JP2931175B2 - Exhaust gas purification device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an exhaust gas purifying apparatus for removing particulates contained in exhaust gas discharged from an internal combustion engine, and more particularly to an exhaust gas purifying apparatus mounted on a diesel vehicle. The present invention relates to a decanter removing device.

[0002]

2. Description of the Related Art As an apparatus for removing particulates contained in exhaust gas discharged from an internal combustion engine, for example, a diesel engine, a large number of gas passage holes (hereinafter, referred to as "gas passage holes") extending parallel to the gas flow direction are known. This is indicated by the reference numeral (10) in Fig. 12. The arrows in the drawings, including other drawings, indicate the gas flow direction), and one end of the hole in the gas flow direction alternates. (Fig. 1
Exhaust gas is supplied to a filter in which a honeycomb-shaped porous ceramic filter made of a ceramic sintered body having holes (the reference numeral 2 (12) is a sealing portion) is housed in a casing through a seal material. Is known in which the particulates in the exhaust gas are collected and separated from the exhaust gas at the wall of the gas passage hole adjacent to the porous ceramic filter.

[0003]

Generally, an internal combustion engine for a vehicle is operated with an irregular load pattern, so that the temperature of exhaust gas also changes irregularly. Normally, the exhaust gas temperature is the lowest during idling (around 80 ° C) and the highest when the engine is running at full speed (around 800 ° C). The temperature of the exhaust gas rapidly changes around 700 ° C. Therefore, the ceramic filter used under such conditions must be able to follow this temperature change (heat shock resistance).

Further, as the collection of particulates in the filter progresses, the filter layer of the filter becomes clogged and the pressure loss increases. As a result, the efficiency of the engine deteriorates. So-called regeneration, in which the collected particulates are burned and removed from the filter, is performed. Burning of the particulates is carried out by heating to 600 ° C. or higher, preferably 800 to 900 ° C. in consideration of shortening the regeneration time (performed with hot air or an electric heater). -The distribution of the collected amount of the particulates is not uniform, and there is also the unburned residue in the previous regeneration, so that the heat generated by the burning of the particulates becomes uneven, and as a result, The temperature at the site where the amount of collected and / or residual amount of the citrate is large rises abnormally and sometimes reaches 1200 ° C. or more. Therefore, the ceramic filter used under such conditions must be able to withstand the local temperature rise (having heat resistance), and of course, due to the uneven temperature distribution. Thermal distortion, which is a cause of crack generation, must be able to avoid the influence of thermal distortion. The non-uniformity of the temperature distribution is a phenomenon caused by the thermal conductivity and size of the ceramic filter itself.

Various devices have been proposed to satisfy the above requirements (typically, Japanese Utility Model Publication No. Sho 63-31690).
No., Japanese Utility Model Application No. 1-63715, Japanese Utility Model Application No. 3-27815
No. JP-A-60-65219, Japanese Utility Model Laid-Open No. 2-11812.
0).

[0006] In these devices, the "heat resistance" and "heat shock resistance" of the above requirements are cleared by appropriately selecting the type of ceramic used as a filter material, and the "thermal distortion" problem is solved. Is a ceramic filter structure that has been overcome, specifically, a single cylindrical or elliptic cylindrical ceramic filter having square cells in cross section. The filter part is divided into a plurality of filter parts (therefore, the sectional shape is 1 / n circle or 1 / n ellipse (n: the number of divisions). Japanese Utility Model Publication No. 63-31690, Japanese Utility Model Publication No. 3-27815, 60-65219) or (B) The filter part is concentrically divided along its axis (therefore, the shape of the filter part after the division is a rod at the center and a cylinder at the outer periphery).
No. 715), and a cushioning material or a heat insulating material is interposed between the divided surfaces of the adjacent filter parts (Japanese Utility Model Publication No. 63-31690,
Japanese Unexamined Utility Model Publication No. 3-27815 and Japanese Utility Model Laid-Open No. 1-63715) or a gap corresponding to the amount of "thermal distortion" is provided (Japanese Unexamined Patent Publication No. Sho 60-1985).
No. 65219) (a cushioning member such as a wire mesh is interposed between a cylindrical or elliptical cylindrical casing and a ceramic filter) and a cell having a square cross section (at the time of filing of the publication). A plurality of small-diameter cylindrical ceramic filters which are separated from each other by a heat insulating material in a cylindrical casing (estimated from the technical level)
118120), but still has the following problems.

