Patent Grant
8968638
1. Field of the Invention
The present invention relates to an apparatus for injecting slurry and a method therefor, specifically to the apparatus for injecting slurry capable of suppressing the generation of remained slurry in the injection hole, and to the method for injecting slurry capable of decreasing the amount of the remained slurry and forming the surface of injected slurry in various shapes with high accuracy.
2. Description of the Related Art
Honeycomb filters made of ceramic are used to collect dust and other particulate matter contained in exhaust gas generated from automobile and in incineration flue gas generated during incineration of waste. In particular, a diesel particulate filter (hereinafter referred to from time to time as “DPF”) is used to remove efficiently the particulate matter (hereinafter referred to from time to time as “PM”) such as soot discharged from internal combustion engines.
To increase the collection effect of particulate matter, DPF is normally provided with plugging at one end face and at the other end face of a cell so as to provide a complementary checkered-flag pattern thereon (for example, refer to Japanese Patent Laid-Open No. 2007-296512). That type of plugging is prepared by sticking an adhesive sheet or the like to one end face of the DPF before firing, by applying a mask while opening a hole on the adhesive sheet or the like only at a portion corresponding to the cells to be plugged by laser machining utilizing image processing, or the like, then by immersing the end face in a slurry via the mask, followed by firing the DPF, (for example, refer to Japanese Patent Laid-Open No. 2001-300922).
The depth of slurry being introduced in the cell to be plugged is preferably uniform because the uniform depth allows suppressing the generation of local shrinkage on firing the DPF, thus enabling the DFP to suppress deterioration. To introduce the slurry to cells to be plugged at a uniform depth, it is preferable for the surface of the slurry used for immersion to be formed in a planar state at a certain height.
The surface of the slurry used for immersion, however, was formed in a planar state using a wheel in the related art so that differences in the surface height appeared depending on the skill of the workers. To this point, there has been developed an apparatus for injecting slurry that can form a uniform height of the surface of slurry in a planar state without using wheel.
The present invention has been perfected to solve these problems of the related art, and an issue of the present invention is to provide an apparatus for injecting slurry capable of suppressing the generation of remained slurry in the injection hole. Another issue of the present invention is to provide a method for injecting slurry capable of decreasing the amount of the remained slurry and forming the surface of injected slurry in various shapes with high accuracy.
The inventors of the present invention conducted detail studies to solve the above issues, found that the above issues can be solved by providing the second member with convex sections, each of which has an injection hole formed therein and has a specified length thereof and a specified spacing therebetween, and thus perfected the present invention. Furthermore, the inventors of the present invention found that the above issues can be solved by using the apparatus for injecting slurry according to the present invention, and by injecting slurry at a specified distance between the flat plane and the protruded end of the convex section, thereby perfected the present invention.
That is, the present invention provides an apparatus for injecting slurry and a method for injecting slurry, described below.
[1] An apparatus for injecting slurry, comprising: a first member having a cavity therein; and a second member having a plurality of convex sections, each of the convex sections having an injection hole formed therein communicating with the cavity, wherein the protrusion length of the convex section is in a range from 3 to 5 mm, and the distance between centers of adjacent convex sections is in a range from 3 to 13 mm.
[2] The apparatus for injecting slurry according to [1], wherein the diameter of the injection hole formed inside of the convex section at outer peripheral part of the second member and the diameter of the injection hole formed inside of the convex section at central part of the second member are not the same with each other.
[3] The apparatus for injecting slurry according to [1] or [2], wherein the diameter of the injection hole formed inside of the convex section at outer peripheral part of the second member is larger than the diameter of the injection hole formed inside of the convex section at central part of the second member.
[4] The apparatus for injecting slurry according to [1] or [2], wherein the diameter of the injection hole successively widens or narrows from the central part toward the outer peripheral part of the second member.
[5] The apparatus for injecting slurry according to any of [1] to [4], wherein the length of the second member in the injection direction at the outer peripheral part thereof and the length of the second member in the injection direction at the central part thereof are not the same with each other.
[6] The apparatus for injecting slurry according to any of [1] to [5], wherein the length of the second member in the injection direction at the outer peripheral part thereof is shorter than the length of the second member in the injection direction at the central part thereof.
[7] The apparatus for injecting slurry according to any of [1] to [5], wherein the length of the second member in the injection direction successively elongates or shortens from the central part toward the outer peripheral part of the second member.
[8] A method for injecting slurry, comprising: a filling step which comprises filling a slurry in the cavity of the apparatus for injecting slurry according to any of [1] to [7]; and, an injection step which comprises above a flat plane in a container, causing a protruded end of the convex section to face the flat plane with the flat plane and the protruded end of the convex section spaced apart from each other by a distance of 3 to 10 mm, and injecting the slurry onto the flat plane.
