JPH04269317A - Exhaust filter for internal combustion engine - Google Patents

Abstract

PURPOSE:To improve collection efficiency by strongly fixing meshy metallic plates of low mechanical strength in a casing, and forming spaces among respective metallic plates. CONSTITUTION:A plurality of meshy metallic plates 12 having different width little by little are assembled together, and both sides are pinchedly held with frames 13. Hereby, a belt-like filter member 11' elastically swollen in the center part is constituted. This ream of filter member 11' is wound around an exhaust inlet pipe 6 having communicating holes 7 by a plurality of times and formed into multiple layers. On the final outer circumference, a metallic plate 14 is wound on the frames 13, and fixed to the exhaust inlet pipe 6 by welding or the like.

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 are a problem in internal combustion engines, particularly diesel engines.

0002

[Prior Art] It has long been considered that exhaust particulates such as carbon, which are a problem in diesel engines, can be collected and removed using an exhaust filter installed in the exhaust system, and various types of exhaust filters have already been proposed. ing.

A typical exhaust filter is of a filtration and collection type, typified by a so-called plugged filter. The above-mentioned sealed filter is, for example, JP-A-56-
As shown in Japanese Patent No. 124417, a large number of fine channels are formed in a ceramic block along the exhaust flow direction, and the ends of each channel are alternately closed with ceramics. The exhaust gas is passed through a ceramic partition wall between the flow channels to filter and collect exhaust particulates.

[0004] Although this filtration and collection type can achieve a very high collection efficiency, it tends to collect excessive exhaust particulates, and it is necessary to perform forced regeneration using a burner or the like frequently at appropriate times. At the same time, it also collects Ash components (oxides of oil additives, etc.) that cannot be removed by incineration.
Eventually, it may become clogged.

[0005] Therefore, instead of this filtration and collection type exhaust filter, an adhesion collection type exhaust filter has been proposed. As an example, a filter element made by laminating a large number of thin heat-resistant fiberboards carrying a catalyst is known, as seen in Japanese Utility Model Application Publication No. 51-23615 and Japanese Utility Model Application Publication No. 51-50109. ing. It is also being considered to use a thin mesh metal plate in place of the fiberboard.

[0006]

[Problems to be Solved by the Invention] However, since the above-mentioned fiberboards and thin mesh metal plates have low mechanical strength, it is difficult to maintain their shape when stacked regularly. In other words, the fibers and mesh tend to be partially crushed or shifted when fixed inside the casing.
As a result, a large amount of exhaust particles are locally collected in areas where the particles have become dense due to collapse, etc., and the distribution of exhaust particles becomes extremely non-uniform. Therefore, during regeneration, there is a possibility that a localized high temperature may be generated at a location where exhaust particulates have accumulated excessively, resulting in burnout of the filter. Moreover, if exhaust particulates are not collected uniformly in each part, the efficiency of contact with the catalyst supported on the filter deteriorates, and the regeneration ability and exhaust purification performance of the catalyst deteriorate.

[0007] In addition, a structure in which a large number of heat-resistant fiberboards are laminated as is, as in the conventional example described above, has the disadvantage that the ventilation resistance increases pointlessly, and the exhaust particulate collection efficiency cannot be obtained as high as that. There is also.

[0008]

[Means for Solving the Problems] An exhaust filter for an internal combustion engine according to the present invention is provided by stacking a plurality of mesh metal plates or metal fiberboards each carrying a catalyst in combinations of slightly different sizes, and The end edge is clamped and fixed by a metal frame having a substantially U-shaped cross section so that the filter member is elastically expanded, and is constructed by laminating a plurality of filter members integrated with this metal frame. It is characterized by what it did.

[0009]

[Function] In the above structure, the edge of the mesh metal plate or metal fiberboard is supported by the metal frame, so
It has improved mechanical strength and can be easily fixed in a casing in a stacked state. At this time, the frame also functions as a spacer, and an appropriate space is maintained between the mesh metal plates or metal fiber plates.

[0010] Furthermore, by clamping and fixing a plurality of thin plates of slightly different sizes with a metal frame,
The center part naturally protrudes and becomes elastically inflated. Therefore, an appropriate space is maintained between each plate, and shifting and sagging over time are prevented.

[0011]

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

FIG. 1 is a cross-sectional view showing the overall structure of an exhaust filter according to the present invention. A partition plate 2 is provided in a cylindrical casing 1, and the inside of the casing 1 is a first It is divided into a chamber 3 and a second chamber 4 at the rear. An exhaust inlet pipe 6 having a flange 5 for connecting the exhaust pipe extends into the first chamber 3 from the front end of the casing 1, and its tip is closed by the partition plate 2. A large number of communication holes 7 are formed in the exhaust inlet pipe 6 so as to communicate with the first chamber 3 . In addition, flange 8 for exhaust pipe connection
The exhaust outlet pipe 9 passes through the rear end wall of the casing 1 and opens into the second chamber 4 . The first chamber 3 and the second chamber 4 in the casing 1 communicate with each other through a large number of communication holes 10 provided on the outer periphery of the partition plate 2.

A filter element 11 for collecting exhaust particulates is housed in the first chamber 3 and is arranged in a cylindrical shape around the outer periphery of the exhaust inlet pipe 6. As shown in FIGS. 2 and 3, this filter element 11 consists of a series of filter members 11' formed in the shape of an elongated strip, and is multilayered by wrapping the filter members 11' around the exhaust inlet pipe 6 multiple times. ing.

