WO2015056651A1

WO2015056651A1 - Exhaust gas purification device

Info

Publication number: WO2015056651A1
Application number: PCT/JP2014/077242
Authority: WO
Inventors: 寿安藤; 将司萩野; 健蔵斎木
Original assignee: イビデン株式会社
Priority date: 2013-10-15
Filing date: 2014-10-10
Publication date: 2015-04-23
Also published as: JPWO2015056651A1; JP6393687B2

Abstract

This exhaust gas purification device is provided with a columnar exhaust gas treatment body, a casing which comprises a tubular body that houses the exhaust gas treatment body, and a mat which comprises inorganic fibers and is inserted between the exhaust gas treatment body and the casing. This exhaust gas purification device is characterized in that the contour of the exhaust gas treatment body, in a cross section perpendicular to the longitudinal direction, comprises three to six corner sections and connecting sections which connect the corner sections of the exhaust gas treatment body; the corner sections of the exhaust gas treatment body are curved, the connecting sections of the exhaust gas treatment body are straight or curved, and the distance from the corner sections of the exhaust gas treatment body to the inner peripheral surface of the casing is greater than the distance from the connecting sections of the exhaust gas treatment body to the inner peripheral surface of the casing.

Description

Exhaust gas purification device

The present invention relates to an exhaust gas purification apparatus.

The exhaust gas discharged from an internal combustion engine such as a diesel engine contains particulate matter (hereinafter also referred to as PM) such as soot, and in recent years, this PM has a problem that it harms the environment and the human body. It has become. Further, since the exhaust gas contains harmful gas components such as CO, HC and NOx, there is a concern about the influence of the harmful gas components on the environment and the human body.

Therefore, as an exhaust gas purification device that collects PM in exhaust gas or purifies harmful gas components, an exhaust gas treatment body made of porous ceramics such as silicon carbide or cordierite, and a casing that houses the exhaust gas treatment body Various types of exhaust gas purifying apparatuses have been proposed that are composed of an inorganic fiber mat disposed between an exhaust gas treating body and a casing.

The mat used in this exhaust gas purification device prevents the exhaust gas treating body from being damaged by contact with the casing covering the outer periphery due to vibrations or impacts caused by running of an automobile, etc., and holds the exhaust gas treating body firmly. Therefore, the main purpose is to prevent the exhaust gas treating body from coming out of the exhaust gas purifying apparatus and to prevent the exhaust gas from leaking between the exhaust gas treating body and the casing.

In order for the mat to exhibit the above-described functions, the conventional casing has a shape that is spaced from the outer peripheral surface of the exhaust gas treating body. Then, a mat slightly thicker than the gap between the casing and the exhaust gas treatment body is wound around the exhaust gas treatment body, and the exhaust gas treatment body around which the mat is wound is press-fitted into the casing having the above-described shape to form an exhaust gas purification device. (Patent Document 1).

JP 2010-228302 A

However, the conventional exhaust gas treatment body is not only a circular cross section in the vertical direction of the cells constituting the exhaust gas treatment body, but is close to an elliptical shape or a shape in which a rectangular corner (corner portion) is chamfered. There is something. In particular, when the rectangular corner (corner portion) is close to a rounded chamfered shape, the distance from the corner portion of the exhaust gas treatment body to the inner peripheral surface of the casing is from the portion other than the corner portion of the exhaust gas treatment body to the inner periphery of the casing. In some cases, the distance was smaller than the distance to the surface.
In such a case, when the exhaust gas treating body around which the mat is wound is press-fitted into the casing, there is a problem that a load on the mat disposed at the corner portion increases, and the mat is likely to be cracked or crushed.

As a result of the occurrence of such a problem, the holding ability of the exhaust gas treating body by the mat is lowered, and the gas sealing performance for preventing the leakage of the exhaust gas is also lowered.

The present invention has been made in order to solve the above-described problem, and an exhaust gas purifying apparatus that is unlikely to cause cracks or crushing in the mat, can securely hold an exhaust gas treatment body by the mat, and can prevent leakage of exhaust gas. The purpose is to provide.

In order to achieve the above object, an exhaust gas purification apparatus of the present invention is inserted between a columnar exhaust gas treatment body, a casing made of a tubular body that houses the exhaust gas treatment body, and the exhaust gas treatment body and the casing. An exhaust gas purifying device comprising a mat made of inorganic fibers, wherein the contour of the cross section perpendicular to the longitudinal direction of the exhaust gas treatment body is between 3 to 6 corner portions and the corner portions of the exhaust gas treatment body. The exhaust gas treating body has a curved corner portion, and the exhaust gas treating body connecting portion has a straight line or a curved line. The exhaust gas treating body corner portion and the inner peripheral surface of the casing are connected to each other. Is longer than the distance from the connecting portion of the exhaust gas treating body to the inner peripheral surface of the casing.

In the present specification, the corner portion of the exhaust gas treating body refers to the following portion.
First, in the cross section perpendicular to the longitudinal direction of the exhaust gas treating body, the minimum value of the radius of curvature at the portion where the contour becomes a curve is obtained. In a portion where the contour is a curve, a continuous portion where the radius of curvature is not more than 8 times the minimum value of the radius of curvature is a corner portion of the exhaust gas treating body.
Moreover, in this specification, the connection part of an exhaust gas treatment body means the part of the curve or straight line which connects the said corner parts in the outline of a cross section perpendicular | vertical with respect to the longitudinal direction of an exhaust gas treatment body. . The connecting part of the exhaust gas treating body may be composed of only a straight line or a curved line, or may be composed of both a straight line and a curved line.

In the present specification, the distance from the corner portion of the exhaust gas treating body to the inner peripheral surface of the casing is a distance obtained by the following method.
First, in the outline of the cross section perpendicular to the longitudinal direction of the exhaust gas treating body, a normal line is drawn at one point where the corner portion of the exhaust gas treating body exists. Next, the distance from the point where the corner portion of the exhaust gas treating body intersects the normal line to the point where the inner peripheral surface of the casing intersects the normal line is determined. Next, the point used to draw the normal line is moved along the corner portion of the exhaust gas treating body, and the normal line at each point is drawn. Next, the distance from each point to the point where the inner peripheral surface of the casing intersects the normal line is obtained. The maximum distance among the distances thus obtained is the distance from the corner portion of the exhaust gas treating body to the inner peripheral surface of the casing.

In this specification, the distance from the connection part of the exhaust gas treatment body to the inner peripheral surface of the casing is the minimum distance among the distances from the connection part of the exhaust gas treatment body to the inner peripheral surface of the casing.

In the present specification, the distance from the corner portion of the exhaust gas treating body to the inner peripheral surface of the casing being larger than the distance from the connecting portion of the exhaust gas treating body to the inner peripheral surface of the casing means the following cases.
First, the distance from the corner portion of the exhaust gas treating body to the inner peripheral surface of the casing is obtained by the above method. Next, the connection part of the two exhaust gas treatment bodies adjacent to the corner portion of the exhaust gas treatment body is certified. Next, the distance from the connection part of the exhaust gas treatment body to the inner peripheral surface of the casing is obtained by the above method at the certified connection part of each exhaust gas treatment body.
If the distance from the corner of the exhaust gas treatment body to the inner peripheral surface of the casing is greater than the distance from any connecting portion of the exhaust gas treatment body to the inner peripheral surface of the casing, It means that the distance to the peripheral surface is greater than the distance from the connecting part of the exhaust gas treating body to the inner peripheral surface of the casing.

In the exhaust gas purification apparatus of the present invention, the distance from the corner portion of the exhaust gas treatment body to the inner peripheral surface of the casing is larger than the distance from the connection portion of the exhaust gas treatment body to the inner peripheral surface of the casing.
For this reason, the mat disposed at the corner portion of the exhaust gas treating body receives less pressure from the casing than the mat disposed at the connecting portion of the exhaust gas treating body.
Therefore, the bulk density of the mat disposed at the corner portion of the exhaust gas treating body is not easily increased. For this reason, cracks and crushing are unlikely to occur in the mat.
Further, when the exhaust gas treating body around which the mat is wound is press-fitted into the casing, the load applied to the mat disposed at the corner portion of the exhaust gas treating body is not easily increased, and the mat is not easily cracked or crushed.

For this reason, in the exhaust gas purifying apparatus of the present invention, it is possible to prevent the exhaust gas treating body from being damaged by contact with the casing covering the outer periphery due to vibrations or impacts caused by traveling of the automobile or the like. The holding capacity of the treatment body is high, and the exhaust gas treatment body can be prevented from coming out from the inside of the exhaust gas purification apparatus. Further, it is possible to prevent the exhaust gas from leaking firmly.

In the exhaust gas purification apparatus of the present invention, the distance from the corner portion of the exhaust gas treatment body to the inner peripheral surface of the casing is greater than one time the distance from the connection portion of the exhaust gas treatment body to the inner peripheral surface of the casing, It is desirable to be smaller than 1.4 times.

