320, the first exhaust pipe 311 to the opposite exhaust ports 117, 1 of the particulate filter 110.
Second and third exhaust pipes 312, 313 connected to 18, and
An exhaust pipe 314 connected to the second and third exhaust pipes 312 and 313 is provided.

The switching valve 320 is, for example, a butterfly type switching valve, and when it is in the first position,
Exhaust gas 81 is engine-first exhaust pipe 311 -second exhaust pipe 3
12-filter 110-third exhaust pipe 313-exhaust pipe 31
It flows in order of 4. Further, when the switching valve 320 is in the second position shown in FIG. 20, the exhaust gas 81 is the engine-first exhaust pipe 311-third exhaust pipe 313-filter 1
It flows in the order of 10-second exhaust pipe 312-exhaust pipe 314.

That is, by switching the position of the switching valve 320, the exhaust ports 117, 118 of the filter 110 into which the exhaust 81 flows can be switched. Then, the controller 40 sets the switching valve 320 to the first position in the case of the region 1 (high load) shown in FIG.
In case of (low load), the second position is set.

Then, the particulate filter 110
Since a large number of channels are formed by the honeycomb lattice and the inlets or outlets are alternately sealed, the exhaust gas 81
By changing the inflow direction of the traps, the trapping portions 115, 116 are trapped on the different passage wall sides in the filter 110.
Formation). That is, as shown in FIG.
The one side of the passage wall 119 is supplemented with the good-burning particulates 821 at the time of low engine load (SOF amount is large) and the other side is provided with the flame-retardant particulates 822 at high load (SOOT amount).

Next, the control flow of the exhaust purification system 1 of this example will be described with reference to FIG. First, in step 641, the operation detecting means 22 is set at a constant sampling time.
Read the engine load status from. And step 6
42, the operating state is in the region 1 of FIG. 4 (load T ≧
T ₀ ).

If YES (YES), the process proceeds to step 643, the switching valve 320 is switched to the first position, and the count value of the first counter in the ECU 4 is incremented. If the determination result of step 642 is negative (NO), the process proceeds to step 644, and the switching valve 3
20 is switched to the second position and the count value of the second counter in the ECU 4 is advanced.

Then, as in FIG. 3, steps 604, 6
If it is determined in 05 that the particulate collection amount m is equal to or greater than the preset set value m ₀ (YES), the process proceeds to the next step 645 and subsequent regeneration processes, and if not (NO), the process proceeds to step 641. Return. If YES in step 605, the flow advances to step 645 to switch the switching valve 320 to the second position.

Then, as in the first embodiment, step 60
At 5,606, the throttle valve 150 is throttled to raise the temperature for regeneration. Then, in the second position, the upstream flammable particulate matter (collecting portion 116) burns at a low temperature, and the combustion heat generated at that time also causes the downstream flame-retardant particulate matter (collecting portion 115). Burns very well.

The other control flow is described in the first embodiment.
Alternatively, it is similar to the second embodiment. In the above, the switching operation of the switching valve 320 at the time of collecting particulates is performed when the transition state between regions in FIG. 4 continues for a certain time (for example, 10 seconds) or more in order to avoid frequent switching and hunting. To do.

Further, according to the present example, in order to effectively utilize both sides of the wall of the filter 110 (FIG. 22), the exhaust 81 is circulated in one direction and only one side of the wall of the filter 110 is utilized (Example 1). As compared with Example 8), the contact area between the particulate and the oxidation catalyst is doubled, and as a result, the burning time of the particulate is greatly shortened. Further, since the operating area of the filter 110 is doubled, the usage of the catalyst for burning the same amount of particulates is halved, and the durability time of the catalyst is significantly improved.

Embodiment 10 In this embodiment, as shown in FIG. 23, a plurality of trapping parts of the trapper 11 in Embodiment 9 are two different particulate filters 110 and 120, and a differential pressure detector 211 is arranged downstream. Installed filter 120 for flame retardant particulates
It is another embodiment provided in.

That is, the fourth and fifth exhaust pipes 315 and 316 are branched from the first exhaust pipe 311 connected to the engine 51, and the first filter 110 is connected to one of the fourth exhaust pipes 315.
Is provided. Then, the fourth and fifth exhaust pipes 315,
The second filter 120 is disposed in the sixth exhaust pipe 317, where the 316 is merged again downstream.

The switching valve 321 connects the first exhaust pipe 311 and the fourth exhaust pipe 315 in the second position, and connects the first exhaust pipe 311 and the fifth exhaust pipe 316 in the first position shown in FIG. To connect. When the operating state of the engine in the particulate trapping and concentration is in the area 2 in FIG. 4, the switching valve 321 is switched to the second position, and the first filter 110 traps the good-burning particulates.

