WO2021079556A1

WO2021079556A1 - Muffler and honeycomb structure for muffler

Info

Publication number: WO2021079556A1
Application number: PCT/JP2020/023802
Authority: WO
Inventors: 由紀夫宮入; 泰之古田; 昌明桝田
Original assignee: 日本碍子株式会社
Priority date: 2019-10-25
Filing date: 2020-06-17
Publication date: 2021-04-29
Also published as: JP7518848B2; JPWO2021079556A1

Abstract

Provided is a muffler comprising a honeycomb structure 1 inside a metal can. The honeycomb structure 1 comprises a honeycomb structure section 6 and mesh sealing parts 7. The honeycomb structure section 6 has an outer circumferential wall 2, and porous partitioning walls 5 that are provided inside the outer circumferential wall 2 and that demarcate and form a plurality of cells 4 which serve as fluid channels extending from a first end face 3a to a second end face 3b. The mesh sealing parts 7 are provided at the first end surface 3a and/or the second end surface 3b of the plurality of cells 4, and the effective lengths of the plurality of cells 4 are uneven in the flow channel direction.

Description

Honeycomb structure for silencer and silencer

The present invention relates to a silencer and a honeycomb structure for a silencer.

Particulate matter such as soot contained in the exhaust gas of automobiles powered by internal combustion engines such as diesel engines and gasoline engines (hereinafter, also referred to as "particulate matter" or "PM") affects human health. In order to provide this, the exhaust system of the automobile is provided with a dust collecting filter for collecting PM. Further, since the internal combustion engine generates an exhaust noise when exhausting the exhaust gas to the outside and also generates an intake noise when sucking air into the intake pipe, these intake and exhaust noises are generated in the exhaust system of the automobile. A silencer (hereinafter, also referred to as "muffler") for reduction is provided. Further, since the exhaust gas contains harmful substances such as NOx, CO and HC, the exhaust system of the automobile is provided with a catalytic converter for reducing the amount of these harmful substances.

As a silencer, those having various structures are known. The structure of the simplest silencer is simply a simple tube attached, but in order to enhance the silencer effect, the following methods (a) to (e) and methods of combining these are known. (Patent Documents 1 and 2).
(A) Partially widen the cross-sectional area of the flow path of the silencer.
(B) Inside the silencer, a double structure is provided through a pipe with a small hole called a punching pipe.
(C) The inner wall of the silencer tube is provided with irregularities.
(D) The silencer is provided with a structure (baffle) that serves as a barrier.
(E) The internal space of the silencer is filled with a sound-absorbing material or structure.
Further, in order to further enhance the muffling effect of the muffler, a plurality of mufflers may be provided in the exhaust system.

Jikkenhei 2-22614 Japanese Unexamined Patent Publication No. 11-223119

In recent years, the demand for a compact exhaust system has been increasing, and the space for installing a silencer, a dust collector filter, and a catalytic converter provided in the exhaust system has become insufficient.
The present invention has been made to solve the above problems, and is a silencer and a honeycomb structure for a silencer, which have a good sound deadening function and can also have a function as a dust collecting filter or a catalytic converter. The purpose is to provide.

As a result of diligent research to solve the above problems, the present inventors have determined the effective flow path direction lengths of a plurality of cells for a honeycomb structure applicable to a dust collecting filter or a catalytic converter. It has been found that a good sound deadening function can be obtained in addition to the function of a dust collecting filter or a catalytic converter by controlling the non-uniformity, and the present invention has been completed.

That is, the present invention is a silencer having a honeycomb structure inside a metal can.
The honeycomb structure
A honeycomb structure having a outer peripheral wall and a porous partition wall provided inside the outer peripheral wall and partitioning a plurality of cells serving as a flow path for a fluid extending from a first end face to a second end face.
It has a mesh sealing portion provided on at least one of the first end surface and the second end surface of the plurality of cells.
It is a silencer having a non-uniform length in the effective flow path direction in the plurality of cells.

