JPH0586835A - Exhaust emission control device - Google Patents

Abstract

PURPOSE:To provide easy assembling of a filter element and great filtering capacity of the whole in an exhaust emission control device which is constituted of a multiple-layer filter where plural filter elements are combined together. CONSTITUTION:A ring 9 which constitutes filter elements 5 has uniform thickness and a central hole in it. At one side surface of the ring 9, an outer periphery rib 10 is formed, and at the other side surface S2, an inner periphery rib 11 is formed. A multiple-layer filter F is formed by jointing many filter elements 5 by means of connecting respective outer periphery ribs 10 and the inner periphery ribs 11 of the adjoining rings 9. The multiple-layer filter F is arranged inside the exhaust passage 2a of an internal combustion engine.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an exhaust gas purifying apparatus for removing particulates contained in exhaust gas of a diesel engine or the like.

[0002]

2. Description of the Related Art A conventional device of this type is disclosed in, for example, Japanese Utility Model Laid-Open No. 63-46097.
This device is provided with a disk-shaped filter element which is formed of ceramic foam or metal foam and has an opening in the center. The filter element is also made of a material similar to that of the filter element, and includes a spacer having a smaller diameter than the filter element. Then, by assembling them alternately, a filter having a multilayer structure is formed. Further, such a multilayer filter is arranged in a casing provided with a passage communicating with the exhaust side of the diesel engine, and is fixed to the casing by a support rod. Further, the central opening of the element located at the gas inflow end is closed by the closing plate. Further, according to the above configuration, when the exhaust gas flowing into the gap between the filter elements passes through the inside of the filter element and the interstitial material and passes through to the central portion side of the multilayer filter, the pattern contained in the exhaust gas is included. The curate is removed.

[0003]

However, in the above-mentioned conventional apparatus, when the filter element and the interstitial material are manufactured, it is necessary to use different molds and the like, which is inconvenient. Further, the work of alternately assembling a large number of filter elements and interstitial materials has been extremely complicated.

Further, the above-mentioned publication discloses a multi-layer filter in which the center portion of each filter element is formed thick so that no interstitial material is required between the filter elements. However, in the device to which such a filter is applied, it is difficult to secure a large filtration area in the gap between the filter elements, so that there is a problem that the exhaust gas purification work cannot be performed for a long period of time.

The present invention has been made in view of the above circumstances, and an object thereof is to improve the filtering performance of the entire apparatus and to easily assemble the filter element with exhaust gas. To provide a purification device.

[0006]

In order to solve the above problems, in the present invention, a casing having a passage communicating with the exhaust side of a diesel engine and a plurality of layers arranged in layers in the passage are provided. In an exhaust gas purification device comprising a filter element and a pair of heat-resistant fixing plates arranged on both sides of the filter element group and for fixing each filter element to a casing, the filter element has a central hole. And a ring having a uniform thickness, an outer peripheral rib is integrally formed on the outer peripheral portion of one side surface of the ring, and the outer peripheral rib is joined to the outer peripheral rib formed on the adjacent ring, An inner peripheral rib is integrally formed on the inner peripheral portion of the other side surface of the ring, and the inner peripheral rib is formed on an adjacent ring. Are joined together with the inner peripheral rib which is,
On one side surface of the ring, an inner peripheral portion thereof is joined to each other so as to maintain a constant gap between the adjacent rings, and a gap for gas passage that communicates with the central hole in the joined state. It is characterized in that a plurality of protrusions forming C are provided.

A multi-layer filter is formed by stacking a large number of filter elements constructed as described above. In this case, the outer peripheral ribs and the inner peripheral ribs of the adjacent rings are joined to each other. In addition, the rings of the respective filter elements are spaced apart while maintaining a constant distance. Further, by joining the protrusions provided on the adjacent rings to each other, a gap C of the gas passage hole communicating with the central hole is formed between the pair of adjacent filter elements.

Since each rib and protrusion can be formed integrally with the ring, the multilayer filter can be constituted by one kind of filter element. Therefore, assembling becomes extremely easy as compared with the conventional device, and the filtering ability of the entire device can be improved.

The pore diameter of the filter element is 5 μm
~ 50μm, porosity 35% ~ 70%, wall thickness 1mm ~ 5
It is desirable to set to mm. If the pore diameter and the porosity are less than the above ranges, the resistance of the exhaust gas when passing through the wall of the filter element increases, and the pressure loss increases, which is not preferable. On the other hand, if the pore diameter and the porosity exceed the above-mentioned ranges, the filter element is likely to be broken due to the decrease in strength and the filtering ability may be deteriorated. Further, if the wall thickness is less than the above range, pressure loss will increase, and if it exceeds the above range, the strength of the filter element will decrease, which is not preferable.

