JP2011224538A - Honeycomb filter and apparatus for cleaning exhaust gas - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a honeycomb filter the pressure loss of which can be reduced drastically without decreasing the collection efficiency of PM (Particulate Matter) so much.SOLUTION: The honeycomb filter has many cells which are arranged side by side in the longitudinal direction thereof with cell walls apart. The majority of many cells are sealed cells one end of each of which is sealed. Some of many cells are open cells both ends of each of which are opened. The number of open cells is 0.1-4.9% of that of many cells.

Description

The present invention relates to a honeycomb filter and an exhaust gas purification device.

In recent years, environmental issues have become more important, and the automobile industry has demanded engines with good fuel efficiency and low environmental load.
Diesel engines have the advantage of better fuel efficiency than gasoline engines. On the other hand, since particulates such as soot (hereinafter also referred to as PM) are generated, it is necessary to mount an exhaust gas purification device to purify PM contained in the exhaust gas.

Gasoline engines have the advantage of lower PM emissions than diesel engines. Therefore, normally, it is not necessary to mount an exhaust gas purification device for purifying PM. On the other hand, gasoline engines have the drawback of inferior fuel efficiency compared to diesel engines.

In recent years, since automobile purchasers tend to place importance on the fuel efficiency of automobiles, it is expected that the number of automobiles equipped with direct-injection gasoline engines (GDI: Gasoline Direct Injection) with excellent fuel economy will increase. ing. However, a small amount of PM is contained in the exhaust gas discharged from the direct-injection gasoline engine, and it is expected that it is necessary to mount the exhaust gas purification device to purify the PM in the exhaust gas.

An exhaust gas purification apparatus used for purification of exhaust gas discharged from a diesel engine is manufactured by housing a honeycomb filter made of a material such as ceramic in a metal container (casing). The exhaust gas can be purified by introducing the exhaust gas into the exhaust gas purification device from the gas inlet side of the exhaust gas purification device, passing the exhaust gas through the filter, and discharging the exhaust gas from the gas outlet side of the exhaust gas purification device.

In such a filter, a large number of cells are juxtaposed in the longitudinal direction across the cell wall. In addition, since any one of the many cells is sealed at one end, the exhaust gas flowing into one cell always flows out from the other cell after passing through the cell wall separating the cells. It has become. That is, when such a filter is provided in the exhaust gas purification device, PM contained in the exhaust gas is captured by the cell wall when passing through the filter, and as a result, the exhaust gas is purified.

Patent Document 1 discloses a honeycomb filter having such a structure and an exhaust gas purification device including the honeycomb filter in a casing.

JP 2001-96113 A

As described above, the gasoline engine has a drawback that the fuel consumption is inferior to that of the diesel engine. Therefore, when using a gasoline engine, it is necessary to prevent deterioration of fuel consumption. Therefore, when considering exhaust gas exhausted from a gasoline engine, a filter for purifying exhaust gas is required to have a low pressure loss. On the other hand, the amount of PM contained in the exhaust gas discharged from the gasoline engine is very small. Therefore, in the filter for purifying the exhaust gas discharged from the gasoline engine, it is considered that the PM collection efficiency may be lower than that of the filter for purifying the exhaust gas discharged from the diesel engine. That is, a gasoline engine filter is required to have a low pressure loss even if the PM collection efficiency is lowered, as compared with a diesel engine filter.

As described above, the present inventor is representative of the exhaust gas discharged from the direct injection gasoline engine because it is highly likely that it is necessary to purify the PM in the exhaust gas discharged from the direct injection gasoline engine. An attempt was made to develop a honeycomb filter for purifying exhaust gas containing a small amount of PM and an exhaust gas purification apparatus using the honeycomb filter.

The present inventor examined factors that affect the pressure loss of the honeycomb filter when purifying exhaust gas.
The main factors that affect the pressure loss of the honeycomb filter are the resistance when the exhaust gas flows into the filter, the resistance when the exhaust gas flows out of the filter, and when passing through the cells (inflow side cell and outflow side cell) Friction, resistance when passing through the cell wall, and the like.

Here, as one method for reducing the pressure loss, it is conceivable to open both ends of the cells of the honeycomb filter.
However, if both ends of the honeycomb filter cell are opened, the pressure loss can be reduced, but PM contained in the exhaust gas that does not pass through the cell wall is not collected by the cell wall. Will drop greatly.

Under such circumstances, the present inventor examined in detail the relationship between the PM collection efficiency and the pressure loss in the honeycomb filter. As a result, the ratio of the number of cells that are not sealed at both ends to the number of cells is within a predetermined range, compared to when many cells are sealed alternately. The present inventors have found that the pressure loss can be significantly reduced without significantly reducing the PM collection efficiency.

That is, the honeycomb filter according to claim 1 is a honeycomb filter in which a large number of cells are arranged in parallel in the longitudinal direction across the cell wall,
Most of the large number of cells are sealed cells in which either one end is sealed,
Some of the multiple cells are open cells with both ends open,
The number of the open cells is 0.1 to 4.9% of the number of the many cells.

The honeycomb filter according to claim 1 has an open cell in which both ends are opened in a part of a large number of cells. Therefore, since a part of the exhaust gas passes through the open cells, the pressure loss can be reduced as compared with the honeycomb filter having no open cells.

In the honeycomb filter according to claim 1, the number of open cells is 0.1 to 4.9% of the number of many cells. When the number of open cells is 0.1 to 4.9% of the number of many cells, the pressure loss can be greatly reduced without significantly reducing the PM collection efficiency.
The honeycomb filter according to claim 1 is suitable for purifying exhaust gas containing a small amount of PM, typified by exhaust gas discharged from a gasoline engine.
If the number of open cells is less than 0.1% of the number of many cells, the effect of reducing the pressure loss cannot be obtained sufficiently. Also, if the number of open cells exceeds 4.9% of the number of many cells, the pressure loss can be reduced, but the PM collection efficiency will be reduced too much, so the function as a filter will be reduced. Inferior.

In the honeycomb filter according to a second aspect, the number of the open cells is 0.2 to 1.1% of the number of the many cells.
When the number of open cells is 0.2 to 1.1% of the number of many cells, pressure loss can be reduced without reducing PM collection efficiency.

In the honeycomb filter according to claim 3, on one end face side of the honeycomb filter, as the plurality of cells, cells having end portions sealed and cells having end portions opened are alternately arranged. And
The cell in which the end on the one end face side is sealed is the sealed cell in which the end on the other end face side is opened,
Most of the cells where the end on the one end face side is opened are the above-described sealed cells in which the end on the other end face side is sealed,
A part of the cell whose end on the one end face side is opened is the open cell in which the end on the other end face side is opened.
In the honeycomb filter according to the third aspect, the number of cells having open ends is larger on the other end face side than on one end face side. Therefore, it is considered that the exhaust gas can smoothly flow through the honeycomb filter, so that the pressure loss can be further reduced.

The exhaust gas purifying device according to claim 4, a metal container provided with a gas inlet side and a gas outlet side;
An exhaust gas purification device comprising a honeycomb filter housed in the metal container,
The honeycomb filter has a large number of cells arranged in parallel in the longitudinal direction across the cell wall,
Most of the large number of cells are sealed cells in which either one end is sealed,
Some of the multiple cells are open cells with both ends open,
The number of the open cells is 0.1 to 4.9% of the number of the many cells.

According to a fourth aspect of the present invention, the exhaust gas purifying apparatus includes a honeycomb filter having an open cell in which both ends are opened in a part of a large number of cells. Therefore, since a part of the exhaust gas passes through the open cells, the pressure loss can be reduced as compared with an exhaust gas purification device including a honeycomb filter that does not have open cells.

In the honeycomb filter constituting the exhaust gas purifying apparatus according to claim 4, the number of open cells is 0.1 to 4.9% of the number of many cells. When the number of open cells is 0.1 to 4.9% of the number of many cells, the pressure loss can be greatly reduced without significantly reducing the PM collection efficiency.
If the number of open cells is less than 0.1% of the number of many cells, the effect of reducing the pressure loss cannot be obtained sufficiently. Also, if the number of open cells exceeds 4.9% of the number of many cells, the pressure loss can be reduced, but the PM collection efficiency will be reduced too much, so the function as a filter will be reduced. Inferior.

In the exhaust gas purifying apparatus according to claim 5, the number of the open cells is 0.2 to 1.1% of the number of the many cells.
When the number of open cells is 0.2 to 1.1% of the number of many cells, pressure loss can be reduced without reducing PM collection efficiency.

In the exhaust gas purifying apparatus according to claim 6, on one end face side of the honeycomb filter, as the plurality of cells, cells whose ends are sealed and cells whose ends are opened are alternately arranged. And
The cell in which the end on the one end face side is sealed is the sealed cell in which the end on the other end face side is opened,
Most of the cells where the end on the one end face side is opened are the above-described sealed cells in which the end on the other end face side is sealed,
A part of the cell in which the end on the one end face side is opened is the open cell in which the end on the other end face side is opened,
One end face side of the honeycomb filter is disposed on the gas inlet side of the metal container,
The other end face side of the honeycomb filter is disposed on the gas outlet side of the metal container.
In the exhaust gas purifying apparatus according to the sixth aspect, there are more cells having open ends on the gas outlet side than on the gas inlet side. Therefore, it is considered that the exhaust gas can smoothly flow through the honeycomb filter, so that the pressure loss can be greatly reduced.

