JPH04279714A - Exhaust filter for internal combustion engine - Google Patents

Abstract

PURPOSE:To facilitate blowoff of ash contents, prevent damages due to thermal strain in the regeneration and downsize a filter. CONSTITUTION:A filter element 4 is formed by laminating a flat first metal plate 6 and a corrugated second metal plate 7, and rolled in a cylindrical shape. A number of tiny passages are formed by means of both metal plates 6,7, and these tiny passages are inclined relative to the center axial line of an element 4 which corresponds to the exhaust gas flow direction. The direction of the inclination is opposite to each other in the respective parts divided into four.

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. has been done.

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] In place of the above-mentioned filtration and collection type exhaust filters, some adhesion collection type exhaust filters have also been proposed. A typical example is a filter element made of a three-dimensional porous ceramic material, so-called ceramic foam, as seen in Japanese Patent Application Laid-Open No. 62-45309. When the exhaust gas flows through the flow path, exhaust particulates adhere to the wall surface of the flow path and are collected.

[0005]

[Problem to be Solved by the Invention] The former type of filtration collection is known to have the advantage of obtaining extremely high collection efficiency, but on the other hand, it is difficult to remove the Ash component (which cannot be removed by incineration).
Oxides of oil additives, etc.) may be collected, and even if regeneration by burner or exhaust heat is performed normally, it may eventually become clogged and cause an increase in exhaust pressure. .

[0006] Furthermore, in the latter type of adhesion collection, the collection efficiency is generally low and, moreover, it is necessary to secure a large surface area of the filter material that comes into contact with the exhaust gas, so that the filter tends to be large. Although clogging due to Ash components is less likely to occur, there is a drawback that when the engine is suddenly accelerated, the accumulated exhaust particulates are rapidly blown off to the outside and discharged as black smoke.

[0007] In any case, structures using ceramics also have the disadvantage that they tend to crack due to thermal strain when regeneration is performed with uneven deposition of exhaust particles, resulting in poor durability. be.

[0008]

[Means for Solving the Problems] Therefore, the present invention uses a net-like metal plate to collect the adhesion, and moreover, allows the exhaust flow to obliquely impinge on a fine channel partitioned by the net-like metal plate. This is intended to improve collection efficiency and prevent blow-off. That is, the exhaust filter for an internal combustion engine according to the present invention includes a casing and a cylindrical filter element housed within the casing, and the filter element includes a first metal plate that is flat and a first metal plate that is bent in the shape of a corrugated plate. 2 metal plates are overlapped and wound into a cylindrical shape, at least the second metal plate is formed into a net shape through which exhaust gas can flow, and a central axis of the cylindrical shape is in the exhaust inflow direction. In contrast, it is characterized in that the microchannel defined by both metal plates is formed at an angle.

[0009]

[Operation] In the above structure, since the exhaust gas flows in along the central axis of the cylindrical filter element, it impinges obliquely on each microchannel. Therefore, a part of the exhaust gas flows along the inflow direction while passing through the mesh metal plate. Further, a part of the exhaust gas is redirected and flows along the microchannel.

[0010] Therefore, the flow of the exhaust air as a whole is disturbed, and exhaust particulates are adhered and collected in wide contact with each metal plate. Since the flow of exhaust gas becomes complicated, exhaust particulates blown off on the upstream side of the filter element are likely to be recaptured on the downstream side, and their discharge to the outside is suppressed.

[0011]

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

FIG. 2 is a sectional view showing the overall structure of the exhaust filter according to the present invention, in which a conical inlet portion 1a is provided at one end of a cylindrical casing 1, and an exhaust inlet pipe 2 is provided with a conical inlet portion 1a. It is connected. Further, a conical outlet portion 1b is provided at the other end, and an exhaust outlet pipe 3 is connected thereto. A cylindrical filter element 4 is housed inside the casing 1 with a cushioning material 5 interposed therebetween.