[Structure-(A)] To manufacture a filter part having a 1 / n circular or 1 / n elliptical cross section in advance and assembling the part into an assembly, it is necessary to use a filter part. The shape of the part cannot be maintained due to shrinkage during firing and drying after molding (it becomes difficult to assemble into an aggregate), and the dimensions of the cell shape become irregular (when exhaust gas is introduced, The pressure drop varies, and the collection density of the particulates becomes non-uniform.) Therefore, it is necessary to first manufacture a cylindrical or elliptical columnar single ceramic filter and cut it precisely. The process becomes complicated.

In addition, a 1 / n-circle or 1 / n-elliptical structure having cells having a square cross section has a 45 ° direction with the expansion of the cells when a thermal load is applied. This is not preferable because a tensile force acts ("thermal distortion" occurs on the outer periphery of the structure due to the difference in expansion of the cells).
(B)] and [Structure-]).

A filter having a gap corresponding to the amount of "thermal distortion" between the divided surfaces of adjacent filter parts (Japanese Patent Application Laid-Open No. 60-65219) is one example of exhaust gas to be treated. This is undesirable because the part will pass through the ceramic filter without being processed.

[Structure-(B)] Publication (Junkai Hei 1-6)
No. 3715), a bar is provided as a buffer material and a heat insulating material for "thermal distortion" interposed between the divided surfaces of adjacent filter parts.
"Heat expansion agent" such as miculite and vermiculite, alumina,
A "heat-expandable ceramic material" comprising "alumina-silica fiber" such as silica and an "organic binder" is disclosed, but vermiculite and vermiculite generate a gas when heated and expand. However, since the coefficient of expansion varies, an uneven force is applied to the filter parts to cause cracks. Further, these materials are vitrified when heated at a low heat-resistant temperature and their strength is remarkably reduced. Therefore, when the material is repeatedly regenerated, the supporting force of the filter part is reduced and the sealing property against exhaust gas is impaired. . Also, in this structure, it is difficult to manufacture a cylinder having a large diameter.

[Structure] Filling efficiency of the filter part into the casing is low (as a result, the size of the device becomes large).

A publication (Japanese Utility Model Laid-Open No. 2-118120)
Discloses that a heat insulating material is filled between the filter parts (see FIGS. 1 (b) and 2 of the publication, which is denoted by reference numeral 6). Since there is no specific description of the heat insulating material, it is presumed that at least the problem described in [Structure --- (B)] was not recognized.

[0013]

SUMMARY OF THE INVENTION The present invention has been made to solve the above-mentioned problems, and has as its object to provide a durable exhaust gas purifying apparatus, in other words, "heat resistance", "Heat shock resistance" as well as "heat distortion"
It is an object of the present invention to provide a practical exhaust gas purifying apparatus which has solved the problem.

That is, the device of the present invention comprises a casing (2) communicating with the exhaust side of the internal combustion engine (E), and a porous ceramic ceramic having a honeycomb structure disposed in the casing.
An exhaust gas purifying apparatus (1) comprising a filter (3), wherein the filter comprises an aggregate of a plurality of prismatic filter parts (4) having an axis extending in parallel to the gas flow direction. Part support members (5) are provided at least in the vicinity of the front and rear end faces of the peripheral surface of each filter part, and alumina is provided at least in the vicinity of the front and rear end faces of the peripheral surface of the assembly of filter parts. An elastic support member (6) comprising a silica fiber and a gas-evolving component is attached to each.

Hereinafter, the present invention will be described in detail with reference to the drawings. As shown in FIG. 1, an exhaust gas purifying apparatus (1) of the present invention includes a cylindrical metal casing (2) and is connected to an exhaust pipe (Ea) of an internal combustion engine (E). Particulates in the exhaust gas are contained in the casing (2).
A porous ceramic filter (3) for trapping / removing the filter is disposed, between the outer periphery of the ceramic filter and the inner wall of the casing, in a region near both front and rear end surfaces of the peripheral surface of the ceramic filter. The elastic support (6) is provided for preventing short-path of particulates in exhaust gas and for holding and insulating the ceramic filter in the casing.