In the exhaust gas purifying apparatus according to claim 7, the gas is exhaust gas discharged from a gasoline engine.
Such an exhaust gas purification device is suitable for purifying exhaust gas discharged from a gasoline engine with a small amount of PM contained in the exhaust gas.

FIG. 1 is a perspective view schematically showing an example of the honeycomb filter of the first embodiment. FIG. 2 is a perspective view schematically showing an example of a honeycomb fired body constituting the honeycomb filter shown in FIG. 3A is a side view schematically showing the cell structure of the honeycomb fired body shown in FIG. 2 from one end face side, and FIG. 3B is a cell of the honeycomb fired body shown in FIG. It is a side view which shows a structure typically from the other end surface side. 4 (a) is a cross-sectional view taken along line AA schematically showing the flow of exhaust gas flowing from one end face side of the honeycomb fired body shown in FIG. 2, and FIG. 4 (b) is shown in FIG. It is an AA line sectional view showing typically the flow of the exhaust gas which flows in from the other end face side of the shown honeycomb calcination object. FIG. 5 (a) is a side view schematically showing an example of the honeycomb filter of the first embodiment from one end face side, and FIG. 5 (b) shows the other side of the honeycomb filter shown in FIG. 5 (a). It is a side view typically shown from the end face side. FIG. 6 is a side view schematically showing an example of a bundling process when the honeycomb filter shown in FIGS. 5A and 5B is manufactured. FIG. 7 is a cross-sectional view schematically showing an example of the exhaust gas purifying apparatus of the present invention. FIG. 8 schematically shows a position where the first honeycomb fired body and the second honeycomb fired body are arranged in the bundling process when the honeycomb filter shown in FIGS. 5A and 5B is manufactured. It is explanatory drawing shown. FIG. 9 is a cross-sectional view schematically showing a PM collection efficiency measuring apparatus. FIG. 10 is a cross-sectional view schematically showing a pressure loss measuring apparatus. FIG. 11 is a graph showing the relationship between the ratio of the number of open cells to the number of many cells included in the honeycomb filter in Examples and Comparative Examples and the PM collection efficiency. FIG. 12 is a graph showing the relationship between the ratio of the number of open cells and the pressure loss with respect to the number of many cells included in the honeycomb filter in Examples and Comparative Examples. Fig. 13 (a) is a perspective view schematically showing an example of the honeycomb filter of the second embodiment from one end face side, and Fig. 13 (b) shows the other side of the honeycomb filter shown in Fig. 13 (a). It is a perspective view shown typically from the end face side. Fig.14 (a) and FIG.14 (b) are BB sectional drawing of the honey-comb filter shown to Fig.13 (a).

(First embodiment)
Hereinafter, a first embodiment which is an embodiment of a honeycomb filter and an exhaust gas purification apparatus of the present invention will be described with reference to the drawings.

First, the honeycomb filter according to the embodiment of the present invention will be described.
FIG. 1 is a perspective view schematically showing an example of the honeycomb filter of the first embodiment. FIG. 2 is a perspective view schematically showing an example of a honeycomb fired body constituting the honeycomb filter shown in FIG. 3A is a side view schematically showing the cell structure of the honeycomb fired body shown in FIG. 2 from one end face side, and FIG. 3B is a cell of the honeycomb fired body shown in FIG. It is a side view which shows a structure typically from the other end surface side.

The honeycomb filter 10 shown in FIG. 1 has one end face 14 and the other end face 15. In addition, a plurality of honeycomb fired bodies 20 made of porous ceramics are bound together via an adhesive layer 11 to form a ceramic block 13. A coat layer 12 for preventing leakage of exhaust gas is formed around the ceramic block 13. In addition, the coat layer should just be formed as needed.
Such a honeycomb filter formed by binding a plurality of honeycomb fired bodies is also referred to as a collective honeycomb filter.
Moreover, the honeycomb fired body 20 has a shape shown in FIG.

The honeycomb fired body 20 shown in FIG. 2 has one end face 24 and the other end face 25. In the honeycomb fired body 20, a large number of cells 21 a, 21 b and 21 c are arranged side by side in the longitudinal direction (in the direction of arrow a in FIG. 2) with the cell wall 23 therebetween.

As shown in FIG. 3 (a), on one end face 24 side of the honeycomb fired body 20, a cell 21a whose end is sealed with a sealing material 22, and a cell 21b or 21c whose end is open, Are arranged alternately.
And as shown in FIG.3 (b), as for the cell 21a, the edge part by the side of the other end surface 25 of the honeycomb fired body 20 is open | released. On the other hand, the cell 21b, which is the majority of the cells in which the end portion on the one end face 24 side of the honeycomb fired body 20 is opened, has the end portion on the other end face 25 side of the honeycomb fired body 20 on the sealing material 22. The cell 21c, which is a part of the cells, is open at the end on the other end face 25 side of the honeycomb fired body 20.
Therefore, on the other end face 25 side of the honeycomb fired body 20, there are more cells whose ends are opened than the one end face 24 side of the honeycomb fired body 20 by the number of open cells 21 c.

As described above, most of the large number of cells provided in the honeycomb fired body 20 are sealed cells in which one end of the honeycomb fired body 20 is sealed. The part is an open cell in which both ends of the honeycomb fired body 20 are opened. That is, in the honeycomb fired body 20 shown in FIG. 2, FIG. 3A and FIG. 3B, the cells 21a and 21b are sealing cells, and the cells 21c are open cells.
A sealed cell in which the end portion on the one end face 24 side of the honeycomb fired body 20 is sealed as the cell 21a is also referred to as a first sealed cell, and the honeycomb fired body as in the cell 21b. The sealed cell in which the end portion on the other end face 25 side of 20 is sealed is also referred to as a second sealed cell.

In the present invention, the number of sealing cells corresponds to the number obtained by removing the number of open cells from the number of many cells of the honeycomb filter or the honeycomb fired body. Therefore, in this specification, for example, when the number of open cells is 0.1 to 4.9% of the number of many cells, “a part of many cells” means “a number of many cells”. “0.1 to 4.9% of the number” means “the majority of many cells” means “95.1 to 99.9% of the number of many cells”.

Further, in the honeycomb fired body constituting the honeycomb filter of the present embodiment, the number of open cells in the entire honeycomb filter formed by binding a plurality of honeycomb fired bodies is 0. Open cells are provided so as to be 1 to 4.9%. It is desirable that the open cells are provided so that the number of open cells in the entire honeycomb filter is 0.2 to 1.1% of the number of cells in the entire honeycomb filter.
When the honeycomb fired body is provided with the open cells, the pressure loss can be reduced as compared with the case where the honeycomb fired body is not provided with the open cells.
If the number of open cells is less than 0.1% of the number of many cells, the effect of reducing the pressure loss cannot be obtained sufficiently. Also, if the number of open cells exceeds 4.9% of the number of many cells, the pressure loss can be reduced, but the PM collection efficiency will be reduced too much, so the function as a filter will be reduced. Inferior.
In particular, when the number of open cells is 0.2 to 1.1% of the number of many cells, the pressure loss can be greatly reduced without reducing the PM collection efficiency.

For example, as shown in FIG. 2, FIG. 3 (a) and FIG. 3 (b), the honeycomb fired body having a total of 324 cells of 18 in the vertical direction and 18 in the horizontal direction is bundled. In consideration of the honeycomb filter, it is desirable that the honeycomb fired body is provided with the open cells so that the number of open cells in the entire honeycomb filter is about 5 to 220. At this time, one honeycomb fired body provided with open cells and 15 honeycomb fired bodies not provided with open cells may be bundled, or a honeycomb fired body provided with a predetermined number of open cells. A predetermined number of honeycomb fired bodies that are not provided with open cells may be bundled. Furthermore, the number of open cells included in the honeycomb fired body constituting the honeycomb filter may be the same for all the honeycomb fired bodies or may be different from each other.

Next, the flow of exhaust gas flowing into the honeycomb fired body will be described.
4 (a) is a cross-sectional view taken along line AA schematically showing the flow of exhaust gas flowing from one end face side of the honeycomb fired body shown in FIG. 2, and FIG. 4 (b) is shown in FIG. It is an AA line sectional view showing typically the flow of the exhaust gas which flows in from the other end face side of the shown honeycomb calcination object.
4 (a) and 4 (b) schematically show an AA line cross section of the honeycomb fired body 20 shown in FIG. 2, and the number of longitudinal cells included in the honeycomb fired body 20 is shown. Is schematically nine.

As shown to Fig.4 (a), the waste gas G1 which flowed into the 2nd sealing cell 21b from the one end surface 24 side of the honeycomb calcination body 20 is the 1st sealing cell 21a and the 2nd sealing cell 21b. After passing through the cell wall 23 separating the first and second cells, the first sealed cell 21a flows out. Accordingly, the cell wall 23 functions as a filter for collecting PM and the like.
On the other hand, the exhaust gas G2 flowing into the open cell 21c from the one end face 24 side of the honeycomb fired body 20 passes through the open cell 21c as it is.

