JPWO2015016097A1 - Exhaust gas purification device - Google Patents

Abstract

An object of the present invention is to provide an exhaust gas purifying apparatus that is unlikely to be cracked or crushed in the mat, and that the exhaust gas treating body is firmly held by the mat and that leakage of exhaust gas can be prevented. The present invention includes a columnar exhaust gas treating body having a corner portion on a side surface, a casing made of a tubular body containing the exhaust gas treating body and having a corner portion on an inner wall surface thereof, and inserted between the exhaust gas treating body and the casing. And the number of corner portions present on the side surface of the exhaust gas treatment body and the inner wall surface of the casing is the same number, and 3 to 6 respectively. From the curvature radius in the cross section perpendicular to the longitudinal direction of the corner portion of the inner wall surface of the casing, the corner portion of the side surface is accommodated in the casing so as to face the corner portion existing on the inner wall surface of the casing. Also, the exhaust gas purifying apparatus is characterized in that the radius of curvature in the cross section perpendicular to the longitudinal direction of the corner portion on the side surface of the exhaust gas treating body is larger.

Description

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. In particular, in the case where the corner portion (corner portion) of the rectangle is close to the shape of the rounded chamfer, the radius of curvature of the corner portion becomes small.
For this reason, when press-fitting the mat, there is a problem that a load on the mat disposed at the corner portion is increased, and the mat is likely to be cracked or crushed.

In addition, when using an exhaust gas purifying apparatus with a mat, the corners of the exhaust gas treatment body are likely to gather at the corner due to vibrations, etc. due to the small radius of curvature of the corner of the exhaust gas treatment body. There is also a problem that the bulk density becomes high and the mat is easily 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 a casing comprising a columnar exhaust gas treatment body having a corner portion on a side surface and a tubular body containing the exhaust gas treatment body and having a corner portion on an inner wall surface thereof. And a mat composed of inorganic fibers inserted between the exhaust gas treating body and the casing,
The number of corner portions existing on the side surface of the exhaust gas treatment body and the inner wall surface of the casing is the same, and each is 3 to 6, and the corner portion on the side surface of the exhaust gas treatment body is the inner wall surface of the casing. And the length of the corner portion on the side surface of the exhaust gas treatment body is larger than the radius of curvature in the cross section perpendicular to the longitudinal direction of the corner portion of the inner wall surface of the casing. The radius of curvature in the cross section perpendicular to the direction is larger.

In the exhaust gas purifying apparatus of the present invention, the side surface of the exhaust gas treatment body is more than the radius of curvature in the cross section perpendicular to the longitudinal direction of the corner portion of the casing inner wall surface (hereinafter also simply referred to as the radius of curvature of the corner portion of the casing inner wall surface). The radius of curvature in the cross section perpendicular to the longitudinal direction of the corner portion of the exhaust gas treatment body (hereinafter, also simply referred to as the radius of curvature of the corner portion of the exhaust gas treatment body side) is larger, and the corner portion of the side surface of the exhaust gas treatment body has a gentle curved surface. Therefore, when using an exhaust gas purification apparatus in which a mat is disposed on the side surface of the exhaust gas treatment body, even if vibration or the like occurs in the exhaust gas purification apparatus due to traveling of an automobile or the like, the mat is difficult to collect at the corner portion of the exhaust gas treatment body .
Further, due to the difference between the curvature radius of the corner portion of the inner wall surface of the casing and the curvature radius of the corner portion of the exhaust gas treatment body, the corner portion of the exhaust gas treatment body has an interval with the inner wall surface of the casing. The bulk density of the mat at the corner portion is difficult to increase. 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 corner portion is hardly 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 treatment body. Further, it is possible to prevent the exhaust gas from leaking firmly.

It is desirable that the exhaust gas treating body and the casing constituting the exhaust gas purifying apparatus of the present invention each have four corner portions.

