JPH0634570Y2 - Exhaust gas purification device for internal combustion engine - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION <Industrial Application Field> The present invention relates to an exhaust gas purification apparatus for an internal combustion engine.

<Prior Art> Since internal combustion engines, especially diesel engines, contain a large amount of exhaust particulates, mainly carbon, in the exhaust, the exhaust particulates are collected by a filter in the exhaust passage from the viewpoint of preventing air pollution. I am trying. In addition, when the exhaust particulates increase, the filter is clogged, the exhaust pressure rises and the engine performance deteriorates.Therefore, the exhaust particulates collected in the filter at a predetermined time should be removed as fuel to regenerate the filter. ing. FIG. 6 shows a conventional example of this type of exhaust emission control device.

That is, the filter 3 is interposed in the exhaust passage 2 of the diesel engine 1, and the filter 3 collects the exhaust particulates in the exhaust. In the filter 3, a large number of cells that are substantially parallel to the exhaust flow are formed by honeycomb-shaped partition walls made of a porous material such as ceramic, and the outlets and inlets of the cells are alternately sealed by a blocking material. Then, when the exhaust gas flows into the adjacent cell through the partition wall, the exhaust particle is collected by the partition wall. Here, the flow passage cross-sectional area of each cell is set to be substantially the same.

When a predetermined amount of exhaust particulate matter is collected by the filter 3, the burner 4 is burned to heat the exhaust particulate matter to burn and remove it.

In addition, 5 is a muffler.

<Problems to be Solved by the Invention> However, in such a conventional exhaust emission control device, when the burner 4 burns the exhaust particulates of the filter 3, the outer peripheral portion is cooled by the outside air to lower the temperature. There is a problem that the temperature of the central portion of the filter is higher than that of the outer peripheral portion thereof, and particularly the temperature of the exhaust outlet side is increased, so that the filter 3 is melted and cracked, and the regeneration efficiency is also reduced.

Therefore, as shown in Japanese Utility Model Publication No. 63-46652, there has been proposed one in which a high frequency induction coil is wound so as to cover the outer periphery of the filter to make the temperature inside the filter uniform and prevent melting damage. In addition, as shown in Japanese Utility Model Publication No. 61-74616,
It has been proposed that a heater is provided so as to cover the outer periphery of the filter to make the temperature inside the filter uniform.

However, these devices have a problem that the cost is significantly increased because the high frequency induction coil and the heater are provided.

The present invention has been made in view of the above circumstances, and an object of the present invention is to provide an exhaust gas purification device for an internal combustion engine that can prevent filter melting loss and improve regeneration efficiency while suppressing an increase in cost. .

<Means for Solving the Problems> Therefore, the present invention is directed to a filter for collecting exhaust gas particles by forming a large number of exhaust gas flow cells substantially parallel to the exhaust gas flow and allowing the exhaust gas to flow to adjacent cells through partition walls. In the exhaust passage, the filter is divided into a plurality of parts along the exhaust passage, and the upstream side filter is configured so that the flow passage cross-sectional area of the central cell is smaller than that of the outer peripheral portion. The cells in the central portion were formed in high density, and the downstream filter was formed in high density in the outer peripheral cells so that the flow passage cross-sectional area of the cells in the outer peripheral portion was smaller than that in the central portion.

<Operation> In this way, in the central portion, the upstream filter removes a large amount of exhaust particulates by combustion, and then the downstream filter quickly circulates the exhaust gas to suppress the temperature rise,
In the outer peripheral portion, a large amount of exhaust particulates are burned and removed by the downstream filter, so that the temperature rise is sufficient, and the temperature inside the filter can be made uniform and the rise in temperature can be suppressed.

<Embodiment> An embodiment of the present invention will be described below with reference to the drawings.

1 to 4 show a first embodiment of the present invention.

In FIG. 1, the exhaust passage 11 is provided with a first filter 12 as an upstream filter, and the exhaust passage 11 downstream of the first filter 12 is provided with a second filter 13 as a downstream filter. It is placed in contact with the downstream end.
Each of the first and second filters 12 and 13 has a large number of cells substantially parallel to the exhaust flow formed by honeycomb-shaped partition walls made of a porous member such as ceramic, and the outlets and inlets of the cells of the filters 12 and 13 are formed. And are alternately sealed by a sealing material. Here, the first filter 12 so that the blocking material at the downstream end and the blocking material at the upstream end of the second filter 13 face each other
12 and the second filter 13 are attached.

