JPH06241018A - Exhaust gas purifier - Google Patents

Abstract

PURPOSE:To prevent a ceramic filter from being damaged due to thermal shock by coating areas near both front and rear ends of the peripheral surface of an aggregate of filter parts with an elastic supporting material composed of alumina silica fiber and a gas generating component. CONSTITUTION:This exhaust gas purifier consists of a casing which communicates with the exhaust side of an internal combustion engine and a porous ceramic filter of honeycomb structure disposed in the easing. The filter consists of an aggregate of multiple prism-shaped filter parts 4 provided with axial lines which extended parallel in a flow direction of gas. The areas near at least both front and rear end faces of the peripheral face of respective filter parts 4 are coated with a parts supporting material 5. The areas near at least both the front and rear faces of the peripheral faces of the aggregate of the filter parts are coated with an elastic supporting material 6 composed of alumina silica fiber and a gas generating component. It is thus possible to prevent the ceramic filter from being damaged due to thermal shock.

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 a particulate exhaust gas mounted on a diesel vehicle. The present invention relates to a ticulate removing device.

[0002]

2. Description of the Related Art As a device for removing particulates contained in exhaust gas discharged from an internal combustion engine, such as 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 used. This is indicated by reference numeral (10) in Fig. 12. It should be noted that, including other drawings, arrows in the drawings indicate the gas flow direction), and one end of the hole in the gas flow direction alternates. Was sealed (Fig. 1
A honeycomb porous ceramic filter made of a ceramic sintered body having holes (reference numeral 2 (12) is a sealing portion) is housed in a casing through a seal material, and exhaust gas is introduced into the filter. Is introduced to collect the particulates in the exhaust gas at the wall surface of the gas passage hole adjacent to the porous ceramic filter and separate the particulates from the exhaust gas.

[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 when idling (around 80 ° C) and the highest when the engine is fully operating (around 800 ° C), so when exhaust braking is applied from a high-speed running state, The temperature of the exhaust gas suddenly changes around 700 ° C. Therefore, the ceramic filter used under such conditions must be able to follow this temperature change (heat shock resistance).

Further, when the collection of particulates in the filter progresses, the filtration layer of the filter becomes clogged and the pressure loss increases. As a result, the efficiency of the engine is deteriorated, so that the collection of the particulate at an appropriate time interval. So-called regeneration is carried out by burning the collecting particulates and removing them from the filter. The particulates are burned by heating to 600 ° C or higher, preferably 800 to 900 ° C in consideration of shortening the regeneration time (by 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 regeneration before that, so that the heat generation due to the burning of the particulates becomes uneven, and as a result, the particulates are generated. The temperature of the part where the collected amount and / or the remaining amount of the ticulate is large rises abnormally and sometimes reaches 1200 ° C or higher. Therefore, the ceramic filter used under such a condition must be able to withstand this local temperature rise (has heat resistance), and of course, it is due to the uneven temperature distribution. Thermal strain, which causes cracks, must be able to avoid the effect of. The nonuniform temperature distribution is a phenomenon caused by the thermal conductivity and size of the ceramic filter itself.

Various devices have been proposed in order to satisfy the above requirements (as a typical one, a Japanese Utility Model Sho 63-31690).
No., Actual Kaihei 1-363715, Actual Kaihei 3-27815
No. 60-65219, Japanese Utility Model Laid-Open No. 2-11812.
No. 0) has been done.

[0006] In these devices, "heat resistance" and "heat shock resistance" among the above requirements are cleared by appropriately selecting the kind of ceramic used as the filter material, and the "heat distortion" problem is solved. Is a ceramic filter structure that cannot be overcome, and more specifically, it is a cylindrical or elliptic cylinder-shaped single ceramic filter having square cells in cross section. Divided into individual filter parts (therefore, the cross-sectional shape is a 1 / n circle or a 1 / n ellipse (n: the number of divisions). JP-B-63-31690, JP-A-3-27815, JP (Sho 60-65219) or (B) Divided concentrically with its axis (thus, the shape of the filter part after the division is rod-shaped at the center and cylindrical on the outer peripheral side).
No. 715), and a cushioning material or a heat insulating material is interposed between the divided surfaces of the adjacent filter parts (Jitsuko Sho 63-31690,
A gap corresponding to the amount of "heat distortion" is provided (Japanese Patent Laid-Open No. 3-27815, No. 1-63715).
No. 65219) (a cushioning member such as a wire mesh is interposed between the cylindrical or elliptic cylindrical casing and the ceramic filter) and a cell having a square cross section (as of the filing date of the publication) Estimated from the technical level) A plurality of small-diameter cylindrical ceramic filters are placed in a cylindrical casing with a heat insulating material, which are separated from each other.
No. 118120), but still leaves the following problems.