Further, as shown in FIG. 4B, the exhaust gas G3 that has flowed into the first sealing cell 21a from the other end face 25 side of the honeycomb fired body 20 flows into the first sealing cell 21a and the second sealing cell. After passing through the cell wall 23 separating the cell 21b, it flows out from the second sealed cell 21b. Accordingly, the cell wall 23 functions as a filter for collecting PM and the like.
On the other hand, the exhaust gas G4 flowing into the open cell 21c from the other end face 25 side of the honeycomb fired body 20 passes through the open cell 21c as it is.

As described above, in the exhaust gas flowing from either end face 24 or 25 side of the honeycomb fired body 20, most of the exhaust gases G1 and G3 pass through the cell wall 23, and some of the exhaust gases G2 and G4 remain as they are. Pass through open cell.

The honeycomb filter of the present embodiment is obtained by binding a plurality of honeycomb fired bodies through an adhesive layer.
Of the plurality of honeycomb fired bodies, at least one honeycomb fired body is a honeycomb fired body having open cells in a part of many cells as described above. Therefore, the honeycomb filter of the present embodiment may be composed only of a honeycomb fired body having an open cell in a part of a large number of cells, or may include a honeycomb fired body having no open cell. .

FIG. 5 (a) is a side view schematically showing an example of the honeycomb filter of the first embodiment from one end face side, and FIG. 5 (b) shows the other side of the honeycomb filter shown in FIG. 5 (a). It is a side view typically shown from the end face side.
In the honeycomb filter 10, a plurality of honeycomb fired bodies 20 shown in FIGS. 2, 3 (a), and 3 (b) are bundled through an adhesive layer 11. In FIGS. 5A and 5B, the number of cells of one honeycomb fired body 20 is schematically 9 in length and 9 in width.
5A and 5B, since the outer periphery of the honeycomb filter 10 is cut as will be described later, the cross-sectional shape of the honeycomb fired body positioned on the outer periphery of the honeycomb filter 10 The shape of the cross section perpendicular to the longitudinal direction is not a shape surrounded by four straight lines. Therefore, the honeycomb filter 10 includes a honeycomb fired body 20 having a cross-sectional shape surrounded by four straight lines, a honeycomb fired body 26 having a cross-sectional shape surrounded by two straight lines and one curve, and 3 It can also be considered that the honeycomb fired body is composed of three types of honeycomb fired bodies 27 having a cross-sectional shape surrounded by a straight line and a single curve.

The honeycomb fired bodies 20, 26, and 27 constituting the honeycomb filter 10 have one end face 24 (end portion sealed) of the honeycomb fired body 20 shown in FIGS. 2, 3A, and 3B. The cells and end cells on the side where the cells with open ends are alternately arranged are bound together so as to be arranged in the same direction (one end surface 14 side of the honeycomb filter 10).

Therefore, the honeycomb filter 10 has a first sealed cell 21a in which an end portion on the one end face 14 side of the honeycomb filter 10 is sealed and an end portion on the other end face 15 side of the honeycomb filter 10 is opened. Both the second sealing cell 21b in which the end portion on the one end face 14 side of the honeycomb filter 10 is opened and the end portion on the other end face 15 side of the honeycomb filter 10 is sealed, and the honeycomb filter 10 are both. The open cell 21c is opened at its end.

On one end face 14 side of the honeycomb filter 10, the cells 21a whose end portions are sealed and the cells 21b or 21c whose end portions are opened are alternately arranged.
On the other hand, on the other end face 15 side of the honeycomb filter 10, there are more cells whose ends are opened than the one end face 14 side of the honeycomb filter 10 by the number of the open cells 21c.

In the honeycomb filter of the present embodiment, the number of open cells is 0.1 to 4.9% of the number of many cells. The number of open cells is preferably 0.2 to 1.1% of the number of cells.

In this specification, when the ratio of the number of open cells to the number of many cells included in the honeycomb filter is obtained, the number of many cells includes the number of cells partially cut away by cutting processing described later. Suppose that there is no.
This will be described with reference to FIG. The cell 21d is a cell existing on the outer peripheral portion of the honeycomb filter 10 and has a cross-sectional shape that is not a quadrangle. As in the cell 21d, most of the cells existing on the outer peripheral portion of the honeycomb filter 10 have a non-square cross section. On the other hand, for cells existing outside the outer peripheral portion of the honeycomb filter 10, the cross-sectional shape of the cells is a quadrangle. As described above, a cell that exists in the outer peripheral portion of the honeycomb filter and has a cross-sectional shape different from that of a cell other than the outer peripheral portion of the honeycomb filter is referred to as a “partially missing cell”.
Therefore, in the honeycomb filter shown in FIG. 5A, the number of cells is the total number of the sealing cells 21a and 21b having a square cross-sectional shape and the number of open cells 21c.

Next, an example of a method for manufacturing the honeycomb filter of the present embodiment will be described. Here, a method for manufacturing the honeycomb filter shown in FIGS. 5A and 5B will be described.
First, a forming process is performed in which a ceramic raw material is formed to produce a columnar honeycomb formed body in which a large number of cells are arranged in parallel in the longitudinal direction with cell walls interposed therebetween.
Specifically, first, a ceramic raw material (wet mixture) for manufacturing a honeycomb formed body is prepared by mixing a silicon carbide powder as a ceramic powder, an organic binder, a liquid plasticizer, a lubricant, and water.
Subsequently, the wet mixture is put into an extruder, and after extrusion, a raw honeycomb formed body having a predetermined shape is manufactured by performing a cutting process of cutting to a predetermined length.
Subsequently, the honeycomb was dried by performing a drying process of drying the raw honeycomb molded body using a microwave dryer, a hot air dryer, a dielectric dryer, a vacuum dryer, a vacuum dryer, a freeze dryer, or the like. A molded body is produced.

Subsequently, a sealing process is performed in which predetermined cells of the dried honeycomb formed body are filled with a sealing material paste to plug the cells.
The sealing step will be described by taking the honeycomb fired body shown in FIGS. 2, 3A and 3B as an example. First, on one end face side of the honeycomb formed body, a sealing material is provided at an end portion of a predetermined cell so that cells whose end portions are sealed and cells whose end portions are opened are alternately arranged. Fill with sealant paste. Next, for the cells in which the end portion on one end face side of the honeycomb formed body is not filled with the plug material paste, the majority of the cells are filled with the plug material paste on the other end face side. However, for some of the cells, the end of the other end face is not filled with the sealing material paste. In addition, for cells in which the end portion on one end face side of the honeycomb formed body is filled with the plug material paste, the end portion on the other end face side is not filled with the plug material paste.
Here, as a sealing material paste, the thing similar to the said wet mixture can be used.

Next, a firing process for producing a honeycomb fired body is performed by firing the honeycomb formed body subjected to the sealing treatment.
After the sealing step, a degreasing process is performed in which the organic matter in the honeycomb molded body in which the end portions of the cells are sealed is removed by heating in a degreasing furnace, and then a firing process is performed, whereby FIGS. A honeycomb fired body as shown in FIGS. 3A and 3B can be manufactured.
In addition, the sealing material paste with which the edge part of the cell was filled is baked by heating and becomes a sealing material.
Moreover, the conditions conventionally used when manufacturing a honeycomb fired body can be applied to the conditions of the cutting treatment, the drying treatment, the sealing treatment, the degreasing treatment, and the firing treatment.

Next, a binding step is performed in which an adhesive layer is formed between the plurality of honeycomb fired bodies and the plurality of honeycomb fired bodies are bonded via the adhesive layer.
FIG. 6 is a side view schematically showing an example of a bundling process when the honeycomb filter shown in FIGS. 5A and 5B is manufactured.
In the bundling step, for example, as shown in FIG. 6, the honeycomb fired body 20 is fired on a table 100 whose upper cross section is configured in a V shape so that the honeycomb fired bodies 20 can be stacked in an inclined state. The body 20 is placed in an inclined state. Thereafter, the adhesive paste 16 is applied to the two side surfaces 28a, 28b of the honeycomb fired body 20 facing upward with a uniform thickness. Then, the process of sequentially stacking the other honeycomb fired bodies 20 on the adhesive paste 16 is repeated.
At this time, in the honeycomb fired body 20, the honeycomb fired so that one end face 24 in which the cells with the sealed end portions and the cells with the open end portions are alternately arranged is all arranged in the same direction. The body 20 is laminated.
By such a method, an aggregate of honeycomb fired bodies in which an adhesive paste is applied to the side surfaces of the honeycomb fired bodies is manufactured.
In FIG. 6, the number of cells included in one honeycomb fired body 20 is schematically set to 5 vertically and 5 horizontally.

As the adhesive paste, for example, a paste containing inorganic fibers such as alumina fibers, inorganic particles such as silicon carbide, and an inorganic binder such as silica sol is used. The adhesive paste may further contain whiskers.