The effect of the present invention cannot be obtained when the distance from the corner portion of the exhaust gas treating body to the inner peripheral surface of the casing is not more than one time the distance from the connecting portion of the exhaust gas treating body to the inner peripheral surface of the casing.
When the distance from the corner portion of the exhaust gas treatment body to the inner peripheral surface of the casing is 1.4 times or more than the distance from the connection portion of the exhaust gas treatment body to the inner peripheral surface of the casing, it is arranged at the corner portion of the exhaust gas treatment body. Since the pressure from the casing received by the mat is reduced, the holding capacity of the exhaust gas treating body by the mat is not sufficiently increased, and it is difficult to prevent the exhaust gas treating body from coming out of the inside of the exhaust gas purifying apparatus. Further, it becomes difficult to sufficiently prevent the exhaust gas from leaking.

In the exhaust gas purifying apparatus of the present invention, in the cross section perpendicular to the longitudinal direction of the exhaust gas treatment body, the connecting portion of the exhaust gas treatment body may be a straight line or a curve that protrudes outside the exhaust gas treatment body. desirable.

When the shape of the exhaust gas treatment body is as described above, the mat is wound around the exhaust gas treatment body without sagging.
Therefore, the pressure applied to the exhaust gas treating body from the casing via the mat is difficult to decrease. Therefore, it becomes easy to prevent the exhaust gas treating body from coming out of the inside of the exhaust gas purification device. Moreover, it is possible to sufficiently prevent the exhaust gas from leaking.

In the exhaust gas purifying apparatus of the present invention, the number of corner portions of the exhaust gas treating body is preferably four.

When there are four corner portions of the exhaust gas treatment body, the distance from the corner portion of the exhaust gas treatment body to the inner peripheral surface of the casing is shorter than the distance from the connection portion of the exhaust gas treatment body to the inner peripheral surface of the casing. Cheap. Therefore, as explained in the background art, cracks and crushing are likely to occur in the mat disposed in the corner portion of the exhaust gas treating body. However, in the exhaust gas purification apparatus of the present invention, as described above, the distance from the corner portion of the exhaust gas treatment body to the inner peripheral surface of the casing is larger than the distance from the connection portion of the exhaust gas treatment body to the inner peripheral surface of the casing. . For this reason, when the exhaust gas purification apparatus provided with the mat is used, the bulk density of the mat is hardly increased. Therefore, it is possible to prevent the mat from being cracked or crushed.

In the exhaust gas purifying apparatus of the present invention, the outline of the inner peripheral surface of the casing having a cross section perpendicular to the longitudinal direction of the casing has three to six corner portions and a connecting portion that connects the corner portions of the casing. The exhaust gas treating body is preferably housed in the casing such that the corner portion of the exhaust gas treating body and the corner portion of the casing face each other.

In this specification, the corner part of a casing means the following parts.
First, in the cross section perpendicular to the longitudinal direction of the casing, the minimum value of the radius of curvature at the portion where the contour becomes a curve is obtained. In the portion where the contour becomes a curve, a continuous portion where the radius of curvature is not more than 8 times the minimum value of the radius of curvature is the corner portion of the casing.
Moreover, in this specification, the connection part of a casing means the straight part or curved part which connects the corner parts of the said casing in the outline of a cross section perpendicular | vertical with respect to the longitudinal direction of a casing. The connection part of a casing may be comprised only from the straight line or the curve, and may be comprised from both the straight line and the curve. Unless otherwise specified, the outline of the cross section perpendicular to the longitudinal direction of the casing means the outline of the inner peripheral surface of the casing.

In the exhaust gas purifying apparatus having the above configuration, since the corner portion of the exhaust gas treatment body and the corner portion of the casing are opposed to each other, the pressure from the casing on the mat disposed at the corner portion of the exhaust gas treatment body is uniform. Prone. Therefore, it is possible to prevent the bulk density of a part of the mat from increasing, and it is possible to prevent the mat from being cracked or crushed.

In the exhaust gas purification apparatus of the present invention, in the cross section perpendicular to the longitudinal direction of the exhaust gas purification apparatus, the connection part of the exhaust gas treating body and the connection part of the casing are straight lines, and the following relational expression (1) It is desirable to satisfy.
R is the minimum value of the radius of curvature of the corner of the exhaust gas treating body.
The minimum value of the radius of curvature of the corner of the casing is R,
In the connection part of the two exhaust gas treatment bodies adjacent to the corner part of the exhaust gas treatment body, d is the average of the distances from the connection parts of the exhaust gas treatment bodies to the inner peripheral surface of the casing.
R−r <d (1)

In the exhaust gas purifying apparatus of the present invention, the exhaust gas treating body and the casing are designed so that the relational expression (1) is satisfied, whereby the distance from the corner portion of the exhaust gas treating body to the inner peripheral surface of the casing is determined as the exhaust gas treating body. It can be made larger than the distance from the connecting part of the body to the inner peripheral surface of the casing. Therefore, it is possible to prevent the mat from being cracked or crushed when the exhaust gas purifying apparatus provided with the mat is used.

In the exhaust gas purifying apparatus of the present invention, in the cross section perpendicular to the longitudinal direction of the casing, a protrusion that expands toward the outside of the casing is formed on the inner peripheral surface of the casing facing the corner portion of the exhaust gas treating body. It is desirable that the part is formed.

When such a protruding portion is formed, the distance from the corner portion of the exhaust gas treatment body to the inner peripheral surface of the casing is easily made larger than the distance from the connection portion of the exhaust gas treatment body to the inner peripheral surface of the casing. . For this reason, when the exhaust gas purification apparatus provided with the mat is used, the bulk density of the mat is hardly increased. Therefore, it is possible to prevent the mat from being cracked or crushed.

In the exhaust gas purifying apparatus of the present invention, the inorganic fiber is desirably at least one selected from the group consisting of alumina fiber, alumina-silica fiber, silica fiber, and biosoluble fiber.
By using the inorganic fiber of the type described above in the exhaust gas purification apparatus of the present invention, the mat using the inorganic fiber has excellent holding power and excellent mechanical properties of the inorganic fiber. And crushing is difficult to occur, and the exhaust gas treatment body is firmly held.

In the exhaust gas purifying apparatus of the present invention, it is desirable that the mat is further subjected to a needle punching process.

In the exhaust gas purifying apparatus of the present invention, by subjecting the mat to needle punching, entanglement of inorganic fibers occurs, and the strength of the mat is improved. Therefore, cracks and crushing are less likely to occur in the mat.

FIG. 1 is a perspective view schematically showing an example of the exhaust gas purifying apparatus of the present invention. FIG. 2 is a cross-sectional view schematically showing an example of the exhaust gas treating body constituting the exhaust gas purifying apparatus of the present invention, cut in a direction perpendicular to the longitudinal direction of the exhaust gas treating body. FIGS. 3-1 (a) and (b) are cross-sectional views schematically showing an example of the exhaust gas treatment body constituting the exhaust gas purification apparatus of the present invention, cut in a direction perpendicular to the longitudinal direction of the exhaust gas treatment body. FIG. FIGS. 3-2 (c) and (d) are cross-sectional views schematically showing an example of the exhaust gas treatment body constituting the exhaust gas purification apparatus of the present invention, cut in a direction perpendicular to the longitudinal direction of the exhaust gas treatment body. FIG. FIG. 4 is a perspective view schematically showing an example of a mat constituting the exhaust gas purifying apparatus of the present invention. FIG. 5 is a cross-sectional view schematically showing an example of a casing constituting the exhaust gas purifying apparatus of the present invention, cut in a direction perpendicular to the longitudinal direction of the casing. FIG. 6 is a cross-sectional view schematically showing an example of the exhaust gas purifying apparatus of the present invention cut perpendicularly to the longitudinal direction of the exhaust gas purifying apparatus. FIGS. 7A to 7C are enlarged views showing the broken line portion in FIG. 6, and schematically showing how to obtain the distance from the corner portion to the inner peripheral surface of the casing. It is an enlarged view which expands and shows the broken-line part in FIG. 6, and is explanatory drawing which shows typically the positional relationship of a waste gas processing body and a casing. FIG. 9 is a view showing an example of the exhaust gas purifying apparatus of the present invention that satisfies the relational expression (1), and pays attention to one corner portion in a cross section cut in a direction perpendicular to the longitudinal direction of the exhaust gas purifying apparatus. FIG. FIGS. 10 (a) to 10 (c) show an exhaust gas purification apparatus in which a casing in which a protruding portion that expands toward the outside of the casing is formed on the inner peripheral surface of the casing facing the corner portion of the exhaust gas treating body is used. It is sectional drawing which cut | disconnected one example in the direction perpendicular | vertical with respect to the longitudinal direction of an exhaust gas purification apparatus. FIG. 11 is a cross-sectional view schematically showing an example of the exhaust gas purifying apparatus of the present invention when an exhaust gas purifying filter is used as the exhaust gas treating body, cut in parallel to the longitudinal direction of the exhaust gas purifying apparatus. FIG. 12 is a perspective view schematically showing an example of a process of housing the wound body constituting the exhaust gas purifying apparatus of the present invention in a casing. FIG. 13A shows dimensions (vertical, horizontal, diagonal 1, diagonal 2, and radius of curvature (r of the corner portion) for specifying the shape of the cross section perpendicular to the longitudinal direction of the exhaust gas purification filter. )) Is a cross-sectional view schematically showing. FIG. 13B is a reference dimension for specifying the shape of the inner wall surface perpendicular to the longitudinal direction of the casing (vertical, horizontal, diagonal 1, diagonal 2, radius of curvature (R) of the corner portion. It is sectional drawing which showed typically. FIGS. 14A to 14E are photographs taken of the state of the mat used in Example 1. FIG. FIGS. 15A to 15E are photographs taken of the state of the mat used in Comparative Example 1. FIG.

