JPS58214316A - Filter for purifying exhaust gas - Google Patents

Abstract

PURPOSE:To make it possible to regenerate a filter in good efficiency, by partially providing a partition wall through which an exhaust gas is not passed in a filter to uniformly transmit combustion heat to the downstream side by the warmth holding action of said partition wall. CONSTITUTION:An exhaust gas is flowed into a cell 2 opened at the upstream side and sealed at the downstream side by an embedded seal 4 from the upstream side of a filter 10 and passes a partition wall 5 to be flowed into a cell 1 sealed at the upstream surface by an embedded seal 3 and opened at the downstream side. In this case, fine particles in the exhaust gas are adhered to an collected by the partition wall 5. In the filter 10, a partition wall 6 through which the exhaust gas is not almost passed because adjacent cells 2 are together sealed by the embedded seal 4 at the downstream side is provided. Therefore, when the filter 10 is heated by a heater at the regeneration time of the filter 10, fine particles adhered to the upstream surface of the filter 10 are burnt and, because this combustion heat is transmitted to the further downstream side by the partition wall 6, the fine particles adherd to the downstream side are reheated and regeneration efficiency becomes well.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a filter that collects fine particles mainly composed of carbon contained in exhaust gas discharged from a diesel engine, and more particularly, the present invention relates to a filter that collects fine particles mainly composed of carbon contained in exhaust gas discharged from a diesel engine, and more particularly, the present invention relates to a filter that collects fine particles mainly composed of carbon contained in exhaust gas discharged from a diesel engine. This invention relates to a filter structure that allows for

Conventionally, filters used for this purpose include a large number of columnar hollow holes 1 arranged parallel to the exhaust gas flow path, as shown in Figures 1 and 2.
．． 2, and a partition wall 5 having air permeability that partitions the columnar hollow hole.
and one end of the columnar hollow hole is a sealing member 3,
A so-called honeycomb-shaped filter is known in which the adjacent columnar hollow holes are sealed by a filter 4 and in which adjacent columnar hollow holes are opened in opposite directions. In this filter, exhaust gas flows in from the inlet of the honeycomb-shaped filter, and by passing the exhaust gas through the partition wall 5, particulates are collected on the partition wall.And, When regenerating the filter by burning and purifying the particulates collected by this filter, near the upstream side,
There is a demand for efficient combustion with small electric power by installing an electric heater. However, in the conventionally known honeycomb-shaped filter, the number of hollow holes 2 opening on the upstream side and the number of hollow holes 1 opening on the downstream side are approximately equal.

Therefore, the exhaust gas flowing in from the upstream opening is transferred to the partition wall 5.
It flows downstream through the , and flows out from the downstream opening.

Therefore, since exhaust gas passes through all the partition walls, the heat that is avoided by combustion on the upstream side is released into the air along with the flow of exhaust gas, and is dissipated to the outside through the downstream opening. This makes it difficult for the partition wall located on the downstream side to reach the heating regeneration temperature, making it difficult to burn and remove the particulates collected on the downstream side.

The present invention was made for the purpose of improving the above-mentioned drawbacks of the conventional technology, and includes a partition wall through which exhaust gas does not pass through, which is partially provided inside the filter. , the purpose is to uniformly avoid the transfer of combustion heat and achieve efficient regeneration of the filter.

That is, in contrast to conventional filters in which adjacent hollow holes are regularly and alternately sealed on the upstream side and downstream side, the present invention provides a partition wall through which exhaust gas does not pass through. Therefore, some of the hollow holes are configured so that the downstream sides of adjacent hollow holes are sealed together.

Here, the number and shape of the hollow holes are not limited.

Among all the partition walls, the proportion of the partition walls that do not allow the exhaust gas to pass through according to the present invention is determined by taking into account particulate collection efficiency, pressure loss, combustion efficiency, heat retention efficiency, etc. If a large number of partition walls according to the present invention are provided, the heat retention efficiency will be high, but the collection efficiency will be reduced and the pressure loss will be large, and if there are too few partition walls,
The collection effect is large and the pressure loss is small, but the heat retention effect is small and the combustion efficiency is low. Therefore, an optimal ratio exists. The ratio is desirably about 1/10 to 315 in conventionally known honeycomb filters.

Hereinafter, the present invention will be explained in detail based on Examples.

