JPH0893444A - Diesel particulate filter - Google Patents

Abstract

(57) [Summary] [Purpose] In a diesel particulate filter, it is resistant to vibration and shock, and has improved heat resistance. [Structure] This diesel particulate filter is composed of laminated fibrous materials 1, and the fibrous material 1 uses as its base material a Ti-Al alloy, an Fe alloy or Fe- containing at least one of Mo, Cr, and Ni. Cr-Al-Y
It is composed of a heat resistant alloy fiber material 2 selected from a group of alloys. The heat resistant alloy fiber material 2 is made of Si-C, Si-Ti-C-
It is covered with a coating layer 3 made of O, Si—C—O silicon carbide ceramics, alumina ceramics, or zirconia ceramics.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a diesel particulate filter incorporated in an exhaust system for purifying exhaust gas discharged from a diesel engine.

[0002]

_2. Description of the Related Art Conventionally, as a material for an exhaust gas treatment filter for collecting particulates such as carbon, soot, HC, etc. from exhaust gas of a diesel engine, for example, cordierite (2MgO.2Al ₂ O
Diesel particulate filter, which is manufactured by ₃ · 5SiO ₂₎ is known. In addition to the cordierite, a filter material using an inorganic fiber is known. The one in which the filter body of the diesel particulate filter is made of inorganic fiber has advantages that the filter itself can be configured to be lightweight, the collection area can be configured to be small, and the entire diesel particulate filter device can be downsized. There is.

[0003]

However, when the filter body is made of inorganic fibers as in the conventional diesel particulate filter, it has the advantages as described above. There is a problem that the inorganic fiber material itself is fragile, is weak against vibration and impact, may be damaged, and is expensive.

By the way, the present applicant has developed a diesel particulate filter made of inorganic long fibers,
I previously filed as Japanese Patent Application No. 6-114131. The diesel particulate filter is a felt-like body obtained by stacking heat-resistant inorganic long fibers cut in a predetermined length in an irregular manner in a horizontal direction and stabbing them to vertically entangle the inorganic long fibers. A wire mesh made of heat-resistant metal is superposed on both upper and lower sides of the above, and both sides are caught by heat-resistant threads. Further, the inorganic long fibers are Si-Ti.
On the surface of the fiber selected from —C—O, Si—C—O, Si—N, SiO, and metal, silicon carbide, aluminum,
At least one kind of alumina is coated.

An object of the present invention is to solve the above problems, and particles of carbon, soot, HC, etc. contained in the exhaust gas incorporated in the exhaust system for purifying the exhaust gas exhausted from the diesel engine. In a diesel particulate filter that collects particulate matter, that is, particulates, in order to improve the drawbacks of inorganic fibers, the filter body is produced by entwining metal fibers made of a heat-resistant alloy by entwining them vertically and horizontally, It is an object of the present invention to provide a diesel particulate filter which has high strength against vibrations and impacts and is low in cost by coating the surface with ceramics having heat resistance and corrosion resistance.

[0006]

In order to achieve the above object, the present invention is configured as follows. That is,
The present invention is a diesel particulate filter that is arranged in an exhaust system of a diesel engine to collect particulates contained in exhaust gas, and heat and incinerate the collected particulates, in which a filter body is laminated with a fiber material. And a fiber material of Ti--Al alloy,
The present invention relates to a diesel particulate filter comprising a heat-resistant alloy fiber material selected from an Fe alloy containing at least one of Mo, Cr, and Ni or an Fe-Cr-Al-Y-based alloy.

In this diesel particulate filter, the heat-resistant alloy fiber material is covered with a coating layer made of ceramics. Further, the ceramics forming the coating layer are Si-C, Si-Ti-C-O,
It is selected from Si—C—O silicon carbide ceramics, alumina or zirconia. Furthermore, the thickness of the coating layer is set to 20% or less of the metal base material of the heat resistant alloy fiber material.