Further, a gas oil burner (7a) for regenerating the ceramic filter (3) may be disposed on the gas inflow side (may be arranged on the outflow side) of the ceramic filter (3) (the heat source is less restricted in terms of capacity). However, the heat source for reproduction is not limited to this, and for example, a ceramic heater, a microwave, or the like may be used).

Here, the ceramic filter (3) is
Filter parts (4) having a triangular, square, rectangular or regular hexagonal cross section may be used alone or in combination and assembled into a prismatic shape (see FIGS. 2 to 5; these are only examples. , The combination is not limited). By making the cross-sectional shape of the filter part (4) in this way, there is no longer a restriction on manufacturing which has been cited as a problem in the prior art (the cross-sectional shape is a 1 / n circle or 1 / n ellipse) By appropriately combining them, a filter suitable for the capacity of the internal combustion engine can be appropriately selected and an arbitrary casing shape can be obtained, so that restrictions on mounting of the exhaust gas purifying device are reduced (here, The cross-sectional shape of the cell is preferably the same as the cross-sectional shape of the filter part, because the tensile force acting on the outer periphery of the filter part due to the difference in expansion of the cell during heating acts isotropically. This is because "thermal distortion" as in the prior art can be prevented. The form of assembly is the ratio of the distance from the center of the assembly to the inner wall of the casing (OB / FIG. 2 to FIG. 5).
OA) is at least 0.5, preferably 1.0. This is because the influence of the temperature difference between the central portion and the outer peripheral portion is reduced.

Materials for the filter part (4) include:
From the viewpoint of “heat resistance”, the flexural strength at a load softening temperature of 1200 ° C. or more and 1200 ° C. (JIS
The three-point bending strength specified in R1601) is preferably 70% or more of that at room temperature. This is because a material of 70% or less is softened and deformed at the time of reproduction and cracks occur. Then, from the viewpoint of "heat shock resistance",
With less amount of deformation upon heating, that is preferred for 1.0 × 10 ^-6 about /℃~5.0×10 ^-6 / ℃ if indicated by the coefficient of thermal expansion (1.0 × 10 ^-6 / ℃ Among the following materials, those satisfying the load softening temperature index are hardly found. On the other hand, those having a temperature of 5.0 × 10 ⁻⁶ / ° C. or more are used in filter parts from the viewpoint of preventing “thermal distortion”. It is not practical because the size must be extremely small). Further, the thermal conductivity is 0.01 to 0.5 cal / cm · sec.
-Those in the range of ° C are preferred. 0.01 cal / c
If the temperature is less than m · sec · ° C., the temperature difference between the center and the periphery of the ceramic filter becomes too large during the regeneration of the ceramic filter. On the other hand, if it exceeds 0.5 cal / cm · sec · ° C., it is necessary for the regeneration. This is because the calorific value becomes too large and is not practically preferable. Materials satisfying these indices include mullite cordierite, silicon carbide, silicon nitride, aluminum nitride, forsterite, and steatite. The porosity of the filter part (4) is 30 to
The average pore diameter is 90%, more preferably 40 to 60% (because the pressure loss becomes too large when it is less than 30%, and the collection rate of particulates becomes worse when it is more than 90%). , 5 to 40 μm (because the pressure loss is too large if it is smaller than 5 μm, whereas the collection rate of particulates becomes worse if it is larger than 40 μm).

The number of cells is 50 to 300 cells / square inch. If the number of cells is less than 50 cells / square inch, the filtration area is reduced, so that the amount of collected particulates per unit time and unit volume is reduced. On the other hand, if it exceeds 300 cells / square inch, the opening area per cell becomes too small and the pressure loss rises), and the thickness of the cell wall (11) (distance between adjacent cell walls) is 0.2 to 0.6 mm (less than 0.2, the mechanical strength of the filter part becomes weaker, whereas, if it exceeds 0.6 mm, the filtration area becomes smaller, so that the particulates per unit time and unit volume are reduced. (The amount of collection is reduced).

The cell walls (11a) and (11b) are further provided with a particulate as in the invention (Japanese Patent Application No. 4-183912) previously filed by the same applicant as the present invention. An inorganic heat-resistant fiber layer serving as a filtration surface may be laminated (this treatment increases the filtration efficiency per unit volume of the filter). Here, the thickness of the heat-resistant fiber layer is set to 1/2 to 3 of the wall thickness (the thickness of the heat-resistant fiber layer is 1/3).
If it is less than 2, the collection rate of particulates in this layer will be small, and the load on the cell wall will increase, causing an early rise in pressure loss of the filter. The pressure loss at this time is undesirably increased.