FIG. 3 is a plan view of the cylindrical honeycomb-shaped particulate filter according to the present invention, viewed from the upstream side of the exhaust gas flow path. Among the square hollow holes (hereinafter referred to as "cells"), the hill 1 drawn with a broken line is sealed with a plug 3 on the upstream side as shown in Fig. 4, and the cell drawn with a solid line is 2 is sealed with a plug 4 on the downstream side.The partition wall 5
and 6 are made of ceramic that controls air permeability, and the exhaust gas flows into the cell 2 from the upstream inlet, and the partition wall 5
The particulates in the exhaust gas arrive at the partition wall 5 and are collected. Since the adjacent cells 2 are both sealed by the plugs 4 on the downstream side, the exhaust gas hardly passes through the partition wall 6. Such partition walls 6 are illustrated in black in FIGS. 3 and 4. As can be seen from FIG. 3, such partition walls 6 are uniformly and regularly distributed over the cross section of the filter.

In the case of this embodiment, the ratio of the partition walls 6 to the total partition walls is about 115. The partition wall 5 through which exhaust gas permeates,
The partition wall 6, which contributes to the collection of particulates and does not allow exhaust gas to pass through, stores the combustion heat ignited and combusted on the upstream side, transmits it to the downstream side, and contributes to efficient regeneration of the filter on the downstream side. Rir.

FIG. 5 shows an example of a particulate collection device using the filter 10 (shown in FIGS. 3 and 4) of the present invention. The filter 10 is held between a stainless steel shell 13 with a sealing material 11 and a buffer material 12 in between. shell 13
A pipe 14 and a flange 15 are welded to both ends thereof, and the flange 15 is connected to an exhaust pipe of an engine (not shown). An electric heater 17 is mounted on the upstream surface of the filter 10 and pressed against a honeycomb-shaped holding member 16 . There are four heaters 17 as shown in FIG. 6, and each heater 17 covers 1/4 area of the filter 10. One end of the heater 17 is taken out from a terminal 19 that passes through an electrically insulating sleeve 18 so that it can be energized. Further, the other end 20 is joined to the shell 13 and grounded through this. The reason why there are multiple heaters is that the power consumption of the heaters cannot be increased unnecessarily, and in order to regenerate the filter 10 (burn and purify the dirty particles), multiple heaters are used intermittently one after another. This is to reduce power consumption by adopting a method in which electricity is applied to the terminals.

In the configuration shown in FIG. 5, when the filter 10 collects particulates in the exhaust gas and the amount exceeds a certain level, the heater 17 is energized and heated. When the heater 17 is heated, the particulates attached to the filter 10 are burned by the heat. In this case, in the conventional honeycomb structure shown in Figs. 1 and 2, the heat of the heater causes the particulates attached to the upstream surface of the filter to burn, and the combustion heat is released to a certain extent. This is transmitted to the downstream side and heats the fine particles adhering to the F basin. However, most of the heat will be carried away directly by the exhaust gas flowing through the cell 1 via the partition wall 5. For this reason, the fine particles adhering downstream are not sufficiently heated, resulting in poor regeneration efficiency.

However, in the filter of the present invention, by properly distributing the partition walls 6 that do not directly communicate with the downstream region, the heat of combustion of the particulates attached to the partition walls 6 is not dissipated from the downstream port by the exhaust gas, and the amount of heat is reduced. The fine particles that have been stored and adhered to the downstream side are reheated, improving regeneration efficiency.

Figure 7 shows diameter ioomm, length 100mm, #100
In the mesh honeycomb structure, after heating the heater for a certain period of time, J
3 shows the results of temperature measurements over time. Here, the regeneration conditions (amount of M attached with particulates, exhaust gas flow rate, heater power) are kept the same. The results of the conventional filter are shown in FIG. 7(a), and the results of the filter according to the present invention are shown in FIG. 7(1). It can be seen that the filter according to the present invention has a higher temperature and burns better. Regarding the regeneration efficiency visually, the conventional filter can only regenerate to a depth of 20 mm from the upstream surface, whereas the filter according to the present invention can regenerate all areas except for the vicinity of the most upstream surface. Regenerated.