Further, a support rod made of at least one of silicon carbide, silicon nitride, alumina and heat-resistant metal is inserted into the center hole of each filter element, and the pair of fixing plates are fixed to the support rod. Is desirable. If each member is arranged and fixed as described above,
This is because each filter element is reliably held in a fixed position. In addition, the heat resistance of the multilayer filter can be improved by using the above materials.

[0011]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT An embodiment of an exhaust gas purifying apparatus embodying the present invention will be described below in detail with reference to the drawings.

As shown in FIG. 1, the exhaust gas purifying apparatus 1 comprises a casing 2 made of a metal pipe, and the casing 2
2a is connected to the exhaust pipe Ea of the diesel engine E. As shown in FIGS. 1 and 2, ring-shaped fixtures 3a and 3b having a plurality of gas passage holes are arranged at intervals in the casing 2, and a plurality of fixtures 3a and 3b are provided. Filter element 5, a pair of heat resistant fixing plates 6 and 7, and a support rod 8 as a multilayer filter F
Is fixed. Further, a burner 4 is provided as a heat source for regeneration processing on the exhaust gas inflow side of the multilayer filter F in the passage 2a.

As shown in FIG. 3, the filter element 5
The ring 9 that constitutes the has a uniform thickness (0.4 mm),
A center hole 9a having an inner diameter of 50 mm is formed in the ring 9, and the outer diameter of the ring 9 is set to 200 mm.
Further, on one side surface S1 of the ring 9, the outer peripheral portion thereof is
An outer peripheral rib 10 having a thickness of 2 mm and a width of 2 mm is formed integrally with the ring 9. Further, a plurality of protrusions 12 (six in this embodiment) are formed integrally with the ring 9 on the inner peripheral portion of the side surface S1 at predetermined intervals.

As shown in FIG. 4, the other side surface S2 of the ring 9 is
In the inner peripheral portion, an inner peripheral rib 11 having a thickness of 2 mm and a width of 2 mm is formed integrally with the ring 9. Then, the ring 9, the outer peripheral ribs 10, the inner peripheral ribs 11, and the protrusions 12 described above.
Porous silicon carbide is used as a material for forming
The filter element 5 having m and porosity of 40% is integrally formed.

Next, a method of arranging the plurality of filter elements 5 in layers will be described. As shown in FIG.
Forty layers of filter elements 5 are used in the multilayer filter F of this embodiment. The filter elements 5 are superposed in close contact with each other so that their side surfaces S1 face each other and their side surfaces S2 face each other. That is, the outer peripheral rib 10 and the inner peripheral rib 11 of each filter element 5 are joined to the outer peripheral rib 10 and the inner peripheral rib 11 of another adjacent filter element 5, respectively. As a result, the pair of adjacent filter elements 5
A hollow portion is formed between them. Further, the projections 12 of each filter element 5 are joined to the projections 12 of the adjacent filter elements 5, and the central hole 9 is provided between the projections 12.
A gas passage space C communicating with a is formed. The void C communicates with the hollow portion.

As shown in FIG. 2, a pair of fixing plates 6 and 7 formed of a heat resistant metal are arranged on both sides of the filter element 5 group. The fixing plate 6 arranged on the upstream side is formed to have an outer diameter of 220 mm and a thickness of 5 mm, and a fixing hole 6a having an inner diameter of 30 mm is provided in the central portion thereof. The fixed plate 7 arranged on the downstream side has an outer diameter of 300 m.
m, thickness 5mm, inner diameter 50mm in the center
Communication hole 7a is provided. A support rod 8 made of porous silicon carbide and having a diameter of 30 mm is inserted into the center hole 9a, the fixing hole 6a, and the communication hole 7a, and both ends thereof are fixed to the fixing plates 6 and 7 via fixing rings 13 and 14, respectively. It is fixed. A gas passage hole 14 a is formed in the downstream fixed ring 14. And by assembling in this way,
A multilayer filter F is formed in which the upstream side is closed and only the downstream side is opened.