On the other hand, the operating condition of the engine is the area 1 in FIG.
In the case of, the switching valve 321 is switched to the first position, and the second filter 120 collects the flame-retardant particulates. Then, at the time of regeneration, the switching valve 321 is switched to the second position and the first filter 110 is positioned upstream of the second filter 120. As a result, the flame-retardant particulates of the second filter 120 are easily ignited and burned by the action of the combustion heat of the particulates of the first filter 110 that ignites at a low temperature. Others are the same as in the ninth embodiment.

Embodiment 11 As shown in FIG. 24, this embodiment is another embodiment in which an exhaust gas temperature sensor 33 is provided upstream of the trapper 11 downstream of the internal combustion engine 51 in Embodiment 1, Embodiment 2 or Embodiment 3. This is an example. Then, according to the exhaust gas temperature t detected by the exhaust gas temperature sensor 33, it is determined whether the temperature raising means 15 (throttle valve 150) is operated to perform the regeneration process or not.

That is, in the first to third embodiments, the regeneration process should be determined in accordance with which of the areas A to C shown in FIG. 5 the engine is currently operating. In the example, it is done by the exhaust temperature t. That is, the playback control flow is as shown in FIG.
In step 651, the exhaust gas temperature sensor 33 measures the exhaust gas temperature t, and in step 652, the low temperature (t <
t ₁ ), high temperature (t> t ₂ ), medium temperature (t ₁ ≦ t ≦
t ₂ ), for example, t ₁ = 250 ° C., t ₂ =
400 ° C).

If the temperature is low, the regeneration process is not performed (step 653). If the temperature is high, the temperature raising means 15 is used.
The regeneration process is performed without using the (throttle valve 150) (step 655), the process proceeds to step 654 only when the temperature is medium, and the temperature raising means 15 is used to perform the regeneration process. as mentioned above,
In this example, since the exhaust gas temperature t is directly measured to determine the control method of regeneration, the regeneration process can be performed more accurately.

That is, according to the area divisions (A to C) in FIG. 5, even in the same area, when the engine temperature is low immediately after the engine is started or when the temperature is high after the high load operation, the exhaust temperature is different from the normal one, There may be some lack of control accuracy,
In this example, there is no such problem. Others are the same as those in the first, second or third embodiment.

Twelfth Embodiment This embodiment is another embodiment of the eleventh embodiment in which the exhaust temperature sensor 33 is provided on the downstream side of the trapper 11, as shown in FIG. In this example, the exhaust temperature sensor 33 can be used for the same purpose as in Example 11, and the exhaust temperature t'downstream of the trapper 11 after the regeneration process is started can be monitored and reflected in the control. .

For example, when the engine is operated at maximum load and a regeneration process is performed, the exhaust gas of the engine becomes hot and the heat of particulate combustion may cause the filter 110 to reach an abnormally high temperature. This causes a problem that durability of the filter 110 and the catalyst is significantly reduced. In this example, such a state is set as the exhaust temperature t ′ downstream of the trapper 11.
You can learn from

That is, as shown in FIG. 27, the trapper 11
When the downstream exhaust gas temperature exceeds a preset limit temperature t _L (eg, 800 ° C.), the throttle amount of the throttle valve 150 is increased. Then, the oxygen concentration in the exhaust gas at the time of maximum load operation of the engine (usually about 3%) further decreases, resulting in an oxygen deficiency state and suppressing the combustion of particulates.

As a result, as shown in FIG. 27, the exhaust temperature t'downstream of the trapper 11 drops again and the filter 110
It is possible to avoid shortening the life of the device. Others are the same as in the eleventh embodiment.

[Brief description of drawings]

FIG. 1 is a system configuration diagram of an exhaust emission control device according to a first embodiment.

FIG. 2 is a correlation diagram between an engine load state and exhaust particulates.

FIG. 3 is a control flowchart of the exhaust emission control device of the first embodiment.

FIG. 4 is a sectional view of an engine operating state during particulate collection and concentration in the exhaust emission control device of the first embodiment.

FIG. 5 is a sectional view of the operating state of the engine that determines the operating conditions in the exhaust emission control device of the first embodiment.

FIG. 6 is a correlation diagram of the intake throttle amount, the exhaust temperature T, and the fuel consumption amount U.

FIG. 7 is a comparison diagram of the operation mode of the temperature raising means and the operation mode of the conventional device in the exhaust emission control device of the first embodiment.

FIG. 8 is a transition diagram of a control mode of the exhaust emission control device according to the second embodiment.

