JP6041599B2 - Manufacturing method of diesel particulate filter - Google Patents

Description

  The present invention relates to a method for manufacturing a diesel particulate filter.

  Conventionally, a honeycomb structure made of porous ceramics is used as a diesel particulate filter for collecting fine particles such as carbon particles contained in exhaust gas discharged from an internal combustion engine such as a diesel engine. (See Patent Document 1 below).

  The honeycomb structure is a columnar body. In the columnar honeycomb structure, a plurality of through holes (cells) penetrating between the opposing end faces are formed. On one end face (first end face) of the honeycomb structure, the opening portions of the through holes and the end portions of the through holes closed by the sealing portions are alternately arranged in a lattice pattern. The through hole in which the opening is located on the first end surface is closed with a sealing portion on the second end surface opposite to the first end surface. In addition, the through hole whose end is closed by the sealing portion on the first end surface has an opening on the second end surface. Therefore, also on the second end surface, the opening portions of the through holes and the end portions of the through holes closed by the sealing portions are alternately arranged in a lattice pattern.

JP 2008-119663 A

  In the production of a diesel particulate filter, a raw material mixture is prepared by mixing ceramic raw material powder (which becomes ceramic upon firing), a pore former, an organic binder, a solvent and the like with a kneader or the like. The raw material mixture is molded using an extruder having a die having a lattice-shaped opening, and dried to form a long columnar body having a plurality of through holes. The long columnar body is cut to a size suitable for processing to form a green molded body. The green molded body means a honeycomb structure before firing. Furthermore, the cutting process for adjusting the dimension of a green molded object correctly is implemented. After the cutting step, a diesel particulate filter is completed through a step of sealing the through hole of the green molded body, a calcination step, a firing step, and the like.

  In the above-described cutting process, a large amount of chips are generated or burrs are formed on the cut surface. When chips and burrs remain on the cut surface or remain in the through hole, it is difficult to perform an accurate sealing process. In addition, chips and burrs are clogged in the through-holes, reducing the exhaust performance of the diesel particulate filter, or being discharged into the atmosphere together with the exhaust gas when the diesel particulate filter is used. In order to prevent these problems, it is necessary to remove chips and burrs in the manufacturing process of the diesel particulate filter.

  However, since the end surface (cut surface) of the green molded body which is not sintered is fragile, if the chips and burrs are removed from the end surface using a brush, the end surface may be damaged. Moreover, it is difficult to remove chips in the through hole of the green molded body. Furthermore, as a result of the time required for removing chips and burrs, the production efficiency of the diesel particulate filter is reduced.

  This invention is made | formed in view of the subject which such a prior art has, and aims at providing the manufacturing method of the diesel particulate filter which can remove a chip and a burr | flash easily.

In order to achieve the above object, one aspect of a method for manufacturing a diesel particulate filter according to the present invention is a method for manufacturing a diesel particulate filter using a columnar honeycomb structure in which a plurality of parallel through holes are formed. The honeycomb structure has a first end surface where one opening of the plurality of through holes is located, and a second end where the other opening of the plurality of through holes is located on the opposite side of the first end surface. And the manufacturing method described above removes chips and burrs adhering to the honeycomb structure by injecting air substantially perpendicularly to the first end surface and simultaneously sucking air on the second end surface side. The second end face by injecting air substantially perpendicularly to the first end face and simultaneously injecting another air to the second end face in a direction of 0 to 45 ° with the second end face. Attached to Comprising a second step of removing Rikuzuoyobi burrs, and carrying out the second step after the first step.

  In one embodiment of the present invention, it is preferable to perform the first step after the step of cutting the columnar body in which the plurality of through holes are formed to form the honeycomb structure.

  ADVANTAGE OF THE INVENTION According to this invention, it becomes possible to provide the manufacturing method of the diesel particulate filter which can remove a chip and a burr | flash easily.