When the exhaust gas treatment body and the casing constituting the exhaust gas purification apparatus have four corner portions as described above, the radius of curvature of the corner portion of the exhaust gas treatment body tends to be small, which has been described in the section of the prior art. Thus, cracks and crushing are likely to occur in the mat disposed at the corner portion. However, in the exhaust gas purification apparatus of the present invention, as described above, the cross section perpendicular to the longitudinal direction of the corner portion on the side surface of the exhaust gas treatment body is larger than the radius of curvature in the cross section perpendicular to the longitudinal direction of the corner portion of the inner wall surface of the casing. Since the radius of curvature at is larger, when using an exhaust gas purification device with a mat, it is difficult for the mat to collect at the corner of the exhaust gas treatment body, and the corner of the exhaust gas treatment body and the corner of the inner wall of the casing Since the volume between them is large, the bulk density of the mat is difficult to increase. For this reason, cracks and crushing are unlikely to occur in the mat.

In the exhaust gas purification apparatus of the present invention, the radius of curvature in the cross section perpendicular to the longitudinal direction of the corner portion on the side surface of the exhaust gas treating body is the same in any cross section perpendicular to the longitudinal direction, and the corner portion of the inner wall surface of the casing The radius of curvature in the cross section perpendicular to the longitudinal direction is the same in any cross section perpendicular to the longitudinal direction.
Therefore, in the exhaust gas purifying apparatus of the present invention, the same effect can be obtained in any part, and the mat disposed in the corner part of the exhaust gas treating body is less likely to be cracked or crushed in all parts. .

In the exhaust gas purification apparatus of the present invention, the curvature radius in the cross section perpendicular to the longitudinal direction of the corner portion on the side surface of the exhaust gas treatment body is 1 rather than the curvature radius in the cross section perpendicular to the longitudinal direction of the corner portion of the inner wall surface of the casing. 0.05 to 4 times larger is desirable.
If the ratio of the curvature radii is smaller than 1.05 times, mats may be easily collected at the corner portion of the exhaust gas treatment body. On the other hand, if the ratio of the curvature radii exceeds four times, The volume from the corner portion to the corner portion on the side surface of the exhaust gas treatment body becomes too large, and a void portion where no mat exists is easily formed, and the holding power of the mat is weakened.

When the exhaust gas purifying apparatus of the present invention is configured as described above, the mat is less likely to gather at the corner portion of the exhaust gas treating body, and the bulk density of the mat is less likely to increase. For this reason, cracks and crushing are less likely to occur in the mat.

In the exhaust gas purification apparatus of the present invention, the inorganic fiber constituting the mat may be at least one inorganic fiber selected from the group consisting of alumina fiber, alumina-silica fiber, silica fiber, and biosoluble fiber. desirable.

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 performing needle punching treatment on the mat, the entanglement between the inorganic fibers occurs, and the inorganic fibers are difficult to move. The mat is less likely to crack or crush.

Fig.1 (a)-(c) is a perspective view which shows typically the shape of the waste gas processing body of this invention. 2A to 2C are cross-sectional views schematically showing a cross section perpendicular to the longitudinal direction of the casing of the exhaust gas purifying apparatus in which a mat is inserted between the exhaust gas treating body and the casing. FIG. 3 is a cross-sectional view schematically showing a cross section parallel to the longitudinal direction of the casing of the exhaust gas purification apparatus including the exhaust gas treating body and the casing shown in FIG. Fig.4 (a) is sectional drawing which shows the simulation result of the bulk density of the mat which comprises the exhaust gas purification apparatus applicable to the Example of this invention, FIG.4 (b) corresponds to the comparative example of this invention. It is sectional drawing which shows the simulation result of the bulk density of the mat | matte which comprises an exhaust gas purification apparatus. FIG. 5 is a perspective view schematically showing a mat used in the exhaust gas purifying apparatus of the present invention. FIG. 6 is a perspective view showing a state in which the wound body constituting the exhaust gas purifying apparatus of the present invention is housed in the casing. FIGS. 7A and 7B are cross-sectional views schematically showing dimensions serving as a reference for specifying the shape of a cross section perpendicular to the longitudinal direction of the exhaust gas purification filter. FIGS. 8A to 8E are photographs taken of the state of the mat used in Example 1. FIG. 9A to 9E are photographs taken of the state of the mat used in Comparative Example 1. FIG.