Further, the present invention is a honeycomb structure portion having a porous partition wall provided inside the outer peripheral wall and the outer peripheral wall and partitioning a plurality of cells serving as a flow path of a fluid extending from a first end face to a second end face. When,
A honeycomb structure for a silencer, which has a sealing portion provided on at least one of the first end surface and the second end surface of the plurality of cells, and has a non-uniform length in the effective flow path direction in the plurality of cells. The body.

According to the present invention, it is possible to provide a silencer and a honeycomb structure for a silencer, which have a good sound deadening function and can also have a function as a dust collecting filter or a catalytic converter.

It is the schematic of the honeycomb structure used for the silencer which concerns on embodiment of this invention. It is the schematic of the honeycomb structure used for the silencer which concerns on embodiment of this invention. It is the schematic of the honeycomb structure used for the silencer which concerns on embodiment of this invention. It is the schematic of the honeycomb structure used for the silencer which concerns on embodiment of this invention. It is sectional drawing parallel to the axial direction of the honeycomb structure of the silencer which concerns on embodiment of this invention. It is sectional drawing parallel to the axial direction of the honeycomb structure of the silencer which concerns on embodiment of this invention. It is sectional drawing parallel to the axial direction of the honeycomb structure of the silencer which concerns on embodiment of this invention.

Hereinafter, embodiments of the present invention will be specifically described with reference to the drawings. The present invention is not limited to the following embodiments, and changes, improvements, etc. have been appropriately added to the following embodiments based on the ordinary knowledge of those skilled in the art without departing from the spirit of the present invention. It should be understood that things also fall within the scope of the present invention.

The silencer according to the embodiment of the present invention includes a honeycomb structure inside a metal can.
The metal can is not particularly limited as long as it has a structure capable of providing a honeycomb structure inside, and a structure known in the art can be adopted.
The honeycomb structure includes a honeycomb structure portion provided on the outer peripheral wall and inside the outer peripheral wall, and having a porous partition wall for partitioning a plurality of cells serving as a flow path for a fluid extending from the first end face to the second end face. A honeycomb structure having a mesh sealing portion provided on at least one of a first end face and a second end face of a plurality of cells is provided. Since this honeycomb structure is used for a silencer, it can be referred to as a honeycomb structure for a silencer.

FIG. 1 is a schematic view of a honeycomb structure used in the silencer according to the embodiment of the present invention. A is a cross-sectional view parallel to the direction in which the cells of the honeycomb structure extend, and B and C are end views of the first end face and the second end face perpendicular to the direction in which the cells of the honeycomb structure of A extend, respectively. is there.
As shown in FIGS. 1A to 1C, the honeycomb structure 1 is provided inside the outer peripheral wall 2 and the outer peripheral wall 2, and serves as a flow path for a fluid extending from the first end surface 3a to the second end surface 3b. It has a honeycomb structure portion 6 having a porous partition wall 5 for partitioning the cell 4 and a mesh sealing portion 7 provided on at least one of the first end surface 3a and the second end surface 3b of the plurality of cells 4. The first end surface 3a is the fluid inflow side, and the second end surface 3b is the fluid outflow side.

The sealing portion 7 has a non-uniform length L in the effective flow path direction in the plurality of cells 4.
Here, in the present specification, the "effective flow path direction length L" means the length of the fluid flow path (cell 4) excluding the sealing portion 7 in the same cell.
Since the frequency of the intake / exhaust sound attenuated in the honeycomb structure 1 depends on the length of the flow path (cell 4) through which the intake / exhaust sound passes together with the exhaust gas, the length in the effective flow path direction in the plurality of cells 4 By making L non-uniform, intake and exhaust sounds of various frequencies can be attenuated. Therefore, by using the honeycomb structure 1 having such a non-uniform length L in the effective flow path direction for the silencer, the sound deadening effect can be improved.