[Structure-(A)] A filter part can be manufactured by previously manufacturing a filter part having a 1 / n circular or 1 / n elliptical cross section and assembling the part into an assembly. The shape of the part cannot be maintained due to shrinkage during baking and drying after molding (it becomes difficult to assemble it into an aggregate), and the cell size becomes uneven (when exhaust gas is introduced, Since the pressure loss varies and the collection density of particulates becomes non-uniform), it is necessary to first manufacture a single cylindrical or elliptic ceramic filter and cut it precisely. The process becomes complicated.

A 1 / n circular or 1 / n elliptical structure having a square cross-section cell has a cross-sectional shape of 45 ° due to expansion of the cell when a thermal load is applied. It is not preferable because tensile force acts (“thermal strain” appears on the outer periphery of the structure due to the difference in expansion of cells) (this problem is not limited to [Structure-(A)] and [Structure--
(B)] and [Structure-] are also problems that are being held).

Further, a filter provided with a gap corresponding to the amount of "thermal strain" between the divided surfaces of adjacent filter parts (Japanese Patent Laid-Open No. 60-65219) is one of the exhaust gases to be treated. It is not preferable because the part passes through the ceramic filter without being processed.

[Structure-(B)] Publications (Actual Kaihei 1-6
No. 3715), a bar as a "heat distortion" cushioning material and a heat insulating material interposed between the divided surfaces of adjacent filter parts.
A "heat expansion agent" such as miculite or vermiculite, and alumina,
A "heat-expandable ceramic material" composed of "alumina-silica fiber" such as silica and "organic binder" is disclosed, but vermiculite and vermiculite generate gas and expand when heated. However, since the expansion coefficient varies, an uneven force is applied to the filter part, which causes cracking. Further, since these materials have low heat resistance and become vitrified when heated, the strength thereof is remarkably lowered, and therefore, if the regeneration is repeated, the supporting force of the filter part is lowered and the sealing property against exhaust gas is deteriorated. . Moreover, in this structure, it is difficult to manufacture a cylindrical body having a large diameter.

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

The publication (Jitsukaihei 2-118120)
Discloses that a space between each filter part is filled with a heat insulating material (see FIGS. 1 (b) and 2 of the same publication; reference numeral 6 is that). Since there is no specific description of the heat insulating material, it is presumed that at least there was no recognition of the problem described in [Structure-(B)].

[0013]

SUMMARY OF THE INVENTION The present invention has been made as a solution to the above problems, and its purpose is to provide a durable exhaust gas purification device, in other words, "heat resistance", "Heat shock resistance" as well as "heat distortion"
An object of the present invention is to provide a practical exhaust gas purification device that solves the problem.

That is, the apparatus of the present invention comprises a casing (2) communicating with the exhaust side of the internal combustion engine (E), and a porous ceramic of honeycomb structure arranged in the casing.
In an exhaust gas purification device (1) comprising a filter (3), the filter comprises an assembly of a plurality of prismatic filter parts (4) having an axis extending parallel to the gas flow direction. A part supporting material (5) at least in the vicinity of both front and rear end surfaces of the peripheral surface of each filter part, and an alumina in at least both front and rear end surface areas of the peripheral surface of the filter part assembly. An elastic supporting material (6) composed of silica fiber and a gas generating component is respectively deposited.

The present invention will be described in detail below with reference to the drawings. As shown in FIG. 1, an exhaust gas purification device (1) of the present invention includes a tubular metal casing (2) and is connected to an exhaust pipe line (Ea) of an internal combustion engine (E). Particulates in the exhaust gas are contained in the casing (2).
A porous ceramic filter (3) for collecting and removing dust is disposed between the outer periphery of the ceramic filter and the inner wall of the casing, in the regions near the front and rear end surfaces of the peripheral surface of the ceramic filter. An elastic support material (6) is provided for preventing the short path of particulates in the exhaust gas and for holding the ceramic filter in the casing and for insulating the same.

