WO2015056652A1

WO2015056652A1 - Exhaust gas purification device

Info

Publication number: WO2015056652A1
Application number: PCT/JP2014/077244
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: JP6419708B2; JPWO2015056652A1

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; the corner sections are curved, the connecting sections are straight or curved; and the distance from the corner sections to the inner peripheral surface of the casing is less than the distance from the connecting sections to the inner peripheral surface of the casing, and the surface specific gravity of the mat arranged on the corner sections is less than the surface specific gravity of the mat arranged on the connecting sections.

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 outline of the cross section perpendicular to the longitudinal direction of the exhaust gas treating body has 3 to 6 corner portions and a connecting portion for connecting the corner portions to each other The corner portion is made of a curve, the connecting portion is made of a straight line or a curve, and the distance from the corner portion to the inner peripheral surface of the casing is from the connecting portion to the inner peripheral surface of the casing. The surface specific gravity of the mat disposed in the corner portion is smaller than the surface specific gravity of the mat disposed in the connecting portion. That.

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 at one point with a corner portion is drawn. Next, the distance from the point where the corner portion and the normal line intersect to the point where the inner peripheral surface of the casing and the normal line intersect is obtained. 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 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 this specification, the distance from the corner portion to the inner peripheral surface of the casing being smaller than the distance from the connecting portion to the inner peripheral surface of the casing means the following case.
First, the distance from the corner portion to the inner peripheral surface of the casing is obtained by the above method. Next, two connecting portions adjacent to the corner portion are recognized. Next, in each of the certified connecting portions, the distance from the connecting portion to the inner peripheral surface of the casing is obtained by the above method.
When the distance from the corner portion to the inner peripheral surface of the casing is smaller than the distance from any connecting portion to the inner peripheral surface of the casing, the distance from the corner portion to the inner peripheral surface of the casing is This means that the distance is smaller than the distance to the inner peripheral surface.

In the exhaust gas purifying apparatus of the present invention, the distance from the corner portion to the inner peripheral surface of the casing is smaller than the distance from the connecting portion to the inner peripheral surface of the casing, and is disposed in the corner portion. The surface specific gravity of the mat is smaller than the surface specific gravity of the mat disposed in the connecting portion.
When the distance from the corner portion to the inner peripheral surface of the casing is smaller than the distance from the connecting portion to the inner peripheral surface of the casing, and the surface specific gravity of the mat is constant, the mat disposed at the corner portion receives The pressure from the casing is greater than the pressure from the casing received by the mat disposed at the connecting portion. In this case, the bulk density of the mat is increased, and cracks and crushing are likely to occur in the mat. However, in the exhaust gas purification apparatus of the present invention, the surface specific gravity of the mat disposed at the corner portion is smaller than the surface specific gravity of the mat disposed at the connecting portion. That is, the density of the fibers of the mat disposed in the corner portion is lower than the density of the fibers of the mat disposed in the connecting portion. Therefore, even if the pressure from the casing is received, the bulk density of the mat disposed at the corner portion 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, a load applied to the mat disposed at 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.

In the exhaust gas purifying apparatus of the present invention, it is desirable that an opening is formed in a part of the mat disposed at the corner.

When the opening is formed, the inorganic fiber can easily move to the opening when the exhaust gas treating body around which the mat is wound is pressed, and the pressure applied to the mat disposed at the corner is reduced. be able to. Therefore, it is possible to prevent the bulk density of the mat disposed at the corner portion from increasing. As a result, it is possible to prevent the mat from being cracked or crushed.

In the exhaust gas purifying apparatus of the present invention, it is preferable that two or more openings are formed in a part of the mat disposed in the corner portion in the width direction of the mat.

When two or more openings are formed in the width direction of the mat, the inorganic fibers easily move uniformly into the openings when the exhaust gas treating body around which the mat is wound is press-fitted.
Therefore, it can prevent that the pressure received from a casing applies only to a part of mat | matte. That is, it is possible to prevent the bulk density of a part of the mat from increasing. As a result, it is possible to prevent the mat from being cracked or crushed.

In the exhaust gas purification apparatus of the present invention, the shape of the opening is at least one shape selected from the group consisting of a substantially circular shape, a substantially elliptical shape, a substantially racetrack shape, a substantially hexagonal shape, a substantially pentagonal shape, a substantially rectangular shape, and a substantially triangular shape. It is desirable that

By selecting the shape of the opening according to the radius of curvature of the corner of the exhaust gas treatment body and the shape of the inner peripheral surface of the casing, when the exhaust gas treatment body around which the mat is wound is press-fitted, inorganic fibers are introduced into the opening. It can be moved easily. Thereby, the pressure which a mat receives from a casing can be disperse | distributed, and it can prevent that the bulk density of a part of mat | matte becomes high. As a result, it is possible to prevent the mat from being cracked or crushed.
Furthermore, when the opening has these shapes, the opening can be easily formed, which is advantageous in manufacturing the exhaust gas purification device.

In the exhaust gas purification apparatus of the present invention, it is desirable that the length of the opening in the width direction of the mat is 1/10 to 9/10 of the width of the mat.

In this specification, the length of the opening in the width direction of the mat means that the distance from one end of the opening in the width direction of the mat to the other end is the length of the opening in the width direction of the mat. I mean.