Fig. 1 (a) is a perspective view of a green molded body (honeycomb structure before firing) used in one embodiment of the present invention, and Fig. 1 (b) is a diagram of the green molded body of Fig. 1 (a). The end face is shown. Drawing 2 is a mimetic diagram showing the 1st process and the 2nd process of one embodiment of the present invention. FIG. 3 is a front view of the air injection device shown in FIG. FIG. 4A is a perspective view of a diesel particulate filter manufactured according to an embodiment of the present invention, and FIG. 4B shows an end face of the diesel particulate filter of FIG. FIG. 5 is a cross-sectional view of the diesel particulate filter shown in FIG.

  Hereinafter, a preferred embodiment of the present invention will be described in detail with reference to the drawings. However, the present invention is not limited to the following embodiments. In addition, the same code | symbol is attached | subjected about the same or equivalent element. In addition, although the positional relationship between the top, bottom, left and right is as shown in the drawing, the ratio of dimensions is not limited to that shown in the drawing.

[Diesel particulate filter manufacturing method]
(Raw material mixture preparation process)
A raw material mixture is prepared by mixing ceramic raw material powder, an organic binder, additives and the like with a kneader or the like.

  Examples of the ceramic raw material powder include alumina, silica, mullite, cordierite, glass, oxides such as aluminum titanate, silicon carbide, and silicon nitride. The aluminum titanate can further contain magnesium and / or silicon. The raw material powder for ceramics is not limited to these.

  When manufacturing a diesel particulate filter made of aluminum titanate or aluminum magnesium titanate, the raw material powder includes an aluminum source powder such as α-alumina powder and a titanium source powder such as anatase type or rutile type titania powder. The raw material powder can further contain a magnesium source powder such as magnesia powder and magnesia spinel powder and / or a silicon source powder such as silicon oxide powder and glass frit, if necessary.

  Examples of the organic binder include celluloses such as methylcellulose, carboxymethylcellulose, hydroxyalkylmethylcellulose, and sodium carboxymethylcellulose; alcohols such as polyvinyl alcohol; and lignin sulfonate.

  Examples of the additive include a pore former, a lubricant and a plasticizer, a dispersant, and a solvent.

  Examples of the pore-forming agent include carbon materials such as graphite; resins such as polyethylene, polypropylene and polymethyl methacrylate; plant materials such as starch, nut shells, walnut shells and corn; ice; and dry ice.

  Lubricants and plasticizers include alcohols such as glycerine; higher fatty acids such as caprylic acid, lauric acid, palmitic acid, arachidic acid, oleic acid and stearic acid; metal stearates such as aluminum stearate, polyoxyalkylene alkyl And ether (POAAE).

  Examples of the dispersant include inorganic acids such as nitric acid, hydrochloric acid and sulfuric acid; organic acids such as oxalic acid, citric acid, acetic acid, malic acid and lactic acid; alcohols such as methanol, ethanol and propanol; ammonium polycarboxylate Surfactant etc. are mentioned.

  As the solvent, alcohols and water can be used. Examples of the alcohol include monohydric alcohols such as methanol, ethanol, butanol, and propanol; dihydric alcohols such as propylene glycol, polypropylene glycol, and ethylene glycol;

(Formation process of raw material mixture)
The raw material mixture described above is molded using an extruder having a die having a grid-like opening to form a long columnar body in which a plurality of through holes are formed. The raw material mixture may be kneaded in an extruder. The long columnar body is cut to a size suitable for processing to form a green molded body. The green molded body is dried with hot air or microwave to remove the solvent. Furthermore, the cutting process for adjusting the dimension of a green molded object correctly is implemented.

  As shown in FIGS. 1 (a) and 1 (b), the honeycomb structure 70 is a cylinder. The honeycomb structure 70 has a plurality of partition walls 70c parallel to the central axis. That is, the honeycomb structure 70 has a lattice structure in a cross section perpendicular to the central axis direction. In other words, the honeycomb structure 70 has a large number of through holes 70a (flow paths) extending in the same direction (center axis direction), and the through holes 70a are separated by the partition walls 70c. The plurality of through holes 70a are parallel to each other. On the first end face of the honeycomb structure 70 and the second end face opposite to the first end face, openings of the respective through holes are located. Each through hole 70 a is perpendicular to both end faces of the honeycomb structure 70. The angle formed by each partition wall 70c is not particularly limited, and may be 90 ° or 120 °.