[9] The method for injecting slurry according to [8], wherein the injection step is the step of holding the slurry injected onto the flat plane at a height ranging from 1 to 10 mm thereon.
[10] The method for injecting slurry according to [8] or [9], wherein the viscosity of the slurry is in a range from 10 to 1000 dP·s.
The apparatus for injecting slurry according to the present invention provides an effect of capable of suppressing the generation of remained slurry in the injection hole.
In addition, the method for injecting slurry according to the present invention provides an effect of capable of decreasing the amount of the remained slurry and forming the surface of injected slurry in various shapes with high accuracy.
1, 31, 41, 51, 61, 71, 81: Apparatus for injecting slurry, 2: First member, 3, 33, 43, 53, 63, 73, 83: Second member, 4: Cavity, 5, 55, 65, 75, 85: Injection hole, 6, 56, 66, 76, 86: Convex section, 35, 45: Injection hole at the outer peripheral part of the second member, 36, 46: Convex section at the outer peripheral part of the second member, 37, 47: Injection hole at the central part of the second member, 38, 48: Convex section at the central part of the second member, 7: Introduction opening, d: Protrusion length, l: Distance between centers, f: Length in the injection direction, 10: Container, 11: Flat plane, 12: Protruded end, 13: Slurry, W: Distance between the flat plane and the protruded end of the convex section, T: Height of the slurry, 20: Apparatus for injecting slurry, 21: Remained slurry
The preferred embodiments for carrying out the present invention are described below. However, the present invention is not restricted to the following embodiments and it should be construed that there are also included, in the present invention, those embodiments in which appropriate changes, improvements, etc. have been made to the following embodiments based on the ordinary knowledge possessed by those skilled in the art, as long as there is no deviation from the gist of the present invention.
1. Apparatus for Injecting Slurry
1.1 First Member
The first member 2 is the one having the cavity 4 therein. The size of the cavity 4 is arbitrary if only the size allows the filling slurry to flow uniformly into the injection holes 5 of the second member 3. In
1.2 Second Member
The second member 3 has a plurality of convex sections 6, each of the convex sections having an injection hole 5 therein communicating with the cavity 4, wherein the protrusion length d of the convex section 6 and the distance l between centers of adjacent convex sections 6 are at a specified value, respectively. With those convex sections 6, generation of the remained slurry in the injection hole 5 during the injection of slurry from the injection hole 5 can be suppressed.
The protrusion length d of the convex section 6 is in a range from 3 to 5 mm, preferably 3.5 mm or more and below 5 mm, and more preferably 4 mm or more and below 5 mm. If the protrusion length d is outside the above range, the amount of remained slurry in the apparatus for injecting slurry 1 may increase. In
The distance l between centers of adjacent convex sections 6 is in a range from 3 to 13 mm, preferably from 4 to 12 mm, and more preferably from 6 to 10 mm. If the distance l between centers is outside the above range, there may occur the case of increase in the amount of slurry remained in the apparatus for injecting slurry 1, and the case of failing in forming accurately the surface of slurry in various shapes. Although it is preferable for the distance l between centers to be uniform over the whole area of bottom of the second member 3, it is possible to arbitrarily select the distance by, for example, shortening thereof at the central part or shortening thereof at the outer peripheral part, responding to the use object. When the distance l between centers is not brought to uniform, it is necessary that 30% or more of all of the injection holes 5 are within the above range, preferably 50% or more thereof are within the above range, and most preferably all of the injection holes are within the above range.
If the distance between centers is within the above range, the distance between centers at the outer peripheral part of the second member and the distance between centers at the central part of the second member may not be the same with each other, and more preferably the distance between centers at the outer peripheral part of the second member is larger than the distance between centers at the central part of the second member. The selection of arbitrary distance between centers allows forming the surface of the injected slurry suitably and accurately.
As illustrated in
The shape of the injection hole is not specifically limited, and for example the shape thereof includes circular, quadrangular, or triangular shape. For example, use of a polygonal shape injection hole having equivalent wet side-length with that of the circular shape attains similar quality with that attained by injection through circular injection hole. The arrangement of the injection holes, (or the arrangement of the convex sections), is not specifically limited either, and arbitrarily selected arrangement is applicable, including random arrangement, radial arrangement, and grid arrangement. Among these arrangements, grid arrangement is preferred from the standpoint such that the distance between injection holes (or the distance l between centers) is easily controlled.
2. Method for Injecting Slurry
The method for injecting slurry according to the present invention has the filling step which contains filling the slurry in the cavity of the apparatus for injecting slurry described in “1. Apparatus for injecting slurry”, and the step which contains causing a protruded end of the convex section to face the flat plane with the flat plane and the protruded end of the convex section spaced apart from each other by a distance of 3 to 10 mm, and injecting the slurry onto the flat plane. By injecting slurry in the above procedure, the amount of slurry remained in the apparatus for injecting slurry can be decreased, and the surface of the injected slurry can be formed in various shapes with high accuracy.