Subsequently, the aggregate of the honeycomb fired bodies is heated using a dryer or the like, and the adhesive paste is dried and solidified to produce a ceramic block in which an adhesive layer is formed between the honeycomb fired bodies. I do.

Then, the outer periphery process process which cuts a ceramic block is performed.
Specifically, a ceramic block whose outer periphery is processed into a substantially cylindrical shape is manufactured by cutting the ceramic block using a diamond cutter.

Subsequently, a coating layer forming step is performed in which the coating material paste is applied to the outer peripheral surface of the ceramic block whose outer periphery is processed into a substantially cylindrical shape, and the coating material paste is dried and solidified to form a coating layer.
First, a coating material paste is applied to the outer peripheral surface of a ceramic block whose outer periphery is processed into a substantially cylindrical shape. Next, by drying and solidifying the coating material paste, a honeycomb filter having a coating layer formed on the outer peripheral surface is manufactured.
Here, as a coating material paste, what consists of the same material as the said adhesive material paste can be used.
Through the above steps, the honeycomb filter of the present embodiment (see FIGS. 5A and 5B) can be manufactured.

Then, the exhaust gas purification apparatus which concerns on embodiment of this invention is demonstrated.
The above-described honeycomb filter of the present embodiment is used in the exhaust gas purification apparatus of the present embodiment.

FIG. 7 is a cross-sectional view schematically showing an example of the exhaust gas purifying apparatus of the present invention.
The exhaust gas purifying apparatus 30 shown in FIG. 7 includes a metal container 31 having a gas inlet side 33 and a gas outlet side 34 and a honeycomb filter 10 accommodated in the metal container 31.
In the exhaust gas purification device 30, the honeycomb filter shown in FIGS. 5A and 5B is used as the honeycomb filter 10. As described above, on one end face 14 side of the honeycomb filter 10, the cells 21a whose end portions are sealed with the sealing material 22 and the cells 21b or 21c whose end portions are opened are alternately arranged. . On the other hand, on the other end face 15 side of the honeycomb filter 10, there are more cells whose ends are opened than the one end face 14 side of the honeycomb filter 10 by the number of the open cells 21c. In the exhaust gas purification device 30, one end face 14 side of the honeycomb filter 10 is arranged on the gas inlet side 33 of the metal container 31, and the other end face 15 side of the honeycomb filter 10 is arranged on the gas outlet side 34 of the metal container 31. Has been.

A holding sealing material 32 is disposed between the honeycomb filter 10 and the metal container 31, and the honeycomb filter 10 is held by the holding sealing material 32.
The holding sealing material is a mat-like member having a substantially rectangular shape in plan view mainly made of inorganic fibers such as alumina.

Further, an inlet pipe for introducing exhaust gas discharged from an internal combustion engine such as a direct injection gasoline engine into the exhaust gas purification device 30 is connected to the gas inlet side 33 of the metal container 31. On the other hand, a discharge pipe for discharging the exhaust gas that has passed through the exhaust gas purification device 30 to the outside is connected to the gas outlet side 34 of the metal container 31.

Next, a method for purifying exhaust gas using the exhaust gas purifying apparatus 30 including such a honeycomb filter 10 will be described below with reference to FIG.
As shown in FIG. 7, the exhaust gas discharged from the internal combustion engine and flowing into the exhaust gas purification device 30 from the gas inlet side 33 (in FIG. 7, the exhaust gas is indicated by G5 and G6, and the flow of the exhaust gas is indicated by an arrow) It flows into the honeycomb filter 10 from one end face 14 side of the honeycomb filter 10. On the one end face 14 side of the honeycomb filter 10, the exhaust gas G5 flows into the second sealing cell 21b, and the exhaust gas G6 flows into the open cell 21c.
Among these, the exhaust gas G5 flowing into the second sealed cell 21b passes through the cell wall 23 separating the first sealed cell 21a and the second sealed cell 21b. At this time, PM in the exhaust gas G5 is collected by the cell wall 23, and the exhaust gas G5 is purified.
The purified exhaust gas G5 flows into the first sealing cell 21a and is discharged out of the honeycomb filter 10 from the other end face 15 side of the honeycomb filter 10. The exhaust gas G <b> 5 is discharged out of the exhaust gas purification device 30 from the gas outlet side 34 of the exhaust gas purification device 30.

The exhaust gas G6 flowing into the open cell 21c passes through the open cell 21c as it is, and is discharged out of the honeycomb filter 10 from the other end face 15 side of the honeycomb filter 10. The exhaust gas G6 is discharged out of the exhaust gas purification device 30 from the gas outlet side 34 of the exhaust gas purification device 30.

Thus, in the exhaust gas purifying apparatus 30, the exhaust gas G5, which is most of the exhaust gas, is purified. On the other hand, the exhaust gas G6, which is a part of the exhaust gas, passes through the open cell 21c. Therefore, in the exhaust gas purification device 30, the pressure loss is lower than that in the exhaust gas purification device including a honeycomb filter that does not have an open cell.

Further, in the exhaust gas purification device 30, since the number of open cells with respect to the number of cells of the entire honeycomb filter 10 is a predetermined ratio, the pressure loss is greatly reduced without significantly reducing the PM collection efficiency. Can be reduced.
Therefore, the exhaust gas purification apparatus of this embodiment can be used as a gasoline particulate filter for purifying exhaust gas discharged from a gasoline engine.

In the exhaust gas purification apparatus of the present embodiment, one honeycomb filter of the present embodiment may be accommodated in a metal container, or may be arranged together with a honeycomb structure used as another catalyst carrier. .

Hereinafter, the manufacturing method of the exhaust gas purifying apparatus of the present embodiment will be described.
The honeycomb filter of this embodiment manufactured by the above method is placed in a metal container. For example, when manufacturing the exhaust gas purification apparatus shown in FIG. 7, in the honeycomb filter, one end face side in which the cells with the sealed end portions and the cells with the open end portions are alternately arranged is the metal container. It arrange | positions in a metal container so that the other end surface side may become a gas outlet side of a metal container so that it may become a gas inlet side.
Specifically, a mat having a substantially rectangular shape in plan view mainly made of inorganic fibers is prepared as a holding sealing material, and the mat is wound around the honeycomb filter. An exhaust gas purification apparatus can be obtained by press-fitting a honeycomb filter in which a mat is wound around a substantially cylindrical metal container.
In addition, the metal container is formed in a shape that can be separated into two parts, a first metal container and a second metal container, and a honeycomb filter around which a mat made of inorganic fibers is wound is placed on the first metal container. It can also be set as an exhaust gas purification apparatus by sealing with a second metal container later.

Hereinafter, functions and effects of the honeycomb filter and the exhaust gas purification apparatus of the present embodiment will be described.
(1) In the honeycomb filter of the present embodiment, most of the large number of cells provided in the honeycomb filter are sealed cells in which any one end is sealed, and a part of the large number of cells. Is an open cell with both ends open.
If some of the many cells have open cells with both ends open, a part of the exhaust gas passes through the open cells, so compared to a honeycomb filter that does not have open cells. Pressure loss can be reduced.

(2) In the honeycomb filter of the present embodiment, the number of open cells is 0.1 to 4.9% of the number of cells provided in the honeycomb filter.
When the number of open cells is 0.1 to 4.9% of the number of many cells, the pressure loss can be greatly reduced without significantly reducing the PM collection efficiency.

(3) In the honeycomb filter of the present embodiment, on one end face side, the cells whose end portions are sealed and the cells whose end portions are opened are alternately arranged, The cell whose end is sealed is open at the end on the other end face, and most of the cells whose end on the one end face is open are sealed at the end on the other end face. A part of the cells that are stopped and open at the end on the one end face are open at the other end face.
That is, in the honeycomb filter of the present embodiment, there are more cells having open ends on the other end face side than on one end face side. Therefore, it is considered that the exhaust gas can smoothly flow through the honeycomb filter, so that the pressure loss can be further reduced.

(4) The exhaust gas purifying apparatus of the present embodiment uses the honeycomb filter of the present embodiment, and the honeycomb filter is alternately arranged with cells whose ends are sealed and cells whose ends are open. One end face side thus arranged is arranged on the gas inlet side, and the other end face side of the honeycomb filter is arranged on the gas outlet side.
That is, in the exhaust gas purifying apparatus according to the present embodiment, there are more cells with open ends on the gas outlet side than on the gas inlet side. Therefore, it is considered that the exhaust gas can smoothly flow through the honeycomb filter, so that the pressure loss can be greatly reduced.

(5) In the exhaust gas purification apparatus of this embodiment, the exhaust gas discharged from the gasoline engine is purified.
The amount of PM contained in the exhaust gas discharged from the gasoline engine is smaller than the amount of PM contained in the exhaust gas discharged from the diesel engine. Therefore, by using the exhaust gas purification apparatus of this embodiment provided with the honeycomb filter that can significantly reduce the pressure loss without significantly reducing the PM collection efficiency, the fuel consumption caused by the increase in pressure loss can be reduced. Deterioration can be prevented and PM contained in the exhaust gas can be sufficiently collected.