(Detailed description of the invention)
Hereinafter, the exhaust gas purifying apparatus of the present invention will be described.
The exhaust gas purifying apparatus of the present invention includes a columnar exhaust gas treating body having a corner portion on a side surface,
Containing the exhaust gas treating body, and comprising a casing made of a tubular body having a corner portion on an inner wall surface thereof, and a mat made of inorganic fibers inserted between the exhaust gas treating body and the casing,
The number of corner portions existing on the side surface of the exhaust gas treatment body and the inner wall surface of the casing is the same, and each is 3 to 6, and the corner portion on the side surface of the exhaust gas treatment body is the inner wall surface of the casing. And the length of the corner portion on the side surface of the exhaust gas treatment body is larger than the radius of curvature in the cross section perpendicular to the longitudinal direction of the corner portion of the inner wall surface of the casing. The radius of curvature in the cross section perpendicular to the direction is larger.

First, the exhaust gas treating body constituting the exhaust gas purifying apparatus of the present invention will be described.
The exhaust gas treating body of the present invention is a columnar exhaust gas treating body having a corner portion on a side surface.
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. What is plugged on either the inlet side or the outlet side, made of a plate-like material, made of a filter, made of a metal porous body having a three-dimensional network structure, made of a laminate of ceramic fibers Etc. 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 has a columnar shape and a shape having a corner portion on the side surface.
Among these, a honeycomb filter made of a porous ceramic such as silicon carbide or cordierite, in which a large number of cells are provided in the longitudinal direction, and either the exhaust gas inlet side or the outlet side is plugged is 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 And a sheet obtained by processing a thin sheet in a wavy shape, and a catalyst supported on the 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 and has a shape having a corner on the side surface. .
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 be mentioned. These catalysts may be used independently and may use 2 or more types together.

The exhaust gas treating body of the present invention is columnar and has a corner portion having a predetermined radius of curvature on the side surface.
The curvature is a quantity representing the degree of curve or curved surface curvature, but the local degree of curvature can be approximated to a circle, and the approximate radius of the circle is called the radius of curvature. For example, the curvature of the circumference of the radius r is 1 / r and the curvature radius is r. The tighter the curve is, the larger the curvature and the smaller the radius of curvature. The radius of curvature can be represented by the radius of the arc if the curve is composed of an arc that constitutes a circle. On the other hand, if the curve is different from the arc, the curvature is determined by a predetermined function that represents the degree of curvature of the curve. A radius can be represented.

Fig.1 (a)-(c) is a perspective view which shows typically the shape of the waste gas processing body of this invention.
FIG. 1 (a) schematically shows an exhaust gas treatment body 10D having a substantially triangular prism shape having a corner portion 10Da having a radius of curvature rd1 in a cross section perpendicular to the longitudinal direction.
The curvature radius rd1 of the corner portion 10Da means that the corner portion 10Da in a cross section perpendicular to the longitudinal direction is composed of a part of a circle (arc) having a radius of rd1.

FIG. 1B schematically shows an exhaust gas treating body 20D having a substantially quadrangular prism shape having a corner portion 20Da having a radius of curvature rd2 in a cross section perpendicular to the longitudinal direction.
Similarly, in the exhaust gas treating body 20D, the corner portion 20Da in a cross section perpendicular to the longitudinal direction is configured by a part (arc) of a circle having a radius of rd2.

FIG. 1C schematically shows an exhaust gas treating body 30D having a substantially pentagonal prism shape having a corner portion 30Da having a radius of curvature rd3 in a cross section perpendicular to the longitudinal direction.
Further, in the exhaust gas treating body 30D, the corner portion 30Da in the cross section perpendicular to the longitudinal direction is constituted by a part of a circle (arc) having a radius of rd3.

In the exhaust gas treatment bodies 10D, 20D, and 30D shown in FIGS. 1A to 1C, the lines that connect the corner portions 10Da, 20Da, and 30Da in a cross section perpendicular to the longitudinal direction are shown in FIGS. A straight line or a curved line may be used as described in (c).
That is, in the exhaust gas treatment bodies 10D, 20D, and 30D, the other side surfaces other than the corner portions 10Da, 20Da, and 30Da may be flat or curved.

The exhaust gas treatment bodies 10D, 20D, and 30D shown in FIGS. 1A to 1C have 3 to 5 corner portions, but may have 6 corner portions. Moreover, the space | interval of corner parts does not need to be the same.