As shown in FIG. 2, the first filter 12 has a central portion A
The cells in the central portion A are formed to have a higher density than the outer peripheral portion B so that the flow passage cross-sectional area of the cell is smaller than that in the outer peripheral portion B. Further, as shown in FIG. 3, the second filter 13 has a cell at the outer peripheral portion B'centered so that the flow passage cross-sectional area of the cell at the outer peripheral portion B'is smaller than that of the central portion A '. It is formed with a higher density than the portion A '.

Here, the cells of the first filter 12 and the second filter along the exhaust passage 11
The total flow resistance of the cells of the filter 13 is set to be substantially the same in the entire area including the central portion and the outer peripheral portion.

A burner (not shown) is provided in the exhaust passage 11 upstream of the first filter 12.

According to this configuration, the first filter 12 and the second filter 13
Since the sum of the flow path resistances is set to be substantially equal over the entire area, substantially the same amount of exhaust gas flows through the entire area including the central portion and the outer peripheral portion.

At this time, the cells in the central portion A of the first filter 12 are formed with a high density and the cells in the outer peripheral portion B ′ of the second filter 13 are formed with a high density, so that the exhaust particulates in the exhaust flowing through the central portion are While the first filter 12 collects a larger amount than the second filter 13, the exhaust particulates in the exhaust flowing through the outer peripheral portion are second
The filter 13 collects a larger amount than the first filter 12.

When the burner operates the burner to remove the exhaust particulate matter collected by the first and second filters 12 and 13, the exhaust gas gently flows through the first filter 12 and then passes through the second filter 13 in the central portion. While flowing quickly, in the outer peripheral portion, after quickly flowing through the first filter 12, the second filter 13
Flowing slowly.

Therefore, in the central portion, a large amount of exhaust particles are burned and removed by the exhaust gas having a high temperature in the first filter 12, and then a small amount of exhaust particles are burned and removed in the second filter 13, so that the exhaust gas is quickly discharged. The second filter 13 can suppress the temperature rise due to the synergistic effect with the effect of flowing into the second filter 13. Further, in the outer peripheral portion, the exhaust gas whose temperature has been raised by the combustion of a small amount of exhaust particulates in the first filter 12 is introduced into the second filter 13 and a large amount of exhaust particulates are burned and removed.
The temperature inside the filter 13 rises. These results, especially the second
As shown in FIG. 4, the temperature inside the filter 13 in the central portion can suppress the temperature rise more than in the conventional example, can prevent the filter from being melted, and can even the temperature to prevent the generation of cracks. Further, also in the outer peripheral portion, a large amount of exhaust fine particles can be sufficiently burned and removed, so that the regeneration efficiency can be improved. In addition, the simple configuration can suppress an increase in cost.

FIG. 5 shows a second embodiment of the present invention.

In the present embodiment, the third filter 14 is interposed between the first filter 12 and the second filter 13 formed in the same manner as the first embodiment. The flow passage cross-sectional area of the cells of the third filter 14 is set to be substantially the same in the central portion and the outer peripheral portion,
It is similar to the conventional example.

Even with this configuration, the same effect as that of the first embodiment can be obtained.

<Effect of the Invention> As described above, according to the present invention, the cells of the upstream filter are formed with high density in the central portion and the cells of the downstream filter are formed with high density in the outer peripheral portion. Since it is possible to make the temperature uniform while suppressing the rise in temperature, it is possible to prevent the occurrence of cracks and melt damage while suppressing the cost increase, and improve the regeneration efficiency.

[Brief description of drawings]

FIG. 1 is a block diagram showing a first embodiment of the present invention, FIG. 2 is a view taken along the line II-II of the same, FIG. 3 is a view taken along the line III-III of the same, and FIG. FIG. 5 is a configuration diagram showing a second embodiment of the present invention, and FIG. 6 is a configuration diagram showing a conventional example of an exhaust emission control device. 11 ... Exhaust passage, 12 ... First filter, 13 ... Second filter, 14 ... Third filter

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Claims (1)

[Scope of utility model registration request] 1. A filter for collecting exhaust gas particles by forming a plurality of exhaust gas flow cells substantially parallel to an exhaust gas flow and allowing exhaust gas to flow to adjacent cells through partition walls, is installed in an exhaust gas passage. In the exhaust gas purifying apparatus for an internal combustion engine, the filter is divided into a plurality of parts along the exhaust passage, and the upstream filter has a central cell so that the flow passage cross-sectional area of the central cell is smaller than that of the outer peripheral portion. Is formed with high density, and the downstream filter is formed with high density in the cells of the outer peripheral portion so that the flow passage cross-sectional area of the cells of the outer peripheral portion is smaller than that of the central portion.