When the length of the opening in the width direction of the mat is less than 1/10 of the width of the mat, the surface specific gravity of the mat disposed in the corner portion is not easily lowered, and the opening is arranged in the corner portion. The bulk density of the mat provided is not likely to be sufficiently low. Therefore, it becomes difficult to obtain the effect of preventing the mat from cracking or crushing.
If the length of the opening in the width direction of the mat is more than 9/10 of the width of the mat, the mat surface gravity will be too small and the mat will be easily cut off Become.

In the exhaust gas purifying apparatus of the present invention, the length of the opening in the width direction of the mat is desirably 10 mm to 70 mm.

When the length of the opening in the width direction of the mat is less than 10 mm, the surface specific gravity of the mat disposed in the corner portion is not easily lowered, and the mat disposed in the corner portion is not sufficiently low. Bulk density is unlikely to be sufficiently low. Therefore, it becomes difficult to obtain the effect of preventing the mat from being cracked or crushed.
If the length of the opening in the width direction of the mat is more than 70 mm, the mat is easily cut off because the surface specific gravity of the mat disposed in the corner portion is too small.

In the exhaust gas purifying apparatus according to the present invention, in the continuous area of the mat disposed in the corner portion, the mat is viewed in plan, and a first straight line perpendicular to the length direction of the mat is defined on the mat. The second straight line perpendicular to the mat length direction is drawn with the other end of the mat length direction opening so as to come into contact with one end of the length length opening. When pulled so as to contact, the surface specific gravity of the mat existing in the region between the first straight line and the second straight line is 30 of the surface specific gravity of the mat disposed in the connecting portion. It is desirable to be 99.5%.

When the surface specific gravity of the mat existing in the region from the first straight line to the second straight line is less than 30% of the surface specific gravity of the mat disposed in the connecting portion, the first straight line to the second straight line Since the amount of inorganic fibers present in the region up to the straight line becomes too small, the mat is easily broken.
When the surface specific gravity of the mat existing in the region between the first straight line and the second straight line exceeds 99.5% of the surface specific gravity of the mat disposed at the connecting portion, the mat is disposed at the corner portion. Since the inorganic fibers of the mat are difficult to move to the opening, the bulk density of the mat disposed at the corner is not sufficiently lowered. Therefore, it becomes difficult to obtain the effect of preventing the mat from cracking or crushing.

In the exhaust gas purification apparatus of the present invention, it is desirable that the density of the inorganic fibers of the mat disposed at the corner portion is lower than the density of the inorganic fibers of the mat disposed at the connecting portion. .

With the above configuration, when the exhaust gas treating body around which the mat is wound is press-fitted, the inorganic fibers can be easily moved to a lower density, and the pressure applied to the mat disposed in the corner portion can be reduced. Can do. Therefore, it is possible to prevent the bulk density of the mat disposed at the corner portion from increasing. As a result, 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. 4A is a perspective view schematically showing an example of a mat constituting the exhaust gas purifying apparatus of the present invention. FIG. 4-2 (b) is a plan view of the mat shown in FIG. 4-1 (a). FIG. 4-2 (c) is a diagram schematically showing a method for calculating the area of the mat in determining the surface specific gravity of the mat shown in FIG. 4-2 (b). FIG. 5 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. 6 (a) to 6 (c) are enlarged views showing the broken line portion in FIG. 5, and schematically showing how to obtain the distance from the corner portion to the inner peripheral surface of the casing. FIG. 7 is an enlarged view showing a broken line portion in FIG. 5 and is an explanatory view schematically showing a positional relationship between the exhaust gas treating body and the casing. FIG. 8 is an enlarged view showing a broken line portion in FIG. 5, and is an explanatory view schematically showing a mat disposed in a corner portion. FIG. 9A is a cross-sectional view schematically showing the broken line portion in FIG. 4-1A cut along the line AA so that the opening passes therethrough. FIG.9 (b) is a schematic diagram which shows typically the state of the part shown to Fig.9 (a) of the mat | matte arrange | positioned at the exhaust gas purification apparatus of this invention. FIGS. 10A to 10G are plan views schematically showing an example of a mat constituting the exhaust gas purifying apparatus of the present invention, and show mats having openings of various shapes. FIGS. 10 (h) and (i) are plan views schematically showing an example of a mat constituting the exhaust gas purifying apparatus of the present invention, and show a mat in which an opening is formed from the side. FIG. 11 is a diagram of a mat showing a region between the first straight line and the second straight line when the first straight line and the second straight line are drawn on an example of the mat constituting the exhaust gas purifying apparatus of the present invention. It is a top view. FIG. 12 is a cross-sectional view schematically showing an example of the exhaust gas purification apparatus of the present invention when an exhaust gas purification filter is used as the exhaust gas treatment body, cut in parallel to the longitudinal direction of the exhaust gas purification apparatus. FIG. 13 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. 14A shows dimensions (vertical, horizontal, diagonal 1, diagonal 2, and radius of curvature (r of the corner portion) for specifying the shape of a cross section perpendicular to the longitudinal direction of the exhaust gas purification filter. )) Is a cross-sectional view schematically showing. FIG. 14B 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, corner radius of curvature (R). Is a cross-sectional view schematically showing. FIG. 15A is a top view schematically showing the experimental apparatus. FIG. 15B is a cross-sectional view taken along the line BB.

(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 curved line, 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 smaller than the distance from each connecting portion to the inner peripheral surface of the casing 20. The surface specific gravity of the mat 30 disposed on the mat is smaller than the surface specific gravity of the mat 30 disposed on each connecting portion.