Further, on the gas inflow side (may be arranged on the outflow side) of the ceramic filter (3), a light oil burner (7a) for regenerating the filter (the point that the capacity of the heat source is small is small. However, the heat source for regeneration is not limited to this, and, for example, a ceramic heater or a microwave may be used).

Here, the ceramic filter (3) is
One or a combination of filter parts (4) having a triangular, square, rectangular or regular hexagonal cross-section is used in the form of a prism (see FIGS. 2 to 5, but these are merely examples. , Not limited to how to combine). By making the cross-sectional shape of the filter part (4) as described above, the manufacturing constraint mentioned as the problem of the prior art (the cross-sectional shape is 1 / n circle or 1 / n ellipse) is eliminated, and By appropriately combining these, it is possible to appropriately select a filter suitable for the capacity of the internal combustion engine, and since it is possible to have an arbitrary casing shape, there are less restrictions on the mounting of the exhaust gas purification device (here, The cross-sectional shape of the cell should be the same as the cross-sectional shape of the filter part because the pulling force acting on the outer periphery of the filter part due to the expansion difference of the cell during heating acts isotropically. This is because it is possible to prevent the occurrence of "thermal distortion" as in the conventional technique). As the assembly form, the ratio of the distance from the center of the assembly to the inner wall of the casing (OB / OB in FIGS. 2 to 5)
OA) should be at least 0.5, preferably 1.0. This is to reduce the influence of temperature difference formation between the central portion of the aggregate and the peripheral portion.

As the material of the filter part (4),
From the viewpoint of “heat resistance”, the load softening temperature is 1200 ° C. or higher and the bending strength at 1200 ° C. (JIS
It is preferable that the three-point bending strength defined in R1601) is 70% or more of that at room temperature. This is because when the content of the material is 70% or less, the material is softened / deformed during 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 / ℃ Expressed in thermal expansion coefficient (1.0 × 10 ^-6 / ℃ Almost none of the following materials satisfy the load softening temperature index, while those of 5.0 × 10 ⁻⁶ / ° C. or higher are used as filter parts from the viewpoint of preventing “heat distortion”. Practicality is poor because the size must be extremely small). Furthermore, 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 it is less than m · sec · ° C, the temperature difference between the central portion and the peripheral portion of the ceramic filter becomes too large during regeneration, while if it exceeds 0.5cal / cm · sec · ° C, it is necessary for regeneration. This is because the amount of heat 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
90%, more preferably 40 to 60% (because the pressure loss becomes too large when it is less than 30%, while the collection rate of particulates becomes worse when it is more than 90%), the average pore diameter is 5 to 40 μm (when it is smaller than 5 μm, the pressure loss becomes too large, while when it is larger than 40 μm, the collection rate of particulates becomes worse).

When the number of cells is 50 to 300 cells / square inch (less than 50 cells / square inch, the filtration area is small, so the amount of particulates per unit time / unit volume is small. On the other hand, if it exceeds 300 cells / square inch, the opening area per cell becomes too small and the pressure loss increases, and the thickness of the cell wall (11) (distance between adjacent cell walls) is 0.2 to 0.6 mm (If it is less than 0.2, the mechanical strength of the filter part will be weak, and if it exceeds 0.6 mm, the filtration area will be small. Therefore, the particulate rate per unit time and unit volume will be small. The collection amount will decrease).

As in the invention previously filed by the same applicant as the invention of this application (Japanese Patent Application No. 4-183912), the wall surface (11a), (11b) of the cell is provided with an additional particulate. You may laminate the inorganic heat resistant fiber layer used as a filtration surface (this treatment raises filtration efficiency per filter unit volume). 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).
When it is less than 2, the collection rate of particulates in this layer is small and the load on the wall of the cell is large, leading to an early increase in pressure loss of the filter. (It is not preferable because the pressure loss at 1) increases significantly.

Here, the average porosity of the heat resistant fiber layer is
Particle size distribution of ticulate (average particle size is 0.1 to 0.2 μm in diesel exhaust) and collection rate (at least 95
% Or more) and pressure loss (3500 mmAq or less) are set to 25% to 75%.