In this diesel particulate filter, there is a reaction layer between the heat resistant alloy of the heat resistant alloy fiber material and the ceramics of the coating layer. The heat-resistant alloy of the heat-resistant alloy fiber material and the ceramics of the coating layer are selected so that the coefficient of linear expansion is within 1.5 times. Alternatively, when the coefficient of linear expansion between the heat-resistant alloy of the heat-resistant alloy fiber material and the ceramic of the coating layer is 1.5 times or more, an intermediate material having a gradient function of the coefficient of linear expansion is used as the heat-resistant alloy fiber material. It is adjusted so that the linear expansion coefficient at the boundary becomes 1.5 times or less by interposing between the above and the coating layer.

[0009]

The diesel particulate filter according to the present invention is constructed as described above and has the following actions. That is, this diesel particulate filter is composed of a laminated fiber material of the filter body,
The fiber material is a Ti-Al alloy, an Fe alloy containing at least one of Mo, Cr, and Ni, or Fe-Cr-Al-Y.
Since it is composed of a heat-resistant alloy selected from alloys, the base material of the filter body is made of metal, not ceramics,
A low cost filter that is strong against vibration and shock can be manufactured. Further, since the filter body is made of heat-resistant alloy fiber, the heat resistance strength can be improved, and when exhaust gas is passed through the filter body, particulate matter such as black smoke, carbon and smoke contained in the exhaust gas. The pressure loss can be suppressed to a low level in spite of the high collection efficiency of.

Further, in this diesel particulate filter, the surface of the heat-resistant alloy fiber material is made of Si-C, Si-
Since it is coated with Ti-C-O, Si-C-O silicon carbide ceramics, alumina or zirconia, it is possible to produce the filter body which is heat resistant and highly corrosion resistant. In particular, since the thickness of the ceramics covering the heat-resistant alloy fiber material is set to 20% or less of the metal base material of the heat-resistant alloy fiber material, the amount of the coating layer, that is, the amount of ceramics falling off after the thermal cycle is reduced. It is possible to manufacture the filter body having a long life and excellent durability.

[0011]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Embodiments of the diesel particulate filter according to the present invention will be described below with reference to the drawings.
FIG. 1 is a graph showing the amount of dropout after a heat cycle with respect to the thickness of a coating layer of ceramics coated on a heat-resistant alloy fiber material constituting a filter body of a diesel particulate filter according to the present invention, and FIG. 2 is a diesel particulate according to the present invention. FIG. 4 is a perspective sectional view showing a wire made of a heat-resistant alloy fiber material that constitutes a filter body of the filter.

This diesel particulate filter collects particulates such as black smoke, carbon, soot and HC contained in exhaust gas discharged from a diesel engine with a filter body, and the collected particulates are heated. The filter body is regenerated by incineration.
In this embodiment, the regeneration of the filter body is carried out in the same manner as the conventional one, so that it will not be described here. This diesel particulate filter is, for example, configured to be housed in a case in the exhaust passage, and when exhaust gas passes through the filter body, particulates such as carbon, smoke, and black smoke in the exhaust gas Are adhered and deposited between the fibers of the filter body, and the particulates in the exhaust gas are collected.

In this diesel particulate filter, the filter body is composed of laminated filter fiber materials 1, and the filter fiber material 1 is a Ti-Al alloy, M
It is composed of a heat-resistant alloy selected from Fe alloys containing at least one of O, Cr, and Ni or Fe-Cr-Al-Y-based alloys. On the surface of the wire made of the heat-resistant alloy fiber material 2 which constitutes the filter fiber material 1, the ceramic coating layer 3 is formed.
Is coated with. Ceramics that coat the filter fiber material 1 are Si-C, Si-Ti-CO, and S.
i-C-O SiC (silicon carbide) ceramics, A
1 ₂ O ₃ (alumina) or ZrO ₂ (zirconia). In particular, the thickness of the ceramic coating the heat resistant alloy fiber material 2 is set to 20% or less of the metal base material of the heat resistant alloy fiber material 2. In addition, a reaction layer exists between the wire of the heat resistant alloy fiber material 2 and the ceramic coating layer 3 coated with the heat resistant alloy. As the reaction layer, for example, when the wire of the heat-resistant alloy fiber material 2 is made of a Ti-Al alloy and alumina is selected as the coating layer 3,
A large amount of the l component is deposited on the surface of the wire, the component forms an alumina reaction layer at the boundary, and the coating layer 3 is firmly bonded to the wire. Further, the heat-resistant alloy of the heat-resistant alloy fiber material 2 and the ceramics of the coating layer 3 are selected such that the linear expansion coefficient is within 1.5 times, so that a peeling phenomenon occurs between the two even when subjected to repeated thermal stress. This is preferable.