(Detailed description of the invention)
Hereinafter, the present invention will be specifically described. However, the present invention is not limited to the following description, and can be appropriately modified and applied without departing from the scope of the present invention. Note that the present invention also includes a combination of two or more desirable configurations of the present invention described below.

The present invention will be described by taking the exhaust gas purification apparatus 1 which is the exhaust gas purification apparatus of the present invention as an example.

FIG. 1 is a perspective view schematically showing an example of the exhaust gas purifying apparatus of the present invention.
As shown in FIG. 1, the exhaust gas purification apparatus 1 of the present invention includes a columnar exhaust gas treatment body 10, a casing 20 made of a tubular body that houses the exhaust gas treatment body 10, and the exhaust gas treatment body 10 and the casing 20. Consists of a mat 30 made of inserted inorganic fibers, the contour 11 of the cross section perpendicular to the longitudinal direction of the exhaust gas treating body 10 is composed of four corner portions and a connecting portion that connects the corner portions, The corner portion is formed of a curve, the connecting portion is formed of a straight line, and the distance from each corner portion to the inner peripheral surface of the casing 20 is larger than the distance from each connecting portion to the inner peripheral surface of the casing 20. To do.

The exhaust gas treating body constituting the exhaust gas purifying apparatus of the present invention will be described.
The exhaust gas treating body has a function of collecting PM in exhaust gas discharged from an internal combustion engine such as a diesel engine, or a function of converting harmful gas components in the exhaust gas into harmless gas components. However, it may have the two functions described above.

In the present invention, what has the function of collecting PM in the exhaust gas is called an exhaust gas purification filter, and what has the function of converting harmful gas components in the exhaust gas into harmless gas components is called a catalytic converter. To do.

The exhaust gas purification filter is not particularly limited. For example, the exhaust gas purification filter is a so-called honeycomb filter made of a porous ceramic such as silicon carbide or cordierite. Of which exhaust gas is sealed at either the inlet side or the outlet side thereof, a plate is used as a filter, a filter is formed of a metal porous body having a three-dimensional network structure, and a laminate of ceramic fibers And the like. These filters are housed in a heat-resistant container of a predetermined shape, such as a filter made by stacking plate-like ones, one made of a metal porous body having a three-dimensional network structure, one made of a laminate of ceramic fibers, etc. In this case, the heat-resistant container is columnar.
Among these, a honeycomb filter made of a porous ceramic such as silicon carbide or cordierite is provided with a large number of cells in the longitudinal direction, and either the exhaust gas inlet side or the outlet side of each cell is plugged. desirable.

The honeycomb filter is made of cordierite or the like, and may be an integrated honeycomb filter integrally formed from one porous ceramic, and a columnar porous ceramic made of silicon carbide or the like is mainly bonded to the ceramic. A collective honeycomb filter formed by bundling a plurality of material layers may be used.

The catalytic converter is not particularly limited, for example, a catalyst in which a catalyst is supported on a porous ceramic in which a number of cells are provided in the longitudinal direction, a catalyst in which a catalyst is supported in a pellet-shaped porous ceramic, a metal A sheet obtained by processing a thin sheet in a wavy shape is used as a carrier, and a catalyst is supported on this carrier. In the case of using a pellet-like carrier or a metal sheet as a carrier, these carriers are accommodated in a heat-resistant container. In this case, the heat-resistant container is columnar.
Among these, a catalytic converter in which a catalyst is supported on a porous ceramic in which a large number of cells are provided in the longitudinal direction is desirable.

Examples of the catalyst supported on the exhaust gas treating body include noble metals such as platinum, palladium and rhodium, alkali metals such as potassium and sodium, alkaline earth metals such as barium, and metal oxides such as cerium oxide. can give. These catalysts may be used independently and may use 2 or more types together.

The shape of the exhaust gas treatment body 10 constituting the exhaust gas purification apparatus 1 of the present invention will be described.
FIG. 2 is a cross-sectional view schematically showing an example of the exhaust gas treating body constituting the exhaust gas purifying apparatus of the present invention, cut in a direction perpendicular to the longitudinal direction of the exhaust gas treating body.

As shown in FIG. 2, the outline 11 of the cross section perpendicular to the longitudinal direction of the exhaust gas treating body 10 has a shape in which square corners are rounded. That is, the contour 11 is composed of four

curves

12a, 12b, 12c and 12d and four

straight lines

13a, 13b, 13c and 13d connecting them.
The

curves

12a and 12b, the

curves

12b and 12c, the

curves

12c and 12d, and the

curves

12d and 12a are connected by

straight lines

13a, 13b, 13c, and 13d, respectively.

Here, a method for determining the corner portion of the exhaust gas treating body 10 will be described below.
First, the minimum value (r ₁₀ ) _min of the radius of curvature in the

curves

12a, 12b, 12c and 12d is obtained. In the

curves

12a, 12b, 12c and 12d, the continuous portions where the radius of curvature is not more than 8 times the minimum value (r ₁₀ ) _min of the radius of curvature are the

corner portions

14a, 14b, 14c and 14d of the exhaust gas treatment body. .

The curvature radius is an amount that represents the degree of bending of a curve or curved surface. In a certain curve, the degree of local bending can be approximated to a circle, and the radius of the approximated circle is called the curvature radius. For example, when it can be approximated to the circumference of the radius r, the curvature is 1 / r and the curvature radius is r. The tighter the curve, the larger the curvature and the smaller the radius of curvature.
In addition, by using the Tokyo Seimitsu Co., Ltd. three-dimensional coordinate measuring machine RVA800A-X1, etc., by measuring the position of multiple points of the exhaust gas treatment body, it is possible to specify the curve, and when this curve is an arc Can determine the radius of curvature of the arc.
Furthermore, if the curvature radius of the exhaust gas treatment body is designed to be a predetermined value, take a photograph of the cross section to check whether it matches the curvature radius curve at the time of design. Thus, the radius of curvature can be obtained.

In the exhaust gas treating body 10, since the curvatures of the

curves

12a, 12b, 12c, and 12d are constant, the respective curves are

corner portions

14a, 14b, 14c, and 14d. That is, the start point and end point of each curve are the start point and end point of each corner portion.
The

straight lines

13a, 13b, 13c, and 13d are connecting

portions

15a, 15b, 15c, and 15d, respectively.
In the exhaust gas treating body 10, the

corner portions

14a and 14b, the

corner portions

14b and 14c, the

corner portions

14c and 14d, and the

corner portions

14d and 14a are connected by connecting

portions

15a, 15b, 15c, and 15d, respectively.

Further, the exhaust gas treating body constituting the exhaust gas purifying apparatus of the present invention may have a shape as shown in FIGS. 3-1 (a) and (b) and FIGS. 3-2 (c) and (d).
FIGS. 3-1 (a) and (b) are cross-sectional views schematically showing an example of the exhaust gas treatment body constituting the exhaust gas purification apparatus of the present invention, cut in a direction perpendicular to the longitudinal direction of the exhaust gas treatment body. FIG. FIGS. 3-2 (c) and (d) are cross-sectional views schematically showing an example of the exhaust gas treatment body constituting the exhaust gas purification apparatus of the present invention, cut in a direction perpendicular to the longitudinal direction of the exhaust gas treatment body. FIG.
The contour 111 of the cross section perpendicular to the longitudinal direction of the exhaust gas treating body 110 shown in FIG. 3-1 (a) is such that the corner of the square is rounded and the straight portion of the square is convex outward. It is a cut shape. That is, it is composed of four

curves

112a, 112b, 112c and 112d having a large curvature, and four

curves

113a, 113b, 113c and 113d having a small curvature connecting them.
The

curves

112a and 112b, the

curves

112b and 112c, the

curves

112c and 112d, and the

curves

112d and 112a are connected by

curves

113a, 113b, 113c, and 113d, respectively.