In terms of satisfying the "heat shock resistance", in addition to consideration of the material, consideration is given to the apparatus structure, that is, exhaust gas or hot air for filter regeneration upstream of the ceramic filter (3). An auxiliary filter (8) may be installed to mitigate the temperature change of (see FIG. 6). Here, since the main purpose of the auxiliary filter is to alleviate the heat load, the auxiliary filter is a full-flow type honeycomb ceramic filter (8a) (cells are not sealed, that is, particulates are used. Exhaust gas passes through the cell with almost no trapping, see Fig. 8.
For this purpose, this filter does not have to be as thick as the particulate trapping filter (length in the gas flow direction), so the need for division is small). A ceramic plate (8b) alone or in the form of foam or fiber (see FIG. 9), which is obtained by adding an acrylic binder and aluminum sulfate to an alumina-silica fiber and dispersing it in water to a predetermined thickness. It is made by filtering the paper in the same manner as paper making, and drying it, and then forming a number of small-diameter through holes in its thickness direction (see FIG. 7 as an example of the combination. In principle, the cross-sectional shape and dimensions of the filter shall be the same shape and the same size as 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 +
30% or less of the heat capacity of the auxiliary filter (if it is 30% or more, the amount of heat required to heat the auxiliary filter becomes too large, which leads to deterioration of fuel consumption and early consumption of the battery), and the ceramic filter and its center. Align the axes (to equalize the relaxation effect), and further 15 from the front end surface.
Install within 0 mm (if it exceeds 150 mm, the above relaxation effect disappears).

Further, a part support material (5) is attached to at least the regions near the 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 resistant temperature of the part support material is required to be 1200 ° C. or higher. Specifically, alumina fiber, silica fiber, alumina-silica fiber, zirconia fiber, cordierite fiber, silicon carbide fiber, etc. can be used, but heat resistance, cost, and availability (production Alumina fiber or alumina-silica fiber is preferable in consideration of the amount. More preferably,
A mixture of a small amount of silicon carbide powder or tungsten carbide powder with the above-mentioned suitable fiber, or a mixture of the above-mentioned suitable fiber with still fiber, stainless fiber, silicon carbide fiber, carbon fiber, etc. (The reason for the same as the filter part, that is, the thermal conductivity of the filter part-0.01 to
0.5cal / cm · sec · ° C-to adjust to the same level). In addition, as the adherence specification, the density is 0.1 to 0.8 g
/ Cm ³ (If less than 0.1 g / cm ³ , there are many voids between the fibers, so the strength is low. As a result, the sealability against exhaust gas is insufficient, and 0.8 g / cm 3
^If it exceeds ³ , the elasticity will be impaired, and the buffering capacity of "heat distortion" will be insufficient), and the thickness will be 1-5 mm (If it is less than 1 mm, adjacent filter parts will contact and interfere with each other and cracks will occur. It becomes easier, and if it exceeds 5 mm, the unit ceramic
The filtration area per filter volume is reduced, resulting in a larger device).

Alumina-silica is formed on at least the regions near both front and rear end surfaces of the peripheral surface of the filter part assembly.
An elastic support material (6) composed of fibers and gas-generating components is applied (see FIGS. 10 and 11; in the figures, only the regions near both front and rear end surfaces are applied, but this is a trade-off with the capacity of the heat source for regeneration. Therefore, when a higher heat insulating effect is desired, it may be applied to the entire peripheral surface). As the elastic support material, one composed of the above-described alumina-silica fiber and vermiculite containing a gas generating component such as ammonia can be used. Even if a material containing a gas generating component is used between the casing and the outer periphery of the filter part assembly as in the present application, the temperature in the vicinity of the casing inner wall is low, As in the prior art, vitrification by heat causes a significant decrease in strength, and as a result, there is no problem that the supporting force of the filter part is lowered and the sealing property against exhaust gas is lost. On the contrary, the expansion of the elastic support material due to the modest foaming is combined with the elasticity exhibited by the alumina-silica fiber coated on the peripheral surface of the filter part, and the assembly of the filter parts. To strongly support the case. The elastic support material is compressed to a thickness of 60 to 80% of the deposition thickness, and then the aggregate of the filter parts to which the elastic support material is deposited is stored in a casing. Preferably. This is because by doing so, the elasticity of the elastic support material is maintained for a long period of time. Incidentally, in the compression operation, after applying the elastic support material, a thin plastic film having heat shrinkability, for example, polyethylene, polyvinyl chloride, polyvinylidene chloride, etc. is applied and heat-shrinked. (This compression operation also makes it possible to store the aggregate of the filter parts in the casing without causing the displacement of the filter parts).