Next, the casing which comprises the exhaust gas purification apparatus of this invention is demonstrated.
The casing of the present invention is made of a tubular body that contains an exhaust gas treating body and has a corner portion on its inner wall surface, and a mat made of inorganic fibers is inserted between the exhaust gas treating body and the casing. The mat made of inorganic fibers is also called a holding sealing material.

The casing 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 so that the exhaust gas treatment body can be accommodated therein. Since the exhaust gas treating body has a corner portion on the side surface, the exhaust gas treating body has a corner portion in a portion facing the corner portion of the inner wall surface of the casing, but has a radius of curvature in a cross section perpendicular to the longitudinal direction of the corner portion of the inner wall surface of the casing. The radius of curvature rd in the cross section perpendicular to the longitudinal direction of the corner portion on the side surface of the exhaust gas treating body is larger than rc.

2A to 2C are cross-sectional views schematically showing a cross section perpendicular to the longitudinal direction of the casing of the exhaust gas purification apparatus in which a mat is inserted between the exhaust gas treating body and the casing. 3 is a cross-sectional view schematically showing a cross section parallel to the longitudinal direction of the casing of the exhaust gas purifying apparatus including the exhaust gas treating body and the casing shown in FIG.

In the exhaust gas purifying apparatus shown in FIGS. 2 (a) to 2 (c), as an exhaust gas treatment body, a large number of cells serving as exhaust gas flow paths arranged in the longitudinal direction, and a porous cell partition wall that partitions the cells. The one with is used.

In the exhaust gas purification apparatus 100 shown in FIG. 2 (a), a substantially triangular prism exhaust gas treatment body 10D is accommodated in the casing 10C via a mat 10S, and the longitudinal direction of the corner portion 10Ca on the inner wall surface of the casing 10C is accommodated. The radius of curvature rd1 in the cross section perpendicular to the longitudinal direction of the corner portion 10Da on the side surface of the exhaust gas treating body 10D is larger than the radius of curvature rc1 in the vertical cross section.

For this reason, the distance between the corner portion 10Da of the exhaust gas treatment body 10D and the corner portion 10Ca of the casing 10C is larger than the distance between the side surface of the exhaust gas treatment body 10D other than the corner portion 10Da and the side surface of the casing 10C other than the corner portion 10Ca. Widely, since the radius of curvature rd1 of the corner portion 10Da of the exhaust gas treatment body 10D is larger, the curved surface is gentle, and the mat 10S disposed at the corner portion 10Da of the exhaust gas treatment body 10D is less likely to crack or collapse. .

In the exhaust gas purifying apparatus 200 shown in FIG. 2B, a substantially square column exhaust gas treatment body 20D is accommodated inside the casing 20C via the mat 20S, and in the longitudinal direction of the corner portion 20Ca of the inner wall surface of the casing 20C. On the other hand, the curvature radius rd2 in the cross section perpendicular to the longitudinal direction of the corner portion 20Da on the side surface of the exhaust gas treating body 20D is larger than the curvature radius rc2 in the cross section perpendicular to the cross section.
Accordingly, in this case as well, the distance between the side surface of the exhaust gas treatment body 20D other than the corner portion 20Da and the side surface of the casing 20C other than the corner portion 20Ca is wider, and the radius of curvature rd2 of the corner portion 20Da of the exhaust gas treatment body 20D is larger. Since it is large, the curved surface is gentle, and the mat 20S disposed in the corner portion 20Da of the exhaust gas treating body 20D is less likely to be cracked or crushed.

In the exhaust gas purifying apparatus 300 shown in FIG. 2 (c), a substantially pentagonal exhaust gas treatment body 30D is accommodated in the casing 30C via the mat 30S, and in the longitudinal direction of the corner portion 30Ca on the inner wall surface of the casing 30C. On the other hand, the curvature radius rd3 in the cross section perpendicular to the longitudinal direction of the corner portion 30Da on the side surface of the exhaust gas treating body 30D is larger than the curvature radius rc3 in the cross section perpendicular to the cross section.
Accordingly, in this case as well, the distance between the side surface of the exhaust gas treatment body 30D other than the corner portion 30Da and the side surface of the casing 30C other than the corner portion 30Ca is wider, and the radius of curvature rd3 of the corner portion 30Da of the exhaust gas treatment body 30D is larger. Since it is large, the curved surface is gentle, and the mat 30S disposed in the corner portion 30Da of the exhaust gas treating body 30D is not easily cracked or crushed.