Here, a method for determining the corner portion of the exhaust gas treating body 110 will be described below.
First, the minimum value (r ₁₁₀ ) _min of the radius of curvature in the

curves

112a, 112b, 112c, 112d, 113a, 113b, 113c, and 113d is obtained.
In the

curves

112a, 112b, 112c, 112d, 113a, 113b, 113c, and 113d, a continuous portion in which the radius of curvature is not more than 8 times the minimum value (r ₁₁₀ ) _min of the radius of curvature is the corner portion 114a of the exhaust gas treatment body. 114b, 114c and 114d.

In the exhaust gas treating body 110, the

corner portions

114a and 114b, the

corner portions

114b and 114c, the

corner portions

114c and 114d, and the

corner portions

114d and 114a are connected by connecting

portions

115a, 115b, 115c, and 115d, respectively.

Thus, in the exhaust gas treating body constituting the exhaust gas purifying apparatus of the present invention, the connecting portion may be composed of only a straight line or only a curve. Moreover, the connection part may be comprised from both the straight line and the curve.

Further, the exhaust gas treating body constituting the exhaust gas purifying apparatus of the present invention has a shape having 3 to 6 corner portions as shown in FIG. 3-1 (b) and FIGS. 3-2 (c) and (d). There may be.
3-1 (b) and FIGS. 3-2 (c) and (d) have exhaust

gas treatment bodies

210, 310, and 410 that are equilateral triangles in cross sections perpendicular to the longitudinal direction of the exhaust gas treatment bodies, respectively. Each part of a regular pentagon and a regular hexagon is R-chamfered.

The shape of the exhaust gas treating body is not limited to the above shape, and it is desirable to select a suitable shape from the relationship with the accommodation space and the like.

In the exhaust gas purifying apparatus of the present invention, the connecting part of the exhaust gas treating body is shown in FIGS. 2, 3A, 3B and 3-2C in a cross section perpendicular to the longitudinal direction of the exhaust gas treating body. ) And (d), it is desirable that the straight line or a curved line that protrudes outward from the exhaust gas treatment body.

As will be described later, a mat is wound around the exhaust gas treating body.
When the shape of the exhaust gas treatment body is as described above, the mat is wound around the exhaust gas treatment body without sagging.
Therefore, the pressure applied to the exhaust gas treating body from the casing via the mat is difficult to decrease. Therefore, it becomes easy to prevent the exhaust gas treating body from coming out of the inside of the exhaust gas purification device. Moreover, it is possible to sufficiently prevent the exhaust gas from leaking.

Next, the mat 30 constituting the exhaust gas purification device 1 will be described.

FIG. 4 is a perspective view schematically showing an example of a mat constituting the exhaust gas purifying apparatus of the present invention.
As shown in FIG. 4, the mat 30 has a predetermined length in the longitudinal direction (hereinafter also simply referred to as a total length; indicated by an arrow L in FIG. 4), a width (indicated by an arrow W in FIG. 4), and a thickness ( 4 is a rectangular mat in a plan view including inorganic fibers having an arrow T in FIG.

The mat 30 includes an end surface 31 on which a convex portion 31a is formed and an end surface 32 on which a concave portion 32a is formed. As will be described later, the mat 30 is wound around the exhaust gas treating body 10. The convex portion 31a and the concave portion 32a are shaped so as to fit each other when the mat 30 is wound around the exhaust gas treating body 10.

The inorganic fiber constituting the mat according to the exhaust gas purification apparatus of the present invention is not particularly limited, but is at least one selected from the group consisting of alumina fiber, alumina-silica fiber, silica fiber, and biosoluble fiber. It is desirable to be a seed.

Mats using these types of inorganic fibers have excellent holding power and excellent mechanical properties of the inorganic fibers, so that the mats are not easily cracked or crushed, and the exhaust gas treating body is firmly held.
The type of inorganic fiber may be changed according to the characteristics required for the mat, such as heat resistance and wind erosion resistance, and large diameter fibers or fiber lengths that can meet the environmental regulations of each country should be used. Is desirable.

Among these, low crystalline alumina inorganic fibers are desirable, and low crystalline alumina inorganic fibers having a mullite composition are more desirable. In addition, inorganic fibers containing spinel type compounds are more desirable. A highly crystalline alumina material is hard and brittle, so it is not suitable for a mat used as a cushioning material.

Further, in the case of inorganic fibers containing a low crystalline alumina material and a spinel type compound, the crystallization ratio is preferably in the range of 0.1 to 30%, and more preferably in the range of 0.4 to 20%. Mats made of inorganic fibers in this range have a high rebound force and a high restoration surface pressure after a durability test. However, when the crystallization ratio is less than 0.1% or more than 30%, the repulsive force and the restoring surface pressure are rapidly reduced. The method for measuring the crystallization ratio can be calculated from the integral intensity ratio of the mullite diffraction line (2θ = 26.4 °) and the γ-alumina diffraction line (2θ = 45.4 °).

It is desirable that the mat is subjected to a needle punching process on a base mat made of inorganic fibers. The needle punching process refers to inserting and removing fiber entanglement means such as a needle with respect to the base mat.

By subjecting the mat to needle punching, entanglement of inorganic fibers occurs, and the strength of the mat is improved. Therefore, cracks and crushing are less likely to occur in the mat.

In order to exhibit an entangled structure, the inorganic fiber desirably has a certain average fiber length. For example, the average fiber length of the inorganic fiber is desirably 4 mm to 120 mm. When the average fiber length is within this range, the fibers are entangled at the location where the needle treatment is performed, and the strength of the mat is increased. A preferable density of needle punches is 10 to 500 per 100 cm ² . When the density of needle punches is less than 10 per 100 cm ² , the mat is torn and separated. Further, when the density of needle punches exceeds 500 per 100 cm ² , the mat becomes difficult to bend, and when it is wound around the exhaust gas treatment body, the mat tends to be formed into a flat shape, and when the string-like member is applied, This is not preferable because a large tension is applied to the member and the string member is broken.

The surface specific gravity of the mat is desirably 400 g / m ² to 2000 g / m ² . When the surface specific gravity of the mat is less than 400 g / m ² , the exhaust gas treating body cannot be sufficiently protected from vibrations when the exhaust gas purifying apparatus is operated, and thus there arises a problem that the exhaust gas treating body is lost or dropped from the casing. On the other hand, if it exceeds 2000 g / m ² , the restoring force of the mat is too strong, so that it exceeds the strength of the exhaust gas treating body and is damaged.

The mat may have a single layer structure or a multilayer structure. When the mat has a multilayer structure, it is desirable that the hooking portion is formed at the same position of the plurality of mats. By doing so, it is possible to prevent the mats having a plurality of string-like members from being peeled off. In ordinary multilayer mats, stitches and adhesives are used, so there is concern about an increase in organic content, and the man-hours become complicated, leading to an increase in defects and a decrease in work efficiency.
When the mat is composed of a single-layered mat, the mat thickness T is desirably 5 to 15 mm.

Next, the casing 20 which comprises the exhaust gas purification apparatus 1 is demonstrated.

The casing 20 is mainly made of a metal such as stainless steel, and the inside thereof has a tubular shape having a space slightly larger than the shape of the exhaust gas treatment body 10 so that the exhaust gas treatment body 10 can be accommodated therein. .

The shape of the casing 20 which comprises the exhaust gas purification apparatus 1 is demonstrated below using drawing.
FIG. 5 is a cross-sectional view schematically showing an example of a casing constituting the exhaust gas purifying apparatus of the present invention, cut in a direction perpendicular to the longitudinal direction of the casing.

In the casing 20 shown in FIG. 5, in the cross section perpendicular to the longitudinal direction of the casing 20, the outline 21 of the inner peripheral surface of the casing 20 has a shape in which square corners are rounded.
That is, the contour 21 is composed of four

curves

22a, 22b, 22c and 22d and four

straight lines

23a, 23b, 23c and 23d connecting them.
The

curves

22a and 22b, the

curves

22b and 22c, the

curves

22c and 22d, and the

curves

22d and 22a are connected by

straight lines

23a, 23b, 23c, and 23d, respectively.

Here, a method for determining the corner portion of the inner peripheral surface of the casing 20 will be described below.
First, the minimum value (r ₂₀ ) _min of the radius of curvature in the

curves

22a, 22b, 22c and 22d is obtained. In the

curves

22a, 22b, 22c and 22d, the continuous portions where the radius of curvature is equal to or less than 8 times the minimum value (r ₂₀ ) _min of the radius of curvature are the

casing corner portions

24a, 24b, 24c and 24d.
The curvature radius of the casing can be measured in the same manner as the curvature radius of the exhaust gas treating body.

In the casing 20, since the curvatures of the

curves

22a, 22b, 22c and 22d are constant, the respective curves are

corner portions

24a, 24b, 24c and 24d. That is, the start point and end point of each curve are the start point and end point of each corner portion.
The

straight lines

23a, 23b, 23c, and 23d are connecting

portions

25a, 25b, 25c, and 25d, respectively.
In the casing 20, the

corner portions

24a and 24b, the

corner portions

24b and 24c, the

corner portions

24c and 24d, and the

corner portions

24d and 24a are connected by connecting

portions

25a, 25b, 25c, and 25d, respectively.