Here, the average porosity of the heat-resistant fiber layer is expressed as a percentage.
Particle size distribution of the citrate (diesel exhaust, average particle size 0.1-0.2 μm) and collection rate (at least 95%)
%) And pressure loss (3500 mmAq or less) are taken into account, and are set to 25% to 75%.

In terms of satisfying the "heat shock resistance", in addition to consideration of the material, consideration of the device configuration, that is, exhaust gas or hot air for filter regeneration upstream of the ceramic filter (3). An auxiliary filter (8) may be provided to reduce the temperature change of the filter (see FIG. 6). Here, since the main purpose of the auxiliary filter is to reduce the heat load, the auxiliary filter is a full-flow type honeycomb-shaped ceramic filter (8a) (the cell is not subjected to a sealing treatment, that is, a particulate is not used. A type in which the exhaust gas passes through the cell with little collection, see FIG.
For this purpose, this filter does not need to be as thick as the filter for collecting particulates (the length in the gas flow direction), so the necessity of division is small. A single or foam-like or fibrous ceramic plate (8b) (see FIG. 9) is obtained by adding an acrylic binder and aluminum sulfate to alumina-silica fiber and dispersing the same in water to a predetermined thickness. Is dried in the same manner as in papermaking, and a large number of small-diameter through-holes are formed in the thickness direction (see FIG. 7 for an example of a combination). The cross-sectional shape and dimensions of the filter are, in principle, the same as and the same as those of the ceramic filter for collecting particulates. It is not necessary to those of the structure to prevent passing through the section, may follow the method) is used. The heat capacity of the auxiliary filter is equal to that of the entire filter (ceramic filter for collecting particulates).
The heat capacity of the auxiliary filter is set to 30% or less (if it is 30% or more, the amount of heat required for heating the auxiliary filter becomes excessively large, leading to deterioration of fuel efficiency and early consumption of the battery). Align the shafts (equalize the relaxing action) and further from the front end face 15
It is set within 0 mm (if it exceeds 150 mm, the above-mentioned relaxation effect is lost).

Further, a part supporting member (5) is attached to at least a region near both front and rear end surfaces of the peripheral surface of each filter part (see FIGS. 10 and 11). As a matter of course, the heat resistance temperature of the part supporting material is required to be 1200 ° C. or more. Specifically, alumina fiber, silica fiber, alumina-silica fiber, zirconia fiber, cordierite fiber, silicon carbide fiber, etc. can be used, but heat resistance, cost, availability (production) In consideration of the amount, alumina fibers or alumina-silica fibers are preferred. More preferably,
A mixture of the preferred fiber with a small amount of silicon carbide powder or tungsten carbide powder, or a mixture of the preferred fiber with a steel fiber, a stainless steel fiber, a silicon carbide fiber, a carbon fiber, or the like. (The same reason as for the filter part, that is, the thermal conductivity is set to 0.01 to that of the filter part.
0.5 cal / cm · sec · ° C.-). In addition, the density is 0.1 to 0.8 g as the adhered specification.
/ Cm ³ (less than 0.1 g / cm ³ , the strength is small due to the presence of many voids between the fibers, and as a result, the sealing property against the exhaust gas becomes insufficient, and 0.8 g / cm 3
^If it exceeds ³ , the elasticity will be impaired and the buffering capacity for "thermal distortion" will be insufficient.) If the thickness is less than 1 mm, adjacent filter parts will contact and interfere with each other, causing cracks. If it exceeds 5mm, the unit ceramic
The filtration area per filter volume is reduced, resulting in a larger device).

