Sealed honeycomb structure and device for cleaning exhaust

Abstract

A sealed honeycomb structure which can suppress increase of pressure loss and improve durability favorably is disclosed. A sealed honeycomb structure 100 including includes a honeycomb structure having porous walls dividedly forming inlet cells and outlet cells, an outlet side sealing portion, and an inlet side sealing portion, wherein an opening area of the inlet cell is larger than an opening area of an outlet cell on a cross-section of the honeycomb structure, wherein at least one outlet cell is a reinforced cell where a reinforcing part for reinforcing the outlet cell is formed at at least one corner portion at which the walls on a cross-section vertical to an extending direction of the cell cross each other, and wherein the inlet cell is a non-reinforced cell where the reinforcing part is not formed at all the corner portions at which the walls on the cross-section vertical to the extending direction of the cell cross each other.

Description

CROSS-REFERENCE TO RELATED APPLICATION[0001]This application is a National Stage of International Patent Application No. PCT / JP2012 / 058727 filed Mar. 30, 2012 and published as WO 2012 / 133847, which claims priority to Japanese Patent Application No. 2011-078694 filed Mar. 31, 2011, the entire contents of which applications is incorporated herein for all purposes by this reference.BACKGROUND OF INVENTION[0002]1. Field of Invention[0003]The present invention relates to a sealed honeycomb structure and a device for cleaning exhaust. More particularly, the present invention relates to a sealed honeycomb structure which can suppress increase of pressure loss and improve durability favorably and a device for cleaning exhaust using the sealed honeycomb structure.[0004]2. Description of Related Art[0005]Gas exhausted from internal combustion engines such as diesel engines or other combustion devices contains a large amount of particulate matter (PM) having soot as main component. Since the P...

AI Technical Summary

Benefits of technology

[0010]In addition, since an inlet cell into which the fluid flows is also reinforced, the volume of the channel (particularly, volume of the inlet side of the fluid) is reduced according to the honeycomb structures disclosed in patent document 1 and patent document 2. Therefore, a filter area that is an area of a filter actually operating as a filter is reduced and pressure loss of the sealed honeycomb structure may increase.

[0013]The present invention has been made in an effort to provide a sealed honeycomb structure having advantages of suppressing increase of pressure loss by sufficiently securing a volume of a cell (inlet cell) into which fluid flows and improving durability favorably.

[0023]According to the sealed honeycomb structure of the present invention, an opening area of the inlet cell on a cross-section vertical to an extending direction of the cell is larger than that of the outlet cell on the cross-section vertical to the extending direction of the cell. Therefore, flowing direction of the fluid is predetermined when the sealed honeycomb structure of the present invention, for example, is used as a filter. In addition, at least one cell among outlet cells (i.e., cells having smaller opening area) is a reinforced cell where a reinforcing part for reinforcing the outlet cell is formed at at least one corner portion at which walls on a cross-section vertical to an extending direction of the cell cross each other, and an inlet cell (i.e., cell having a larger opening area) has a reinforcing part for reinforcing the inlet cell formed at at least one corner portion at which walls on the cross-section vertical to the extending direction of the cell cross each other wherein the number of the corner portions reinforcing the inlet cells is smaller than the number of the corner portions reinforcing the outlet cells, or the inlet cell is a non-reinforced cell where the reinforcing part is not formed at all the corner portions at which the walls on the cross-section vertical to the extending direction of the cell cross each other. Therefore, volume and opening area of the inlet cell where the reinforcing part is not formed (i.e., non-reinforced cell) can be sufficiently secured. Therefore, increase of pressure loss may be suppressed. Meanwhile, durability of the sealed honeycomb structure may be improved favorably because the reinforcing part is formed at at least one corner portion of the outlet cell which has smaller influence on pressure loss than the inlet cell does. Therefore, mechanical strength of the sealed honeycomb structure may be excellent.

[0024]Particularly, occupying volume of the reinforcing part in the channel according to the sealed honeycomb structure of the present exemplary embodiment is less than half of that according to a conventional honeycomb structure having the inlet cells and the outlet cells where the reinforcing part is formed. However, durability of the honeycomb structure can be improved more than volume ratio of the reinforcing part. In addition, since the number of the reinforcing parts formed at the outlet cells at which maximum thermal stress occurs in the sealed honeycomb structure is greater than the number of the reinforcing parts formed at the inlet cells, or only the outlet cells are reinforced, excess increase in mass of the sealed honeycomb structure may be suppressed. Therefore, if the sealed honeycomb structure is mounted at an exhaust gas channel of an internal combustion engine, that is if a device for cleaning exhaust of the present invention provided with the sealed honeycomb structure of the present invention is used, the sealed honeycomb structure is easily heated and degradation of purifying performance of exhaust gas may be suppressed favorably. In addition, even though temperature of the sealed honeycomb structure is controlled by temperature of the exhaust gas, deterioration of fuel economy of the internal combustion engine may be suppressed because the sealed honeycomb structure is easily heated. According to the sealed honeycomb structure of the present invention, improvement of durability of the honeycomb structure and suppression of increase of pressure loss that were regarded as trade-off relation may be satisfied. In addition, degradation of purifying performance or fuel consumption of the internal combustion engine may be suppressed. In addition, since volume is not reduced by deposition of ash, the sealed honeycomb structure according to the present exemplary embodiment may improve strength of the honeycomb structure without influence on the increase of the pressure loss, cleaning period of the ash, and replacement period of a filter of purifying the exhaust gas (for example, DPF) after the ash is deposited.

Problems solved by technology

As a result, durability of the sealed honeycomb structure may be deteriorated due to deposits of ash contained in the exhaust gas.

Because mass of the sealed honeycomb structure also increases by forming the reinforcing part, forming the reinforcing part excessively may cause deterioration of performance of the sealed honeycomb structure.

Therefore, purifying performance of the exhaust gas may be deteriorated.

In this case, fuel consumption of an internal combustion engine of vehicles may be deteriorated.

In this case, durability may be improved by forming the reinforcing part but other characteristics of the filter such as the pressure loss or the purifying performance may be deteriorated.

Particularly, improvement of strength and increase of the pressure loss in the honeycomb structure are regarded to be incompatible.

Therefore, it is very difficult to obtain both of them.