As illustrated in
2.1 Filling Step
The filling step is the step of filling the slurry in the cavity 4 existing inside of the first member 2 of the apparatus for injecting slurry 1. The method for filling the slurry is not specifically limited, and for example, a method of filling the slurry via the introduction hole 7 is applied.
The slurry can be prepared by kneading at least a ceramic powder and a disperser for slurry. The kind of the ceramic powder is not specifically limited, and for example, a silicon carbide powder and a cordierite powder can suitably be applied. Preferable disperser for slurry includes organic solvent such as acetone, ethanol, and methanol, and water or the like.
The slurry may further contain, as needed, additives such as binder and deflocculant. The binder may be a resin such as polyvinylalcohol (PVA) and a polysaccharide such as starch. Combined use of a thermal-gel-setting binder having a characteristic of gelling under heating is more preferable. A preferable thermal-gel-setting binder is methylcellulose.
The viscosity of slurry is preferably in a range from 10 to 1000 dP·s, more preferably from 50 to 500 dP·s, and most preferably from 100 to 300 dP·s. If the viscosity is below 10 dP·s, the slurry cannot be held at a specified height T on the flat plane 11 in some cases. If the viscosity exceeds 1000 dP·s, the shape of the surface of the injected slurry cannot be formed in various shapes with high accuracy in some cases.
2.2 Injection Step
The injection step is the step of causing the apparatus for injecting slurry 1 to face the protruded end 12 of the convex section 6 spaced apart from each other by a specified distance W above the flat plane 11 of the container 10, and of injecting the slurry filled in the cavity 4 inside of the first member 2 of the apparatus for injecting slurry 1 onto the flat plane 11 via the injection hole 5. The injection step is preferably the step of holding the slurry 13 at a height T in a range from 1 to 10 mm on the flat plane 11. There is also a suitable method in which the slurry is injected while measuring the height T so as to attain the height T ranging from 1 to 10 mm on the flat plane 11. To obtain the specified height T more simply in a mass-production line, however, there may be adopted a method in which a preliminary survey is given to determine the volume of filling slurry in the filling step to attain the specified height T by injecting the filled slurry, and the control of the height T is done by the filling amount of the slurry.
The distance W between the flat plane 11 and the protruded end 12 of the convex section 6 is in a range from 3 to 10 mm, more preferably from 4 to 9 mm, and most preferably from 5 to 8 mm. If the distance W is outside the above range, the amount of slurry remained in the apparatus for injecting slurry 1 increases, or the surface shape of the injected slurry gives a dispersion in some cases.
The height T of the slurry 13 held on the flat plane 11 is preferably in a range from 1 to 10 mm, more preferably from 2 to 9 mm, and most preferably from 3 to 8 mm. If the height T is below 1 mm, the amount of slurry remained in the apparatus for injecting slurry 1 increases in some cases. If the height T exceeds 10 mm, the amount of slurry remained in the apparatus for injecting slurry 1 increases, or the shape of the surface of the injected slurry cannot be formed in various shapes with high accuracy, in some cases. The height T can be determined by a simple method such as mounting a gauge on an inside face of the container or erecting a gauge after injecting the slurry. The height of slurry is determined immediately after the slurry injection. If the injected slurry holds as-injected shape, the apex height is adopted as the slurry height. If the injected slurry does not hold as-injected shape, the maximum height in the shape immediately after the injection is adopted as the slurry height.
A preferable relation between the height T of the slurry 13 and the distance W from the slurry 13 is T≦W, more preferably T≦0.9 W, and most preferably T≦0.8 W. The height T is not necessarily required to be uniform (flat) over the whole flat plane, and arbitrary selection can be applied such as widened central part (convex shape) and widened outer peripheral part (concave shape), depending on the use object. In that case, it is necessary to have a portion in which at least the height T satisfies the above range, and it is more preferable that the portion of the lowest height T satisfies the above range. The height T of both portions most preferably satisfies the above range. The height T of the slurry 13 can be controlled by the injection length, the distance between centers, a gradient in diameter of the injection holes, and the distance between the flat plane and the ejection end of the apparatus for injecting slurry.
The slurry injected using the method for injecting slurry according to the present invention is suitably used as, for example, a plugging member for plugging a honeycomb structure. Different from the conventional method, the injected slurry can form the surface of slurry in various shapes with high accuracy. Consequently, on using the honeycomb structure as DPF, arbitrary selection of filling the plugging member is applied such as shallower plugging for a cell of large pressure loss, and deeper plugging for a cell of small pressure loss.