As will be described later, the exhaust gas treating body 10 is accommodated in the casing 20. However, the casing constituting the exhaust gas purifying apparatus of the present invention is not limited to the shape of the casing 20 that can accommodate the exhaust gas treating body 10, and can be selected according to the shape of the exhaust gas treating body.
In addition, in the cross section perpendicular to the longitudinal direction of the casing 20, it is desirable that the corner portion of the inner peripheral surface of the casing 20 is formed of a curve that protrudes outward from the casing 20. It is desirable to consist of a straight line or a curve that protrudes outward from the casing 20.

The positional relationship between the exhaust gas treating body 10 and the casing 20 in the exhaust gas purification apparatus 1 will be described.
In the following description of the exhaust gas purifying apparatus 1, there are cases in which the description is focused on the structure in the vicinity of the corner portion 14 a, but unless otherwise specified, the structures in the vicinity of the

other corner portions

14 b, 14 c, and 14 d. Are the same as the structure in the vicinity of the corner portion 14a.

FIG. 6 is a cross-sectional view schematically showing an example of the exhaust gas purifying apparatus of the present invention cut perpendicularly to the longitudinal direction of the exhaust gas purifying apparatus.
As shown in FIG. 6, in the exhaust gas purification apparatus 1, the exhaust gas treatment body 10 is accommodated in the casing 20 so that each corner portion of the exhaust gas treatment body and each corner portion of the casing 20 face each other.
Further, in the exhaust gas purifying apparatus 1, the distance from each corner portion to the inner peripheral surface of the casing 20 is larger than the distance from each connection portion to the inner peripheral surface of the casing 20.

Here, the distance from each corner part to the inner peripheral surface of the casing 20 will be described focusing on the vicinity of the corner part 14a.
FIGS. 7A to 7C are enlarged views showing the broken line portion in FIG. 6, and schematically showing how to obtain the distance from the corner portion to the inner peripheral surface of the casing.

The distance from the corner portion 14a to the inner peripheral surface of the casing 20 refers to the following distance.
First, as shown in FIG. 7 (a), in a cross section perpendicular to the longitudinal direction of the exhaust gas treating body 10, pulling the normal alpha ₁ at a point 14a ₁ with a corner section 14a. Then, from 14a ₁ that corner portion 14a and the normal alpha ₁ intersect, obtains a distance _{I 1} to 24a ₁ that the inner peripheral surface and the normal alpha ₁ of the casing 20 intersect.
Next, as shown in FIG. 7 (b), subtracting the normal alpha _n at each point while moving along the point 14a _n the corner portion 14a. From point 14a _n, determine the distance _{I n} to the point where the inner peripheral surface and the normal alpha _n of the casing 20 intersect.
As shown in FIG. 7C, the maximum distance I _max among the distances obtained by the above method is the distance from the corner portion 14 to the inner peripheral surface of the casing 20.

Moreover, the distance from the connection part of the exhaust gas treatment body 10 to the inner peripheral surface of the casing 20 is a minimum distance i _min among the distances from the connection part of the exhaust gas treatment body 10 to the inner peripheral surface of the casing 20. is there.

In the exhaust gas purification apparatus 1, the fact that the distance from each corner portion to the inner peripheral surface of the casing 20 is larger than the distance from the connecting portion adjacent to each corner portion to the inner peripheral surface of the casing 20 is near the corner portion 14a. Focus on the explanation.
FIG. 8 is an enlarged view showing a broken line portion in FIG. 6 and is an explanatory view schematically showing a positional relationship between the exhaust gas treating body and the casing.
As shown in FIG. 8, the corner portion 14a is adjacent to the connecting

portions

15a and 15d. The distance from the corner portion 14a to the inner peripheral surface of the casing 20 is the distance (i _15a ) _min from the connecting portion 15a to the inner peripheral surface of the casing 20, and the distance (i _15d ) from the connecting portion 15d to the casing 20 ) Greater than any of _min . In such a case, the distance from each corner part to the inner peripheral surface of the casing is said to be larger than the distance from the connecting part adjacent to each corner part to the inner peripheral surface of the casing.

Therefore, the mat 30 disposed in the corner portion 14a receives less pressure from the casing 20 than the mat 30 disposed in each of the connecting portion 15a and the connecting portion 15d.
Therefore, the bulk density of the mat 30 disposed in the corner portion 14a is difficult to increase. For this reason, the mat 30 is not easily cracked or crushed.
Further, when the exhaust gas treating body 10 around which the mat 30 is wound is press-fitted into the casing 20, the load applied to the mat 30 disposed in the corner portion 14 a of the exhaust gas treating body 20 is difficult to increase, Crash is unlikely to occur.

For this reason, in the exhaust gas purifying apparatus 1, it is possible to prevent the exhaust gas treating body 10 from coming into contact with the casing 20 covering its outer periphery and being damaged by vibrations or impacts caused by traveling of the automobile or the like. The holding ability of the exhaust gas treating body 10 is high, and the exhaust gas treating body 10 can be prevented from coming out of the exhaust gas purifying apparatus 1. Further, it is possible to prevent the exhaust gas from leaking firmly.

Moreover, focusing on the corner portion 14a, the exhaust gas purifying apparatus 1, the distance _{I max} from the corner portion 14a to the inner peripheral surface of the casing 20, the distance from the connecting portion 15a to the inner peripheral surface of the casing 20 _{(i 15a)} It is desirable that each of the distances (i _15d ) _min from _min and the connecting portion 15d to the inner peripheral surface of the casing 20 is greater than 1 and less than 1.4 times.

The distance I _max from the corner portion 14a to the inner peripheral surface of the casing 20 is the distance (i _15a ) _min from the connecting portion 15a to the inner peripheral surface of the casing 20, and from the connecting portion 15d to the inner peripheral surface of the casing 20 The effect of this invention cannot be acquired as it is 1 times or less of each distance ( _i15d ) _min of distance.
The distance I _max from the corner portion 14a to the inner peripheral surface of the casing 20 is the distance (i _15a ) _min from the connecting portion 15a to the inner peripheral surface of the casing 20, and from the connecting portion 15d to the inner peripheral surface of the casing 20 When the distance (i _15d ) _min is 1.4 times or more of each distance, the pressure from the casing 20 received by the portion 30a of the mat 30 disposed in the corner portion 14a is reduced, so that the exhaust gas treatment by the mat 30 is performed. The holding capacity of the body 30 is not sufficiently high, and it is difficult to prevent the exhaust gas treating body 10 from coming out of the exhaust gas purification device 1. Further, it becomes difficult to sufficiently prevent the exhaust gas from leaking.

In the exhaust gas purification apparatus 1, it is desirable that the following relational expression (1) is satisfied in a cross section perpendicular to the longitudinal direction of the exhaust gas purification apparatus.
The minimum value of the radius of curvature of the corner of the exhaust gas treatment body is r,
The minimum value of the radius of curvature of the corner of the casing is R,
In the connection part of the two exhaust gas treatment bodies adjacent to the corner part of the exhaust gas treatment body, d is the average distance from the connection part of each exhaust gas treatment body to the inner peripheral surface of the casing,
R−r <d (1)

A case where the above relational expression (1) holds will be described.
FIG. 9 is a view showing an example of the exhaust gas purifying apparatus of the present invention that satisfies the relational expression (1), and pays attention to one corner portion in a cross section cut in a direction perpendicular to the longitudinal direction of the exhaust gas purifying apparatus. FIG.

9 includes an exhaust gas treatment body 510, a casing 520 that accommodates the exhaust gas treatment body 510, and a mat 530 that is inserted between the exhaust gas treatment body 510 and the casing 520.
The exhaust gas treating body 510 has a corner portion 514a, and the radius of curvature of the corner portion 514a is r _514a . A broken-line circle c _{514a in} FIG. 9 has a radius r _514a , and the corner portion 514a is a part of the circle c _514a . Connecting

portions

515a and 515d are connected to the corner portion 514a, and the connecting

portions

515a and 515d are straight lines. Straight lines extending from the connecting

portions

515a and 515d intersect at a point 561. The connecting

portions

515a and 515d are part of a tangent line drawn from the point 561 to the circle c _514a .
The casing 520 has a corner portion 524a, and the radius of curvature of the corner portion 524a is R _524a . A broken-line circle C _{524a in} FIG. 9 has a radius R _524a , and the corner portion 524a is a part of the circle C _524a . Connecting