(Dust removal process)
Below, the process (dust removal process) of removing the chips and burrs adhering to the honeycomb structure 70 after the cutting process will be described with reference to FIGS. The dust step, carrying out the following second step after the following first step. In addition, the code | symbol 32 described in FIG. 2 shows a chip or a burr | flash. The arrows shown in FIG. 2 indicate the direction of air flow.

<First step>
In the first step, the air injection device 20 (first injection device) is disposed on the first end face side of the honeycomb structure 70. The openings 22a of the plurality of nozzles 22 provided in the injection device 20 are opposed to the first end surface. The area of the circular side surface on which the nozzle 22 is disposed in the injection device 20 is substantially equal to the area of the first end surface, and the injection device 20 faces the entire surface of the first end surface. The number and arrangement of the plurality of nozzles 22 are not limited to those shown in FIG. The injection device 20 is connected to a compressor (compressor) or a gas cylinder, and can inject high-pressure air from the opening 22 a of the nozzle 22. An air suction device 26 is disposed on the second end face side of the honeycomb structure 70. The opening area of the suction port 28 of the suction device 26 is substantially equal to the area of the second end surface, and the suction port 28 faces the entire surface of the second end surface. However, the shape and width of the air inlet 28 are not limited to those shown in FIG.

  In the first step, high-pressure air is jetted from the nozzle 22 toward the first end surface in a direction substantially perpendicular to the first end surface. Simultaneously with this injection, air is sucked by the suction device 26 in a direction substantially perpendicular to the second end face on the second end face side. Chips and burrs adhering to the first end surface are removed by the air injection.

  When the air injected to the first end surface is introduced into each through hole, the flow velocity of the air increases due to the rectifying effect inherent in the through hole. This air flow carries the chips and burrs detached from the first end face, and the chips in each through hole to the second end face side, and discharges them from the honeycomb structure 70. The discharged chips and burrs are sucked into the intake port 28 together with air. This rectifying effect is manifested not only by air injection to the first end face but also by simultaneously sucking air on the second end face side. It is difficult to sufficiently remove chips and burrs from the honeycomb structure 70 only by injecting air onto the first end surface.

  When air is not sucked on the second end face side, chips and burrs detached from the honeycomb structure 70 are scattered by the injection of air onto the first end face, and it is difficult to collect the air. However, in this embodiment, chips and burrs can be reliably collected by suction of air on the second end face side. Moreover, it is difficult to remove chips and burrs adhering to the second end surface only by injecting air onto the first end surface. However, in the present embodiment, chips and burrs attached to the second end surface are also removed by suction of air on the second end surface side.

  In the present embodiment, since it is possible to remove chips and burrs without bringing a brush or the like into direct contact with each end surface, there is no possibility that each end surface is damaged.

  In the present embodiment, chips and burrs can be easily removed in a short time, so that the production efficiency of the diesel particulate filter is improved.

<Second step>
When performing a 2nd process, the injection apparatus 30 (2nd injection apparatus) different from what was used at the 1st process is arrange | positioned beside a 2nd end surface. In the second step, as in the first step, high-pressure air is injected to the first end surface, and another high-pressure air is injected in a direction in which the angle (angle θ) with the second end surface is 0 to 45 °. It injects toward the 2nd end surface from the apparatus 30. FIG. In the second step, as in the first step, high-pressure air is jetted onto the first end face and sucked on the second end face side, and at the same time, an angle (angle θ) between another high-pressure air and the second end face is set. You may inject toward the 2nd end surface from the injection apparatus 30 in the direction which is 0-45 degrees. In the first step, since air is not jetted onto the second end face, chips and burrs may remain on the second end face. However, it is possible to reliably remove chips and burrs remaining on the second end face by injecting high-pressure air onto the second end face in the second step.

  The pressure of the air injected from the first injection device 20 in the first step may be about 0.3 to 1.5 MPa, and may be 0.5 to 2 MPa. The pressure of the air injected from the first injection device 20 in the second step may be about 0.2 to 1 MPa, and the pressure of the air injected from the second injection device 30 may be about 0.3 MPa. The flow rate of air injected from each injection device may be about 30 to 50 m / s. The flow rate of the air sucked by the suction device 26 may be about 1 to 20 m / s.