In the plurality of cells 4, the ratio of the maximum value L _max _{(L max} / L _min _{) to the minimum value L min} of the effective flow path direction length L is preferably 1.25 or more, more preferably 1.30 or more. .. _{By controlling L max} / L _min within such a range, the effect of attenuating the intake and exhaust sounds of various frequencies can be stably enhanced.
The upper limit of L _max / L _min is not particularly limited, but is generally 2.0 or less, preferably 1.9 or less.

In the honeycomb structure 1, as shown in B and C of FIG. 1, the cell 4 in which the second end surface 3b is opened and the first end surface 3a is provided with the sealing portion 7 and the first end surface 3a are open. Then, the cells 4 provided with the sealing portions 7 on the second end surface 3b may be alternately arranged in a staggered manner. With such an arrangement, it is possible to achieve both a muffling function and a function as a dust collecting filter in a well-balanced manner.

In the silencer provided with the honeycomb structure 1 having the above structure, when the exhaust gas is supplied, the exhaust gas is internally provided from the first end surface 3a of the honeycomb structure 1 in which the sealing portion 7 is not provided. Inflow. Then, the exhaust gas passes through the porous partition wall 5 and is discharged from the second end surface 3b in which the sealing portion 7 is not provided. In this way, when the exhaust gas passes through the inside of the honeycomb structure 1, the intake / exhaust sounds of various frequencies can be attenuated. Further, when the exhaust gas passes through the inside of the honeycomb structure 1, the PM contained in the exhaust gas is captured by the partition wall 5, so that the honeycomb structure 1 can function as a dust collecting filter. Further, when the catalyst is supported on the partition wall 5, when the exhaust gas passes through the inside of the honeycomb structure 1, harmful substances such as NOx, CO and HC contained in the exhaust gas are purified by the catalyst, so that the catalyst is used. It can also function as a converter.

In the honeycomb structure 1, the central regions of the first end surface 3a and the second end surface 3b have a staggered arrangement, and in the outer peripheral region located on the outer peripheral side of the central region, the first end surfaces 3a and the first end surface 3a and the first of the plurality of cells 4 are arranged. The structure may have a structure in which the sealing portions 7 are provided on at least one of the two end faces 3b. With such a structure, the cross-sectional area of the flow path of the intake / exhaust sound that enters from the first end surface 3a of the honeycomb structure 1 together with the exhaust gas and passes through the second end surface 3b is the second end surface of the honeycomb structure 1. Since it suddenly expands when it passes through 3b, the muffling effect can be improved.

Specific examples (schematic views) of the honeycomb structure 1 having the above structure are shown in FIGS. 2 to 4. In FIGS. 2 to 4, A is a cross-sectional view parallel to the direction in which the cell 4 of the honeycomb structure 1 extends, and B and C are first units perpendicular to the direction in which the cell 4 of the honeycomb structure 1 of A extends. It is an end view of the end face and the second end face.