portions

525a and 525d are connected to the corner portion 524a, and the connecting

portions

525a and 525d are straight lines.
The connecting

portions

525a and 525d are not parallel, and a straight line extending the connecting

portions

525a and 525d intersects at a point 562. The connecting

portions

525a and 525d are part of a tangent line drawn from the point 562 to the circle C _524a .
In FIG. 9, the center point 563 of the circle c _514a , the center point 564, the point 561, and the point 562 of the circle C _524a are on the same straight line β in this order from the center of the cross section of the exhaust gas treatment body 510 to the outside. The connecting portion 515a of the exhaust gas treating body 510 and the connecting portion 525a of the casing 520 are parallel, and the connecting portion 515d of the exhaust gas treating body 510 and the connecting portion 525d of the casing 520 are parallel.
Here, a point where the straight line β and the corner part 514a intersect is a point 565, and a point where the straight line β and the corner part 524a intersect is a point 566. A point where the circle c _514a and the connecting portion 515d are in contact with each other is 567. Further, a straight line γ passing through the center point 564 and a point 568 where the circle C _524a and the connecting portion 525d contact each other is drawn, and a point where the straight line γ intersects the connecting portion 515d is set as a point 569. An angle formed by the straight line β and the straight line γ is defined as θ. The straight line γ and the connecting portion 515d are orthogonal to each other.
A distance from the center point 563 of the circle c _514a to the center point 564 of the circle C _524a is set to L. In this case, the distance D ₅₀₀ from the corner portion 514 of the gas processing body 510 to the inner peripheral surface of the casing 520, that is, the distance D ₅₀₀ from the point 565 to the point 566 can be expressed as R _524a -r _514a + L.
Furthermore, if the distance from the point 565 to the point 561 is a, the

points

561, 563, and 567 form a right triangle, and therefore r _514a / (r _514a + a) = cos θ. When this is transformed, a = r _514a (1-cos θ) / cos θ is obtained. The distance from the point 564 to the point 565 is r _514a -L. Using these, the distance from the point 564 to the point 569 is obtained as (a + r _514a −L) cos θ, that is, {r _514a (1-cos θ) / cos θ + r _514a −L} cos θ. When this is deformed, the distance from the point 564 to the point 569 is r _514a −L cos θ. Using these, the distance from the point 569 to the point 568 can be calculated as R _524a − (r _514a −L cos θ). This value is a distance d ₅₀₀ from the connecting portion 515a of the exhaust gas treating body 510 to the inner peripheral surface of the casing 520. That is, d ₅₀₀ = R _524a −r _514a + L cos θ.
In the exhaust gas purification apparatus of the present invention, the distance from the corner portion of the exhaust gas treatment body to the inner peripheral surface of the casing is larger than the distance from the connection portion of the exhaust gas treatment body to the inner peripheral surface of the casing.
In the exhaust gas purifying apparatus 501, the case where the distance D ₅₀₀ > the distance d ₅₀₀ , that is, the case where R _524a −r _514a + L> R _524a −r _514a + L cos θ is the exhaust gas purifying apparatus of the present invention. When the above inequality is transformed, L (1-cos θ)> 0. Since the range of cos θ that can be taken by the structure of the exhaust gas purification device is 0 <cos θ <1, the exhaust gas purification device of the present invention is obtained when L> 0. L is larger than 0 in the case where the center point 563 and the center point 564 are arranged in this order on the straight line β from the center of the exhaust gas purifying device 501 to the outside. When the center point 564 and the center point 563 are arranged in this order on the straight line β from the center to the outside of the exhaust gas purifying apparatus 501, it means that L is smaller than 0.
Furthermore, because of the structure of the exhaust gas purifying device 501, the distance from the connecting portion 515 of the exhaust gas treating body 510 to the inner peripheral surface of the casing 520, that is, the distance from the point 569 to the point 568 must be greater than 0. ₅₀₀ = R _524a −r _514a + L cos θ> 0.
In the exhaust gas purifying apparatus of the present invention, L> 0 and the range that cosθ can take is 0 <cosθ <1, so Lcosθ is greater than 0. Therefore, in the exhaust gas purifying apparatus of the present invention, R _524a −r _514a <R _524a −r _514a + L cos θ = d ₅₀₀ , that is, R _524a −r _514a <d ₅₀₀ .

So far, the casing 20 has been described as an example of the casing constituting the exhaust gas purification apparatus.
However, in the casing constituting the exhaust gas purifying apparatus of the present invention, in the cross section perpendicular to the longitudinal direction of the casing, the inner peripheral surface of the casing facing the corner portion of the exhaust gas treating body faces the outside of the casing. An inflating protrusion may be formed.
FIGS. 10 (a) to 10 (c) show an exhaust gas purification apparatus in which a casing in which a protruding portion that expands toward the outside of the casing is formed on the inner peripheral surface of the casing facing the corner portion of the exhaust gas treating body is used. It is sectional drawing which cut | disconnected one example in the direction perpendicular | vertical with respect to the longitudinal direction of an exhaust gas purification apparatus.

As shown to Fig.10 (a), the exhaust gas purification apparatus 601 which is an example of the exhaust gas purification apparatus of this invention is the exhaust gas processing body 10, the casing 620 which accommodates the exhaust gas processing body 10, the exhaust gas processing body 10, and a casing. The mat 30 is inserted between the 620 and the 620. In the exhaust gas purification device 601, arc-shaped

protrusions

626a, 626b, and 626c that expand toward the outside of the casing are formed on the inner peripheral surface of the casing 620 facing the

corner portions

14a, 14b, 14c, and 14d of the exhaust gas treatment body 10. And 626d are formed. Each protrusion is connected by a linear connecting part 625.

When such projecting

portions

626a, 626b, 626c, and 626d are formed, the distance from each corner portion of the exhaust gas treatment body 10 to the inner peripheral surface of the casing 620 is determined from each connection portion of the exhaust gas treatment body 10 to the casing 626. It becomes easy to make it larger than the distance to the inner peripheral surface. Therefore, when the exhaust gas purification device 601 provided with the mat 30 is used, the bulk density of the mat 30 is difficult to increase. Therefore, it is possible to prevent the mat 30 from being cracked or crushed.

As a casing in which the protrusion part which expands toward the outer side of a casing is formed in the inner peripheral surface of a casing, the casing 720 and the casing 820 which are shown to FIG.10 (b) and (c) may be sufficient.
A casing 820 shown in FIG. 10B has the same shape as the casing 620 except that each protrusion is substantially square in a cross section perpendicular to the longitudinal direction of the exhaust gas treating body.
The casing 820 shown in FIG. 10 (c) is the same as the casing 620 except that each connection portion is a curve that is recessed toward the inside of the casing in a cross section perpendicular to the longitudinal direction of the exhaust gas treating body. It is the shape.
Even the casing of these shapes has the above effects.

Although the exhaust gas treating body constituting the exhaust gas purifying apparatus of the present invention has been described before, the case where the exhaust gas purifying filter 50 is used as the exhaust gas treating body 10 will be described in more detail with reference to the drawings.
FIG. 11 is a cross-sectional view schematically showing an example of the exhaust gas purifying apparatus of the present invention when an exhaust gas purifying filter is used as the exhaust gas treating body, cut in parallel to the longitudinal direction of the exhaust gas purifying apparatus.
As shown in FIG. 11, the exhaust gas discharged from the internal combustion engine and flowing into the exhaust gas purification device 1 (in FIG. 11, the exhaust gas is indicated by an arrow G and the flow of the exhaust gas is indicated by an arrow) is an exhaust gas treatment body (honeycomb filter). 50 flows into one cell 51 opened in the exhaust gas inflow side end face 50 a and passes through a cell partition wall 52 that separates the cells 51. At this time, PM in the exhaust gas is collected by the cell partition wall 52, and the exhaust gas is purified. The purified exhaust gas flows out from the other cells 51 opened in the exhaust gas outflow side end face 50b and is discharged to the outside. Reference numeral 53 denotes a plugged portion.

As shown in FIG. 11, the exhaust gas purification filter 50 is mainly made of a porous ceramic such as silicon carbide, and has a column shape. However, the specific shape is not particularly limited, and for example, a substantially triangular column shape, a substantially square column shape, Examples include a pentagonal prism. Further, on the side surface (outer periphery) of the exhaust gas purification filter 50, an outer peripheral coat layer 54 is provided for the purpose of reinforcing the side surface of the exhaust gas purification filter 50, adjusting the shape, and improving the heat insulation of the exhaust gas purification filter 50. Is provided.

Hereinafter, an example of the manufacturing method of the exhaust gas purifying apparatus of the present invention will be described.

In order to manufacture the exhaust gas purification apparatus of the present invention, first, a mat constituting the exhaust gas purification apparatus is produced.
When producing a mat, first, a mat material having a predetermined size is prepared. Since the mat material has been described above, the description thereof is omitted here.

A binder is attached to the mat material having the above-described configuration as necessary. By adhering the binder to the mat material, the entangled structure between the inorganic fibers can be strengthened, and the bulk of the mat material can be suppressed. The amount of binder added is preferably 0.01 to 10.0% based on the weight of the mat material. 0.05 to 3.0% is more desirable, and the range of 0.1 to 1.5% is most desirable.

