JP2008093664A - Manufacturing method of honeycomb structure - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a manufacturing method of a honeycomb structure capable of acquiring required cleaning performance by remaining a decrease in a catalyst volume to a minimum while securing a space for disposing a sensor. <P>SOLUTION: The method comprising the steps of: forming a plastic clay including a ceramic and/or a metal as principal components into a honeycomb formed article; drying and calcinating the honeycomb formed article; and thereafter cutting the dividing wall of an obtained honeycomb calcinated article in the cutting direction oblique to a main face of the dividing wall to provide at least one of a groove, a hole, and a bordering on the honeycomb calcinated article. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a method for manufacturing a honeycomb structure. More specifically, the present invention relates to a method for manufacturing a honeycomb structure in which a sensor or the like can be inserted into a part of the honeycomb structure.

  With the strengthening of exhaust gas regulations, various attempts have been made to improve exhaust gas purification performance even in the honeycomb structure carrying a catalyst, but most of the harmful substances subject to regulation are immediately after the start of operation. A large amount of catalyst is discharged at a low catalyst temperature.

  For this reason, in recent years, a honeycomb structure carrying a catalyst is mounted immediately below an exhaust manifold (hereinafter sometimes referred to as “exhaust manifold”), and the catalyst is immediately activated by high-temperature exhaust gas. A converter system that reduces harmful substances discharged immediately after the engine is started has been put into practical use.

  On the other hand, in a honeycomb structure carrying a catalyst, after mounting as a purification means, monitoring the purification performance to determine the deterioration status of the purification performance also reduces the emission of harmful substances. It is extremely important, and usually two oxygen sensors are arranged before and after the honeycomb structure for monitoring.

  However, when the honeycomb structure and sensor are mounted directly under the exhaust manifold, the space for arranging the honeycomb structure and sensor is narrow, and the honeycomb structure is greatly reduced in order to secure the sensor space. Inevitably, there was a problem that the intended purification performance could not be obtained due to a significant reduction in the catalyst capacity.

  The present invention has been made in view of the above-described problems, and the object of the present invention is to achieve a desired purification while minimizing the reduction in catalyst capacity while securing the sensor installation space. An object of the present invention is to provide a method for manufacturing a honeycomb structure capable of obtaining performance.

  The present inventor has made various studies to achieve the above-described object. First, the knowledge that a sensor insertion region is ensured by cutting a part of the partition walls of the honeycomb structure and providing grooves, holes, or edges. It came to.

  However, when a part of the partition walls of the honeycomb structure was actually cut from the direction perpendicular to the side surfaces of the partition walls, the partition walls were sometimes extremely thin (currently a thickness of about 0.1 to 0.2 mm). Walls are mainly used, and thin walls with a thickness of less than 0.1 mm are also used.) Due to breakage of the partition walls, grooves having a desired shape cannot be provided in desired parts, and the catalyst In addition to being unable to suppress the reduction in capacity, in some cases, even the entire structure was damaged.

  Therefore, the present inventor has further studied how to form grooves and the like, and found that such a problem can be solved by cutting the main surface of the partition wall from an oblique direction. It came to complete.

  That is, according to the present invention, a honeycomb-shaped formed body is obtained by molding a clay mainly composed of ceramics and / or metal, and the honeycomb-shaped formed body is dried and fired, and then the obtained honeycomb-shaped fired body is obtained. The honeycomb structure is provided in the honeycomb-shaped fired body by cutting at least one of grooves, holes, or edging as a sensor insertion region by cutting the partition walls in an oblique cutting direction with respect to the main surface of the partition walls. A manufacturing method is provided.

  Here, the “main surface of the partition wall” means a surface having the largest area among the surfaces of the partition wall, and usually corresponds to a partition wall surface facing the exhaust gas flow path.

  In addition, when the main surface of the partition wall is a curved surface, the relationship between the main surface of the partition wall and the cutting progress direction is as follows. Then, a surface that contacts the partition wall extending in the axial direction of the honeycomb structure including the tangent line on one line is assumed, and the cutting progress direction is defined in relation to this surface.

  In the present invention, it is preferable to cut the partition walls of the honeycomb fired body at an angle of 15 to 75 ° with respect to the main surface of the partition walls, and an angle of 25 to 65 °. More preferred.