FIG. 9 is a sectional view of an engine operating state during particulate collection and concentration in the exhaust emission control device of the third embodiment.

FIG. 10 is a system configuration diagram of an exhaust emission control device according to a fourth embodiment.

FIG. 11 is a system configuration diagram of an exhaust emission control device according to a fifth embodiment.

FIG. 12 is a control flowchart of the exhaust emission control device of the fifth embodiment.

FIG. 13 is a system configuration diagram of an exhaust emission control device according to a sixth embodiment.

FIG. 14 is a control flow chart of the exhaust purification system of the sixth embodiment.

FIG. 15 is a system configuration diagram of an exhaust emission control device according to a seventh embodiment.

FIG. 16 is a sectional view of the operating state of the engine that determines the operating conditions of the exhaust emission control device of the seventh embodiment.

FIG. 17 is a control flow chart of the exhaust purification system of the eighth embodiment.

FIG. 18 is a system configuration diagram of an exhaust emission control device according to an eighth embodiment.

FIG. 19 is a control flow chart of the exhaust purification system of the seventh embodiment.

FIG. 20 is a system configuration diagram of an exhaust emission control device according to a ninth embodiment.

FIG. 21 is a control flow chart of the exhaust purification system of the ninth embodiment.

FIG. 22 is a diagram showing how particulates adhere to the passage walls of the particulate filter of the ninth embodiment.

FIG. 23 is a system configuration diagram of an exhaust emission control device according to a tenth embodiment.

FIG. 24 is a system configuration diagram of an exhaust emission control device according to an eleventh embodiment.

FIG. 25 is a control flow chart of the exhaust purification system of the eleventh embodiment.

FIG. 26 is a system configuration diagram of an exhaust emission control device according to a twelfth embodiment.

FIG. 27 is a transition diagram of the exhaust temperature t ′ downstream of the trapper and the intake throttle amount f in the exhaust purification system of the twelfth embodiment.

[Explanation of symbols]

 1. ． ． Exhaust gas purification device, 11. ． ． Trapper, 15. ． ． Temperature raising means, 21. ． ． Status detection means, 22. ． ． Operation detection means, 40. ． ． Controller, 51. ． ． Internal combustion engine,

─────────────────────────────────────────────────── ─── Continuation of the front page (51) Int.Cl. ⁶ Identification code Internal reference number FI Technical display location B01D 46/42 B 7446-4D ZAB A 7446-4D

Claims (5)

[Claims] 1. A trapper with an oxidation catalyst for trapping particulates in exhaust gas, which is interposed in an exhaust passage of an internal combustion engine, and a condition detecting means for detecting a trapped state of particulates trapped by the trapper. An exhaust gas purification apparatus for an internal combustion engine, comprising: an operation detecting means for detecting an operating state of the internal combustion engine; a temperature raising means for burning particulates; and a controller for operating the temperature raising means to regenerate a trapper. The controller is connected to the operation detecting means, and the ratio of the flame-retardant particulates and the good-burning particulates discharged according to the operation history of the internal combustion engine in the particulate trapping concentration and the current internal combustion An exhaust emission control device for an internal combustion engine, characterized in that the temperature raising means is operated according to the operating state of the engine. 2. The trapper according to claim 1, wherein the trapper has a plurality of particulate collecting portions for separating and collecting the flame-retardant particulates and the good-burning particulates, and the exhaust gas is exhausted as described above. It has a means for switching the exhaust passages leading to different traps and distributes it so that the trap for the flame-retardant particulates can be located downstream of the trap for the good-burning particulates when the trapper is regenerated. The controller operates the switching means so as to introduce the exhaust gas into a separate collecting portion in accordance with the operating state of the internal combustion engine, and at the time of regeneration, the collecting portion for the flame-retardant particulates. The exhaust gas purifying apparatus for an internal combustion engine, wherein the flow passage is formed so as to be located downstream of the good-burning particulates. 3. The flame-retardant particulate trap portion and the good-flammability particulate trap portion according to claim 2,
A single particulate filter is formed on the opposite exhaust port side, and an exhaust passage switching means for reversing the exhaust gas inlet to the particulate filter is provided, and the controller responds to the operating state of the internal combustion engine. The exhaust gas purifying apparatus for an internal combustion engine, wherein the exhaust gas inlet to the particulate filter is reversed. 4. The collecting part for flame-retardant particulates and the collecting part for good-burning particulates according to claim 2,
An exhaust gas purification device for an internal combustion engine, which is a separate particulate filter. 5. The exhaust gas purifying apparatus for an internal combustion engine as claimed in claim 1, wherein the temperature raising means is an intake throttle means provided in an intake passage of the internal combustion engine.