As shown in FIG. 1, the filter element 4 is made by overlapping two continuous thin metal plates in a band shape, that is, a first metal plate 6 and a second metal plate 7, and winding them into a cylindrical shape. It is constructed by turning. As shown in FIG. 3, the first metal plate 6 is a flat metal plate and has a width equal to the length of the filter element 4 in the axial direction. The second metal plate 7 is made of a reticulated metal plate with an appropriate mesh,
Moreover, this is formed into a continuous corrugated plate shape by pressing with a gear-shaped roller or the like. The ridgeline of this unevenness is inclined at a predetermined angle with respect to the axis of the cylindrical filter element 4. Further, in this embodiment, the second metal plate 7 is formed by dividing into four metal plates 7a to 7d so that the filter element 4 is divided into four in the axial direction, and the inclination direction of the unevenness is are sequentially reversed. That is, when the entire second metal plate 7 is unfolded, as shown in FIG. 4, unevenness is formed in a herringbone shape. In FIG. 4, solid lines A indicate mountain portions, and broken lines B indicate valley portions. Here, the net-like metal plate that becomes the second metal plate 7 is made by forming a large number of slits 9 alternately in a base material 7' made of a thin metal plate, and arranging the slits 9 orthogonally to each other, as shown in FIG. It is stretched in the direction of arrow C-C to form a diamond-shaped grid.

The second metal plate 7 divided into four parts as described above is overlapped with the first metal plate 6, which is wound into a cylindrical shape and fixed together by, for example, spot welding. Further, the catalyst is supported after being rolled into a cylindrical shape.

Note that the first metal plate 6 may be divided into four parts like the second metal plate 7, wound individually, and then arranged in series.

By winding the first metal plate 6 and the second metal plate 7 into a cylindrical shape as described above, both the concave portion and the convex portion of the corrugated second metal plate 7 are able to form the first metal plate. A microchannel 8 is defined between the channel 6 and the channel 6. The large number of microchannels 8 are formed to be inclined like helical gears with respect to the central axis of the cylindrical filter element 4. The direction of inclination is sequentially reversed for each of the second metal plates 7a to 7d divided into four parts.

Therefore, in the exhaust filter having the above structure, as shown in the explanatory diagram of FIG. 6, the exhaust gas flows into a large number of microchannels 8 from an oblique direction as indicated by arrow G. Therefore, a part of the exhaust gas, as shown by arrow G1,
It passes through the second metal plate 7 along the exhaust inflow direction and flows across each microchannel 8 . Further, a relatively large portion of the exhaust gas flows within the microchannel 8 along the microchannel 8, as shown by arrow G2. As a result, within the microchannel 8,
Both flows G1 and G2 collide, resulting in a very turbulent flow. Furthermore, since the flow G2 along the microchannel 8 flows into the next stage microchannel 8 having a different inclination direction from an oblique direction, the flow G2 that flows across the second metal plate 7 and the microchannel 8 also flow across the second metal plate 7. The flow is divided into a flow along the flow path 8 and a flow along the flow path 8. In this way, the flow inside the filter element 4 becomes very complicated, and the exhaust gas efficiently contacts the second metal plate 7 and the first metal plate 6.

Therefore, the exhaust particulates such as carbon, etc., pass through the mesh-like second metal plate 7 or the exhaust gas passes through the first and second metal plates 7.
When it comes into contact with the metal plates 6 and 7, it is deposited and collected. In particular, with the above configuration, the collection efficiency is increased due to the turbulence of the exhaust gas, and a small filter with high collection efficiency can be obtained. In addition, the first
Since the contact efficiency with the catalyst supported on the second metal plates 6 and 7 is also increased, the regeneration ability and exhaust purification effect due to the catalytic action are also excellent.

Furthermore, since the above-mentioned filter is of an adhering collection type using a net-like metal plate, excessive collection, which tends to occur in the case of a filtration collection type, is prevented. In particular, when the Ash component is collected, the Ash component remaining after the filter element 4 is regenerated is easily blown off by the exhaust flow.
No clogging caused by sh components occurs.