  Moreover, in this invention, it is preferable to provide a groove | channel or a hole in the area | region where the projection area in these cell opening end faces becomes 2 times or more with respect to the same projection area of a sensor. However, the groove or hole is preferably provided in a region where the projected area on the cell opening end face is 40% (area%) or less with respect to the total area of the cell opening end face. More preferably, it is provided in an area of 0.5 to 20% (volume%) with respect to the total volume. The groove or hole is preferably provided via the central axis of the honeycomb fired body.

  Moreover, it is preferable that bordering is provided in the area | region used as 0.2-30% (volume%) with respect to the whole volume of a honeycomb-shaped sintered body.

  Here, the “projected area on the cell opening end face” means that the groove or hole is projected in a direction perpendicular to the cell opening end face on the cell opening end face in the honeycomb fired body before forming the groove or hole. Means the projected area. Further, the “total volume of the honeycomb-shaped fired body” means the total volume of the honeycomb-shaped fired body including the space occupied by the cells and the pores, and the volume of the groove, hole, or border is the honeycomb before cutting. It means the volume obtained by subtracting the entire volume of the honeycomb-like fired body after forming these by cutting from the overall volume of the shaped fired body.

  In the method for manufacturing a honeycomb structured body of the present invention, as described above, a part of the partition walls of the honeycomb fired body is cut to provide at least one of a groove, a hole, and an edge, so that the honeycomb structure is mounted directly below the exhaust manifold together with the sensor. Even in this case, it is possible to obtain a honeycomb structure that exhibits desired purification performance while minimizing the reduction in catalyst capacity while disposing the sensor at an appropriate position.

  Further, the honeycomb structure manufacturing method of the present invention cuts the partition walls of the honeycomb-shaped fired body in the cutting progress direction oblique to the main surface of the partition walls, so that the stress during the cutting is relieved and the partition wall breaks. It is possible to form a groove, a hole, or an edge having a desired shape without generating the above. Therefore, it can be preferably applied particularly when a honeycomb structure having a thickness of 0.01 to 0.30 mm is manufactured.

  In the method for manufacturing a honeycomb structured body of the present invention, it is preferable that the groove or the edge cut as described above is provided on the cell opening end face.

  As described above, according to the present invention, it is possible to provide a method for manufacturing a honeycomb structure capable of obtaining a desired purification performance while minimizing a reduction in catalyst capacity while securing a sensor installation space.

Hereinafter, embodiments of the present invention will be specifically described.
In the method for manufacturing a honeycomb structured body of the present invention, first, a clay-based body mainly composed of ceramics and / or metal is formed to obtain a honeycomb-shaped formed body.

  Examples of ceramics that are the main component of clay include silicon, titanium, zirconium, silicon carbide, boron carbide, titanium carbide, zirconium carbide, silicon nitride, boron nitride, aluminum nitride, alumina, zirconia, mullite, and cordierite forming raw materials. , At least one selected from the group consisting of aluminum titanate and sialon. Examples of the metal that is the main component of the clay include at least one selected from the group consisting of copper, aluminum, iron, nickel, and silicon. In addition, these ceramics and metals can be used individually by 1 type or in combination of 2 or more types.

  The clay may contain components other than ceramics and metals as necessary, and may contain, for example, a binder, a crystal growth aid, a dispersant, or a pore-forming agent. Examples of the binder include hydroxypropylmethylcellulose, methylcellulose, hydroxyethylcellulose, carboxymethylcellulose, and polyvinyl alcohol. Examples of the crystal growth aid include magnesia, silica, yttria, and iron oxide. . Examples of the dispersant include ethylene glycol, dextrin, fatty acid soap, or polyalcohol. Examples of the pore-forming agent include graphite, wheat flour, starch, phenol resin, or polyethylene terephthalate. be able to.

  The clay can be obtained by mixing a predetermined amount of water with a raw material containing ceramics and / or metal as a main component, adding a binder or the like as necessary, and then kneading by a usual method.

  In the production method of the present invention, there is no particular limitation on the method for molding the clay, but extrusion molding is preferable in terms of excellent mass productivity. For example, a ram type extrusion molding device, a biaxial screw type continuous extrusion molding device, etc. It is preferable to perform extrusion molding from a mold having a desired pattern using the above extrusion molding apparatus.