Also, alumina-silica-coated silica particles are provided at least in the vicinity of the front and rear end faces of the peripheral surface of the filter part assembly.
An elastic support member (6) composed of a fiber and a gas generating component is applied (see FIGS. 10 and 11. In the drawing, the elastic support material (6) is applied only in the vicinity of the front and rear end faces, but also in consideration of the capacity of the heat source for regeneration. Therefore, when a higher heat insulating effect is desired, the film may be applied to the entire peripheral surface.) As the elastic support material, a material comprising the above-mentioned alumina-silica fiber and a gas generating component such as vermiculite containing ammonia can be used. Even if a material containing a gas generating component is used between the casing and the outer periphery of the assembly of the filter parts as in the present application, the temperature near the inner wall of the casing is low. As a result, the vitrification due to heat and the remarkable decrease in strength as in the prior art do not cause the problem that the support capacity of the filter part is reduced and the sealing property against exhaust gas is lost. Conversely, the expansion of the elastic support due to moderate foaming is combined with the elasticity exhibited by the alumina-silica fiber adhered to the peripheral surface of the filter part, whereby the aggregate of the filter part is assembled. Is strongly supported by the case. After the elastic support material is compressed so that its thickness becomes 60 to 80% of the thickness of the adhered part, the assembly of the filter parts on which the elastic support material is adhered is stored in a casing. Is preferred. This is because the elasticity of the elastic support material is maintained for a long period of time. In the compression operation, after the elastic support material is applied, a thin plastic film having heat shrinkability, for example, polyethylene, polyvinyl chloride, polyvinylidene chloride, or the like is applied thereon, and then heat-shrinks. (By this compression operation, it is also possible to store the aggregate of the filter parts in the casing without causing any deviation of the filter parts).

Here, the thickness of the elastic support member (6) is 1/40 to 1/40 of the distance from the center to the outer periphery of the assembly of filter parts (in this case, OA in FIGS. 2 to 5). Set to 1/7 (If the thickness of the elastic support material is smaller than 1/40,
When the heat insulation loss is small and the heat loss in the regeneration of the filter is large, on the other hand, when it is larger than 1/7, the heat capacity of the elastic support material becomes large and not only takes time to heat the entire filter, but also the filter becomes long. Is unfavorable because the outer shape becomes larger).

These filters are made as follows. For the filter part, a molded article having a desired shape is first produced by extrusion molding from the various materials described above. Thereafter, the above-mentioned molded body is dried after sealing the cells alternately, and then under an inert gas atmosphere at about 2200 ° C. (for silicon carbide) or under an oxidizing atmosphere at about 1200 ° C. (for mullite and cordierite). (A sintered body is obtained).

Next, the part supporting material (5) is applied. The plain or mixed water slurry (slurry concentration: 1 wt%) of various fibers described above is made of polyacrylonitrile or latex. To a suspension containing an organic binder (about 2 wt% with respect to the fiber) and an adhesive such as alumina sol (about 4 wt% with respect to the fiber). )
Is added to agglomerate the fiber, and the sintered body (a part other than the part to be adhered is wrapped in advance) is immersed in a suspension of the aggregated body. Suction and dehydration from the end surface of the sintered body at a pressure of about 300 mmHg (since the sintered body is a porous body having continuous pores, the suspension is sucked through a part of the sintered body that is not wrapped, so At this time, the aggregates are laminated on a portion of the sintered body that is not wrapped.If the suspension is not aggregated, the fibers enter the cell wall and the function of the filter is reduced. By not wrapping the opening of the cell that is not sealed, the inorganic heat-resistant fiber layer on the cell wall surface is also laminated at the same time. ° C
To dry the sintered body.

Next, the above-mentioned filter parts are assembled into a predetermined shape to form an aggregate, and an elastic support manufactured by the same method as the part support member (5) is formed on the peripheral surface of the aggregate. The material (6) is applied, and its peripheral surface is finally covered with a heat-shrinkable thin plastic film, and heat is applied to compress the elastic support.

[0029]

Next, the operation of the apparatus of the present invention will be described based on the apparatus of the present invention illustrated in FIG.

As indicated by the arrow in FIG. 1, the internal combustion engine (E)
When the exhaust gas is introduced into the filter (3), the gas flows into the cell whose gas inflow side is not sealed, and the heat-resistant fiber layer (in the case where this layer is laminated), the inter-wall portion of the cell When the gas flows out to the adjacent cell where the gas outflow side is not sealed, the particulates in the gas are filtered and captured by the heat-resistant fiber layer and the interwall of the cell, and the purified exhaust gas is exhausted. Gas is exhausted from the filter (3).
The trapping of particulates in the heat-resistant fiber layer (when the layer is subjected to a laminating treatment) is performed on the entire layer (all-layer filtration).