The exhaust gas treatment body 10 constituting the exhaust gas purification apparatus 1 of the present invention will be described.
The exhaust gas treating body 10 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.

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

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

FIG. 4A is a perspective view schematically showing an example of a mat constituting the exhaust gas purifying apparatus of the present invention. FIG. 4-2 (b) is a plan view of the mat shown in FIG. 4-1 (a). FIG. 4-2 (c) is a diagram schematically showing a method for calculating the area of the mat in determining the surface specific gravity of the mat shown in FIG. 4-2 (b).
As shown in FIG. 4-1 (a), 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. 4-1 (a)) and a width (FIG. 4). -1 (a) is a mat having a rectangular shape in plan view including inorganic fibers having a thickness (indicated by an arrow W) and a thickness (indicated by 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.

Furthermore, four substantially rectangular openings 33 are formed in the mat 30. The opening 33 in the mat 30 is a portion to be disposed at each corner portion of the exhaust gas treatment body 10 when the mat 30 is wound around the exhaust gas treatment body 10.

This will be described in detail below with reference to the drawings.
As shown in FIG. 4B, the mat 30 can be divided into a first region 34 in which the opening 33 is formed and a second region 35 in which the opening is not formed.
The first region 34 is a region disposed at each corner portion when the mat 30 is wound around the exhaust gas treating body 10.
The second region 35 is a region disposed in each connection portion when the mat 30 is wound around the exhaust gas treating body 10.

In the mat 30, since the opening 33 is formed in the first region 34, the surface specific gravity of the first region 34 is smaller than the surface specific gravity of the second region 35.

In the second region 35 of the mat 30 to be disposed in each connecting portion of the exhaust gas treating body 10, the weight of the portion of the second region 35 of the mat 30 is divided by the area of the second region 35 of the mat. The value is the surface specific gravity.
In the first region 34 of the mat 30 to be disposed at each corner portion of the exhaust gas treating body 10, the surface specific gravity is obtained as follows.
An opening 33 is formed in the first region 34. When obtaining the surface specific gravity of the first region 34 of the mat 30, first, the area of the first region 34 is obtained assuming that the opening 33 has fibers or the like. Next, the weight of the portion of the first region 34 of the mat 30 is divided by the area of the first region 34 obtained by assuming that the opening 33 has fibers or the like. This value is the surface specific gravity of the portion of the first region 34 of the mat 30.
That is, in the first region 34, the “area of the first region 34” for obtaining the surface specific gravity of the mat is the area of the plane 33 ′ surrounded by the diagonally right oblique line in FIG. 4-2 (c). And the area of the plane 36 surrounded by the left diagonal line. A plane 33 ′ in FIG. 4-2 (c) coincides with the opening 33 in the mat 30 in FIG. 4-2 (b). A plane 36 in FIG. 4-2 (c) coincides with the portion of the first region 34 other than the opening 33 in the mat 30 in FIG. 4-2 (b).

In a region where the surface specific gravity of the mat is small, the bulk density of the mat is difficult to increase even if the mat is subjected to pressure. For this reason, even if it is a case where such a pressure is received, a crack and crushing are hard to generate | occur | produce in a mat.

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.

Further, it is desirable that the surface specific gravity of the mat at the portion to be disposed at the connecting portion of the exhaust gas treating body is 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 surface density of the mat portion which is to be disposed in a corner portion of the exhaust gas treating ^body, and more desirably about ^{390g / m 2 ~ 1990g / m} 2.

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 is not limited to a shape that can accommodate the exhaust gas treating body 10, and is preferably selected according to the shape of the exhaust gas treating body.

Next, the positional relationship among the exhaust gas treating body 10, the casing 20, and the mat 30 constituting the exhaust gas purification apparatus 1 will be described with reference to the drawings.
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. 5 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. 5, the distance from each corner portion of the exhaust gas treatment body 10 to the inner peripheral surface of the casing 20 is smaller than the distance from each connection portion of the exhaust gas treatment body 10 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.
6 (a) to 6 (c) are enlarged views showing the broken line portion in FIG. 5, 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. 6 (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. 6 (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. 6C, 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 the minimum distance i _min among the distances from the connection parts of the exhaust gas treatment body 10 to the inner peripheral surface of the casing 20. It is.

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 smaller 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. 7 is an enlarged view showing a broken line portion in FIG. 5 and is an explanatory view schematically showing a positional relationship between the exhaust gas treating body and the casing.
As shown in FIG. 7, 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. Smaller than any of _min . In this case, the distance from each corner portion to the inner peripheral surface of the casing is smaller than the distance from the connecting portion adjacent to each corner portion to the inner peripheral surface of the casing 20.

Moreover, in the exhaust gas purification apparatus 1, the surface specific gravity of the mat 30 disposed at each corner portion is smaller than the surface specific gravity of the mat 30 disposed at each connection portion.

Here, the mat 30 disposed in the corner portion will be described focusing on the vicinity of the corner portion 14a.
FIG. 8 is an enlarged view showing a broken line portion in FIG. 5, and is an explanatory view schematically showing a mat disposed in a corner portion.

In order to determine the area of the mat 30 disposed in the corner portion 14a, first, as shown in FIG. 8, a normal α _14a is drawn at both ends of the corner portion 14a. The area delimited by the normal α _14a is the area of the mat 30 disposed in the corner portion 14a, that is, the first area 34 of the mat 30.

