JP2000130150A - Exhaust particulate filter of diesel engine - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain the exhaust particulate filter of a diesel engine durable for a long term use in which the collection rate of an exhaust particulates is high and the collection area is wide, while being small. SOLUTION: This filter A is constituted by bending the piled body in a bellow shape section, in which the dense felt 5 piled an inorganic fiber 62a irregularly and densely is piled together on the rearside of the rough felt 4 piled the inorganic fiber 62 irregularly and roughly and a cloth 6 is piled on the rearside of this dense felt 5 and a heat resistant wire netting 6 is piled on the frontside of the rough felt 4.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an exhaust particulate filter for a diesel engine using inorganic fiber felt.

[0002]

2. Description of the Related Art Conventionally, in order to reduce exhaust particulates (PM) mainly composed of black smoke discharged from a diesel internal combustion engine, for example, a filter of a porous honeycomb type cordierite or a fiber is made of a porous metal cylinder. Various filters have been devised and tested, including filters wound around the body, filters using porous metal, filters using fiber woven fabric, filters using metal wire mesh, and filters in which inorganic fibers are laminated in a felt shape. Have been.

However, each of the above-described filters has the following problems. For example, a filter of cordierite can collect exhaust particles having a large particle size, but cannot collect exhaust particles having a small particle size. A filter made of a woven fabric of inorganic fibers can collect exhaust fine particles, but it is difficult to increase the collection area, and it is difficult to reduce the size of the filter. In addition, a filter made of felt made of inorganic fiber can collect exhaust particulates widely, regardless of the particle size, compared to a filter made of cordierite. The disadvantage is that the rate is low.

[0004]

SUMMARY OF THE INVENTION In view of the above-mentioned problems, it is an object of the present invention to provide an exhaust particulate filter for a diesel engine which has a high exhaust particulate collection rate, is small in size, has a large collecting area, and can be used for a long time. Is to do.

[0005]

In order to solve the above-mentioned problems, a structure of the present invention is to provide a felt in which inorganic fibers are irregularly and densely laminated, behind a coarse felt in which inorganic fibers are irregularly and coarsely laminated. Pile, woven fabric behind the dense felt,
A laminated filter in which a heat-resistant wire mesh is stacked in front of the coarse felt is bent in a bellows shape in a circumferential direction to form a cylindrical filter.

[0006]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS In the present invention, as an exhaust particulate filter of a diesel engine, an irregularly laminated inorganic fiber felt is provided with a coarse felt in front (upstream) of an exhaust gas flow path and a dense felt in rear (downstream) denseness, respectively. In addition, a woven fabric of inorganic fibers or a woven fabric of metal fibers is arranged behind the dense felt, a wire mesh is arranged on at least one side of the filter, and the filter is folded in a bellows shape in a circumferential direction to form a cylindrical shape. By configuring the filter described above, a filter having a small size and a high collection rate of exhaust fine particles can be obtained.

[0007]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS As shown in FIG. 1, thin inorganic fibers 62a having a fiber diameter of 9 .mu.m are densely arranged behind coarse felt 4 in which thick inorganic fibers 62 having a fiber diameter of 14 .mu.m are coarsely and irregularly laminated. The dense felts 5 stacked irregularly are arranged. A woven fabric 6 knitted with inorganic fibers is disposed behind the dense and dense felts 4 and 5 to form a filter A. Heat-resistant wire meshes 61 and 63 having a wire diameter of 0.3 mm and a mesh of 15 are arranged on both sides of the obtained filter A, and are bent in a bellows shape in the circumferential direction to form a cylindrical filter A.

As shown in FIG. 2, the exhaust gas purifying apparatus 20 comprises a cylindrical case 54 and a cylindrical filter A which is folded in a bellows shape or a waveform in a circumferential direction. The central opening of 53 is connected to the inlet pipe 51.
On the other hand, the center opening of the end plate 55 is connected to the outlet pipe 58.
The filter A is not a simple cylindrical one, but a meandering filter A having a star-shaped or bellow-shaped cross section alternately inward and outward in diameter. Increase.

The filter A is formed into a corrugated shape by a jig in advance and then curved into a tubular shape. A plurality of portions at both ends and an intermediate portion in the axial direction are formed from, for example, ceramics as shown in FIG. It is sandwiched between the inner holding plate 37 and the outer holding plate 35 having an appropriate thickness. The inner holding plate 37 is engaged with a large number of projecting pieces 37b projecting radially outward from the annular portion 37a into grooves on the inner peripheral side of the filter A. The outer holding plate 35 has a large number of protruding pieces 35b projecting radially inward from the annular portion 35a.
To the groove on the outer peripheral side of the filter A. Preferably, the outer retaining plate 35 is divided in the circumferential direction and is captured by the metal band 34.

The left end of the filter A is closed by an end plate 60 having the same shape as the inner holding plate 37 having no center opening. On the other hand, the right end of the filter A is an annular end plate 6 similar to the outer holding plate 35.
4 are combined. The outer peripheral edge of the end plate 64 is fitted and fixed to the inner peripheral wall of the case 54. Both ends of the heat-resistant wire mesh 61 are electrodes 7
3,74 are combined.