(Sealing process)
In the sealing step, a first mask is attached to the first end surface of the honeycomb structure 70 where one opening of the plurality of through holes 70a is located. In the first mask, a mask portion having substantially the same dimensions as the through hole 70a and a plurality of openings are arranged in a staggered manner. A first mask is affixed to the first end surface of the honeycomb structure 70 so that each through-hole 70a overlaps with each mask portion and opening. In addition, a second mask is attached to the second end surface of the honeycomb structure 70 opposite to the first end surface. The arrangement relationship between the opening and the mask portion of the second mask is opposite to that of the first mask. Therefore, the through hole 70a closed by the mask portion of the first mask on the first end surface side overlaps the opening portion of the second mask on the second end surface side. The through hole 70a closed by the mask portion of the second mask on the second end surface side overlaps with the opening portion of the first mask on the first end surface side. Therefore, any of the plurality of through holes 70a formed in the honeycomb structure 70 is open at either the first end face or the second end face and is closed by the mask portion at the other end.

  In the sealing step for the first end surface, the sealing material is introduced into the opening (end) of each through hole 70a that overlaps the opening of the first mask. In addition, after introducing the sealing material into the through hole 70a, the entire honeycomb structure 70 may be vibrated by a vibrator. As a result, the sealing material is easily filled in the gaps at the end portions of the through holes 70a. What is necessary is just to use a substantially the same thing as said raw material mixture as a sealing material.

  After the above sealing step for the first end surface, the sealing step for the second end surface to which the second mask is attached is performed in the same manner as the sealing step for the first end surface. After performing the sealing step on both end faces, each mask is peeled off from each end face.

(Housing process and firing process of honeycomb structure 70)
After the sealing step, the honeycomb structure 70 (green molded body) is calcined (degreasing) and fired. Through the above steps, a diesel particulate filter 170 made of porous ceramics can be obtained (see FIGS. 4 and 5).

  Calcination (degreasing) is a process for removing the organic binder in the green molded body and the organic additive blended as necessary by burning, decomposition, or the like. The calcining process corresponds to an initial stage of the firing process, that is, a temperature raising stage (for example, a temperature range of 300 to 900 ° C.) until the green molded body reaches the firing temperature. In the calcination (degreasing) step, it is preferable to suppress the temperature increase rate as much as possible.

  The firing temperature of the green molded body is preferably 1300 ° C. or higher, more preferably 1400 ° C. or higher. The firing temperature is preferably 1650 ° C. or lower, more preferably 1550 ° C. or lower. The rate of temperature increase up to the firing temperature is not particularly limited, but is usually 1 ° C./hour to 500 ° C./hour.

  Firing is usually performed in the air. Depending on the type of raw material powder used, that is, aluminum source powder, titanium source powder, magnesium source powder, and silicon source powder and the usage ratio, firing may be performed in an inert gas such as nitrogen gas or argon gas. Firing may be performed in a reducing gas such as carbon oxide gas or hydrogen gas. Further, the firing may be performed in an atmosphere in which the water vapor partial pressure is lowered.

  Firing is usually performed using a conventional firing furnace such as a tubular electric furnace, a box-type electric furnace, a tunnel furnace, a far-infrared furnace, a microwave heating furnace, a shaft furnace, a reflection furnace, a rotary furnace, or a roller hearth furnace. Firing may be performed batchwise or continuously. Moreover, you may carry out by a stationary type and may carry out by a fluid type.

  The time required for firing varies depending on the composition and amount of the raw material powder constituting the honeycomb structure 70, the form of the firing furnace, the firing temperature, the firing atmosphere, and the like, but may be 10 minutes to 24 hours.

  You may perform calcination and baking separately. In the calcining step, the honeycomb structure 70 may be heated at a temperature equal to or higher than the thermal decomposition temperature of the organic binder and other organic additives and lower than the sintering temperature of the inorganic compound powder. In the firing step, the honeycomb structure 70 after the calcining step may be heated at a temperature equal to or higher than the sintering temperature of the raw material powder.