On the other hand, with the adhesion collection type, blow-off of the collected carbon to the outside tends to be a problem, but with the above configuration, the exhaust particulates such as carbon that have accumulated on the upstream side of the filter element 4 are removed. Even if it blows off when the engine suddenly accelerates, it is likely to be recaptured downstream due to turbulence in the exhaust flow inside the filter element 4. In other words, the exhaust particles are diffused widely throughout the filter element 4 in the form of slow internal blow-off, making it difficult for external blow-off to occur.

Furthermore, during regeneration using exhaust heat, etc., the amount of heat generated may vary locally due to unevenness in the amount of exhaust particulate matter deposited. However, if the filter element 4 is entirely made of metal as described above, thermal distortion may occur. There are no problems such as damage caused by.

[0022] By making the entire filter element 4 made of metal, there is an advantage that the heat capacity is reduced and regeneration using exhaust heat is quickly performed.

Next, FIGS. 7 to 9 show different embodiments of the present invention.

In the embodiment shown in FIG. 7, the first metal plate 6 is constructed in the same net shape as the second metal plate 7, and the flow across the microchannel 8 is increased, and the exhaust particulates in the first metal plate 6 are reduced. It is designed to improve adhesion collection.

In the embodiment shown in FIG. 8, the second metal plate 7 is formed into a net shape by forming a large number of small holes 10 in a thin metal plate. Further, in the embodiment shown in FIG. 9, both the first metal plate 6 and the second metal plate 7 have a net shape in which fine small holes 10 are opened.

[0026] In this way, a metal plate having a large number of small holes 10 has the advantage that its mechanical strength can be maintained relatively high.

[0027] In the above-mentioned embodiment, an example was explained in which a catalyst was supported on the first and second metal plates 6, 7, but this catalyst support is not necessarily essential.

[0028]

Effects of the Invention As is clear from the above explanation, according to the exhaust filter for an internal combustion engine according to the present invention, by using a mesh metal plate as a filter element, the Ash component remaining after regeneration can be easily blown off. Clogging is reliably prevented. By letting the exhaust flow in from an oblique direction into a microchannel that is partially defined by a mesh metal plate, it is possible to achieve a small size and high collection rate even though it is an adhesion collection method using a mesh metal plate. Efficiency can be obtained, and blow-off of exhaust particulates to the outside during acceleration can be suppressed.

[0029] Furthermore, since the entire element is made of metal,
Unlike ceramics, there is no risk of damage due to thermal distortion during playback.

[Brief explanation of the drawing]

FIG. 1 is a perspective view showing a filter element of an exhaust filter according to the present invention.

FIG. 2 is a sectional view showing the overall configuration of the exhaust filter.

FIG. 3 is an enlarged perspective view showing the main parts of the filter element.

FIG. 4 is a plan view showing the second metal plate in an expanded state.

FIG. 5 is an explanatory diagram showing an example of a method for manufacturing a second metal plate.

FIG. 6 is an explanatory diagram showing the flow of exhaust gas in a microchannel.

FIG. 7 is a perspective view of a main part of a filter element showing a different embodiment of the present invention.

FIG. 8 is a perspective view of a main part of a filter element showing another embodiment of the invention.

FIG. 9 is a perspective view of a main part of a filter element showing still another embodiment of the invention.

[Explanation of symbols]

1...Casing 4...Filter element 6...First metal plate 7...Second metal plate 8...Minute channel

Claims (1)

[Claims] Claim 1: Consisting of a casing and a cylindrical filter element housed within the casing, the filter element comprises a first flat metal plate and a second metal plate bent into a corrugated plate shape, which are stacked together, In addition, this is wound into a cylindrical shape, and at least the second metal plate is formed into a mesh shape through which exhaust gas can flow, and both metal plates are wound with respect to the central axis of the cylindrical shape which is the exhaust inflow direction. An exhaust filter for an internal combustion engine, characterized in that defined microchannels are formed at an angle.