As shown in FIG. 3, the inner diameter of both ends of the casing 20 </ b> C may be gradually smaller than the inner diameter of the central part in which the exhaust gas treating body 20 </ b> D is accommodated, and the inner diameter is constant. It may be a shape. The same applies to casings other than the casing 20C shown in FIG.

The exhaust gas treating body of the present invention has a shape as shown in FIGS. 1A to 1C, and the radius of curvature in the cross section perpendicular to the longitudinal direction of the corner portion of the side surface is any cross section perpendicular to the longitudinal direction. It is desirable that they are the same. Further, the casing of the present invention has a shape as shown in FIGS. 2A to 2C, and the radius of curvature in a cross section perpendicular to the longitudinal direction of the corner portion of the inner wall surface is perpendicular to the longitudinal direction. It is desirable that they are the same in any cross section.

In the exhaust gas purification apparatus of the present invention, the curvature radius in the cross section perpendicular to the longitudinal direction of the corner portion on the side surface of the exhaust gas treatment body is 1 rather than the curvature radius in the cross section perpendicular to the longitudinal direction of the corner portion of the inner wall surface of the casing. It is preferably 0.05 to 4 times larger, and more preferably 1.1 to 1.5 times larger.

Further, as described above, by increasing the radius of curvature in the cross section perpendicular to the longitudinal direction of the corner portion on the side surface of the exhaust gas treatment body, the radius of curvature in the cross section perpendicular to the longitudinal direction of the corner portion of the inner wall surface of the casing is increased. The distance between the inner wall surface of the casing and the side surface of the exhaust gas treatment body is wider than the portion other than the corner portion at both corner portions. The difference between the narrowest part distance and the distance dmin of the narrowest part, dmax−dmin = 2-8 mm, is preferred, and the ratio dmax / dmin = 1.5-3.0 is preferred. Note that the distance between the inner wall surface of the casing and the side surface of the exhaust gas treatment body is such that when a straight line is drawn from the center of gravity in the cross section perpendicular to the longitudinal direction of the side surface of the exhaust gas treatment body toward the casing, The length of the straight line up to the point crossing the inner wall of the casing.

In addition, using a three-dimensional coordinate measuring machine RVA800A-X1 from Tokyo Seimitsu Co., Ltd., and measuring the position of multiple points on the corners of the exhaust gas treatment body and casing, the curve can be specified. In the case of an arc, the radius of curvature of the arc can be obtained.
Furthermore, if the curvature radius of the exhaust gas treatment body or casing 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 By doing so, the radius of curvature can be obtained. Usually, the exhaust gas treating body and the casing are designed and manufactured so as to have a predetermined radius of curvature, so that it is considered that no major problem arises in obtaining the value of the radius of curvature.

Fig.4 (a) is sectional drawing which shows the simulation result of the bulk density of the mat which comprises the exhaust gas purification apparatus applicable to the Example of this invention, FIG.4 (b) corresponds to the comparative example of this invention. It is sectional drawing which shows the simulation result of the bulk density of the mat | matte which comprises an exhaust gas purification apparatus.
That is, FIG. 4 (a) shows an exhaust gas purification apparatus 200 shown in FIG. 2 (b) in which the radius of curvature rc2 of the corner portion 20Ca of the casing 20C is 16 mm and the radius of curvature rd2 of the corner portion 20Da of the exhaust gas treatment body 20D is 17 mm. And the bulk density in the vicinity of the corner when the interval between the exhaust gas treating body 20D and the casing 20C other than the corners 20Ca and 20Da is 3.3 mm and the bulk density of the mat 20S is 0.50 g / cm ^3. It is the figure which simulated.

FIG. 4B shows an exhaust gas purifying apparatus 200 shown in FIG. 2B, in which the radius of curvature rc2 of the corner portion 20Ca of the casing 20C is 20 mm, the radius of curvature rd2 of the corner portion 20Da of the exhaust gas treatment body 20D is 17 mm, The space density between the exhaust gas treating body 20D other than the corner portions 20Ca and 20Da and the casing 20C was 3.3 mm, and the bulk density near the corner portion was simulated when the bulk density of the mat 20S was 0.50 g / cm ³ . FIG.