Exhaust gas from the engine is supplied to a filter A from an inlet pipe 51. That is, while the exhaust gas passes through the coarse and dense felts 4 and 5 from the outer space 71 of the filter A to the radial inside,
Exhaust particulates contained in the exhaust are collected. The exhaust gas from which the exhaust fine particles have been removed flows out from the inner space 72 to the outlet pipe 58. When regenerating the filter A, the electrodes 73 and 74 at both ends of the heat-resistant wire mesh 61 are connected to a power source (not shown), and when the heat-resistant wire mesh 61 is energized, the exhaust fine particles are burned out.

FIG. 4 shows the relationship between the particle size of exhaust fine particles and the passage rate (collection rate) by the filter A. By applying heat to the heat-resistant wire net 61, the exhaust fine particles trapped in the filter A are burned off, and the filter A can be easily regenerated. Since the filter A according to the present invention performs the depth filtration, it is considered that the collection of the exhaust fine particles is appropriately performed. On the other hand, conventional porous cordierite is considered to trap only large-diameter exhaust fine particles due to surface filtration.

In the above-described embodiment, the woven fabric 6 is made of inorganic fibers, but a woven fabric of metal fibers may be used. In addition, although the heat-resistant wire nets 61 and 63 of 15 meshes are arranged on both sides of the filter A, it is also possible to omit to overlap the woven fabric 6. In addition, felt was used for coarse and dense felt 4,5.
Although two layers are used, if it is one layer or more, it can be constituted by controlling the fiber amount.

[0014]

As described above, according to the present invention, a felt in which inorganic fibers are irregularly and densely laminated is superimposed on a coarse felt in which inorganic fibers are irregularly and coarsely laminated, and a fabric is woven behind the dense felt. Cloth is laminated, a laminated body obtained by laminating a heat-resistant wire mesh in front of the coarse felt is bent in a bellows shape in the circumferential direction to form a cylindrical filter, and the exhaust fine particles discharged from the diesel internal combustion engine are reduced from small particles. Large particles can be collected, which is effective in reducing exhaust particulates.
In addition, a compact filter with a long collection time can be obtained by stacking coarse and dense felts and bending them into a bellows shape.
It can be mounted on a vehicle equipped with a diesel engine, which is industrially very advantageous.

[Brief description of the drawings]

FIG. 1 is a side sectional view showing a schematic configuration of an exhaust particulate filter of a diesel engine according to the present invention.

FIG. 2 is a side sectional view of an exhaust gas purifying apparatus using the exhaust particulate filter.

FIG. 3 is a front sectional view of the exhaust particulate filter.

FIG. 4 is a diagram showing a relationship between a particle size of exhaust fine particles and a collection rate by the filter.

[Explanation of symbols]

A: Filter 4: Coarse felt 5: Dense felt 6:
Woven fabric 20: Exhaust gas purification device 34: Metal band 35:
Outer holding plate 35a: annular portion 35b: protrusion 37: inner holding plate 37a: annular portion 37b: protrusion 51: inlet tube 53: end plate 54: case 55: end plate 58: outlet tube 60: end plate 61: heat resistant Wire mesh 62: Inorganic fiber 62a: Inorganic fiber 63: Heat resistant wire mesh 64: End plate 71: Outside space 72: Inner space 73: Electrode 74: Electrode

──────────────────────────────────────────────────続 き Continued on the front page (51) Int.Cl. ⁷ Identification symbol FI Theme coat ゛ (Reference) B01D 46/42 B01D 46/42 B 46/52 46/52 C

Claims (5)

[Claims] 1. A coarse felt in which inorganic fibers are irregularly and densely laminated is overlapped with a felt in which inorganic fibers are irregularly and densely laminated, and a woven fabric is overlapped behind the dense felt. An exhaust particulate filter for a diesel engine, wherein a cylindrical filter is formed by bending a laminated body in which a heat-resistant wire mesh is stacked forward in a bellows shape in a circumferential direction. 2. The coarse felt and the dense felt are made of alumina (Al ₂ O ₃ ) fiber, silicon nitride (Si ₃ N ₄ ) fiber, silicon carbide (Si
The exhaust particulate filter of a diesel engine according to claim 1, wherein the filter is at least one selected from the group consisting of C) fibers and mullite fibers. 3. The woven fabric is at least one inorganic material selected from alumina (Al ₂ O ₃ ) fibers, silicon nitride (Si ₃ N ₄ ) fibers, silicon carbide (SiC) fibers, and mullite fibers. Fiber or iron
The exhaust particulate filter of a diesel engine according to claim 1, comprising at least one heat-resistant metal fiber selected from (Fe), chromium (Cr), and aluminum (Al). 4. The exhaust particulate filter of a diesel engine according to claim 1, wherein a thick fiber is used for the coarse felt and a thin fiber is used for the dense felt. 5. The exhaust particulate filter of a diesel engine according to claim 1, wherein the heat resistant wire mesh is energized and heated, and the exhaust particulate collected on the inorganic fiber felt is incinerated to regenerate the inorganic fiber felt. .