  In the present invention, the thickness of the partition wall of the honeycomb-shaped formed body is not particularly limited, and it can be applied to a honeycomb structure having a thin partition wall which has been manufactured in recent years due to demands for pressure loss and reduction of heat capacity. is there. Specifically, the partition wall thickness can be set to 0.01 to 0.30 mm.

Examples of the cells formed by the partition walls of the honeycomb-shaped formed body include, for example, those having a circular, elliptical, oval, quadrangular, octagonal, or left-right asymmetrical irregular shape. In addition, the cell density of the cells formed by the partition walls is 6 to 2000 cells / square in consideration of the strength and effective GSA (geometric surface area) of the obtained honeycomb structure and the pressure loss when the gas flows. Inch (0.9 to 311 cells / cm ² ) is preferable, and 50 to 400 cells / square inch (7.8 to 62 cells / cm ² ) is more preferable.

  In addition, the shape of the honeycomb-shaped formed body may be a preferable shape according to the purpose. For example, the cross-sectional shape in the radial direction may be a triangle, a rectangle, a square, a rhombus, a trapezoid, an ellipse, a circle, a track circle, An elliptical shape or a semicircular shape can be used.

  In the method for manufacturing a honeycomb structured body of the present invention, the honeycomb formed body is then dried and fired, and then the partition walls of the obtained honeycomb fired body are cut in a cutting progress direction oblique to the main surface of the partition walls. And providing at least one kind of groove, hole or border.

  There is no particular limitation on the drying method of the honeycomb-shaped formed body, and examples thereof include hot air drying, microwave drying, dielectric drying, reduced pressure drying, vacuum drying, freeze drying and the like. Among them, dielectric drying, microwave or It is preferable to perform hot air drying alone or in combination. Moreover, what is necessary is just to select desired conditions suitably according to the kind of material to be used about baking conditions.

  In the present invention, the partition wall may be cut with the cutting progress direction oblique to the main surface of the partition wall, but the cutting progress direction may be cut at an angle of 15 to 75 ° with respect to the main surface of the partition wall. It is preferable to cut at an angle of 25 to 65 °.

  If cutting is performed in the cutting progress direction that is an angle in this range, as shown in FIG. 1, the shearing force 18 generated during the cutting is substantially evenly distributed. Even so, the desired groove 10 or the like can be formed without causing shear damage to the partition wall 2 during cutting.

  As shown in FIGS. 2A and 2B, the angle of the cutting progress direction with respect to the main surface of the partition wall is an angle perpendicular to the horizontal direction, that is, the axial direction Y of the honeycomb fired body 41. However, the main surface 3 of the partition wall 2 may have an angle other than the vertical direction. As shown in FIGS. By setting an angle other than perpendicular to the axial direction Y, the main surface 3 of the partition wall extending in the same direction as the axial direction Y may have an angle other than the perpendicular direction.

  In the present invention, the size of the groove, hole, or rim is not limited to a range in which the sensor can be appropriately installed, but the honeycomb structure obtained has a reduction in purification performance due to a reduction in useless catalyst supporting area. It is preferable to set the pressure range so that no significant increase in pressure loss occurs during sensor installation.

  Specifically, the groove or hole is preferably provided in a region where the projected area on the cell opening end face is twice or more the same projected area of the sensor, and preferably provided in a region where the projected area is 3 times or more. More preferred. As shown in FIG. 4B, if a groove 10 or a hole (not shown) is provided in a region having the projected area, the projected area on the cell opening end face of the groove 10 shown in FIG. Unlike the case where the sensor is provided in a region that is less than twice the same projected area of the sensor, the region 16 in which the flow of the exhaust gas 20 is hindered by the presence of the sensor 5 can be significantly reduced. Therefore, the sensor can be installed without causing a significant increase in pressure loss.

However, in the present invention, it is preferable to provide the groove or hole in a region where the projected area of these cell opening end faces is 40% (area%) or less with respect to the total area of the cell opening end faces.
As shown in FIG. 5, in the portion 19 of the honeycomb structure corresponding to the projection plane, the flow path is shorter than the other portions, and as a result, the flow passage resistance is reduced, and the exhaust gas 20 tends to concentrate on the portion 19. . For this reason, if the projected area at the cell opening end face of the groove 10 or hole (not shown) is larger than the above, the purification performance and the thermal shock resistance are significantly reduced due to the non-uniform gas flow velocity distribution.

