JPH051523A - Exhaust filter for internal combustion engine - Google Patents

Abstract

PURPOSE:To improve a collection efficiency, and restrict blow-off at the time of acceleration of an engine by fixing and supporting a number of mesh metal fiber plates having a low mechanical strength tightly but without getting in contact with each other. CONSTITUTION:Wavily bent mesh metal fiber plates 6 are combined on both sides of a flat mesh metal fiber plate 5, and their edges are held and fixed by a metal frame 7 to form a disc-like filter member 3. A filter element comprises lamination of a plural filter members 3, and the mesh of the mesh metal fiber plates 5, 6 becomes finer as it goes to the downstream of exhaust.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an exhaust filter for collecting and removing exhaust particulates such as carbon, which is a problem in internal combustion engines, especially diesel engines.

[0002]

2. Description of the Related Art It has been conventionally considered to collect and remove exhaust particulates such as carbon, which is a problem in diesel engines, by an exhaust filter interposed in an exhaust system, and various types of exhaust filters have already been proposed. Has been done.

A typical one of the exhaust filters is a filtration and collection type, which is represented by a so-called plugged filter. The above-mentioned plugged filter is disclosed, for example, in Japanese Patent Laid-Open No. 56-
As disclosed in Japanese Patent No. 124417, many fine flow passages are formed in a ceramic block along the exhaust flow direction, and the ends of the flow passages are alternately closed with ceramics. Then, the exhaust gas passes through the ceramic partition walls between the flow paths to filter and collect the exhaust fine particles.

[0004] With this filtration and collection type, although very high collection efficiency is obtained, exhaust particulates are easily collected excessively, and the particulate collection amount easily exceeds the burnout limit of the filter. That is, if the timing of forced regeneration using a burner or the like or regeneration by exhaust heat is delayed for some time, a large amount of exhaust particulates may rapidly burn, resulting in burnout of the filter. Moreover, even Ash components (oxides of oil additives, etc.) that cannot be removed by incineration are collected, and eventually there is a possibility that clogging will occur.

Therefore, an exhaust filter of adhering trapping type has been proposed in place of the filter trapping type. As one example thereof, as disclosed in Japanese Utility Model Publication No. 51-23615 and Japanese Utility Model Publication No. 51-50109, a filter element is known in which a large number of thin heat-resistant fiber plates carrying a catalyst are laminated. ing. With this adhering and collecting type, when exhaust gas flows through the complicated flow path generated inside the filter element, exhaust particulates adhere to and collect on the surface of the flow path. It is unlikely that excessive collection such as.

[0006]

However, since the thin fiberboard as described above has a low mechanical strength, it is difficult to maintain the shape in a regularly laminated state. That is, when fixed in the casing, the fibers and meshes are likely to be partially crushed or biased, and as a result, many exhaust particulates are locally collected at the places where the meshes are dense due to crushing and the like, and The distribution is very uneven. Therefore, at the time of regeneration, there is a possibility that the temperature of the exhaust particulates may locally become high and the filter may be burned out. Moreover, if the collection of exhaust particulates is non-uniform in each part in this way, the contact efficiency between the exhaust gas and the catalyst becomes poor, even if the catalyst is carried on the filter, and the regeneration performance and exhaust purification performance by the catalyst are reduced. descend.

Further, in the structure in which a large number of heat-resistant fiber boards are laminated as they are as in the above-mentioned conventional example, the ventilation resistance is meaninglessly increased, and the exhaust particulate collection efficiency cannot be so high. There is also. Further, blow-off of exhaust particulates during engine acceleration, which is one of the drawbacks of the adhering and collecting method, cannot be sufficiently suppressed.

[0008]

An exhaust gas filter for an internal combustion engine according to the present invention has a mesh-like metal fiber board bent in a corrugated plate shape, which is superposed on one side or both sides of a flat mesh-like metal fiber board, and has an end edge thereof. Is sandwiched and fixed by a metal frame having a substantially U-shaped cross section to form a plate-shaped filter member, and a plurality of types of filter members having different meshes are used. It is characterized in that the sheets are stacked so that the eyes become finer toward the downstream side and are housed in the casing.