As the binder, an emulsion prepared by dispersing acrylic latex or rubber latex in water can be used. The binder is sprayed uniformly on the entire mat material using a spray or the like, and the binder is adhered to the mat material. Moreover, although the said binder is an organic component, the inorganic binder containing an alumina particle etc. may be used with the said organic binder, and only the inorganic binder may be used without using the said organic binder.

Thereafter, the mat material is dried to remove moisture in the binder. As drying conditions, for example, drying may be performed at 95 to 150 ° C. for 1 to 30 minutes. A mat member can be manufactured through a drying process. Desirably, a ventilation dryer is used for drying. By using a ventilation dryer, the drying speed of the mat material is increased, and further, the amount of binder attached is not uniform in the thickness direction of the mat material, and distribution can be achieved by resin migration. For example, it is possible to adjust the distribution such as increasing or decreasing the amount of resin in the central portion in the thickness direction of the mat material by setting various conditions such as the aeration speed and temperature of the aeration dryer.
Further, it is possible to dry under compression or decompression environment, and the drying time can be reduced.

Next, a punching process is performed to produce a mat having a shape as shown in FIG.

When the exhaust gas purifying apparatus of the present invention is manufactured, after the mat having the shape shown in FIG. 4 is manufactured, the mat is exhausted so that the mated convex and concave mating portions are fitted. It winds around a process body and produces the wound body 40 shown in FIG.
The exhaust gas treating body can be produced by a conventionally known method. Since the shape of the exhaust gas treating body to be manufactured has already been described, the description thereof is omitted here.

After this step, a housing step is performed.
FIG. 12 is a perspective view schematically showing an example of a process of housing the wound body constituting the exhaust gas purifying apparatus of the present invention in a casing.
As shown in FIG. 12, the exhaust gas treating body 10 (wound body 40) around which the mat 30 is wound is press-fitted into a casing 20 having a predetermined size and mainly made of metal or the like.

In order to exhibit a predetermined repulsive force (that is, a force for holding the honeycomb filter) by compressing the mat 30 after the press-fitting, the inner diameter of the casing 20 is the thickness of the mat 30 of the exhaust gas treating body 10 around which the mat 30 is wound. It is a little smaller than the outermost diameter.

The method of accommodating the exhaust gas treating body around which the mat is wound in the casing 20 is not limited to the press-fitting method (stuffing method), and includes a sizing method (swaging method), a clamshell method, and the like.
In the sizing method (swaging method), an exhaust gas treating body around which a mat is wound is inserted into the casing, and then compressed from the outer peripheral side so as to reduce the inner diameter of the casing. In the clamshell method, the casing is shaped so as to be separable into two parts, a first casing and a second casing, and after the exhaust gas treating body around which the mat is wound is placed on the first casing, the second Cover with a casing and seal.
Of the methods for accommodating the exhaust gas treating body wrapped with the mat in the casing, the press-fitting method (stuffing method) or the sizing method (swaging method) is desirable. This is because in the press-fitting method (stuffing method) or the sizing method (swaging method), it is not necessary to use two parts as the casing, so the number of manufacturing processes can be reduced.

Below, it enumerates about the effect of the exhaust gas purification apparatus of this invention.

(1) In the exhaust gas purification apparatus of the present invention, the distance from the corner portion of the gas treatment body to the inner peripheral surface of the casing is larger than the distance from the connection portion of the exhaust gas treatment body to the inner peripheral surface of the casing.
For this reason, the mat disposed at the corner portion of the exhaust gas treating body receives less pressure from the casing than the mat disposed at the connecting portion of the exhaust gas treating body.
Therefore, the bulk density of the mat disposed at the corner portion of the exhaust gas treating body is difficult to increase. For this reason, cracks and crushing are unlikely to occur in the mat.

(2) In the exhaust gas purification apparatus of the present invention, even when the exhaust gas treating body around which the mat is wound is press-fitted into the casing, the load applied to the corner portion is not easily increased, and the mat is not easily cracked or crushed.
For this reason, in the exhaust gas purifying apparatus of the present invention, it is possible to prevent the exhaust gas treating body from being damaged by contact with the casing covering the outer periphery due to vibrations or impacts caused by traveling of the automobile or the like. The holding capacity of the treatment body is high, and the exhaust gas treatment body can be prevented from coming out from the inside of the exhaust gas purification apparatus. Further, it is possible to prevent the exhaust gas from leaking firmly.

(3) In the exhaust gas purifying apparatus of the present invention, when the distance from the corner portion of the gas treatment body to the inner peripheral surface of the casing is greater than one time the distance from the connection portion of the exhaust gas treatment body to the inner peripheral surface of the casing, The effects of the present invention are exhibited. Further, if the distance from the corner of the gas treatment body to the inner peripheral surface of the casing is less than 1.4 times the distance from the connection portion of the exhaust gas treatment body to the inner peripheral surface of the casing, the corner of the gas treatment body Since the pressure from the casing received by the arranged mat does not become small, the holding ability of the exhaust gas treating body by the mat becomes sufficiently high, and the exhaust gas treating body can be prevented from coming out from the inside of the exhaust gas purifying apparatus. Moreover, it is possible to sufficiently prevent the exhaust gas from leaking.

(4) In the exhaust gas purification apparatus of the present invention, when the connecting portion of the exhaust gas treatment body is a straight line or a curve that protrudes outside the exhaust gas treatment body in a cross section perpendicular to the longitudinal direction of the exhaust gas treatment body, Will be wound around the exhaust gas treatment body without slack. Therefore, the pressure applied to the exhaust gas treating body from the casing via the mat is difficult to decrease. Therefore, it becomes easy to prevent the exhaust gas treating body from coming out of the inside of the exhaust gas purification device. Moreover, it is possible to sufficiently prevent the exhaust gas from leaking.

(5) In the exhaust gas purifying apparatus of the present invention, when the number of corner portions of the exhaust gas treatment body is four, the distance from the corner portion of the exhaust gas treatment body to the inner peripheral surface of the casing is from the connection portion of the exhaust gas treatment body. It was likely to be shorter than the distance to the inner peripheral surface of the casing, and cracks and crushing were likely to occur in the mat disposed at the corner portion of the exhaust gas treating body. However, in the exhaust gas purification apparatus of the present invention, the distance from the corner portion of the exhaust gas treatment body to the inner peripheral surface of the casing is larger than the distance from the connection portion of the exhaust gas treatment body to the inner peripheral surface of the casing. For this reason, when the exhaust gas purification apparatus provided with the mat is used, the bulk density of the mat is hardly increased. Therefore, it is possible to prevent the mat from being cracked or crushed.

(6) In the exhaust gas purifying apparatus of the present invention, when the exhaust gas treatment body is accommodated in the casing so that the corner portion of the exhaust gas treatment body and the corner portion of the casing face each other, the exhaust gas treatment body is disposed at the corner portion of the exhaust gas treatment body. The pressure from the casing on the provided mat tends to be uniform. Therefore, it is possible to prevent the bulk density of a part of the mat from increasing, and it is possible to prevent the mat from being cracked or crushed.

(7) In the exhaust gas purifying apparatus of the present invention, by designing the exhaust gas treating body and the casing so that the following relational expression (1) is satisfied, the distance from the corner portion of the exhaust gas treating body to the inner peripheral surface of the casing is It can be made larger than the distance from the connecting part of the treatment body to the inner peripheral surface of the casing, and when the exhaust gas purification apparatus provided with the mat is used, the mat can be prevented from being cracked or crushed. .
R is the minimum value of the radius of curvature of the corner of the exhaust gas treating body.
The minimum value of the radius of curvature of the corner of the casing is R,
In the connection part of the two exhaust gas treatment bodies adjacent to the corner part of the exhaust gas treatment body, d is the average of the distances from the connection parts of the exhaust gas treatment bodies to the inner peripheral surface of the casing.
R−r <d (1)

(8) In the exhaust gas purifying apparatus of the present invention, in a cross section perpendicular to the longitudinal direction of the casing, a protruding portion that expands toward the outside of the casing is formed on the inner peripheral surface of the casing facing the corner portion of the exhaust gas treating body. If formed, the distance from the corner portion of the exhaust gas treating body to the inner peripheral surface of the casing is easily made larger than the distance from the connecting portion of the exhaust gas treating body to the inner peripheral surface of the casing. For this reason, when the exhaust gas purification apparatus provided with the mat is used, the bulk density of the mat is hardly increased. Therefore, it is possible to prevent the mat from being cracked or crushed.

(9) In the exhaust gas purifying apparatus of the present invention, the inorganic fiber constituting the mat is at least one inorganic fiber selected from the group consisting of alumina fiber, alumina-silica fiber, silica fiber, and biosoluble fiber. If so, the mat using the inorganic fiber has excellent holding power and excellent mechanical properties of the inorganic fiber, so that the mat is not easily cracked or crushed, and the exhaust gas treating body is firmly held. .

(10) In the exhaust gas purifying apparatus of the present invention, if the mat is further subjected to needle punching treatment, the entanglement between the inorganic fibers occurs and the inorganic fibers are difficult to move. This makes it difficult for the mat to gather at the portion, and it is difficult for the mat to crack or collapse.