  In the present invention, the groove or hole is preferably provided in a region of 0.5 to 20% (volume%) with respect to the total volume of the honeycomb fired body, and preferably 0.5 to 10% (volume%). It is more preferable to provide in the area | region which becomes. If the area | region which provided the groove | channel or the hole is this range, since required catalyst capacity | capacitance can be ensured, desired purification performance can be maintained.

  On the other hand, the border is preferably provided in a region that is 0.2 to 30% (volume%) with respect to the total volume of the honeycomb fired body in the same point as the groove or hole, and is 0.2 to 15%. It is more preferable to provide in a region where (volume%).

  In the present invention, the shape or position of the groove, hole or rim is provided in consideration of the shape and installation position of the sensor from the viewpoint of preventing unnecessary reduction of the catalyst carrying area and enabling accurate detection of the sensor. It is preferable.

  For example, regarding the shape of the groove or hole, if the sensor has a shape approximate to a cylindrical shape, a cylindrical hole 1 corresponding to the shape of the sensor 5 is provided as shown in FIG. a) (b) (c) As shown in FIG. 8 and FIG. 9, provision of a semi-cylindrical groove 10 corresponding to the semi-cylindrical portion of the sensor 5 reduces unnecessary catalyst loading area. It is preferable in terms of prevention.

  Further, the shape of the hole is preferably a cylindrical shape, an elliptical column shape, or a semi-elliptical column shape from the viewpoint of suppressing a decrease in thermal shock resistance of the honeycomb structure. In addition, the shape of the groove is also preferably a semi-cylindrical shape, a semi-elliptical column shape, or a half-bottom shape, in particular, when forming the groove, in addition to easy work and no breakage of the partition wall, The half-bottom shape is preferable in that a decrease in thermal shock resistance of the honeycomb structure can be significantly suppressed.

  When a groove having a half ship bottom shape or the like is provided, as shown in FIG. 10B, the groove 10 is formed in the opening 15 in the outer peripheral side surface 14 of the groove 10. It is preferable that the radius of curvature (R1) is within the range of the conditional expression (1) shown below because the decrease in thermal shock resistance of the honeycomb structure can be significantly suppressed.

  “In the above conditional expression (1), L means the width of the groove.”

  Similarly, as shown in FIG. 10 (c), when the semi-bottom-bottomed groove 10 is provided, the groove 10 has a cross-section in the cross-sectional shape in the honeycomb structure axial direction Y including the bottommost portion 10c of the groove. The radius of curvature (R2) of the curved portion 10b of the shape is preferably in the range of the following conditional expression (2).

  “In the above conditional expression (2), d means the depth of the groove in the axial direction Y of the honeycomb structure.”

  On the other hand, as the position of the groove or hole, since it is preferable for accurate measurement to place the sensing part of the sensor near the central axis of the honeycomb structure having the largest flow rate of exhaust gas, for example, as shown in FIG. Thus, it is preferable to provide via the central axis Z of the honeycomb fired body 41.

  Further, as the shape of the edging, as shown in FIG. 12, a plane (slope) is formed from the cell opening end face 8 to the outer peripheral side surface 14 of the honeycomb fired body 41, as shown in FIG. It is preferable that the concave curved surface is formed from the cell opening end surface 8 to the outer peripheral side surface 41 of 41 because the decrease in the thermal shock resistance of the honeycomb structure 51 can be significantly suppressed.

  In addition, in the honeycomb structure provided with these borders, for example, as shown in FIG. 14, a plurality of honeycomb structures 51 and 52 are arranged so that the borders 11 and 12 face each other. An arrangement | positioning area | region can be ensured.

  In the present invention, as a method for forming the groove, hole or edging, it is preferable that the groove or the like is formed by cutting or the like so that the stress on the partition wall is small and the groove or the like can be easily formed. Specifically, in the case of a groove or edging, a grinder may be used, and in the case of a hole, a drill or the like may be used. In addition, a mill such as an end mill may be used.

  The manufacturing method of the honeycomb structure of the present invention is as described above. The manufacturing method may be applied when manufacturing a honeycomb filter such as a diesel particulate filter (DPF). The present invention can be preferably applied to a honeycomb structure as a catalyst carrier that requires walling.