[0009]

In the above structure, since the edge of the mesh-like metal fiber board is supported by the metal frame, the mechanical strength is improved, and a large number of laminated sheets can be easily fixed in the casing. At this time, the frame also functions as a spacer, and an appropriate space is maintained between the mesh metal fiber boards between the filter members.

Further, since the flat mesh-like metal fiber board is fixed to the frame together with the corrugated mesh-like metal fiber board by the frame, the shape of the corrugated fiber board is surely maintained.
An appropriate space is maintained between the plates, and deviation and sagging with time are prevented.

[0011]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described in detail below with reference to the drawings.

FIG. 2 is a sectional view showing an embodiment of the exhaust filter according to the present invention, in which a cylindrical filter element 2 is housed in a casing 1.

The casing 1 is inserted in the middle of an exhaust pipe of a diesel engine, for example, and has a cylindrical main body 1
a and a substantially conical inlet portion 1b and outlet portion 1c. It should be noted that the casing 1 is formed by being vertically divided into two parts, and after housing the filter element 2, it is integrated by welding or the like.

As shown in FIG. 3, the filter element 2 is composed of a plurality of disc-shaped filter members 3. That is, a plurality of filter members 3 are stacked, housed in the tubular case 4, and the open end edges 4a on both sides of the tubular case 4 are caulked to be firmly integrated.

As shown in FIG. 1, each filter member 3 is formed by stacking three mesh-like metal fiber plates carrying a catalyst. The mesh-like metal fiber board 5 located at the center has a flat disk shape, and a pair of mesh-like metal fiber boards 6 bent in a corrugated shape are superposed on both surfaces thereof. The three mesh-shaped metal fiber plates 5 and 6 are sandwiched and fixed by a metal frame 7 having a substantially U-shaped cross section in a state where the peripheral edges of the mesh-shaped metal fiber plates 5 and 6 are overlapped. The mesh-like metal fiber plates 5 and 6 are formed by forming metal fibers into a thin sheet having meshes, and constitute one filter member 3
The mesh-like metal fiber boards 5 and 6 have the same mesh roughness.

As the filter element 2 as a whole, a plurality of types of filter members 3 having different meshes are used. As shown in FIG. 4, the mesh is relatively coarse on the upstream side of the exhaust flow and downstream, as shown in FIG. A plurality of filter members 3 are stacked in such an order that the eyes become finer toward the bottom.

The mesh-shaped metal fiber plate 6 bent into a corrugated plate shape
As is clear from FIG. 1, the height of the unevenness is set smaller than the protruding amount of the metal frame 7.

According to the configuration of the above embodiment, when exhaust gas passes through the filter element 2, that is, a large number of filter members 3, exhaust gas particulates adhere to the surfaces of the reticulated metal fiber plates 5, 6 and are collected. .. Then, the collected exhaust particulates are reburned when, for example, the exhaust temperature becomes high, and the filter element 2 is regenerated.

Here, in the above structure, a plurality of mesh-shaped metal fiber plates 5 and 6 are laminated in a state separated from each other by corrugated unevenness without being in close contact with each other as shown in FIG. Moreover, the metal frame 7 functions as a kind of spacer to prevent the mesh-shaped metal fiber plates 6 from adhering to each other even between the adjacent filter members 3. In addition, a mesh-shaped metal fiber plate 6 having a corrugated plate shape
Has a large surface area due to the unevenness. Therefore, a large substantial contact area with the exhaust gas can be obtained, and the trapping efficiency can be improved without significantly increasing the ventilation resistance. In addition, the contact efficiency with the catalyst is also good,
Exhaust gas purification effect and regeneration capacity by the catalyst are improved. Since the corrugated mesh-like metal fiber board 6 is integrated with the flat mesh-like metal fiber board 5 by the metal frame 7, the flat mesh-like metal fiber board 5 is tensioned as shown in FIG. The cross-sectional shape is surely maintained, and for example, it is not crushed by its own weight and the density of eyes is not biased. Therefore, exhaust particulates are relatively evenly collected in each part, and local overheating during regeneration is prevented.

Further, in the above structure, since the plurality of mesh-shaped metal fiber plates 5 and 6 are integrated in advance by the metal frame 7, the mesh-shaped metal fibers are easy to handle and have low mechanical strength. It becomes possible to firmly fix and support a large number of plates 5 and 6 in a laminated state, and the durability becomes excellent. In particular, when caulking the opening edge 4a of the tubular case 4, a force is applied to the metal frame 7 of each filter member 3, so that deformation during caulking is also prevented, and it is possible to firmly integrate them. it can.