[Diesel particulate filter]
In the diesel particulate filter 170, the through hole 70a closed by the sealing portion 70b on the first end surface side has an opening on the second end surface side. The through-hole 70a closed by the sealing part 70b on the second end face side has an opening on the first end face side (see FIGS. 4 and 5). A platinum-based metal catalyst supported on a carrier such as alumina or a promoter such as ceria or zirconia may be attached to the partition wall surface of the through hole 70a.

The dimensions of the diesel particulate filter 170 are not limited. The inner diameter (the length of one side of the square) of the cross section perpendicular to the longitudinal direction of the through hole 70a is, for example, 0.5 to 2.5 mm. The length of the diesel particulate filter in the direction in which the through hole 70a extends is, for example, 30 to 350 mm. Moreover, the outer diameter of a diesel particulate filter is 10-320 mm, for example. The number (cell density) of the through holes 70a opened in the end face of the diesel particulate filter is, for example, 150 to 450 cpsi. The unit of cpsi means “/ inch ² ” and is equal to “/(0.0254m) ² ”. The thickness of the partition wall of the through hole 70a is, for example, 0.1 to 0.76 mm. The porosity (open porosity) of the partition wall 70c is, for example, 30 to 70% by volume.

  As mentioned above, although one suitable embodiment of the present invention was described in detail, the present invention is not limited to the above-mentioned embodiment.

  In a 1st process and a 2nd process, you may inject air to a part of 1st end surface using a small-sized injection apparatus. Air may be sucked from a part of the second end surface using a small suction device. In this case, the honeycomb structure 70 may be moved while fixing the positions of the injection device and the suction device. Alternatively, the position of the honeycomb structure 70 may be fixed, and the injection device and the suction device may be moved along the first end surface and the second end surface, respectively. In any case, since the entire first end surface and second end surface are swept by the injection device and the suction device, respectively, chips and burrs are removed from the honeycomb structure 70 as in the above embodiment.

  The diesel particulate filter may be a porous ceramic made of cordierite or silicon carbide. In this case, cordierite, silicon carbide, or a mixture thereof may be used as the raw material powder. The cross-sectional shape of the through hole is not limited to a square, and may be a rectangle, a circle, an ellipse, a triangle, a hexagon, an octagon, or the like. A plurality of types of through-holes having different cross-sectional shapes and dimensions may be formed in the diesel particulate filter. The spacing between the through holes and the arrangement of the through holes are not particularly limited. The external shape of the diesel particulate filter is not limited to a cylinder, and may be, for example, a triangular prism, a quadrangular prism, a hexagonal prism, an octagonal prism, or the like.

  DESCRIPTION OF SYMBOLS 20 ... 1st injection apparatus, 22 ... Nozzle, 22a ... Opening part of nozzle, 26 ... Suction apparatus, 28 ... Intake port, 30 ... Second injection apparatus, 32 ... -Chips or burrs, 70 ... green molded body (dried honeycomb structure), 70a ... through hole, 70b ... sealing part, 70c ... partition wall, 170 ... diesel particulate filter, θ is an angle formed between the direction in which air is injected from the second injection device and the second end face.

Claims (2)

A method for manufacturing a diesel particulate filter using a columnar honeycomb structure in which a plurality of through holes parallel to each other is formed,
The honeycomb structure is
A first end surface where one opening of the plurality of through holes is located;
A second end face located on the opposite side of the first end face, on which the other opening of the plurality of through holes is located;
Have
The manufacturing method includes:
A first step of removing chips and burrs adhering to the honeycomb structure by simultaneously injecting air substantially perpendicularly to the first end surface and sucking the air on the second end surface side ;
By injecting the air substantially perpendicularly to the first end surface, and simultaneously injecting another air to the second end surface in a direction of 0 to 45 ° with the second end surface, A second step of removing attached chips and burrs;
Equipped with a,
Performing the second step after the first step;
Manufacturing method of diesel particulate filter. The first step is performed after the step of cutting the columnar body in which the plurality of through holes are formed to form the honeycomb structure,
The manufacturing method of the diesel particulate filter of Claim 1 .

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