The present invention will be described in detail in the following referring to the examples. The present invention, however, is not limited to these examples. The term “part” given in Examples and Comparative Examples is mass basis unless otherwise notified. The method for determining physical properties and the method for evaluating characteristics are described below.
[Shape of Surface of Slurry]
The surface of slurry injected onto the flat plane of the container was determined by a laser displacement meter (trade name “LK-G35”, manufactured by KEYENCE). For one shot of injection, when the dispersion of high-low height of the injected slurry height T set at the central part (within 50 mm in diameter from the center) was within ±0.2 mm, the evaluation was given to “small dispersion”, and when the dispersion thereof was than ±0.2 mm or more, the evaluation was given to “large dispersion”. Furthermore, for the case of evaluation of “small dispersion”, when the difference in the height T between the central part and the outer peripheral part (5 mm inside from the outermost periphery of the injected slurry) was below 0.3 mm, the evaluation was given to “flat”, when the height at the central part was higher than the height at the outer peripheral part by 0.3 to 0.5 mm, the evaluation was given to “somewhat convex”, when the height at the central part was higher than the height at the outer peripheral part by 0.5 mm or more, the evaluation was given to “convex”, when the height at the central part was lower than the height at the outer peripheral part by 0.3 to 0.5 mm, the evaluation was given to “somewhat concave”, and when the height at the central part was lower than the height at the outer peripheral part by 0.5 mm or more, the evaluation was given to “concave”.
[Evaluation of Amount of Injected Slurry]
The difference in mass between the filled slurry and the injected slurry was determined by an electronic balance (trade name “GX-12X”, manufactured by A & D Co., Ltd.) When the difference was below 5% by mass, the evaluation was given to “good”, when the difference was in a range from 5 to 8% by mass, the evaluation was given to “average”, and when the difference was exceeding 8% by mass, the evaluation was given to “poor”.
[Viscosity of Slurry (dP·s)]
The viscosity of slurry was determined by a rotary viscometer (trade name “VT-04F”, manufactured by RION Co., Ltd.).
(Preparation of Slurry)
The slurry was prepared by adding and kneading 100 parts of ceramic powder, 50 parts of water, and 5 parts of methylcellulose.
The apparatus for injecting slurry according to the present invention was used to inject thus prepared slurry having a viscosity of 200 dP·s. In detail, the applied apparatus for injecting slurry was the apparatus 71 for injecting slurry with the bottom (provided with the injection holes arranged in grid pattern) as illustrated in
The slurry was injected in a similar procedure with that of Example 1 except that the condition given in Table 1 was applied. The evaluation is also given in Table 1.
The slurry was injected in a similar procedure with that of Example 1 except that the condition given in Table 2 was applied. The evaluation is also given in Table 2.
The slurry was injected in a similar procedure with that of Example 1 except that the condition given in Table 3 was applied. The evaluation is also given in Table 3.
When the slurry was injected using the method for injecting slurry according to the present invention, the evaluation of the amount of injected slurry was “good” or “average” (Examples 9 and 14) independent of the size of the apparatus for injecting slurry, the shape of injection hole, the gradient in diameter of the injection holes, and the injection length of the convex section, and the height difference of slurry at central part was “small dispersion”, thus the shape of the surface of slurry could be brought to the desired shape or near the desired shape (Examples 9 and 14). To the contrary, when the slurry was injected not using the method for injecting slurry of the present invention, specifically when the protrusion length of the convex section was not in the desired range (Comparative Examples 1 to 4), and when the height of injected slurry was short (Comparative Example 7), the evaluation of the amount of injected slurry was “poor”. When the distance between centers of adjacent convex sections was not in the desired range (Comparative Examples 5 and 6), when the height of injected slurry was high (Comparative Example 8), or when the distance between the flat plane of the container and the protruded end of the convex section of the container was outside the desired range (Comparative Examples 9 and 10), the evaluation of the amount of injected slurry was “poor”, and further the difference in height of the slurry at the central part was “large dispersion”, thus failing to attain the desired shape of surface of the slurry. When slurry having extremely high or extremely low viscosity was injected (Comparative Examples 5 and 6), the evaluation of the amount of injected slurry was “average”, and the shape of the surface of injected slurry was not able to attain the desired shape, though the difference in height of the slurry at the central part was “small dispersion”.
The slurry was injected using the conventional apparatus for injecting slurry, or the apparatus for injecting slurry having no convex section.
The results of Example 1 and Comparative Example 11 show that the injection of slurry using the apparatus for injecting slurry according to the present invention can suppress the generation of remained slurry in the injection hole.
The apparatus for injecting slurry according to the present invention and the method for injecting slurry using the same can be economically and efficiently used to provide plugging of DPF and the like. Accordingly, the apparatus and the method of the present invention are suitably applicable to the manufacture of filter used in environmental measures such as pollution prevention, in product-collection from high temperature gas, and the like.
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