In the exhaust gas purification apparatus, when the distance from each corner portion to the inner peripheral surface of the casing 20 is smaller than the distance from each connection portion to the inner peripheral surface of the casing 20, and the surface specific gravity of the mat is constant, The pressure from the casing received by the mat disposed at the corner portion is greater than the pressure from the casing 20 received by the mat disposed at each connecting portion. In this case, the bulk density of the mat is increased, and cracks and crushing are likely to occur in the mat. However, in the exhaust gas purification apparatus 1, the surface specific gravity of the mat 30 disposed at each corner is smaller than the surface specific gravity of the mat 30 disposed at each connecting portion. That is, the density of the fibers of the mat 30 disposed at each corner is lower than the density of the fibers of the mat 30 disposed at each connecting portion. Therefore, even if the pressure from the casing 20 is received, the bulk density of the mat 30 disposed at each corner portion is not easily increased. 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 each corner portion is not easily increased, and the mat 30 is not easily cracked or crushed. .

For this reason, in the exhaust gas purifying apparatus 1, it is possible to prevent the exhaust gas treating body 1 from being damaged by contact with the casing 20 covering the outer periphery due to 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.

That is, in the exhaust gas purifying apparatus 1, the density of the inorganic fibers of the mat 30 disposed at each corner portion is lower than the density of the inorganic fibers of the mat 30 disposed at each connection portion.

Therefore, when press-fitting the exhaust gas treating body 10 around which the mat 30 is wound, the inorganic fibers can be easily moved to a lower density, and the pressure applied to the mat 30 disposed at each corner portion is reduced. Can do. Therefore, it is possible to prevent the bulk density of the mat 30 disposed at each corner portion from increasing. As a result, it is possible to prevent the mat from being cracked or crushed.

Moreover, in the exhaust gas purification apparatus 1, the opening part 33 is formed in the mat 30 arrange | positioned at each corner part. When such an opening 33 is formed, the inorganic fibers can easily move to the opening 33 when the exhaust gas treating body 10 around which the mat 30 is wound is press-fitted. That is, when the inorganic fiber easily moves to the opening 33, the thickness of the first region 34 of the mat 30 becomes thinner than the thickness of the second region 35 of the mat 30 as shown in FIG.
Thereby, the pressure which the mat | matte 30 arrange | positioned at each corner part receives can be reduced.
Therefore, it is possible to prevent the bulk density of the mat 30 disposed at each corner portion from increasing. As a result, it is possible to prevent the mat 30 from being cracked or crushed.

The fact that inorganic fibers can easily move to the opening 33 will be described below with reference to the drawings.
FIG. 9A is a cross-sectional view schematically showing the broken line portion in FIG. 4-1A cut along the line AA so that the opening passes therethrough. FIG.9 (b) is a schematic diagram which shows typically the state of the part shown to Fig.9 (a) of the mat | matte arrange | positioned at the exhaust gas purification apparatus of this invention.
As shown in FIG. 9A, an opening 33 is formed in the first region 34 of the mat 30 and has a thickness T. In addition, the inorganic fiber 37 is present around the opening 33 in the mat 30.
As shown in FIG. 9B, when the mat 30 is wound around the exhaust gas treating body 10 and accommodated in the casing 20, the mat 30 receives pressure from these and is compressed. The thickness of the mat 30 disposed in the exhaust gas purification device is reduced.
When there is such compression, if there are no openings in the mat, there are few places where the mat fibers can move, so the bulk density of the mat increases. Therefore, cracks and crushing are likely to occur in the mat.
However, when the opening 33 is formed like the mat 30, the inorganic fibers 37 around the opening 33 can easily move to the space of the opening 33 (in FIG. 9B, inorganic fibers 37 The direction in which the fiber 37 moves is indicated by an arrow). That is, the center part of the mat in the thickness direction is depressed. Therefore, the bulk density of the mat 30 is difficult to increase.
In particular, the first region 34 of the mat 30 disposed at each corner portion receives a strong pressure.
Even in such a case, the inorganic fibers 37 around the opening 33 can easily move into the space of the opening 33 in the first region 34 of the mat 30 as described above. Therefore, it is possible to prevent the bulk density of the mat 30 disposed at each corner portion from increasing. As a result, it is possible to prevent the mat 30 from being cracked or crushed.

In the exhaust gas purification apparatus 1, only one opening 33 of the mat 30 is formed in the width direction of the mat 30, but in the mat constituting the exhaust gas purification apparatus of the present invention, it is disposed at each corner portion. Two or more openings may be formed in a part of the mat in the width direction of the mat.

Further, the shape of the opening 33 when the mat 30 is viewed in plan is substantially rectangular. However, as shown in FIGS. 10A to 10G, in the exhaust gas purification apparatus of the present invention, the shape of the opening is However, it is not particularly limited, and it may be at least one shape selected from the group consisting of a substantially circular shape, a substantially elliptical shape, a substantially racetrack shape, a substantially hexagonal shape, a substantially pentagonal shape, a substantially quadrangular shape, and a substantially triangular shape.
FIGS. 10A to 10G are plan views schematically showing an example of a mat constituting the exhaust gas purifying apparatus of the present invention, and show mats having openings of various shapes.
A mat 30a shown in FIG. 10A has a substantially circular opening 33a.
The mat 30b shown in FIG. 10B has a substantially elliptical opening 33b.
A mat 30c shown in FIG. 10C has a substantially racetrack-shaped opening 33c.
A mat 30d shown in FIG. 10D has a substantially hexagonal opening 33d.
A mat 30e shown in FIG. 10E has a substantially pentagonal opening 33e.
A mat 30f shown in FIG. 10 (f) has a substantially parallelogram opening 33f.
A mat 30g shown in FIG. 10 (g) has a substantially triangular opening 33g.