In this embodiment, the cells have a rectangular shape as shown in FIG. 3, but may be a honeycomb structure having hexagonal cells as shown in FIGS. 8 and 9. The hatched cells in FIGS. 8 and 9 are plugged on the upstream surface, and the other cells are plugged on the upstream surface. The blacked-out portion is the partition wall 6'c through which exhaust gas permeation is small. The occupation ratio of the partition walls 6 to all the partition walls is 1/3 in the case of FIG. 8 and 1/2 in the case of FIG. 9. Therefore, when comparing FIG. 8 and FIG. 9, the number of partition walls 6 through which exhaust gas does not permeate to the downstream side is greater in FIG. 9, and the regeneration efficiency is better. However, since the area through which exhaust gas passes decreases, the exhaust pressure will increase when installed in the engine, so when determining the proportion of the partition wall 6 that does not directly communicate with the downstream region, it is important to consider engine output, regeneration, etc. It is necessary to meet certain conditions.

Next, a second embodiment will be explained. In the previous example, the method of arranging the plugs was regular, but in this example, the method of placing the plugs was regular.
As shown in the figure, a gap that does not directly connect to the F basin! I! 6,
1/4 of the filter, which is the unit heated by the heater
This means that when using the heater arrangement as shown in Fig. 6, the center of the heater is
In other words, the aim is to improve the heat retention performance of the combustion center during combustion. As a result, combustion efficiency can be increased with small electric power.

In the above embodiments, the cross-sectional shapes of the filters are all circular, but they may also be rectangular or oval. It is not limited to shape.

In summary, the present invention provides a partition wall that partitions the hollow hole of a particulate-collecting filter, through which exhaust gas permeates, flows out into the hollow hole opening on the downstream side, and collects particulates during permeation; A partition wall that partitions an adjacent hollow hole that has a small amount of exhaust gas permeation and is not open to the downstream side, at a certain ratio,
The ends of the hollow holes are sealed either uniformly or locally. Therefore, a partition wall with a small permeation of exhaust gas has an excellent heat retention effect without dissipating combustion heat into the exhaust gas, and functions to effectively transfer heat to the downstream side.

Therefore, this filter can effectively perform combustion and regeneration up to the downstream portion, and has extremely high regeneration efficiency.

Further, since the above-mentioned partition wall is provided in a portion, the efficiency of collecting fine particles is not reduced, and the pressure loss is not significantly increased.

[Brief explanation of the drawing]

FIG. 1 shows a filter with a conventional honeycomb structure, FIG. 2 shows a sectional view taken along the arrow 1 in FIG. 1, and FIG. 3 shows an upstream filter of an embodiment of the present invention. Viewed from the side 1 [Plan view, FIG. 4 is a view taken along the IV-IV arrow MfIi in FIG. 3. , FIG. 5 is a cross-sectional view taken along the exhaust gas outlet path of a particulate collector having an electric heating regeneration means equipped with a filter according to an embodiment of the present invention, and FIG. Vl-Vl arrow sectional view,
Figure 7 is a graph showing the combustion characteristics.
1 shows the measurement results for a conventional type filter, and FIG. Figures 8 and 9
The figure shows another example showing the cross-sectional shape of the hollow hole according to the same embodiment and the distribution of the partition walls according to the present invention. FIG. 10 shows the distribution of the partition walls according to the present invention according to the second embodiment. It is a diagram. 1.2... Hollow hole (cell), 3.4. ...Plug 5 ...Partition wall 6 ...Partition wall according to the present invention 10 ...Filter patent applicant Nippondenso Co., Ltd. Agent Patent attorney Ana Okawa Hajime Fujitani Jo Akira Maruyama Beam 1 Figure 2 Figure 3/2: (5 Figure 6:,)r Figure 7 (a) (b)

Claims (1)

[Claims] Having a large number of columnar hollow holes parallel to the gas flow path,
A honeycomb-shaped exhaust gas purifying filter in which one end of the columnar hollow holes is sealed, and a partition wall that partitions two adjacent columnar hollow holes is a filter for exhaust gas purification of the exhaust gas purifying filter. A partition wall defining columnar hollow holes that are both sealed on the outflow end surface, and at least one of the two adjacent columnar hollow holes are sealed on the exhaust gas outflow end surface of the exhaust gas purifying filter. 1. A filter for purifying exhaust gas, comprising a partition wall that partitions columnar hollow holes.