4A and 4B, when the curvature radius rd2 of the corner portion 20Da of the exhaust gas treatment body 20D is larger than the curvature radius rc2 of the corner portion 20Ca of the inner wall surface of the casing 20C, Compared with the case where the radius of curvature rc2 of the corner portion 20Ca of the inner wall surface of the casing 20C and the radius of curvature rd2 of the corner portion 20Da of the exhaust gas treatment body 20D are the same, the bulk density of the mat becomes low, and cracks and crushing occur in the mat. I find it difficult.

The exhaust gas treating body of the present invention has been described before, but the case where an exhaust gas purifying filter is used as the exhaust gas treating body will be described in more detail.
As shown in FIG. 3, the exhaust gas discharged from the internal combustion engine and flowing into the exhaust gas purification apparatus 200 (in FIG. 3, the exhaust gas is indicated by G and the flow of the exhaust gas is indicated by an arrow) is an exhaust gas treatment body (honeycomb filter) 20D. Flows into one cell 20D1 opened in the exhaust gas inflow side end face 20Dc and passes through the cell partition 20D2 separating the cell 20D1. At this time, PM in the exhaust gas is collected by the cell partition wall 20D2, and the exhaust gas is purified. The purified exhaust gas flows out from another cell 20D1 opened in the exhaust gas outflow side end face 20Dd and is discharged to the outside. Reference numeral 20D3 denotes a plugging portion.

As shown in FIG. 3, the exhaust gas purification filter 20D is mainly made of a porous ceramic such as silicon carbide and has a columnar shape, but the specific shape is not particularly limited. For example, the exhaust gas purification filter 20D has a substantially triangular column shape, a substantially square column shape, A substantially pentagonal prism can be mentioned. Further, on the side surface (outer periphery) of the exhaust gas purification filter 20D, an outer peripheral coat layer 20D4 is provided for the purpose of reinforcing the side surface of the exhaust gas purification filter 20D, adjusting the shape, and improving the heat insulation of the exhaust gas purification filter 20D. Is provided.

In the exhaust gas purification apparatus of the present invention, a mat made of inorganic fibers is inserted between the exhaust gas treating body and the casing.
The inorganic fibers constituting the mat are not particularly limited, and may be alumina-silica fibers, alumina fibers, silica fibers, or the like. Moreover, glass fiber and biosoluble fiber may be sufficient. What is necessary is just to change according to the characteristics requested | required of mat | matte, such as heat resistance and wind erosion resistance, and it is preferable to use the thing of the large diameter fiber and fiber length which can be adapted to the environmental regulation of each country.

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 a spinel compound are more preferable. 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 an inorganic fiber 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 the crystallization rate of 0.4 to 20%. Mats made of inorganic fibers in this range have a high repulsive force and a high restoration surface pressure after a durability test, and have good performance. However, when the crystallization ratio is less than 0.1% or exceeds 30%, the repulsive force and the restoring surface pressure are rapidly decreased. The method for measuring the crystallization rate 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 °).

The mat is desirably a needle mat obtained by subjecting a base mat made of inorganic fibers to needle punching. The needle punching process refers to inserting and removing fiber entanglement means such as a needle with respect to the base mat.

In the mats shown in FIGS. 2A to 2C, inorganic fibers having a relatively long average fiber length are entangled three-dimensionally by the needle punching process. The mat is subjected to needle punching in the width direction perpendicular to the longitudinal direction.

In addition, in order to exhibit an entanglement structure, the inorganic fiber 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 sealing material is torn and separated. Further, when the density of needle punches exceeds 500 per 100 cm ² , it becomes difficult to bend the sealing material, and when the winding material is wound around the exhaust gas treatment body, the sealing material tends to be flat, and a string-like member is applied. This is not preferable because a large tension is applied to the string-like member and the string-like member is broken.

The surface density of the mat ^is desirably ^{400g / m 2 ~2000g / 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 11 has a multilayer structure, it is desirable that the hooking portions are 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-layer mat, the mat thickness T is desirably 5 to 15 mm.