This diesel particulate filter can be manufactured as follows. A having a thickness of 2 μm is formed on the outer peripheral portion of the heat-resistant alloy fiber material 2 made of a Ti—Al-based alloy having a fiber diameter of 6 μm that constitutes the filter fiber material 1.
A coating layer 3 made of l ₂ O ₃ was formed by using the alkoxide method 1
It is formed by firing at 000 ° C. At this time, the coefficient of linear expansion of the Ti-Al-based alloy that is the heat-resistant alloy fiber material 2 is 8.8 x 1
0 ^{- 6} / a ° C., the linear expansion coefficient of Al ₂ O ₃ is a coating layer 3 is 7.7 × 10 ^- is a ⁶ / ° C.. As described above, the coating layer 3 coated on the heat resistant alloy fiber material 2 does not peel off at the operating temperature of the diesel particulate filter, and maintains a state of being stably bonded to the base material of the heat resistant alloy fiber material 2. it can. The reason for this is that in the heat treatment for firing the ceramic film, a large amount of Al component of the Ti-Al alloy is deposited on the surface, and both the Al component and the Al component of the sol-gel are formed at the boundary as an alumina reaction layer. That is,
A film of a strong reaction layer is formed at the boundary between the Ti—Al-based alloy that is the heat-resistant alloy fiber material 2 and the alumina of the coating layer 3, and the coating layer 3 does not peel off from the heat-resistant alloy fiber material 2. .

Further, in order to check the proper thickness of the coating layer 3 on the heat-resistant alloy fiber material 2, the heat-resistant alloy fiber material 2 having a diameter of 6 μm is used.
The coating layer 3, which is an alumina layer having a thickness of 10, 15, 20, 25, 30%, is formed on the wire rod of No.
The heat cycle test of raising the temperature to ℃ and lowering it to 100 ℃ was repeated 100 times, and the coating layer 3 after the heat cycle was performed.
The amount of falling off of the ceramics film was measured. The results are shown in FIG. 1 as a percentage of the amount of ceramics dropped off. As can be seen from FIG. 1, when the thickness of the ceramic film of the coating layer 3 exceeds 20% of the base material of the heat resistant alloy fiber material 2, the falling amount of the coating layer 3 rapidly increases, and the heat resistance of the filter fiber material 1 increases. It was found to be unfavorable from the viewpoint of improving strength.

Further, in this diesel particulate filter, a filter fiber material containing only the heat resistant alloy fiber material 2 forming the filter body and a heat resistant alloy fiber material 2 are used.
The heat resistance strength of the filter fiber material 1 obtained by applying the ceramic coating layer 3 to the surface of the wire was measured.
The heat resistance strength of both is measured at 800 ° C for both.
The tensile strength MPa was measured. The tensile strength of the filter fiber material 1 in which the ceramic coating layer 3 was applied to the heat-resistant alloy fiber material 2 was 500 MPa, whereas the tensile strength of the filter fiber material of only the heat-resistant alloy fiber material 2 was 30 MPa.
It was 0 MPa. As a result, regarding the filter fiber material, the ceramic coating layer 3 is formed on the surface of the heat resistant alloy fiber material 2.
It has been found that the heat treatment improves the heat resistance.