(Example)
Examples in which the embodiments of the present invention are disclosed more specifically are shown below, but the embodiments of the present invention are not limited to these examples.

Example 1
A substrate mat having a composition ratio of Al ₂ O ₃ : SiO ₂ = 72: 28 was prepared as an alumina fiber substrate mat having an alumina-silica composition. The base mat was subjected to needle punching to produce a needle mat having a bulk density of 0.20 g / cm ³ and a basis weight of 1591 g / m ² .

Separately, an acrylic latex emulsion was prepared by sufficiently dispersing acrylic latex in water, and this was used as a binder.

Next, the needle mat was cut into a total length of 1100 mm × width of 1280 mm in plan view. The cut needle mat was impregnated with a binder so that the amount of alumina fiber of the cut needle mat was 1.0% by weight.

Then, the mat material was produced by carrying out 6 minutes ventilation drying of the needle mat to which the binder was adhered at the temperature of 140 degreeC.

Subsequently, a mat having a shape as shown in FIG. 4 was punched from the mat material.
The mat material was punched using a Thomson blade and a hydraulic press.
The dimensions of the punched mat are the length L in the longitudinal direction L = 545 mm, the width W = 110 mm, the thickness T = 9.1 mm, and the length in the longitudinal direction of the concave and convex fitting portions D = 50 mm. .

FIG. 13A shows dimensions (vertical, horizontal, diagonal 1, diagonal 2, and radius of curvature (r of the corner portion) for specifying the shape of the cross section perpendicular to the longitudinal direction of the exhaust gas purification filter. )) Is a cross-sectional view schematically showing.
FIG. 13B is a reference dimension for specifying the shape of the inner wall surface perpendicular to the longitudinal direction of the casing (vertical, horizontal, diagonal 1, diagonal 2, radius of curvature (R) of the corner portion. It is sectional drawing which showed typically.
When the exhaust gas purification filter made of SiC used in this example is represented by the reference shown in FIG. 13, the length is 143.8 mm, the width is 143.8 mm, the diagonal is 1: 179.6 mm, and the diagonal is 2: 179.6 mm. The radius of curvature r of the corner portion is 20 mm.
A mat having the above-described characteristics was wound around the exhaust gas purification filter having the above shape.

Finally, the wound body was accommodated in the casing using a press-fitting method. The casing has a length of 151.8 mm, a width of 151.8 mm, a diagonal of 1: 189.4 mm, a diagonal of 2: 189.4 mm, a corner radius of curvature R of 22 mm, and a longitudinal length of 150 mm. .
In the exhaust gas purification apparatus manufactured in this way, in the cross section perpendicular to the longitudinal direction of the exhaust gas purification apparatus, the distance from the corner portion of the exhaust gas treatment body to the inner peripheral surface of the casing is 4.83 mm. The distance from the connection part of a process body to the internal peripheral surface of a casing was 4.00 mm.
24 hours after the press-fitting, the mat was taken out of the casing, the state of the mat was observed, and a photograph was taken. FIGS. 14A to 14E are photographs taken of the state of the mat used in Example 1. FIG.

(Comparative Example 1)
Except for the difference in the shape of the casing, a mat is manufactured in the same manner as in Example 1, and the wound body is manufactured by winding the mat around the same side surface of the exhaust gas purification filter as in Example 1. The wound body is press-fitted into the casing. did. The casing has a length of 151.8 mm, a width of 151.8 mm, a diagonal of 1: 187.7 mm, a diagonal of 2: 187.7 mm, a corner radius of curvature R of 24 mm, and a longitudinal length of 150 mm. .
In the exhaust gas purification apparatus manufactured in this way, in the cross section perpendicular to the longitudinal direction of the exhaust gas purification apparatus, the distance from the corner portion of the exhaust gas treatment body to the inner peripheral surface of the casing is 4.00 mm, The distance from the connection part of a process body to the internal peripheral surface of a casing was 4.00 mm.
24 hours after the press-fitting, the mat was taken out of the casing, the state of the mat was observed, and a photograph was taken.
Then, in the same manner as in Example 1, the mat was taken out from the casing 24 hours after the press-fitting, the state of the mat was observed, and a photograph was taken. FIGS. 15A to 15E are photographs taken of the state of the mat used in Comparative Example 1. FIG.

As is clear from the comparison between FIGS. 14 (a) to 14 (e) and FIGS. 15 (a) to 15 (e), the mat used in Example 1 shows some wrinkle marks, but cracks and crushing. It was found that there was no problem with the mat. On the other hand, it was found that the mat used in Comparative Example 1 was cracked or crushed, and there was a risk that the holding power would be reduced or the exhaust gas might leak.

1, 501, 601 Exhaust

gas purification device

10, 110, 210, 310, 410, 510 Exhaust

gas treatment body

11, 21, 111

Contours

12a, 12b, 12c, 12d, 22a, 22b, 22c, 22d, 112a, 112b, 112c, 112d, 113a, 113b, 113c, 113d Curves 13a, 13b, 13c, 13d, 23a, 23b, 23c,

23d Straight lines

14a, 14b, 14c, 14d, 114a, 114b, 114c, 114d, 514a Corner portion 15a of the exhaust gas treatment body , 15b, 15c, 15d, 115a, 115b, 115c, 115d, 515a, 515d Exhaust gas treatment

body connection parts

20, 520, 620, 720, 820

Casing

24a, 24b, 24c, 24d, 524a Casing

corner parts

25a, 25b , 5c, 25d, 525a, 525d, 625

Casing connecting portion

30, 530

Mat

31, 32 End surface 31a Convex portion 32a Concave 40 Winding body 50 Exhaust gas purification filter 50a Exhaust gas inflow end surface 50b Exhaust gas outflow side end surface 51 Cell 52 Cell wall 53 Plugging portion 54 Outer

peripheral coat layer

626a, 626b, 626c, 626d Protrusion c _514a , C _524a circle r _514a , R _524a radius of curvature

Claims

A columnar exhaust gas treatment body;
A casing made of a tubular body containing the exhaust gas treating body;
An exhaust gas purification apparatus comprising a mat made of inorganic fibers inserted between the exhaust gas treating body and the casing,
The outline of the cross section perpendicular to the longitudinal direction of the exhaust gas treatment body is composed of 3 to 6 corner portions and a connecting portion for connecting the corner portions of the exhaust gas treatment body, and the corner portion of the exhaust gas treatment body. Consists of a curve, and the connecting part of the exhaust gas treating body consists of a straight line or a curve
An exhaust gas purification apparatus, wherein a distance from a corner portion of the exhaust gas treatment body to an inner peripheral surface of the casing is larger than a distance from a connection portion of the exhaust gas treatment body to an inner peripheral surface of the casing.
The distance from the corner portion of the exhaust gas treatment body to the inner peripheral surface of the casing is greater than 1 time and less than 1.4 times the distance from the connection portion of the exhaust gas treatment body to the inner peripheral surface of the casing. The exhaust gas purification apparatus according to 1.
3. The exhaust gas purification according to claim 1, wherein a connecting portion of the exhaust gas treatment body is a straight line or a curve that protrudes outward from the exhaust gas treatment body in a cross section perpendicular to the longitudinal direction of the exhaust gas treatment body. apparatus.
The exhaust gas purifying apparatus according to any one of claims 1 to 3, wherein the number of corner portions of the exhaust gas treating body is four.
The outline of the inner peripheral surface of the casing having a cross section perpendicular to the longitudinal direction of the casing is composed of 3 to 6 corner portions and a connecting portion for connecting the corner portions of the casing,
The exhaust gas purifying apparatus according to any one of claims 1 to 4, wherein the exhaust gas treating body is housed in the casing so that a corner portion of the exhaust gas treating body and a corner portion of the casing face each other.
The exhaust gas purifying apparatus according to claim 5, wherein the connection part of the exhaust gas treating body and the connection part of the casing are straight lines and satisfy the following relational expression (1).
The minimum value of the radius of curvature of the corner portion of the exhaust gas treatment body is r,
R is the minimum value of the radius of curvature of the corner of the casing.
In the connection part of the two exhaust gas treatment bodies adjacent to the corner part of the exhaust gas treatment body, the average of the distance from the connection part of each exhaust gas treatment body to the inner peripheral surface of the casing is d,
R−r <d (1)
A projecting portion that expands toward the outside of the casing is formed on an inner peripheral surface of the casing facing a corner portion of the exhaust gas treating body in a cross section perpendicular to the longitudinal direction of the casing. The exhaust gas purifying apparatus according to any one of 1 to 6.
The exhaust gas purifying apparatus according to any one of claims 1 to 7, wherein the inorganic fiber is at least one selected from the group consisting of alumina fiber, alumina-silica fiber, silica fiber, and biosoluble fiber.
The exhaust gas purifying apparatus according to any one of claims 1 to 8, wherein the mat is further subjected to a needle punching process.