(6) In the exhaust gas purification apparatus of this embodiment, one honeycomb filter is accommodated in the metal container.
When exhaust gas discharged from a gasoline engine is purified using the exhaust gas purifying apparatus of the present embodiment, since the amount of PM contained in the exhaust gas is small, even if the number of honeycomb filters is one, PM is sufficiently Can be collected.
Moreover, since it is not necessary to house a plurality of honeycomb filters in the metal container, the size of the entire exhaust gas purification device can be reduced.

Examples that more specifically disclose the first embodiment of the present invention will be described below. In addition, this invention is not limited only to this Example.

(1) Production of honeycomb filter (Example 1)
A mixture of 52.8% by weight of silicon carbide coarse powder having an average particle diameter of 22 μm and 22.6% by weight of fine powder of silicon carbide having an average particle diameter of 0.5 μm was obtained. 0.1% by weight, 4.6% by weight of organic binder (methylcellulose), 2.8% by weight of lubricant (Unilube manufactured by NOF Corporation), 1.3% by weight of glycerin and 13.8% by weight of water and kneaded. To obtain a wet mixture. Then, the wet mixture is extruded and then cut to obtain a shape substantially the same as the shape shown in FIGS. 2, 3 (a) and 3 (b), in which the cells are not sealed. A honeycomb formed body was prepared. Next, the dried honeycomb formed body was manufactured by drying the raw honeycomb formed body using a microwave dryer.

The cells were sealed by filling predetermined cells of the dried honeycomb formed body with a sealing material paste having the same composition as the wet mixture.
In this example, as will be described later, a first honeycomb fired body having one open cell and a second honeycomb fired body having no open cell are manufactured. The honeycomb molded body that is the first honeycomb fired body was subjected to the first sealing, while the honeycomb molded body that was the second honeycomb fired body was subjected to the second sealing.
In the first sealing, first, on one end face side of the dried honeycomb formed body, a predetermined number of cells are arranged so that cells whose end portions are sealed and cells whose end portions are opened are alternately arranged. The end of the cell was filled with a sealing material paste. Next, among the cells in which the end portion on one end face side of the dried honeycomb formed body is not filled with the plug material paste, one of the cells also has the end plug on the other end face side. The paste was not filled, and the remaining cells were filled with the sealing material paste at the other end face side. In addition, in the cells in which the end portion on one end surface side of the dried honeycomb formed body was filled with the plug material paste, the end portion on the other end surface side was not filled with the plug material paste.
In the second sealing, first, in one end face side of the dried honeycomb formed body, a predetermined number of cells are arranged so that cells whose end portions are sealed and cells whose end portions are opened are alternately arranged. The end of the cell was filled with a sealing material paste. Next, for all cells in which the end portion on one end face side of the dried honeycomb formed body was not filled with the plug material paste, the end part on the other end face side was filled with the plug material paste.
After sealing the cells, the honeycomb formed body filled with the plug material paste was dried again using a dryer.

After placing the honeycomb molded body with the cells sealed on a firing jig, degreasing treatment is performed at 400 ° C., and further, firing treatment is performed under conditions of 2200 ° C. and 3 hours in an atmospheric pressure of argon. Therefore, the porosity is 42%, the average pore diameter is 11 μm, the size is 34.3 mm × 34.3 mm × 150 mm, the number of cells (cell density) is 31.0 / cm ² (200 / inch ² ), A first honeycomb fired body and a second honeycomb fired body made of a silicon carbide sintered body having a cell wall thickness of 0.4 mm (16 mil) were produced.
The cell structure of the first honeycomb fired body subjected to the first sealing is the same as the cell structure shown in FIGS. 3A and 3B, and there is one open cell. ing.
On the other hand, the cell structure of the second honeycomb fired body subjected to the second sealing is the same as the cell structure shown in FIG. 3A on both end surfaces of the honeycomb fired body, and the end portions are sealed. The cells and the cells whose ends are opened are alternately arranged.

In each example and comparative example, a honeycomb fired body having open cells is referred to as a first honeycomb fired body, like the honeycomb fired body subjected to the first sealing. A honeycomb fired body having no open cells, such as the honeycomb fired body subjected to the second sealing, is referred to as a second honeycomb fired body.

Next, 30% by weight of alumina fibers having an average fiber length of 20 μm, an average fiber diameter of 2 μm, 21% by weight of silicon carbide particles having an average particle diameter of 0.6 μm, 15% by weight of silica sol (solid content 30% by weight), 5.6 carboxymethylcellulose. A heat-resistant adhesive paste containing 2% by weight and 28.4% by weight of water was prepared.
Then, using five first honeycomb fired bodies and eleven second honeycomb fired bodies, as shown in FIG. 6, an adhesive paste was applied to the side surfaces of the honeycomb fired bodies. A bundle of honeycomb fired bodies was produced by performing a bundling process in which a total of 16 first honeycomb fired bodies or second honeycomb fired bodies were bonded in a vertical direction and 4 lateral widths.

FIG. 8 schematically shows a position where the first honeycomb fired body and the second honeycomb fired body are arranged in the bundling process when the honeycomb filter shown in FIGS. 5A and 5B is manufactured. It is explanatory drawing shown.
When the positions of the 16 honeycomb fired bodies constituting the aggregate of honeycomb fired bodies are the positions 101a to 101p as shown in FIG. 8, the first honeycomb fired bodies are located at the positions 101f, 101g, 101j, 101k, and The first honeycomb fired body and the second honeycomb fired body are disposed at 101o and the second honeycomb fired bodies are disposed at the remaining positions (101a to 101e, 101h, 101i, 101l to 101n and 101p). Were laminated.
In addition, the first honeycomb fired body has the first end face in which the end faces in which the cells with the sealed end portions and the cells with the open end portions are alternately arranged are all arranged in the same direction. A honeycomb fired body was laminated.

Furthermore, the aggregate of honeycomb fired bodies was heated at 120 ° C. to dry and solidify the adhesive paste, thereby producing a quadrangular columnar ceramic block with an adhesive layer having a thickness of 1.0 mm.

Next, the outer periphery of the ceramic block was cut using a diamond cutter to produce a ceramic block whose outer periphery was processed into a cylindrical shape.
Next, a coating material paste was applied to the outer peripheral surface of the ceramic block whose outer periphery was processed into a columnar shape to form a coating material paste layer. Then, this coating material paste layer was dried and solidified at 120 ° C. to form a coating layer, whereby a cylindrical honeycomb filter having a diameter of 143.8 mm and a length of 150 mm with a coating layer formed on the outer periphery was manufactured.
At this time, a paste having the same composition as the adhesive paste was used as the coating material paste.

The honeycomb filter manufactured in Example 1 had five open cells. The number of open cells was 0.1% of the number of cells (about 4500) included in the honeycomb filter.

(Example 2)
First, a first honeycomb fired body having one open cell and a second honeycomb fired body having no open cell were manufactured by the same method as in Example 1.
Next, an aggregate of honeycomb fired bodies was manufactured by the same method as in Example 1 using 10 first honeycomb fired bodies and 6 second honeycomb fired bodies. At this time, in FIG. 8, the first honeycomb fired bodies are disposed at the positions 101b, 101e to 101l and 101o, and the second honeycomb fired bodies are disposed at the remaining positions (positions 101a, 101c, 101d, 101m, 101n and 101 p), the first honeycomb fired body and the second honeycomb fired body were laminated.
Thereafter, a honeycomb filter was produced in the same manner as in Example 1.
The number of open cells included in the honeycomb filter manufactured in Example 2 was 10, and the ratio of the number of open cells to the number of cells (approximately 4500) included in the honeycomb filter was 0.2%. .

(Examples 3 to 7)
By changing the number of open cells included in the first honeycomb fired body as shown in Table 1, the number of open cells included in the honeycomb filter and the number of open cells relative to the number of cells included in the honeycomb filter are increased. A honeycomb filter was manufactured in the same manner as in Example 2 except that the ratio was changed as shown in Table 1.
The ratio of the number of open cells to the number of cells (about 4500) included in the honeycomb filters of Examples 3 to 7 was 1.1%, 2.2%, 3.3%, and 4.4%, respectively. It was 4.9%.

(Comparative Example 1)
First, by the same method as in Example 1, a first honeycomb fired body having 23 open cells and a second honeycomb fired body having no open cells were produced.
Next, an aggregate of honeycomb fired bodies was produced by the same method as in Example 2 using 10 first honeycomb fired bodies and 6 second honeycomb fired bodies.
Thereafter, a honeycomb filter was produced in the same manner as in Example 1.
The number of open cells included in the honeycomb filter manufactured in Comparative Example 1 was 230, and the ratio of the number of open cells to the number of cells (about 4500) included in the honeycomb filter was 5.1%. .

(Comparative Example 2)
A honeycomb filter was manufactured in the same manner as in Example 1, except that the first honeycomb fired body was not used, and 16 second honeycomb fired bodies were used to produce an aggregate of honeycomb fired bodies.
In the honeycomb filter manufactured in Comparative Example 2, all the cells were alternately sealed, and there were no open cells. That is, the ratio of the number of open cells to the number of cells (about 4500) included in the honeycomb filter is 0%.