In the exhaust gas purification apparatus of the present invention, the opening may be formed from the side surface of the mat.
FIGS. 10 (h) and (i) are plan views schematically showing an example of a mat constituting the exhaust gas purifying apparatus of the present invention, and show a mat in which an opening is formed from the side.
In FIG. 10H, a substantially rectangular opening 33h is formed from one side surface of the mat 30h.
In FIG. 10 (i), a substantially rectangular opening 33i is formed from both side surfaces of the mat 30i. That is, in the portion where the opening 33i exists in the width direction of the mat 30i, the mat 30i is connected to the center portion in the width direction of the mat 30i.

In the exhaust gas purification apparatus 1, the length of the opening 33 in the width direction of the mat 30 is desirably 1/10 to 9/10 of the width of the mat 30.
In this specification, the length of the opening in the width direction of the mat refers to the distance from one end of the opening 33 in the width direction of the mat 30 to the other end.
Further, when there are two or more openings in the width direction of the mat, the length of each opening in the width direction of the mat 30 is preferably within the above range.

When the length of the opening 33 in the width direction of the mat 30 is less than 1/10 of the width of the mat 30, the surface specific gravity of the mat 30 disposed in each corner portion is not easily lowered. In addition, the bulk density of the mat 30 disposed at each corner is unlikely to be sufficiently low. Therefore, it becomes difficult to obtain the effect of preventing the mat 30 from being cracked or crushed.
If the length of the opening 33 in the width direction of the mat 30 is longer than 9/10 of the width of the mat 30, the surface specific gravity of the mat 30 disposed in each corner portion becomes too small. The mat 30 is easily cut off.

In the exhaust gas purification apparatus 1, the length of the opening 33 in the width direction of the mat 30 is desirably 10 mm to 70 mm.

In the exhaust gas purifying apparatus 1, when the length of the opening 33 in the width direction of the mat 30 is less than 10 mm, the surface specific gravity of the mat 30 disposed at each corner portion is not sufficiently low, The bulk density of the mat 30 disposed at each corner is unlikely to be sufficiently low. Therefore, it becomes difficult to obtain the effect of preventing the mat 30 from being cracked or crushed.
If the length of the opening 33 in the width direction of the mat 30 is more than 70 mm, the mat 30 is easily cut off because the surface specific gravity of the mat 30 disposed at each corner portion is too small. .

In the exhaust gas purifying apparatus 1, in a continuous area of the mats 30 arranged at each corner portion, the mat 30 is viewed in plan, and a first straight line 38 perpendicular to the length direction of the mat 30 is set to the length of the mat 30. The second straight line 39 perpendicular to the longitudinal direction of the mat 30 is drawn with the other end of the longitudinal opening 33 of the mat 30 so as to come into contact with one end of the longitudinal opening 33. When pulled so as to come in contact, the surface specific gravity of the mat 30 existing in the region between the first straight line 38 and the second straight line 39 is 30 of the surface specific gravity of the mat 30 disposed in each connecting portion. It is desirable to be 99.5%.

This will be described with reference to the drawings.
FIG. 11 is a diagram of a mat showing a region between the first straight line and the second straight line when the first straight line and the second straight line are drawn on an example of the mat constituting the exhaust gas purifying apparatus of the present invention. It is a top view.

As shown in FIG. 11, an opening 33 is formed in the mat 30. In order to obtain the above range, first, a first straight line 38 perpendicular to the length direction of the mat 30 is drawn so as to contact one end of the opening 33. Next, a second straight line 39 perpendicular to the length direction of the mat 30 is drawn so as to come into contact with one end of the opening 33.
The mat 30 existing in the region between the first straight line 38 and the second straight line 39 is a mat existing in a range divided by the first straight line 38 and the second straight line 39.

When the surface specific gravity of the mat 30 existing in the region between the first straight line 38 and the second straight line 39 is less than 30% of the surface specific gravity of the mat 30 disposed in each connecting portion, the first Since the amount of inorganic fibers present in the region between the straight line 38 and the second straight line 39 becomes too small, the mat 30 is easily cut off.
When the surface specific gravity of the mat 30 existing in the region between the first straight line 38 and the second straight line 39 exceeds 99.5% of the surface specific gravity of the mat 30 disposed in each connecting portion, Since the inorganic fibers of the mat 30 disposed in the corner portion are difficult to move to the opening 33, the bulk density of the mat 30 disposed in each corner portion is not easily lowered. Therefore, it becomes difficult to obtain the effect of preventing the mat 30 from being cracked or crushed.

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. 12 is a cross-sectional view schematically showing an example of the exhaust gas purification apparatus of the present invention when an exhaust gas purification filter is used as the exhaust gas treatment body, cut in parallel to the longitudinal direction of the exhaust gas purification apparatus.
As shown in FIG. 12, the exhaust gas discharged from the internal combustion engine and flowing into the exhaust gas purification device 1 (in FIG. 12, 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 to 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. 12, the exhaust gas purification filter 50 is mainly made of a porous ceramic such as silicon carbide and has a column shape, but 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.