Here, the thickness of the elastic support member (6) is 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,
The heat insulation effect becomes small and the heat dissipation loss becomes large when the filter is regenerated. On the other hand, when it is larger than 1/7, not only the heat capacity of the elastic support material becomes large and it takes time to heat the entire filter, Is not preferable because the outer shape of the product becomes large).

These filters are made as follows. The filter part is produced by first extruding various materials described above to form a molded body having a desired shape. Then, the molded body is dried after sealing cells alternately and then at about 2200 ° C. (in the case of silicon carbide) under an inert gas atmosphere or about 1200 ° C. (in the case of mullite cordierite) under an oxidizing atmosphere. Bake (to obtain a sintered body).

Next, a part supporting material (5) is applied. To the water slurry (slurry concentration: 1 wt%) of the above-mentioned various fibers, which is a simple substance or a mixture thereof, polyacrylonitrile or latex is added. Such 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) are added to the respective suspensions, and an aqueous solution of sulfuric acid band (about 5 wt% against the fiber) is added. )
Is added to agglomerate the fibers, and the sintered body (the portion other than the portion to be adhered is previously wrapped by wrapping) is dipped in a suspension of the agglomerates, and then one of the sintered bodies is added. 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 portion of the sintered body that has not been wrapped, which is inevitable. The agglomerates are laminated on the non-lapped part of the sintered body, and if the suspension is not agglomerated, the fibers enter the cell wall and function as a filter. It should be noted that by not lapping the mouth of the unsealed cell, the inorganic heat resistant fiber layer on the wall surface of the cell is also laminated at the same time), and finally 80 to 100 ℃
To dry the sintered body.

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

[0029]

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

As shown by the arrow in FIG. 1, the internal combustion engine (E)
When the exhaust gas of (3) 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 (when the layer is laminated) and the cell wall When passing through the adjacent cell where the gas outflow side is not sealed, the particulates in the gas are filtered and trapped in the heat-resistant fiber layer and the wall of the cell, and the purified exhaust gas is discharged. Gas is discharged from the filter (3).
Incidentally, the capture of the particulates in the heat resistant fiber layer (when the layer is laminated) is carried out in the entire layer (all-layer filtration).

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

[0032]

EXAMPLES Next, examples illustrating the present invention will be described.

Example 1 A honeycomb-structured filter part (detailed specifications are as follows) made of a silicon carbide sintered body and having an outer dimension of 30 mm square and a length of 150 mm. (1) Thickness of 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 (vs. normal temperature): 90
% (7) Thermal expansion coefficient: 4.0 × 10 ⁻⁶ / ° C. (8) Thermal conductivity: 0.1 cal / cm · sec · ° C.

Further, in the regions near the front and rear end surfaces of the peripheral surface of the filter part, the diameter is 1 to 3 μm and the length is 100 to 300.
A 00 μm alumina-silica fiber (composition: alumina: 45%, silica 55%) was applied (details are as follows). (1) Thickness: 1 mm (2) Density: 0.3 g / cm ³ (3) Heat resistance temperature: 1400 ° C. (4) Thermal conductivity: 0.08 cal / cm · sec · ° C.

A total of 49 filter aggregates (7 × 7 in total) having the above-mentioned alumina-silica fiber adhered thereon were assembled (cross-sectional shape of the aggregate: square), and the peripheral surface of the aggregate was collected. An elastic support material consisting of 50 parts of alumina-silica fiber, 50 parts of heat-expandable obsidian, majuite and 50 parts of organic foaming material was adhered to the regions near the front and rear end surfaces of each of the above (details are below). . (1) Thickness: 5 mm (2) Density: 0.6 g / cm ³ (3) Thermal expansion coefficient: 150% (600 ° C)

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

As a heating source for regeneration, 10000 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 the exhaust gas was introduced into the filter (3). During the introduction of the exhaust gas, the pressure in the exhaust pipe line (Ea) was monitored by the monitoring / control device (C) via the pressure sensor (Ps) and the piezoelectric conversion element (Pe). The engine load is idling mode (engine speed: 700
rpm) and accelerator fully open mode (engine speed: 2
200 rpm) was repeated at 5 second intervals.