When the capture of the particulates progresses and the pressure loss in the filter (3) reaches a predetermined value, the filter is subjected to a regeneration process. The filter (3) is heated by a light oil burner (7a), and when the temperature of the filter near the heater reaches a predetermined temperature (300 to 800 ° C.), secondary air for promoting combustion is provided in the casing (2). Is started, the particulates trapped in the filter are burned and removed, and the regeneration is terminated when the temperature in the upstream part of the filter is rapidly lowered.

[0032]

Next, examples illustrating the present invention will be described.

(Example 1) A filter part of honeycomb structure (external dimensions: 30 mm square, length: 150 mm) made of a silicon carbide sintered body (detailed specifications are as follows) was manufactured. (1) Thickness of the wall between adjacent cells: 0.43 mm (2) Number of cells: 170 cells / square inch (3) Porosity: 50% (4) Average pore diameter: 14 μm (5) Softening temperature under load: 1400 ° C (6) Flexural strength ratio at 1200 ° C (to ordinary temperature): 90
% (7) Thermal expansion coefficient: 4.0 × 10 ⁻⁶ / ° C. (8) Thermal conductivity: 0.1 cal / cm · sec · ° C.

Further, a diameter: 1 to 3 μm and a length: 100 to 300 in the area near the front and rear end faces of the peripheral surface of the filter part.
A 00 μm alumina-silica fiber (composition: alumina: 45%, silica 55%) was applied (detailed specifications are given below). (1) Thickness: 1 mm (2) Density: 0.3 g / cm ³ (3) Heat resistant temperature: 1400 ° C. (4) Thermal conductivity: 0.08 cal / cm · sec · ° C.

A total of 49 (7 × 7) filter parts coated with the above alumina-silica fiber are assembled (cross-sectional shape of the aggregate: square), and the peripheral surface of the aggregate An elastic support consisting of 50 parts of alumina-silica fiber, 50 parts of heat-expandable obsidian, brassite, and an organic foam material was applied to the area near both front and rear end faces (detailed specifications are as follows). . (1) thickness: 5 mm (2) density: 0.6 g / cm ³ (3) coefficient of thermal expansion: 150% (600 ° C.)

The ceramic filter thus obtained has a capacity corresponding to an engine displacement of 12 liters.

As a regeneration heating source, 10,000 Kc
An al / hr gas oil burner was used.

As shown in FIG. 1, the exhaust gas purifying apparatus (1) having the above specifications was connected to a diesel engine (E), the engine was operated, and exhaust gas was introduced into a filter (3). During the introduction of the exhaust gas, the pressure in the exhaust pipe (Ea) was monitored by the monitoring and control device (C) via the pressure sensor (Ps) and the piezoelectric conversion element (Pe). The engine load is in the idling mode (engine speed: 700).
rpm) and accelerator full-open mode (engine speed: 2)
200 rpm) at intervals of 5 seconds.

20 g of particulates in exhaust gas
/ M ^{2 is} collected, the burner (7a) is started by the monitoring and control device (C), and when the temperature (T ₁ ) at the position (P ₁ ) reaches about 750 ° C. (C
o), secondary air is supplied from the air supply pipe (Ca) to the filter (3) at a rate of 50 l / min, and the temperature (T ₂ ) of the gas inlet side end (P ₂ ) of the filter (3) is increased. ₂ )
The fuel supply to the burner (7a) was stopped at the time when the temperature suddenly dropped, and the regeneration was terminated.

This series of operations was repeated 100 times.
The ceramic filter was not damaged by the thermal shock.

(Embodiment 2) A system in which an auxiliary filter is added to the exhaust gas purifying apparatus of Embodiment 1 is constructed.
The exhaust gas purification operation and the ceramic filter regeneration operation were performed in the same pattern as described above. The auxiliary filter (8) is a fibrous ceramic plate (the physical properties of the fiber used are the same as those of the part supporting material.
2 g / cm ³ . Hole diameter of through hole: 10 mm. Board thickness: 1
0 mm) for a full-flow honeycomb ceramic filter (having the same specifications as a filter for collecting particulates except that the number of cells is 100 cells / square inch and the thickness is 15 mm). (Shape and size of cross section: same shape and same size as filter for collecting particulates. Installation position:
10 mm from the front end of the filter for collecting citrate
Separated positions).