(2) Characteristic Evaluation of Honeycomb Filter In the honeycomb filters manufactured in Examples 1 to 7 and Comparative Examples 1 and 2, PM collection efficiency and pressure loss were evaluated.
In addition, in order to evaluate the PM collection efficiency and pressure loss, an exhaust gas purification apparatus including the honeycomb filter manufactured in Examples 1 to 7 and Comparative Examples 1 and 2 was manufactured, and PM was obtained using this exhaust gas purification apparatus. The collection efficiency and pressure loss were measured.

(2-1) Preparation of Exhaust Gas Purifying Device An exhaust gas purifying device is formed by winding a mat-like holding sealing material made of alumina around the honeycomb filters manufactured in Examples 1 to 7 and Comparative Examples 1 and 2 and placing the holding filter in a metal container. Was made.
When the honeycomb filters manufactured in Examples 1 to 7 and Comparative Example 1 are arranged in the metal container, the cells with the end portions sealed and the cells with the end portions opened alternately in the honeycomb filter. One end face side arranged in the metal container was placed on the gas inlet side of the metal container, and the other end face side was placed on the gas outlet side of the metal container.

(2-2) Measurement of PM collection efficiency Measurement of PM collection efficiency was performed using a PM collection efficiency measurement apparatus as shown in FIG. FIG. 9 is a cross-sectional view schematically showing a PM collection efficiency measuring apparatus.
In the PM collection efficiency measuring device 40, the gas inlet side 33 of the exhaust gas purification device 30 is disposed in the exhaust gas pipe 42 of a 1.6 L common rail diesel engine 41. Further, the PM collection efficiency measuring device 40 is sampled by the sampler 43 that samples the exhaust gas before flowing through the honeycomb filter 110, the sampler 44 that samples the exhaust gas after flowing through the honeycomb filter 110, and the sampler 43 or 44. And a PM counter 46 (manufactured by TSI, agglomerated particle counter 3022A-S) for measuring the amount of particulates contained in the diluted exhaust gas. It is comprised as a diameter analyzer (Scanning Mobility Particle Sizer SMPS).
The PM collection efficiency was measured using a diesel engine having a high PM content in the exhaust gas so that the measurement time can be shortened and the measurement can be performed with high accuracy.

The engine 41 was operated for 2 hours so that the rotational speed of the engine 41 was 2500 min ⁻¹ and the torque was 40 Nm, and the exhaust gas from the engine 41 was circulated through the honeycomb filter 110. At this time, the PM amount P ₀ before passing through the honeycomb filter 110 and the PM amount P ₁ after passing through the honeycomb filter 110 were grasped from the number of PM particles using the PM counter 46. And PM collection efficiency was computed using the following formula (1).
PM collection efficiency (%) = (P ₀ −P ₁ ) / P ₀ × 100 (1)
Table 1 shows the measurement results of PM collection efficiency.

(2-3) Measurement of pressure loss The pressure loss was measured using a pressure loss measuring apparatus as shown in FIG. FIG. 10 is a cross-sectional view schematically showing a pressure loss measuring apparatus.
In the pressure loss measuring device 50, the gas inlet side 33 of the exhaust gas purification device 30 is disposed in the exhaust gas pipe 52 of the blower 51, and a pressure gauge 53 is attached so that the pressure before and after the honeycomb filter 110 can be detected. Yes.

The blower 51 was operated so that the flow rate of gas (air) was 750 m ³ / h, and the differential pressure (pressure loss) after 5 minutes from the start of the operation was measured.
Table 1 shows the measurement results of the pressure loss.

For the honeycomb filters of Examples 1 to 7 and Comparative Examples 1 and 2, the number of open cells included in the first honeycomb fired body, the first honeycomb fired body and the second honeycomb fired body constituting the aggregate of honeycomb fired bodies Table shows the number of bodies, the number of open cells in the honeycomb filter, the ratio of the number of open cells to the number of many cells in the honeycomb filter, the measurement result of PM collection efficiency, and the measurement result of pressure loss. It was shown in 1.
Further, from the measurement results of the PM collection efficiency in Examples 1 to 7 and Comparative Examples 1 and 2, the relationship between the ratio of the number of open cells to the number of many cells included in the honeycomb filter and the PM collection efficiency is shown. This is shown in the graph of FIG. Further, from the measurement results of pressure loss in Examples 1 to 7 and Comparative Examples 1 and 2, the graph of FIG. 12 shows the relationship between the ratio of the number of open cells to the number of cells in the honeycomb filter and the pressure loss. It was.
In Table 1, the graph of FIG. 11 and the graph of FIG. 12, the “ratio of the number of open cells to the number of cells included in the honeycomb filter” is simply referred to as “ratio of open cells”.

First, as a result of measuring the PM collection efficiency, as in Comparative Example 2, when the ratio of the number of open cells to the number of cells included in the honeycomb filter is 0%, that is, the honeycomb filter When not having, PM collection efficiency was 99.9%.
On the other hand, when the ratio of the number of open cells to the number of many cells included in the honeycomb filter is 0.1 to 4.9% as in Examples 1 to 7, the PM collection efficiency is 60 to 99. %Met. That is, it can be seen that when the honeycomb filter has open cells, the PM collection efficiency is lower than when the honeycomb filter does not have open cells.
On the other hand, when the ratio of the number of open cells to the number of many cells included in the honeycomb filter was 5.1% as in Comparative Example 1, the PM collection efficiency was 59%.

Further, it can be seen from FIG. 11 that the PM collection efficiency decreases substantially linearly with an increase in the ratio of the number of open cells to the number of cells in the honeycomb filter.

Next, the result of measuring the pressure loss is shown. When the ratio of the number of open cells to the number of many cells included in the honeycomb filter is 0% as in Comparative Example 2, that is, when the honeycomb filter has no open cells, the pressure loss is 5. The value was as high as 5 kPa.
On the other hand, as in Examples 1 to 7, when the ratio of the number of open cells to the number of many cells included in the honeycomb filter is 0.1 to 4.9%, the pressure loss is 3.0 to 4. It was 8 kPa. That is, it can be seen that when the honeycomb filter has open cells, the pressure loss is lower than when the honeycomb filter does not have open cells.
On the other hand, when the ratio of the number of open cells to the number of many cells included in the honeycomb filter was 5.1% as in Comparative Example 1, the pressure loss was 2.9 kPa.

Further, from FIG. 12, when the ratio of the number of open cells to the number of many cells of the honeycomb filter is 0.2 to 1.1%, the number of open cells to the number of cells of the honeycomb filter is It can be seen that the pressure loss significantly decreases as the ratio increases.

From the above, by providing open cells in the honeycomb filter and setting the ratio of the number of open cells to the number of many cells to be 0.1 to 4.9%, the pressure of PM collection is not reduced so much. It has been found that the loss can be greatly reduced.
In particular, when the ratio of the number of open cells to the number of cells of the honeycomb filter is 0.2 to 1.1%, the PM collection efficiency is maintained at a high value of 91 to 98%. As for pressure loss, a low value of 3.8 to 4.4 kPa could be obtained.

When the PM collection efficiency is 60% or more and the pressure loss is 5 kPa or less, it is practically used as a honeycomb filter for purifying exhaust gas containing a small amount of PM, represented by exhaust gas discharged from a gasoline engine. It can be thought of as a level that can be used. Therefore, it is considered that the honeycomb filter having the open cells at a predetermined ratio can be used as a gasoline particulate filter.

(Second embodiment)
Hereinafter, a second embodiment which is an embodiment of the present invention will be described.
In the present embodiment, the honeycomb filter is composed of one honeycomb fired body. Such a honeycomb filter made of one honeycomb fired body is also referred to as an integral honeycomb filter.

Fig. 13 (a) is a perspective view schematically showing an example of the honeycomb filter of the second embodiment from one end face side, and Fig. 13 (b) shows the other side of the honeycomb filter shown in Fig. 13 (a). It is a perspective view shown typically from the end face side. Fig.14 (a) and FIG.14 (b) are BB sectional drawing of the honey-comb filter shown to Fig.13 (a).

The honeycomb filter 60 shown in FIG. 13A has one end face 64 and the other end face 65. The honeycomb filter 60 has a ceramic block 63 made of a single pillar-shaped honeycomb fired body in which a large number of cells 71 a, 71 b and 71 c are arranged in parallel in the longitudinal direction with a cell wall 73 interposed therebetween. A coat layer 62 is formed on the surface. In addition, the coat layer should just be formed as needed.
Cordierite or aluminum titanate can be used as the main constituent material of the honeycomb fired body constituting the integral honeycomb filter.

As shown in FIGS. 13 (a) and 13 (b), the honeycomb filter 60 has one end surface 64 side end sealed with a sealing material 72, and the other end surface side 65 end portion is sealed. The first sealed cell 71a opened and the second sealed cell in which the end on the one end face 64 side is opened and the end on the other end face 65 side is sealed with the sealing material 72 71b, and an open cell 71c in which both ends on one end face 64 side and the other end face 65 side are opened.