Now, the multilayer filter F is fixed to the fixtures 3a and 3b in the casing 2, and the diesel engine E is started. Then, the exhaust gas introduced into the upstream region R1 of the multilayer filter F passes between the inner wall of the casing 2 and the multilayer filter F through the hole of the fixture 3a as shown by an arrow A1 in FIG. It flows into the outer region R2.
Then, as indicated by arrow A2, each filter element 5
The exhaust gas reaching the gap G between the two passes through the filter element 5 and flows into the inner region R3 of the multilayer filter F. At this time, the particulates in the exhaust gas are collected by the wall of the filter element 5, and the particulates are oxidized and removed by the action of the catalyst carried on the wall. Then, the purified exhaust gas is discharged to the downstream region R4 of the multilayer filter F through the communication hole 7a of the fixed plate 7 and the gas passage hole 14a of the fixed ring 14, as shown by an arrow A3. It should be noted that such a collecting operation is continuously performed until a predetermined amount of particulates are collected by the multilayer filter F.

A case where the multi-layer filter F used as described above is reproduced will be described. When it is detected that the predetermined amount of particulates are collected in the multilayer filter F by the pressure loss of the exhaust gas, that is, the increase in the pressure difference before and after the gas passes through the multilayer filter F, the burner 4 is ignited, The multilayer filter F is heated until it reaches a predetermined temperature. By this process, the particulates in the multilayer filter F are burned, and the multilayer filter F is regenerated to its original state.

In the multilayer filter F constructed as described above, the inner peripheral ribs 11 and the protrusions 12, and further the outer peripheral ribs 1 are provided.
Since 0 can be formed integrally with the ring 9, the multilayer filter F can be configured with only one type of filter element 5. Therefore, unlike the conventional device in which the filter element and the interstitial material are alternately arranged, the assembly is extremely easy. Further, according to the present invention, a large filtration area can be secured in the gap G between the filter elements 5 unlike the conventional device in which the intermediate member is made unnecessary by making the center portion of each filter element thick. The particulate collecting operation can be performed over a period of time.

Further, in the above-mentioned conventional apparatus, since the entire filter element is formed in a thick plate shape by the ceramic foam or the metal foam, the pressure loss when the exhaust gas passes through the filter element is large. There was a problem. However, by providing the hollow portion between the pair of adjacent rings 9 as in the present invention, it is possible to form a suitable multilayer filter F with a small pressure loss.

[0021]

As described above in detail, according to the exhaust gas purifying apparatus of the present invention, the filtering ability of the entire apparatus can be improved and the filter element can be easily manufactured and assembled. It has an excellent effect.

[Brief description of drawings]

FIG. 1 is a partial front sectional view showing an embodiment of an exhaust gas purifying device embodying the present invention.

FIG. 2 is an enlarged front sectional view showing the multilayer filter of FIG.

FIG. 3 is an enlarged left side view of the filter element.

FIG. 4 is an enlarged right side view of the filter element.

[Explanation of symbols]

2 casing, 2a passage, 5 filter element, 6 (heat resistant) fixing plate, 8 support rod, 9 ring,
9a center hole, 10 outer peripheral ribs, 11 inner peripheral ribs, 12
Protrusions, S1, S2 (ring) sides, E diesel engine, C air gap.

Claims (3)

[Claims] 1. A casing (2) having a passage (2a) communicating with the exhaust side of a diesel engine (E), and a plurality of filter elements (5) arranged in layers within the passage (2a). A pair of heat-resistant fixing plates (6, 6) arranged on both sides of the filter element (5) group for fixing each filter element (5) to the casing (2).
7), the filter element (5) comprises a ring (9) having a central hole (9a) and having a uniform thickness, and one side surface (9) of the ring (9). In S1), an outer peripheral rib (10) is integrally formed on the outer peripheral portion of the ring, and the outer peripheral rib (10) is joined to the outer peripheral rib (10) formed on the adjacent ring (9). (9) The inner peripheral rib (11) is integrally formed on the inner peripheral portion of the other side surface (S2), and the inner peripheral rib (11) is formed on the adjacent ring (9). The ribs (11) are joined to each other, and the one side surface (S1) of the ring (9) is joined to the inner peripheral portion of the ring (9) so as to keep a constant gap between the adjacent rings (9). Together with the center in the joined state Gas passage (C) communicating with the hole (9a)
And a plurality of protrusions (12) that form the exhaust gas. 2. The filter element (5) has a pore diameter of 5 μm to 50 μm, a porosity of 35% to 70% and a wall thickness of 1
The exhaust gas purifying apparatus according to claim 1, wherein the exhaust gas purifying apparatus is set to mm to 5 mm. 3. A support rod (8) made of at least one of silicon carbide, silicon nitride, alumina and heat-resistant metal is inserted through the center hole (9a) of each filter element (5), and the support rod is formed. In (8), the pair of fixing plates (6, 6
The exhaust gas purifying device according to claim 1 or 2, wherein 7) is fixed.