Further, since the filter element 2 is composed of a plurality of filter members 3 so that the mesh is coarse on the upstream side of the exhaust flow and finer on the downstream side, the engine is rapidly accelerated, for example. In such a case, even if the exhaust particulate matter blows off from the mesh-shaped metal fiber plates 5 and 6 on the upstream side, it is easily collected again on the mesh-shaped metal fiber plates 5 and 6 on the downstream side, and blow-off to the outside is prevented. It

Next, FIGS. 5 and 6 show different embodiments of the present invention. In this embodiment, one filter member 3A, 3B has two mesh-like metal fiber plates 5, 6, that is, a flat mesh-like metal fiber plate 5 and a corrugated plate-like mesh metal which is superposed on the upstream surface thereof. It is composed of a fiber board 6. Then, two types of filter members 3A and 3B having different configurations of the metal frame 7 are alternately laminated.

In one filter member 3A, a baffle plate portion 7a is formed at the center of the downstream surface of the metal frame 7, and this baffle plate portion 7a is connected to the peripheral portion of the frame 7 by a substantially cross-shaped bridge portion 7b. ing. Further, in the other filter member 3B, the downstream surface of the metal frame 7 is extended to the inner peripheral side, whereby a baffle plate portion 7c that covers the outer peripheral portion is formed. The roughness of the mesh-like metal fiber plates 5 and 6 of the filter members 3A and 3B is
Similar to the embodiment described above, the setting is made finer toward the downstream side.

Therefore, in this embodiment, as shown by the arrow in FIG. 6, the exhaust gas flows through the filter element 2 in a very turbulent manner, and the exhaust particulate collection efficiency is improved. At the same time, the contact efficiency with the catalyst becomes even better. Further, since the baffle plates 7a and 7c and the bridge portion 7b support the mesh-like metal fiber plates 5 and 6 as a part of the metal frame 7, the mesh-like metal fiber plates 5 and 6 are provided.
Is more reliably supported, and the filter members 3A and 3B are
As a result, the mechanical strength is improved.

In any of the embodiments, it is not always necessary to continuously change the roughness of the mesh-shaped metal fiber plates 5 and 6 one by one. It may be changed.

[0026]

As is apparent from the above description, in the exhaust gas filter of the internal combustion engine according to the present invention, the mesh-like metal fiber plate having a low mechanical strength, particularly the mesh-like metal fiber plate bent in a corrugated plate shape, is used. It becomes possible to stably fix and support, improving durability and stabilizing performance. Further, it is possible to maintain a large number of mesh-shaped metal fiber plates in a non-adhered state, and a high collection efficiency can be obtained compared to the ventilation resistance, and crushing due to its own weight and deviation of coarse and dense are prevented, and each part is relatively uniform. Collection can be done.

Blow-off at the time of sudden acceleration of the engine or the like is prevented by sequentially laminating the filter members having different meshes.

[Brief description of drawings]

FIG. 1 is a sectional view showing a main part of an exhaust filter according to the present invention.

FIG. 2 is a sectional view showing the overall structure of an exhaust filter according to the present invention.

FIG. 3 is a partially cutaway perspective view showing only a filter element.

FIG. 4 is an explanatory view showing a laminated state of filter members.

FIG. 5 is a sectional view of an essential part showing a different embodiment of the present invention.

FIG. 6 is an explanatory view showing a laminated state of filter members in this embodiment.

[Explanation of symbols]

 2 ... Filter element 3 ... Filter member 5, 6 ... Mesh-shaped metal fiber board 7 ... Metal frame

Claims (1)

Claim: What is claimed is: 1. A mesh-like metal fiber board bent in a corrugated plate shape is superposed on one or both sides of a flat mesh-like metal fiber board, and its edge is made of a metal having a substantially U-shaped cross section. While sandwiching and fixing with a frame to form a plate-shaped filter member,
An internal combustion engine characterized in that a plurality of types of filter members having different meshes are used, and the plurality of filter members are stacked and housed in a casing so that the eyes become finer toward the exhaust flow downstream side. Exhaust filter.