On the one end face 64 side of the honeycomb filter 60, the cells 71a whose end portions are sealed and the cells 71b or 71c whose end portions are open are alternately arranged.
On the other hand, on the other end face 65 side of the honeycomb filter 60, there are more cells whose ends are opened than the one end face 64 side of the honeycomb filter 60 by the number of the open cells 71c.
As described above, in the honeycomb filter 60, most of the large number of cells are sealed cells in which one of the ends is sealed, and some of the large number of cells have both ends. It is an open cell.

Furthermore, in the honeycomb filter of the present embodiment, the number of open cells is 0.1 to 4.9% of the number of many cells, as in the honeycomb filter of the first embodiment. The number of open cells is preferably 0.2 to 1.1% of the number of cells.
When the honeycomb filter is provided with the opening cell, the pressure loss can be reduced as compared with the case where the honeycomb filter is not provided with the opening cell.
If the number of open cells is less than 0.1% of the number of many cells, the effect of reducing the pressure loss cannot be obtained sufficiently. Also, if the number of open cells exceeds 4.9% of the number of many cells, the pressure loss can be reduced, but the PM collection efficiency will be reduced too much, so the function as a filter will be reduced. Inferior.
In particular, when the number of open cells is 0.2 to 1.1% of the number of many cells, the pressure loss can be greatly reduced without reducing the PM collection efficiency.

Next, the flow of exhaust gas flowing into the honeycomb filter will be described.
As shown to Fig.14 (a), the waste gas G7 which flowed into the 2nd sealing cell 71b from the one end surface 64 side of the honey-comb filter 60 is the 1st sealing cell 71a, the 2nd sealing cell 71b, After passing through the cell wall 73 separating the two, the first sealed cell 71a flows out. Accordingly, the cell wall 73 functions as a filter for collecting PM and the like.
On the other hand, the exhaust gas G8 flowing into the open cell 71c from the one end face 64 side of the honeycomb filter 60 passes through the open cell 71c as it is.

Further, as shown in FIG. 14 (b), the exhaust gas G9 that has flowed into the first sealing cell 71a from the other end face 65 side of the honeycomb filter 60 is separated into the first sealing cell 71a and the second sealing cell. After passing through the cell wall 73 separating 71b, it flows out from the second sealed cell 71b. Accordingly, the cell wall 73 functions as a filter for collecting PM and the like.
On the other hand, the exhaust gas G10 flowing into the open cell 71c from the other end face 65 side of the honeycomb filter 60 passes through the open cell 71c as it is.

In this way, in the exhaust gas flowing in from either end face 64 or 65 side of the honeycomb filter 60, most of the exhaust gases G7 and G9 pass through the cell wall 73, and some of the exhaust gases G8 and G10 are opened as they are. Pass through the cell.

In the exhaust gas purifying apparatus of the present embodiment, such a honeycomb filter has an end surface side in which cells having end portions sealed and cells having end portions opened alternately arranged on the gas inlet side of the metal container. This is an exhaust gas purification device in which the other end face side is disposed on the gas outlet side of the metal container. In the exhaust gas purification apparatus of the present embodiment, exhaust gas is purified in the same manner as when the exhaust gas purification apparatus of the first embodiment is used.

When manufacturing the honeycomb filter of the present embodiment, the size of the honeycomb formed body formed by extrusion is larger than the size of the honeycomb formed body described in the first embodiment, and the outer shape is different. In the same manner as in the first embodiment, a honeycomb formed body is manufactured.

Other processes are almost the same as the manufacturing process of the honeycomb filter in the first embodiment. However, in this embodiment, since the honeycomb filter is formed of one honeycomb fired body, it is not necessary to perform a bundling process and it is not necessary to perform an outer periphery processing process.

And an exhaust gas purification device can be manufactured like the first embodiment using the manufactured honeycomb filter.
Also in the honeycomb filter and the exhaust gas purification device of the present embodiment, the effects (1) to (6) described in the first embodiment can be exhibited.

(Other embodiments)
In the honeycomb filter shown in the first embodiment and the second embodiment, the cells whose end portions are sealed and the cells whose end portions are opened are alternately arranged on one end face side of the honeycomb filter. . However, in the honeycomb filter of the present invention, the ratio of the number of open cells to the number of many cells may be within a predetermined range, and the position where the open cells are provided is not particularly limited. Therefore, the cells whose end portions are sealed and the cells whose end portions are open may not be alternately arranged on both end face sides of the honeycomb filter.

Further, in the exhaust gas purification apparatus shown in the first embodiment and the second embodiment, on one end face side of the honeycomb filter, the cells whose end portions are sealed and the cells whose end portions are opened are alternately arranged. Using the honeycomb filter, the one end face side is disposed on the gas inlet side of the metal container, and the other end face side is disposed on the gas outlet side of the metal container. However, in the exhaust gas purifying apparatus of the present invention, it is only necessary to use a honeycomb filter having an open cell in a part of the cell, and the direction in which the honeycomb filter is arranged is not particularly limited.

When the honeycomb filter of the present invention is a collective honeycomb filter, the honeycomb fired body constituting the collective honeycomb filter is provided with open cells as long as a predetermined ratio of open cells is provided in the entire honeycomb filter. The number of the honeycomb fired bodies is not particularly limited.
For example, all the honeycomb fired bodies constituting the aggregated honeycomb filter may be provided with open cells, or only one of the honeycomb fired bodies constituting the aggregated honeycomb filter may be provided with open cells. .

The shape of the honeycomb filter of the present invention is not limited to a substantially cylindrical shape, and may be any column shape such as a substantially elliptical column shape or a substantially polygonal column shape.

In the honeycomb filter of the present invention, the porosity of the honeycomb fired body constituting the aggregated honeycomb filter and the honeycomb fired body constituting the integral honeycomb filter is not particularly limited, but is preferably 35 to 60%.
If the porosity of the honeycomb fired body is less than 35%, the honeycomb filter may be clogged immediately. On the other hand, when the porosity of the honeycomb fired body exceeds 60%, the strength of the honeycomb filter may be lowered and easily broken.

The average pore diameter of the honeycomb fired body constituting the aggregated honeycomb filter and the honeycomb fired body constituting the integrated honeycomb filter is preferably 5 to 30 μm.
When the average pore diameter of the honeycomb fired body is less than 5 μm, the particulates may easily clog. On the other hand, if the average pore diameter of the honeycomb fired body exceeds 30 μm, the particulates may pass through the pores, and the particulates cannot be collected and may not function as a filter.

The porosity and pore diameter can be measured by a conventionally known method such as a mercury intrusion method, an Archimedes method, or a measurement using a scanning electron microscope (SEM).

The thickness of the cell wall of the honeycomb fired body is not particularly limited, but is desirably 0.2 to 0.4 mm.
When the cell wall thickness is less than 0.2 mm, the cell wall thickness becomes thin, and the strength of the honeycomb fired body may not be maintained. On the other hand, if the cell wall thickness exceeds 0.4 mm, the pressure loss of the honeycomb filter may be increased.

The cell density in the cross section perpendicular to the longitudinal direction of the honeycomb fired body is not particularly limited, but a desirable lower limit is 31.0 cells / cm ² (200 cells / inch ² ), and a desirable upper limit is 93.0 cells / cm ^2. (600 pieces / inch ² ), the more desirable lower limit is 38.8 pieces / cm ² (250 pieces / inch ² ), and the more desirable upper limit is 77.5 pieces / cm ² (500 pieces / inch ² ).
As described above, the number of cells is the total number of sealed cells and the number of open cells, and does not include the number of cells having a cross-sectional shape different from the cross-sectional shape of other cells. .

In the honeycomb filter of the present invention, the shape of the cross section perpendicular to the longitudinal direction of the honeycomb fired body of each cell is not limited to a substantially square shape, for example, a substantially circular shape, a substantially elliptical shape, a substantially pentagonal shape, a substantially hexagonal shape, Any shape such as a substantially trapezoidal shape or a substantially octagonal shape may be used. Various shapes may be mixed.

The bundling process when manufacturing the aggregated honeycomb filter is substantially the same as the shape of the ceramic block (or aggregate of honeycomb fired bodies) to be produced, for example, in addition to the method of applying the adhesive paste to the side surfaces of each honeycomb fired body. Alternatively, the honeycomb fired bodies may be temporarily fixed in a shape mold, and an adhesive paste may be injected between the honeycomb fired bodies.

Further, when manufacturing a collective honeycomb filter, a plurality of types of honeycomb fired bodies having different cross-sectional shapes are manufactured, and a plurality of types of honeycomb fired bodies are combined, and a plurality of honeycomb fired bodies are bundled through an adhesive layer. The outer peripheral machining step may be omitted by producing a ceramic block.
For example, the following three types of honeycomb fired bodies having different cross-sectional shapes may be manufactured. The first honeycomb fired body has a cross-sectional shape surrounded by two straight lines and one arc. The second honeycomb fired body has a cross-sectional shape surrounded by three straight lines and one arc. The third honeycomb fired body has a cross-sectional shape surrounded by four straight lines (substantially square). These three types of honeycomb fired bodies having different cross-sectional shapes can be manufactured by changing the shape of a die used in extrusion forming. Then, a substantially cylindrical honeycomb filter can be manufactured by combining eight first honeycomb fired bodies and four second honeycomb fired bodies and four third honeycomb fired bodies.