In order to produce a mat constituting the exhaust gas purification apparatus of the present invention, 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 the binder attached 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 a drying condition, for example, it may be dried 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.
That is, FIG. 5 is a perspective view schematically showing a mat used in the exhaust gas purifying apparatus of the present invention. The mat 20S has a predetermined length (indicated by an arrow L in FIG. 5) and a width (FIG. 5 is indicated by an arrow W) and a thickness (indicated by an arrow T in FIG. 5) and a substantially rectangular flat plate shape in plan view.

In the mat 20S shown in FIG. 5, a convex portion 20S2 is formed at one end portion of the end portions on the length direction side of the mat 20S, and a concave portion 20S3 is formed at the other end portion. The convex portion 20S2 and the concave portion 20S3 of the mat 20S are shaped so as to fit each other when the mat 20S is wound around the exhaust gas treatment body 20D in order to assemble the exhaust gas purification device.

When producing the exhaust gas purifying apparatus of the present invention, after the mat having the shape shown in FIG. 5 is produced, the mat is placed in the exhaust gas so that the mated convex and concave mating portions are fitted. The winding body 250 shown in FIG. 6 is produced by winding around the processing body.

After this step, a housing step is performed.
FIG. 6 is a perspective view showing a state in which the wound body constituting the exhaust gas purifying apparatus of the present invention is housed in the casing.
As shown in FIG. 6, the exhaust gas treating body (wound body 250) around which the mat 20 </ b> S is wound is press-fitted into a casing 20 </ b> C 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 sealing material after the press-fitting, the inner diameter of the casing 20C is the thickness of the mat 20S of the exhaust gas treating body 20D around which the mat 20S 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 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 radius of curvature in the cross section perpendicular to the longitudinal direction of the corner portion on the side surface of the exhaust gas treating body is larger than the radius of curvature in the cross section perpendicular to the longitudinal direction of the corner portion of the inner wall surface of the casing. Because the corners on the side of the exhaust gas treatment body are gentler, when using an exhaust gas purification device with a mat placed on the side of the exhaust gas treatment body, the exhaust gas purification device vibrates due to running of an automobile, etc. Even if this occurs, it is difficult for the mats to gather at the corners of the exhaust gas treatment body. Further, due to the difference between the curvature radius of the corner portion of the inner wall surface of the casing and the curvature radius of the corner portion of the side surface of the exhaust gas treatment body, the interval between the corner surface of the exhaust gas treatment body and the inner wall surface of the casing is It is wider than the portion other than the portion, and the bulk density of the corner portion mat 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 treatment body. Further, it is possible to prevent the exhaust gas from leaking firmly.

(3) In the exhaust gas purification apparatus of the present invention, when the exhaust gas treatment body and the casing constituting the exhaust gas purification apparatus have four corner portions, the radius of curvature of the corner portion of the exhaust gas treatment body tends to be small, In the conventional exhaust gas purifying apparatus, cracks, crushing, etc. are likely to occur in the mat disposed in the corner portion. However, in the exhaust gas purification apparatus of the present invention, the radius of curvature in the cross section perpendicular to the longitudinal direction of the corner portion on the side surface of the exhaust gas treatment body is larger than the radius of curvature in the cross section perpendicular to the longitudinal direction of the corner portion of the inner wall surface of the casing. Therefore, when using the exhaust gas purification apparatus provided with a mat, the mat is difficult to gather at the corner portion of the exhaust gas treating body and the volume is large, so the bulk density of the mat is difficult to increase. For this reason, cracks and crushing are unlikely to occur in the mat.

(4) In the exhaust gas purification apparatus of the present invention, the radius of curvature in the cross section perpendicular to the longitudinal direction of the corner portion on the side surface of the exhaust gas treating body is the same in any cross section perpendicular to the longitudinal direction, and the inner wall surface of the casing If the radius of curvature in the cross section perpendicular to the longitudinal direction of the corner portion is the same in any cross section perpendicular to the longitudinal direction, the same effect can be obtained in any part of the exhaust gas purification device, In the mat disposed at the corner portion of the exhaust gas treating body, cracks and crushing hardly occur in all portions.