This series of operations was repeated 100 times.
The ceramic filter was not damaged by the thermal shock. The temperature difference between the center and the outer periphery of the ceramic filter was within 50 ° C.

(Comparative Example 1) A filter part having a cross-sectional shape of 1/6 circle was used (material specifications of the filter part were the same as those in Example 1. The size of the assembled ceramic filter was , A cylinder having a diameter of 240 mm and a length of 150 mm), a "heat expanding agent" such as vermiculite or vermiculite between the divided surfaces of the adjacent filter parts, and an "alumina" such as alumina or silica. A "heat-expandable ceramic material" consisting of "silica fiber" and "organic binder" is interposed, and a wire mesh is filled between the casing and the ceramic filter. Example 1
An exhaust gas purification operation and a regeneration operation of the ceramic filter were performed in the same manner as described above. The detailed specifications of the heat-expandable ceramic material are as follows. (1) thickness: 2 mm (2) density: 0.6 g / cm ³ (3) coefficient of thermal expansion: 150% (4) thermal conductivity: 0.007 cal / cm · sec · ° C.

In the first operation, cracks occurred in the center of the filter part. The temperature difference between the central part and the outer peripheral part was as large as 350 ° C.

[0045]

As described above, according to the apparatus of the present invention, the ceramic filter is not damaged by thermal shock even if the collection and regeneration of the particulates are repeated, so that the mobile type internal combustion engine can be used. The present invention is highly practical as an exhaust gas purifying apparatus for an engine, for example, a diesel vehicle.

[Brief description of the drawings]

FIG. 1 is a partial cross-sectional view illustrating one embodiment of the device of the present invention together with a system using the same.

FIG. 2 is a cross-sectional view schematically illustrating a mode of collecting filter parts of the ceramic filter of the present invention.

FIG. 3 is a cross-sectional view schematically illustrating another filter part assembly mode of the ceramic filter of the present invention.

FIG. 4 is a cross-sectional view schematically illustrating still another filter part of the ceramic filter of the present invention.

FIG. 5 is a cross-sectional view schematically exemplifying a mode of assembling filter parts of the ceramic filter of the present invention different from those described above.

FIG. 6 is a partial cross-sectional view illustrating one embodiment of the device of the present invention in which an auxiliary filter is disposed on the exhaust gas inflow side together with a system using the same.

FIG. 7 is an enlarged cross-sectional view illustrating one embodiment of an auxiliary filter.

8 is a sectional view of the auxiliary filter shown in FIG. 7 taken along the line CC.

9 is a cross-sectional view of the auxiliary filter shown in FIG. 7 taken along the line DD.

FIG. 10 is a circle mark of the filter part assembly shown in FIG. 2;
Enlarged sectional view (cut along the line AA in FIG. 1)

FIG. 11 is a circle map of the filter / part assembly shown in FIG. 2;
Enlarged sectional view (cut along the line BB in FIG. 1)

FIG. 12 is a cross-sectional view illustrating a cell structure of a ceramic filter.

[Explanation of symbols]

1 ... Exhaust gas purifier, 2 ... Casing, 3 ...
..... ceramic filter, 4 ... filter par
, 5 ... part support material, 6 ... elastic support material 7a ...
·········································································································· 1
2 Sealing part

──────────────────────────────────────────────────続 き Continuation of front page (56) References JP-A-63-197511 (JP, A) JP-A-2-61313 (JP, A) JP-A-3-121213 (JP, A) JP-A-4- JP-A-6-146849 (JP, A) JP-A-1-63715 (JP, U) JP-A-6-47620 (JP, U) JP-A-63-31690 (JP, Y2) (58) Field surveyed (Int.Cl. ⁶ , DB name) F01N 3/02

Claims (1)

(57) [Claims] An exhaust gas purifying device (1) comprising: a casing (2) communicating with the exhaust side of an internal combustion engine (E); and a porous ceramic filter (3) having a honeycomb structure disposed in the casing. 5), the filter comprises an aggregate of a plurality of prismatic filter parts (4) having an axis extending in parallel with the gas flow direction.
Part support members (5) are provided at least in the vicinity of the front and rear end faces of the part, and alumina-silica fibers are provided at least in the vicinity of the front and rear end faces of the filter part assembly. An apparatus characterized in that elastic supports (6) made of a gas generating component are respectively applied.