The main component of the constituent material of the honeycomb fired body constituting the aggregated honeycomb filter and the honeycomb fired body constituting the integral honeycomb filter is not limited to silicon carbide, but as other ceramic raw materials, for example, aluminum nitride, Nitride ceramics such as silicon nitride, boron nitride and titanium nitride, carbide ceramics such as zirconium carbide, titanium carbide, tantalum carbide and tungsten carbide, ceramics such as oxide ceramics such as alumina, zirconia, cordierite, mullite and aluminum titanate A powder is mentioned.
Among these, the main component of the constituent material of the honeycomb fired body constituting the aggregated honeycomb filter is preferably a non-oxide ceramic, and particularly preferably silicon carbide. It is because it is excellent in heat resistance, mechanical strength, thermal conductivity and the like. In addition, ceramic raw materials such as silicon-containing ceramics in which metallic silicon is mixed with the above-mentioned ceramics, and ceramics in which the above-described ceramics are bonded with silicon or a silicate compound can be cited as constituent materials. Those containing silicon (silicon-containing silicon carbide) are desirable.
In particular, a silicon-containing silicon carbide ceramic containing 60% by weight or more of silicon carbide is desirable.
Further, cordierite or aluminum titanate is desirable as a main component of the constituent material of the honeycomb fired body constituting the integral honeycomb filter.

The organic binder contained in the wet mixture used in manufacturing the honeycomb fired body constituting the aggregated honeycomb filter and the honeycomb fired body constituting the integral honeycomb filter is not particularly limited, and examples thereof include methyl cellulose, carboxymethyl cellulose, Examples thereof include hydroxyethyl cellulose and polyethylene glycol. Of these, methylcellulose is desirable. In general, the blending amount of the organic binder is desirably 1 to 10 parts by weight with respect to 100 parts by weight of the ceramic powder.

It does not specifically limit as a plasticizer contained in a wet mixture, For example, glycerol etc. are mentioned.
The lubricant contained in the wet mixture is not particularly limited, and examples thereof include polyoxyalkylene compounds such as polyoxyethylene alkyl ether and polyoxypropylene alkyl ether.
Specific examples of the lubricant include polyoxyethylene monobutyl ether and polyoxypropylene monobutyl ether.
In some cases, the plasticizer and the lubricant may not be contained in the wet mixture.

In preparing the wet mixture, a dispersion medium liquid may be used. Examples of the dispersion medium liquid include water, an organic solvent such as benzene, and an alcohol such as methanol.
Furthermore, a molding aid may be added to the wet mixture.
The molding aid is not particularly limited, and examples thereof include ethylene glycol, dextrin, fatty acid, fatty acid soap, polyalcohol and the like.

Furthermore, a pore-forming agent such as balloons that are fine hollow spheres containing oxide ceramics, spherical acrylic particles, and graphite may be added to the wet mixture as necessary.
The balloon is not particularly limited, and examples thereof include an alumina balloon, a glass micro balloon, a shirasu balloon, a fly ash balloon (FA balloon), and a mullite balloon. Of these, alumina balloons are desirable.

In 1st embodiment, the thing similar to a wet mixture is used as a sealing material paste which seals a cell. However, the sealing material paste is not particularly limited, and it is desirable that the sealing material manufactured through a subsequent process has a porosity of 30 to 75%.

Examples of the inorganic binder contained in the adhesive paste and the coating material paste include silica sol and alumina sol. These may be used alone or in combination of two or more. Among inorganic binders, silica sol is desirable.

Examples of the organic binder contained in the adhesive paste and the coating material paste include polyvinyl alcohol, methyl cellulose, ethyl cellulose, carboxymethyl cellulose, and the like. These may be used alone or in combination of two or more. Among organic binders, carboxymethylcellulose is desirable.

Examples of inorganic fibers contained in the adhesive paste and the coating material paste include ceramic fibers such as silica-alumina, mullite, alumina, and silica. These may be used alone or in combination of two or more. Among inorganic fibers, alumina fiber is desirable.

Examples of the inorganic particles contained in the adhesive paste and the coating material paste include carbide particles and nitride particles. Specific examples include silicon carbide particles, silicon nitride particles, and boron nitride particles. These may be used alone or in combination of two or more. Among the inorganic particles, silicon carbide particles having excellent thermal conductivity are desirable.

Furthermore, a pore-forming agent such as balloons that are fine hollow spheres containing oxide-based ceramics, spherical acrylic particles, and graphite may be added to the adhesive paste and the coating material paste as necessary. The balloon is not particularly limited, and examples thereof include an alumina balloon, a glass micro balloon, a shirasu balloon, a fly ash balloon (FA balloon), and a mullite balloon. Among these, alumina balloons are more desirably.

A catalyst may be supported on the cell wall of the honeycomb filter of the present invention.
By carrying a catalyst capable of purifying harmful gas components in exhaust gas such as CO, HC and NOx on the cell wall of the honeycomb filter, the harmful gas components in the exhaust gas are sufficiently purified by catalytic reaction. It becomes possible. In addition, by supporting a catalyst that assists in burning PM on the cell wall of the honeycomb filter, it becomes possible to burn and remove PM more easily.

The catalyst may be supported on the cell wall of the honeycomb filter or on the cell wall of the honeycomb fired body.
When the catalyst is supported, an alumina film having a high specific surface area may be formed on the surface of the cell wall of the honeycomb filter or the honeycomb fired body, and a promoter such as a catalyst and platinum may be applied to the surface of the alumina film. desirable.

As a method for forming an alumina film on the surface of the cell wall of the honeycomb filter, for example, a method of impregnating a honeycomb filter with a solution of a metal compound containing aluminum such as Al (NO ₃ ) ₃ and heating, a method including an alumina powder Examples of the method include impregnating a honeycomb filter with a solution to be heated and heating.
Examples of the method for applying a promoter to the alumina film include a method in which a honeycomb filter is impregnated with a solution of a metal compound containing a rare earth element such as Ce (NO ₃ ) ₃ and heated.
As a method for imparting a catalyst to the alumina membrane, for example, a dinitrodiammine platinum nitrate solution ([Pt (NH ₃ ) ₂ (NO ₂ ) ₂ ] HNO ₃ , platinum concentration of about 4.53% by weight) or the like is used. A method of impregnating the cell wall and heating it may be mentioned.
Alternatively, the catalyst may be applied by a method in which a catalyst is applied to alumina particles in advance, and a cell wall of the honeycomb filter is impregnated with a solution containing the alumina powder to which the catalyst is applied and heated.

10, 60, 110 Honeycomb filter 14, 64 One end face 15, 65 of honeycomb filter The other end face 21a, 21b, 71a, 71b of honeycomb filter Sealed cell 21c, 71c Open cell 23, 73 Cell wall 24 Honeycomb fired body One end face 25 The other end face 30 of the honeycomb fired body Exhaust gas purification device 31 Metal container 33 Gas inlet side 34 Gas outlet side

Claims (7)

A honeycomb filter in which a large number of cells are arranged in parallel in the longitudinal direction across a cell wall,
Most of the large number of cells are sealed cells in which either one end is sealed,
A portion of the plurality of cells is an open cell with both ends open;
The honeycomb filter according to claim 1, wherein the number of open cells is 0.1 to 4.9% of the number of cells. The honeycomb filter according to claim 1, wherein the number of the open cells is 0.2 to 1.1% of the number of the plurality of cells. On one end face side of the honeycomb filter, as the numerous cells, cells whose ends are sealed and cells whose ends are opened are alternately arranged,
The cell in which the end on the one end face side is sealed is the sealed cell in which the end on the other end face side is opened,
Most of the cells whose end on the one end face side is opened are the sealed cells in which the end on the other end face side is sealed,
3. The honeycomb filter according to claim 1, wherein a part of the cells having an open end on the one end face side is the open cell having an open end on the other end face side. A metal container having a gas inlet side and a gas outlet side;
An exhaust gas purification device comprising a honeycomb filter housed in the metal container,
In the honeycomb filter, a large number of cells are arranged in parallel in the longitudinal direction across the cell wall,
Most of the large number of cells are sealed cells in which either one end is sealed,
A portion of the plurality of cells is an open cell with both ends open;
The number of open cells is 0.1 to 4.9% of the number of cells. The exhaust gas purification apparatus according to claim 4, wherein the number of the open cells is 0.2 to 1.1% of the number of the plurality of cells. On one end face side of the honeycomb filter, as the numerous cells, cells whose ends are sealed and cells whose ends are opened are alternately arranged,
The cell in which the end on the one end face side is sealed is the sealed cell in which the end on the other end face side is opened,
Most of the cells whose end on the one end face side is opened are the sealed cells in which the end on the other end face side is sealed,
A part of the cell in which the end on the one end face side is opened is the open cell in which the end on the other end face side is opened,
One end face side of the honeycomb filter is disposed on the gas inlet side of the metal container,
The exhaust gas purification apparatus according to claim 4 or 5, wherein the other end face side of the honeycomb filter is disposed on a gas outlet side of the metal container. The exhaust gas purification apparatus according to any one of claims 4 to 6, wherein the gas is exhaust gas discharged from a gasoline engine.

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