(5) In the exhaust gas purifying apparatus of the present invention, the radius of curvature in the cross section perpendicular to the longitudinal direction of the corner portion on the side surface of the exhaust gas treatment body is larger than the radius of curvature in the cross section perpendicular to the longitudinal direction of the corner portion of the inner wall surface of the casing. If it is 1.05 to 4 times larger, the mat is less likely to gather at the corner of the exhaust gas treating body, and the bulk density of the mat is less likely to be higher. For this reason, cracks and crushing are less likely to occur in the mat.

(6) 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. .

(7) In the exhaust gas purifying apparatus of the present invention, if the mat is further subjected to needle punching treatment, entanglement between the inorganic fibers occurs and the inorganic fibers are difficult to move. The mats are less likely to gather at the corners, and the mats are less likely to crack or collapse.

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. 5 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. 7 (a) shows dimensions (vertical, horizontal, diagonal 1, diagonal 2, and radius of curvature of the corner portion) for specifying the shape of a cross section perpendicular to the longitudinal direction of the exhaust gas purification filter. FIG. 7B is a cross-sectional view schematically showing dimensions (vertical, horizontal, diagonal 1, diagonal) for specifying the shape of the inner wall surface perpendicular to the longitudinal direction of the casing. 2 is a cross-sectional view schematically showing a curvature radius of a corner portion.
The exhaust gas purification filter made of SiC used in this example is represented by the standard shown in FIG. 7, length: 143.8 mm, width: 143.8 mm, diagonal 1: 179.6 mm, diagonal 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 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: 191 mm, a diagonal of 2: 191 mm, a radius of curvature of the corner portion rc of 19 mm, and a length of 150 mm in the longitudinal direction.
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. 8A to 8E 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 rc of 24 mm, and a longitudinal length of 150 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. 9A to 9E are photographs taken of the state of the mat used in Comparative Example 1. FIG.

As is clear from the comparison between FIGS. 8 (a) to 8 (e) and FIGS. 9 (a) to 9 (e), the mat used in Example 1 has cracks and crushing although some traces of wrinkles are seen. 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.

10D, 20D, 30D Exhaust gas treatment body 10Da, 20Da, 30Da Corner portion 10S, 20S, 30S Mat 10C, 20C, 30C Casing 10Ca, 20Ca, 30Ca Corner portion 20D1 Cell 20D2 Cell partition 20D3 Sealing portion 20Dc Exhaust gas inflow side end face 20Dd Exhaust gas Outflow side end face 20S2 Convex part 20S3 Concave part 100, 200, 300 Exhaust gas purification device 250 Wound body

Claims (6)

A columnar exhaust gas treating body having a corner on the side surface;
A casing made of a tubular body containing the exhaust gas treating body and having a corner portion on the inner wall surface thereof;
It consists of a mat made of inorganic fibers inserted between the exhaust gas treating body and the casing,
The number of corner portions existing on the side surface of the exhaust gas treatment body and the inner wall surface of the casing is the same, and each is 3 to 6, and the corner portion on the side surface of the exhaust gas treatment body is the inner wall surface of the casing. And is housed in the casing so as to face the corner portion present in the
Exhaust gas purification characterized in that the radius of curvature in the cross section perpendicular to the longitudinal direction of the corner portion on the side surface of the exhaust gas treatment body is larger than the radius of curvature in the cross section perpendicular to the longitudinal direction of the corner portion of the inner wall surface of the casing. apparatus. The exhaust gas purifier according to claim 1, wherein each of the exhaust gas treating body and the casing has four corner portions. The radius of curvature in the cross section perpendicular to the longitudinal direction of the corner portion on the side surface of the exhaust gas treatment body is the same in any cross section perpendicular to the longitudinal direction, and is perpendicular to the longitudinal direction of the corner portion of the inner wall surface of the casing. The exhaust gas purifying apparatus according to claim 1 or 2, wherein the curvature radius in the cross section is the same in any cross section perpendicular to the longitudinal direction. The curvature radius in the cross section perpendicular to the longitudinal direction of the corner portion on the side surface of the exhaust gas treatment body is 1.05 to 4 times larger than the curvature radius in the cross section perpendicular to the longitudinal direction of the corner portion of the inner wall surface of the casing. The exhaust gas purification apparatus according to any one of 1 to 3. The exhaust gas purification apparatus according to any one of claims 1 to 4, wherein the inorganic fiber is at least one inorganic fiber 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 5, wherein the mat is further subjected to a needle punching process.