The filter member 11' is mainly composed of a plurality of mesh metal plates 12 carrying a catalyst, and a metal plate having an appropriate thickness is attached to the side edge of the mesh metal plates 12. A frame 13 is provided. Specifically, as shown in FIG. 4, the mesh metal plates 12 have slightly different widths, specifically, the width of the mesh metal plates 12 is the narrowest at the center, and the width of the outer mesh is the narrowest. A plurality of sheets are combined so as to gradually become wider, and with their end positions aligned, they are clamped and fixed by a metal frame 13 having a substantially U-shaped cross section. Therefore, as shown in FIG. 3, based on the difference in width, the mesh metal plates 12 located on the outside tend to naturally protrude outward.
The integrated filter member 11' has an elastically expanded central portion.

As described above, the filter member 11' is wound around the outer circumference of the exhaust inlet pipe 6 a plurality of times so as to cover the communication hole 7, and is further wrapped around the outermost metal frame 13. A band-shaped metal plate 14 is wound and fixed by welding or the like.

In the exhaust filter configured as described above, the exhaust gas introduced into the exhaust inlet pipe 6 flows in the radial direction through the communication hole 7 and passes through the filter element 11. In other words,
The exhaust gas passes through a large number of mesh metal plates 12 one after another, and at that time, exhaust particulates are attached and collected.

[0017] In the above structure, the plurality of mesh metal plates 12 are spread out slightly without coming into close contact with each other as shown in FIG. function, and appropriate gaps are provided between each layer. Therefore, the substantial contact area with the exhaust gas increases, and the collection efficiency can be improved without causing a significant increase in ventilation resistance.

Since the cross-sectional shape as shown in FIG. 3 is maintained by the elastic force of the mesh metal plate 12, it will not be crushed by its own weight or the mesh density will be uneven. Therefore, exhaust particulates are collected relatively uniformly in each part, and local overheating during regeneration is prevented. In addition, since exhaust particulates are collected relatively uniformly in this way,
The contact efficiency with the catalyst is improved, and the regeneration ability and exhaust purification effect due to the catalytic action are improved.

Further, in the above structure, since the plurality of thin mesh metal plates 12 are integrated in advance with the metal frame 13, handling becomes easy, and the mesh metal plates 12 with low mechanical strength are integrated. can be firmly fixed to the outer periphery of the exhaust inlet pipe 6, resulting in excellent durability.

According to the above embodiment, the collection efficiency can be improved by appropriately changing the number of mesh metal plates 12 integrated with the metal frame 13 or the number of turns of the filter member 11' around the outer periphery of the exhaust inlet pipe 6. Another advantage is that characteristics such as the like can be easily adjusted according to specifications.

Next, FIGS. 5 to 7 show different embodiments of the present invention. In this example, as shown in FIG.
Each filter member 21 is formed into a disk shape, and a filter element 23 is constructed by stacking a plurality of filter members 21 and housing them in a cylindrical case 22.

The filter member 21 is made by stacking a plurality of mesh metal plates 24 carrying a catalyst and having their outer peripheral edges clamped and fixed by a metal frame 25. Each mesh metal plate 24 is , are combined so that their diameters are slightly different. In other words, the diameter gradually becomes larger as the outermost one is located. Therefore, when integrated by the metal frame 25, as shown in FIG. 7, the central portion elastically swells and each mesh metal plate 24 has a cross-sectional shape that is slightly spaced apart.

A plurality of the filter members 21 are stacked in a cylindrical case 22, and are finally firmly integrated by caulking the opening edge 22a of the cylindrical case 22.

[0024] Also in this embodiment, an appropriate space can be secured between the large number of mesh metal plates 24, and the mesh metal plates 24 are prevented from being crushed or unevenly distributed.

Furthermore, when caulking the opening edge 22a of the cylindrical case 22, the metal frame 25 of each filter member 21
Since force is applied to the parts, deformation during caulking is prevented, and the parts can be firmly integrated.

[0026] In each of the above embodiments, a mesh metal plate is used as the filter material, but instead of this, a metal fiber board made of metal fibers formed into a sheet may also be used.

[0027]

[Effects of the Invention] As is clear from the above explanation, in the exhaust filter for an internal combustion engine according to the present invention, a thin mesh metal plate or metal fiberboard with low mechanical strength is firmly fixed in the casing. This makes it possible to improve durability and stabilize performance. In addition, a small space can be secured between a large number of mesh metal plates, etc., and this is ensured by the elastic force of the mesh metal plates, etc., so a high collection efficiency can be obtained compared to the ventilation resistance. At the same time, collapse due to its own weight and uneven distribution of density are prevented, and relatively uniform collection can be performed at each part.

[Brief explanation of the drawing]

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

FIG. 2 is a plan view showing the filter member of this embodiment in an expanded state.

FIG. 3 is a sectional view of the filter member taken along line A-A in FIG. 2;

FIG. 4 is an explanatory diagram showing the state of the filter member before assembly.

FIG. 5 is a sectional view showing different embodiments of the exhaust filter according to the present invention.

FIG. 6 is a perspective view showing the filter member of this embodiment.

7 is a sectional view of the filter member taken along line BB in FIG. 6. FIG.

[Explanation of symbols]

1...Casing 6...Exhaust inlet pipe 11...filter element 11'...filter member 12...Mesh metal plate 13...Metal frame

Claims (1)

[Claims] Claim 1: A plurality of mesh metal plates or metal fiber plates carrying a catalyst are stacked together in combinations of slightly different sizes, and the edges are arranged so that the center part is elastically swollen. An exhaust filter for an internal combustion engine, characterized in that it is constructed by laminating a plurality of filter members that are sandwiched and fixed by a metal frame having a substantially U-shaped cross section and integrated by the metal frame.