Regarding this diesel particulate filter, in the above-mentioned embodiment, Ti-A was used as the metal fiber material.
The heat-resistant alloy fiber material 2 was produced using an l-based alloy, but an alloy containing at least one of Mo, Cr, and Ni in Fe, or an Fe-Cr-Al-Y-based alloy was used as the metal fiber material. Even when the heat-resistant alloy fiber material was produced, similarly good measurement results could be obtained. Further, as the ceramic of the coating layer 3 for coating the heat-resistant alloy fiber material 2, alumina Al ₂ O ₃ was used in the above-mentioned embodiment to fabricate the filter fiber material 1, but Si—C, Si—Ti—C—O, Si
It has been found that it is also possible to use —C—O silicon carbide ceramics, zirconia ceramics, or the like. In this way, various materials can be selected for the heat-resistant alloy fiber material 2 and the ceramic coating layer 3, but when the linear expansion coefficients are significantly different between them, the difference in linear expansion coefficient in the boundary layer is 1.5. An intermediate layer made of an intermediate material having a gradient function of the linear expansion coefficient is provided between the heat-resistant alloy fiber material 2 and the ceramic coating layer 3 so that the linear expansion coefficient is 1.5 times in the boundary layer. It can be adjusted to:

[0018]

The diesel particulate filter according to the present invention is constructed as described above and has the following effects. That is, in this diesel particulate filter, the filter body is made of Ti-Al alloy, M
Since it is made of a heat-resistant alloy fiber material selected from an Fe alloy containing at least one of o, Cr, and Ni or an Fe-Cr-Al-Y-based alloy, it is not fragile like a conventional ceramic fiber material, and has shock and vibration. In contrast, a high-strength filter body can be manufactured, and a low-cost filter body can be manufactured. In addition, Si-C, Si-
When coating a coating layer of Ti-C-O, Si-C-O silicon carbide ceramics, alumina, or zirconia, heat resistance and corrosion resistance are improved, and heat resistance strength of the filter body is further improved. It is possible to provide a durable and stable long-life diesel particulate filter.

[Brief description of drawings]

FIG. 1 is a graph showing the amount of dropout after a heat cycle with respect to the thickness of a coating layer of ceramics coated on a heat-resistant alloy fiber material that constitutes a filter body in a diesel particulate filter according to the present invention.

FIG. 2 is a perspective sectional view showing a wire made of a heat-resistant alloy fiber material that constitutes a filter body in the diesel particulate filter according to the present invention.

[Explanation of symbols]

 1 Filter fiber material 2 Heat resistant alloy fiber material 3 Coating layer

Claims (7)

[Claims] 1. A diesel particulate filter disposed in an exhaust system of a diesel engine for collecting particulates contained in exhaust gas and heating and incinerating the collected particulates, wherein a filter body is laminated with fibers. Fe containing at least one of Ti—Al alloy, Mo, Cr and Ni.
A diesel particulate filter comprising a heat-resistant alloy fiber material selected from an alloy or an Fe-Cr-Al-Y-based alloy. 2. The heat-resistant alloy fiber material is coated with a coating layer made of ceramics.
Diesel particulate filter described in. 3. The ceramic constituting the coating layer is S
The diesel particulate filter according to claim 2, wherein the diesel particulate filter is selected from iC, Si-Ti-C-O, and Si-C-O silicon carbide ceramics, alumina, or zirconia. 4. The diesel particulate filter according to claim 2, wherein the thickness of the coating layer is set to 20% or less of the metal base material of the heat resistant alloy fiber material. 5. The diesel particulate according to claim 3, wherein a reaction layer exists between the heat-resistant alloy of the heat-resistant alloy fiber material and the ceramic of the coating layer. filter. 6. The heat-resistant alloy of the heat-resistant alloy fiber material and the ceramics of the coating layer are selected so that the linear expansion coefficient is within 1.5 times.
The diesel particulate filter according to any one of 1. 7. When the linear expansion coefficient between the heat-resistant alloy of the heat-resistant alloy fiber material and the ceramics of the coating layer is 1.5 times or more, the intermediate material having the gradient function of the linear expansion coefficient is used as the heat-resistant material. 6. The interposition between the alloy fiber material and the coating layer is adjusted so that the coefficient of linear expansion at the boundary is within 1.5 times. Diesel particulate filter.