20 g of particulates in the exhaust gas
/ M ^{2 is} collected, the burner (7a) is started by the monitoring and control device (C), and the compressor is operated when the temperature (T ₁ ) at the position (P ₁ ) reaches about 750 ° C. (C
o), the 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) (T _{2 2} )
The fuel supply to the burner (7a) was stopped at the time point when the temperature suddenly dropped, and the regeneration was completed.

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

(Embodiment 2) A system is constructed in which an auxiliary filter is added to the exhaust gas purifying apparatus of Embodiment 1, and Embodiment 1
The same pattern was used to perform the exhaust gas purification operation and the ceramic filter regeneration operation. The auxiliary filter (8) has a fibrous ceramic plate (the physical properties of the fibers used are the same as those of the part supporting material. Density: 0.
2 g / cm ³ . Through hole diameter: 10 mm. Board thickness: 1
0 mm) to a full-flow type honeycomb ceramic filter (the same specifications as the filter for collecting particulates except that the number of cells is 100 cells / square inch and the thickness is 15 mm). (The shape and dimensions of the cross section are the same shape and the same size as the filter for collecting particulates. Installation position: The rear end face is
10 mm from the front end face of the filter for collecting triculate
Separated positions).

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

(Comparative Example 1) A filter part having a sectional shape of 1/6 circle was used (the material specifications of the filter part are the same as in Example 1. The size of the assembled ceramic filter is , A cylinder having a diameter of 240 mm and a length of 150 mm), "heat expander" such as vermiculite and vermiculite, and "alumina such as alumina and silica" between the dividing surfaces of the adjacent filter parts. 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
The same exhaust gas purification operation and ceramic filter regeneration operation were performed. The detailed specifications of the heat-expandable ceramic material are as follows. (1) Thickness: 2 mm (2) Density: 0.6 g / cm ³ (3) Thermal expansion coefficient: 150% (4) Thermal conductivity: 0.007 cal / cm · sec · ° C

The first operation caused a crack in the center of the filter part. The temperature difference between the central portion and the outer peripheral portion was 350 ° C., which was extremely large.

[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 internal combustion engine is not damaged. It is highly practical as an exhaust gas purifying apparatus for engines, for example, diesel vehicles.

[Brief description of drawings]

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

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

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

FIG. 4 is a cross-sectional view schematically illustrating an assembly mode of yet another filter part of the ceramic filter of the present invention.

FIG. 5 is a cross-sectional view schematically illustrating an assembly mode of filter parts different from those of the ceramic filter of the present invention.

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

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

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

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

FIG. 10 is a circle marker of the filter part assembly shown in FIG.
Enlarged cross-sectional view of the black part (cut along the line AA in FIG. 1)

FIG. 11 is a circle marker of the filter part assembly shown in FIG.
Enlarged cross-sectional view of the black section (cut along the line BB in FIG. 1)

FIG. 12 is a sectional view for explaining a cell structure of a ceramic filter.

[Explanation of symbols]

1 ... Exhaust gas purifier, 2 ... Casing, 3 ...
.... Ceramic filters, 4 .... Filter filters
5 ... Part support material, 6 ... elastic support material 7a ...
・ ・ ・ Light oil burner, 8 ・ ・ ・ Auxiliary filter, 10 ・ ・ ・ ・ Cell, 11 ・ ・ ・ ・ Interior wall part, 11a, 11b ・ ・ ・ Wall surface, 1
2 ... Sealing part

Claims (1)

[Claims] 1. An exhaust gas purification device (1) comprising a casing (2) communicating with the exhaust side of an internal combustion engine (E) and a honeycomb ceramic porous ceramic filter (3) arranged in the casing. ), The filter comprises an assembly of a plurality of prismatic filter parts (4) having an axis extending parallel to the gas flow direction.
A part supporting material (5) is provided at least in the regions near the front and rear end faces of the peripheral surface of the part, and an alumina-silica fiber is provided in at least the regions near the front and rear end faces of the peripheral surface of the assembly of the filter parts. An apparatus characterized in that elastic support materials (6) composed of gas generating components are respectively deposited.