Next, an example of the manufacturing method of the exhaust gas purification apparatus 1 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, and for example, a mat 30 having a contour as shown in FIG.
Further, in a later step, the mat 30 is punched so that the opening 33 is formed in a portion of the mat 30 disposed at each corner portion of the exhaust gas treating body 10.
The portion of the mat 30 disposed at each corner of the exhaust gas treatment body 10 can be calculated in advance from the size of the exhaust gas treatment body 10 and the like.

When the exhaust gas purifying apparatus of the present invention is manufactured, after the mat 30 having the shape shown in FIG. 4A is manufactured, the convex portion 31a and the concave portion 32a of the mat 30 are fitted. The mat 30 is wound around the exhaust gas treating body 10 to produce a wound body 40 shown in FIG.
The exhaust gas treating body 10 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. 13 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. 13, an exhaust gas treating body 10 (wound body 40) around which a 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 for the mat 30 to compress after press-fitting and exhibit a predetermined repulsive force (that is, a force for holding the honeycomb filter), the inner diameter of the casing 20 includes the thickness of the mat 30 of the exhaust gas treatment body 10 around which the mat 30 is wound. It is slightly 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 to the inner peripheral surface of the casing is smaller than the distance from the connecting portion to the inner peripheral surface of the casing, and the mat surface disposed at the corner portion Specific gravity is smaller than the surface specific gravity of the mat | matte arrange | positioned at the connection part.
Therefore, even if the pressure from the casing is received, the bulk density of the mat disposed at the corner portion 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, a load applied to the mat disposed at 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.

(2) In the exhaust gas purifying apparatus of the present invention, when an opening is formed in a part of the mat disposed in the corner portion, when the exhaust gas treating body around which the mat is wound is press-fitted, the inorganic fibers It can be easily moved to the opening, and the pressure applied to the mat disposed at the corner can be reduced. Therefore, it is possible to prevent the bulk density of the mat disposed at the corner portion from increasing. As a result, it is possible to prevent the mat from being cracked or crushed.

(3) In the exhaust gas purifying apparatus of the present invention, if two or more openings are formed in a part of the mat disposed in the corner portion in the width direction of the mat, the exhaust gas treatment in which the mat is wound When press-fitting the body, the inorganic fibers easily move to the openings.
Therefore, it can prevent that the pressure received from a casing applies only to a part of mat | matte. That is, it is possible to prevent the bulk density of a part of the mat from increasing. As a result, it is possible to prevent the mat from being cracked or crushed.

(4) In the exhaust gas purifying apparatus of the present invention, the shape of the opening is at least selected from the group consisting of a substantially circular shape, a substantially elliptical shape, a substantially racetrack shape, a substantially hexagonal shape, a substantially pentagonal shape, a substantially square shape, and a substantially triangular shape. When the shape is one, the shape of the opening can be selected in accordance with the radius of curvature of the corner portion of the exhaust gas treating body and the shape of the inner peripheral surface of the casing. In this case, when the exhaust gas treating body around which the mat is wound is press-fitted, the inorganic fibers can easily move to the opening. Thereby, the pressure which a mat receives from a casing can be disperse | distributed, and it can prevent that the bulk density of a part of mat | matte becomes high. As a result, it is possible to prevent the mat from being cracked or crushed.

(5) In the exhaust gas purifying apparatus of the present invention, when the length of the opening in the width direction of the mat is 1/10 to 9/10 of the width of the mat, the mat disposed at the corner portion The surface specific gravity of the mat is sufficiently low, and the bulk density of the mat disposed in the corner portion is sufficiently low. Therefore, it is possible to obtain the effect of preventing the mat from being cracked or crushed. In addition, the surface specific gravity of the mat disposed in the corner portion does not become too small, and the mat becomes difficult to break.

(6) In the exhaust gas purifying apparatus of the present invention, if the length of the opening in the width direction of the mat is 10 mm to 70 mm, the surface specific gravity of the mat disposed in the corner is sufficiently low, and the corner The bulk density of the mat disposed in the is sufficiently low. Therefore, it is possible to obtain the effect of preventing the mat from being cracked or crushed. In addition, the surface specific gravity of the mat disposed in the corner portion does not become too small, and the mat becomes difficult to break.

(7) In the exhaust gas purifying apparatus of the present invention, in a continuous area of the mats arranged at the corner portions, the mat is viewed in plan, and the first straight line perpendicular to the length direction of the mat is the length of the mat. The second straight line perpendicular to the mat length direction is drawn so as to contact the other end of the mat length opening. In this case, when the surface specific gravity of the mat existing in the region from the first straight line to the second straight line is 30 to 99.5% of the surface specific gravity of the mat disposed in the connecting portion, The amount of inorganic fibers present in the region between the first straight line and the second straight line does not become too small, and the mat is difficult to break. In addition, the inorganic fibers of the mat disposed in the corner portion do not easily move to the opening, and the bulk density of the mat disposed in the corner portion is likely to be sufficiently low. Therefore, it is possible to obtain the effect of preventing the mat from being cracked or crushed.