In this invention, it is a schematic diagram which shows typically one Embodiment provided with the groove | channel, and demonstrates the relationship between a cutting progress direction and a shear force. In this invention, it is explanatory drawing which shows typically one Embodiment provided with the hole, (a) is a top view, (b) is a side view. In this invention, it is explanatory drawing which shows typically another embodiment provided with the hole, (a) is a top view, (b) is a side view. In the present invention, the relationship between the projected area at the cell opening end face of the groove and the same area of the sensor will be described. (A) The projected area at the cell opening end face of the groove is twice the same area of the sensor. (B) shows an example that becomes twice or more. In this invention, it is a side view which shows typically embodiment which provided the groove | channel, and demonstrates the relationship between the projection area in the cell opening end surface of a groove | channel, and the flow of exhaust gas. In this invention, it is explanatory drawing which shows typically one Embodiment provided with the groove | channel, (a) is a top view, (b) is a side view, (c) is a front view. It is a schematic diagram which shows one example which installed the honeycomb structure provided with the hole manufactured by this invention in the converter system. It is a schematic diagram which shows the other example which installed the honeycomb structure provided with the groove | channel manufactured by this invention in the converter system. FIG. 6 is a schematic view showing still another example in which a honeycomb structure provided with grooves manufactured according to the present invention is installed in a converter system. In this invention, it is explanatory drawing which shows typically one embodiment which provided the groove | channel, (a) is a perspective view, (b) is a partially expanded front view, (c) is (a). It is a partially expanded view of XX 'cross section in. In this invention, it is explanatory drawing which shows typically one Embodiment which provided the hole via the central axis of the honeycomb-shaped fired body, (a) is a top view, (b) is a side view. . In this invention, it is explanatory drawing which shows typically one Embodiment provided with the edging, (a) is a top view, (b) is a side view. In the present invention, it is a side view schematically showing another embodiment provided with a border. It is a schematic diagram which shows the example which installed the honeycomb structure provided with the border manufactured by this invention in the converter system.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 ... Hole, 2 ... Partition, 3 ... Main surface of partition, 5, 6 ... Sensor, 8, 9 ... Cell opening end surface, 10 ... Groove, 10a ... Curve part, 10b ... Curve part, 10c ... Bottom part, 11, DESCRIPTION OF SYMBOLS 12 ... Edging, 14 ... Outer peripheral side surface, 15 ... Opening part, 16 ... Area | region where the flow of waste gas is prevented, 18 ... Shear force, 19 ... The site | part of the honeycomb structure corresponding to a projection surface, 20 ... Exhaust gas, 41, 42 ... Honeycomb fired bodies, 51, 52... Honeycomb structures.

Claims (9)

Forming a kneaded clay mainly composed of ceramics and / or metal to obtain a honeycomb-shaped formed body;
After drying and firing the honeycomb formed body,
The partition walls of the obtained honeycomb-shaped fired body are cut in the cutting progress direction oblique to the main surface of the partition walls, and at least one of grooves, holes, or borders is provided in the honeycomb-shaped fired body as a sensor insertion region. A method for manufacturing a honeycomb structure, comprising:   The method for manufacturing a honeycomb structure according to claim 1, wherein the partition walls of the honeycomb-shaped fired body are cut at an angle of 15 to 75 degrees with respect to a main surface of the partition walls.   The method for manufacturing a honeycomb structured body according to claim 1 or 2, wherein the groove or the hole is provided in a region where a projected area at the end surface of the cell opening is twice or more than the projected area of the sensor.   The manufacturing of the honeycomb structure according to claim 3, wherein the groove or the hole is provided in a region in which a projected area on the cell opening end face is 40% (area%) or less with respect to a total area of the cell opening end face. Method.   The manufacturing of the honeycomb structure according to any one of claims 1 to 4, wherein the groove or the hole is provided in a region of 0.5 to 20% (volume%) with respect to the total volume of the honeycomb-shaped fired body. Method.   The method for manufacturing a honeycomb structure according to any one of claims 1 to 5, wherein the groove or the hole is provided via a central axis of the honeycomb fired body.   The method for manufacturing a honeycomb structure according to claim 1 or 2, wherein the border is provided in a region that is 0.2 to 30% (volume%) with respect to the total volume of the honeycomb-shaped fired body.   The method for manufacturing a honeycomb structured body according to any one of claims 1 to 7, wherein the partition walls of the honeycomb fired body have a thickness of 0.01 to 0.30 mm.   The method for manufacturing a honeycomb structured body according to any one of claims 1 to 8, wherein the groove or the edging is provided on a cell opening end face.

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