(8) In the exhaust gas purifying apparatus according to the present invention, when the density of the inorganic fibers of the mat disposed in the corner portion is lower than the density of the inorganic fibers of the mat disposed in the connecting portion, the mat is wound. When the exhaust gas treatment body is press-fitted, the inorganic fibers can be easily moved to a lower density, and the pressure applied to the mat disposed at the corner portion can be reduced. Therefore, it is possible to prevent the bulk density of the mat disposed at the corner portion from increasing. As a result, 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 material having a contour as shown in FIG. 4-1 (a) was punched from the mat material.
The mat material was punched using a Thomson blade and a hydraulic press.
The dimensions of the punched-out mat are such that the length L in the longitudinal direction is L = 545 mm, the width W is 110 mm, the thickness T is 9.1 mm, and the length in the longitudinal direction of the concave and convex fitting portions is D = 50 mm.

Subsequently, the mat material was punched out so that an opening was formed in the portion of the mat material to be disposed at the corner portion of the exhaust gas treating body, thereby producing a mat.
The shape of the opening is substantially rectangular, the opening length = 10 mm, and the opening width = 70 mm. The length from each side surface of the mat to the opening is 20 mm.
The opening length is the length of the opening in the longitudinal direction of the mat member. The opening width is the length of the mat member in the width direction.
Further, Table 1 shows the “percentage of the opening in the first region”, “ratio of the opening in the entire mat”, “surface specific gravity of the first region”, “second” of the mat according to the first embodiment. “Area specific gravity” and “surface specific gravity of the entire mat” are shown.

FIG. 14A shows dimensions (vertical, horizontal, diagonal 1, diagonal 2, and radius of curvature (r of the corner portion) for specifying the shape of a cross section perpendicular to the longitudinal direction of the exhaust gas purification filter. )) Is a cross-sectional view schematically showing.
FIG. 14B 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, corner radius of curvature (R). Is a cross-sectional view schematically showing.
When the exhaust gas purification filter made of SiC used in this example is represented by the reference shown in FIG. 14, 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 of the corner 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 housed in the casing using a press-fitting method to manufacture an exhaust gas purification device. The casing has a length of 151.8 mm, a width of 151.8 mm, a diagonal of 1: 186.8 mm, a diagonal of 2: 186.8 mm, and a corner radius of curvature R of 25 mm.

(Matte condition evaluation)
24 hours after the press-fitting, the mat was taken out of the casing, visually observed, and evaluated as follows. The results are shown in Table 2.
A: The mat is not cut.
○: The mat fibers are crushed, but the mat is not cut.
X: The mat is cut.

(Durability test on retention)
As an endurance test regarding the holding property, Example 1 was used to perform a thermal cycle evaluation in which the engine speed was increased or decreased with a bench tester. Specifically, the engine speed was increased or decreased between 1000 rpm and 5000 rpm, and this was repeated 1000 cycles. The state of the exhaust gas treating body at this time was evaluated as follows. The results are shown in Table 2.
A: The amount of movement of the exhaust gas treating body is less than 0.5 mm.
○: The exhaust gas treating body is moving, but the moving amount is 0.5 mm or more and less than 3.0 mm.
X: The exhaust gas treating body is displaced, and the moving amount is 3.0 mm or more.

(Gas sealability test)
FIG. 15 is an explanatory diagram of the gas sealability test, and FIG. 15A is a top view schematically showing the experimental apparatus. FIG. 15B is a cross-sectional view taken along the line BB. In the experimental apparatus used here, an air pipe 61 is attached to the flat container 60, and air is allowed to flow into the flat container 60 through the air pipe 61. In the gas sealability test, a part of the mat is inserted into the flat container 60, and the static pressure of the space S when the air is injected into the space S surrounded by the flat container 60 and a part of the mat in that state. This is done by measuring with the pressure gauge 62. The flat container 60 has a width of 110 mm, a height of 3.6 mm, and a depth of 120 mm.
From the exhaust gas purifying apparatus of Example 1, the mat 24 hours after the press-fitting was taken out from the casing.
Next, the portion disposed in the corner portion of the exhaust gas purification apparatus was cut and inserted into the flat container 60, and the static pressure was measured by the above method.
Further, as a comparative sample, a mat that was not press-fitted into the exhaust gas purification device was prepared, cut in the same manner, inserted into the flat container 60, and the static pressure was measured by the above method.
The gas sealability of the mat was evaluated as follows. The results are shown in Table 2.
(Double-circle): The static pressure using an Example is 90% or more of the static pressure using a comparative sample.
(Circle): The static pressure using an Example is 70% or more and less than 90% of the static pressure using a comparative sample.
X: The static pressure using an Example is less than 70% of the static pressure using a comparative sample.

(Example 2)
Exhaust gas purifying apparatus according to Example 2 was manufactured in the same manner as in Example 1 except that two openings having an opening length of 10 mm and an opening width of 25 mm were formed in the width direction of the mat. .

Example 3
Exhaust gas purifying apparatus according to Example 3 was manufactured in the same manner as in Example 1 except that in the punching of the opening, three openings having an opening length of 10 mm and an opening width of 10 mm were formed in the mat width direction. .

Example 4
Exhaust gas purifying apparatus according to Example 4 was manufactured in the same manner as in Example 1 except that three circular openings having a diameter of 10 mm were formed in the width direction of the mat in the punching of the openings.

(Examples 5 to 7)
Exhaust gas purifying apparatuses according to Examples 5 to 7 were manufactured in the same manner as in Example 1 except that the size of the opening was changed as shown in Table 1 in punching the opening.

(Comparative Example 1)
Exhaust gas purifying apparatus according to Comparative Example 1 was manufactured in the same manner as Example 1 except that the opening was not punched.

For Examples 2 to 7 and Comparative Example 1, as in Example 1, evaluation of the state of the mat after press-fitting, an endurance test on retention, and a gas sealability test were performed. The results are shown in Table 2.

As shown in Table 2, in the condition evaluation of the mat after press-fitting, in Examples 1 to 7, the condition of the mat was good. In particular, in Examples 1 and 2 and 5 to 6, there was almost no change in the mat. On the other hand, in Comparative Example 1, the mat was cut.

As shown in Table 2, in the endurance test relating to retention, in Examples 1 to 7, the retention of the exhaust gas treating body was good. In particular, in Examples 1 to 6, there was no evidence of displacement of the exhaust gas treating body. In addition, Comparative Example 1 also had good retention.

As shown in Table 2, in Examples 1 to 7, the gas sealability was good in the gas sealability test. On the other hand, in Comparative Example 1, the gas sealability of the mat after being disposed in the exhaust gas purification device was significantly reduced.

The exhaust gas purification apparatus of the present invention includes a columnar exhaust gas treatment body, a casing made of a tubular body that houses the exhaust gas treatment body, and a mat made of inorganic fibers inserted between the exhaust gas treatment body and the casing. And the contour of the cross section perpendicular to the longitudinal direction of the exhaust gas treating body is composed of 3 to 6 corner portions and a connecting portion for connecting the corner portions, and the corner portion is a curve, The connecting portion is formed of a straight line or a curve, and the distance from the corner portion to the inner peripheral surface of the casing is smaller than the distance from the connecting portion to the inner peripheral surface of the casing, and is disposed in the corner portion. It is an essential constituent requirement that the surface specific gravity of the mat is smaller than the surface specific gravity of the mat disposed in the connecting portion.
The essential components include various configurations detailed in the detailed description of the present invention (for example, formation of an opening, shape of the opening, length of the opening, surface specific gravity of the mat, density of inorganic fibers, inorganic The desired effect can be obtained by appropriately combining the types of fibers, needle punching on the mat, and the like.

1 Exhaust

gas purification apparatus

10, 110, 210, 310, 410 Exhaust

gas treatment body

11, 111

Contours

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

13d Straight lines

14a, 14b, 14c, 14d, 114a, 114b, 114c,

114d Corner portions

15a, 15b, 15c, 15d, 115a, 115b, 115c, 115d Connecting portion 20

Casing

30, 30a, 30b, 30c, 30d, 30e, 30f, 30g, 30h, 30i

Mat

31, 32 End surface 31a Convex part 32a

Concave part

33, 33a, 33b, 33c, 33d, 33e, 33f, 33g, 33h, 33i Opening part 33 ', 36 Flat surface 34 First region 35 First 2 region 37 inorganic fiber 38 First straight line 39 Second straight line 40 Wound body 50 Exhaust gas purification filter 50a Exhaust gas inflow side end face 50b Exhaust gas outflow side end face 51 Cell 52 Cell wall 53 Plugging portion 54 Outer peripheral coat layer 60 Flat vessel 61 Air piping 62 Pressure gauge

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 treating body is composed of 3 to 6 corner portions and a connecting portion connecting the corner portions, and the corner portion is formed of a curve and the connecting portion. The part consists of straight lines or curves,
The distance from the corner portion to the inner peripheral surface of the casing is smaller than the distance from the connecting portion to the inner peripheral surface of the casing,
The exhaust gas purifying apparatus according to claim 1, wherein a surface specific gravity of the mat disposed in the corner portion is smaller than a surface specific gravity of the mat disposed in the connecting portion.
The exhaust gas purifying apparatus according to claim 1, wherein an opening is formed in a part of the mat disposed in the corner portion.
The exhaust gas purification apparatus according to claim 2, wherein two or more openings are formed in a part of the mat disposed in the corner portion in the width direction of the mat.
The shape of the opening is at least one shape selected from the group consisting of a substantially circular shape, a substantially elliptical shape, a substantially racetrack shape, a substantially hexagonal shape, a substantially pentagonal shape, a substantially rectangular shape, and a substantially triangular shape. The exhaust gas purification apparatus as described.
The exhaust gas purifying apparatus according to any one of claims 2 to 4, wherein a length of the opening in the width direction of the mat is 1/10 to 9/10 of a width of the mat.
The exhaust gas purifying apparatus according to any one of claims 2 to 5, wherein a length of the opening in the width direction of the mat is 10 mm to 70 mm.
In the continuous area of the mat disposed in the corner portion,
In the plan view of the mat, a first straight line perpendicular to the length direction of the mat is drawn so as to contact one end of the opening in the length direction of the mat, and the length direction of the mat A second straight line perpendicular to the mat is brought into contact with the other end of the opening in the longitudinal direction of the mat,
The surface specific gravity of the mat existing in a region between the first straight line and the second straight line is 30 to 99.5% of the surface specific gravity of the mat disposed in the connecting portion. Item 7. The exhaust gas purifying device according to any one of Items 2 to 6.
The density of the inorganic fibers of the mat disposed in the corner portion is lower than the density of the inorganic fibers of the mat disposed in the connecting portion. Exhaust gas purification device.
The exhaust gas purifying apparatus according to any one of claims 1 to 8, 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 9, wherein the mat is further subjected to a needle punching process.