In the honeycomb structure 1 shown by FIGS. 2A to 2C, the entire region of the first end surface 3a and the central region of the second end surface 3b have a staggered arrangement, and the honeycomb structure 1 is located on the outer peripheral side of the central region of the second end surface 3b. Sealing portions 7 are provided in all of the plurality of cells 4 in the located outer peripheral region. In the honeycomb structure 1 shown by FIGS. 2A to 2C, the cross-sectional area of the flow path of the intake / exhaust sound entering from the first end surface 3a and passing through the second end surface 3b is sharply reduced immediately before the second end surface 3b. Then, it expands rapidly immediately after the second end surface 3b.
Further, the honeycomb structure 1 shown by A to C in FIG. 2 has a staggered arrangement in the entire region of the first end surface 3a, but the honeycomb structure 1 shown by A to C in FIG. 3 has a staggered arrangement. As described above, the central region of the first end surface 3a has a staggered arrangement, and the sealing portions 7 are provided in all of the plurality of cells 4 in the outer peripheral region located on the outer peripheral side of the central region of the first end surface 3a. It may have no structure. In the honeycomb structure 1 shown by FIGS. 3A to 3C, the cross-sectional area of the flow path of the intake / exhaust sound entering from the first end surface 3a and passing through the second end surface 3b is sharply reduced immediately before the second end surface 3b. Then, it expands rapidly immediately after the second end surface 3b.
Further, as in the honeycomb structure 1 shown by FIGS. 4A to 4C, the central region of the first end surface 3a has a staggered arrangement, and the outer peripheral region is located on the outer peripheral side of the central region of the first end surface 3a. The structure may be such that all of the plurality of cells 4 in the above are provided with the sealing portions 7. In the honeycomb structure 1 shown by FIGS. 4A to 4C, the cross-sectional area of the flow path of the intake / exhaust sound that enters from the first end surface 3a and passes through the second end surface 3b suddenly passes when it passes through the first end surface 3a. It is further reduced immediately before the second end surface 3b, and rapidly expanded immediately after the second end surface 3b.
In the above figure, the dotted line is the boundary line between the central region and the outer peripheral region on the first end surface 3a and the second end surface 3b, the inside of the dotted line represents the central region, and the outside of the dotted line represents the outer peripheral region. Therefore, in the present specification, the "outer peripheral region" means a region near the outer peripheral wall 2 when observing the first end surface 3a and the second end surface 3b, and the "central region" is more than the outer peripheral region. It means the inner area.

The size of the central region of the first end surface 3a and the second end surface 3b is not particularly limited, but the area of the second end surface 3b is from the viewpoint of sufficiently ensuring the sound deadening effect due to the rapid expansion of the flow path cross-sectional area of the intake and exhaust sounds. It is preferable to determine the area of the central region in the second end surface 3b according to the above. Specifically, the area of the second end surface 3b is preferably 1.1 times or more, and preferably 1.3 times or more, the area of the central region of the second end surface 3b. By controlling the area to such an area, it is possible to sufficiently obtain a muffling effect due to a rapid expansion of the flow path cross-sectional area of intake / exhaust sound.
The upper limit of the magnification of the area of the second end surface 3b with respect to the area of the central region of the second end surface 3b is not particularly limited, but is generally 3.0 times or less, preferably 2.5 times or less.

The shape of the honeycomb structure 6 is not particularly limited, and may be an elliptical column, a quadrangular column, another polygonal column, or the like, in addition to the cylinder illustrated above.
The shape of the cell 4 is not particularly limited, and on the end faces of the first end face 3a and the second end face 3b, in addition to the quadrangle exemplified above, a circle, an ellipse, a triangle, a hexagon, or another polygon may be used. May be good.

The cell density of the honeycomb structure portion 6 is not particularly limited, but is preferably 5 to 320 cells / cm ² ^{, more preferably 10 to 300 cells / cm 2} , and even more preferably 10 to 300 cells / cm 2 in the first end surface 3a and the second end surface 3b. 20-250 cells / cm ² . By setting the cell density to 5 cells / cm ² or more, the strength of the partition wall 5, the strength of the columnar honeycomb structure 6 itself, and the effective GSA (geometric surface area) can be sufficiently secured. Further, by setting the cell density to 320 cells / cm ² or less, an increase in pressure loss can be suppressed.

The thickness of the partition wall 5 is not particularly limited, but is preferably 0.1 to 1.0 mm, more preferably 0.2 to 0.6 mm. By setting the thickness of the partition wall 5 to 0.1 mm or more, the mechanical strength of the honeycomb structure 1 can be made sufficient. Further, by setting the thickness of the partition wall 5 to 1.0 mm or less, it is possible to suppress an increase in pressure loss due to a decrease in the opening area.
The thickness of the outer peripheral wall 2 is not particularly limited, but is preferably larger than the thickness of the partition wall 5. With such a configuration, it is possible to suppress destruction (for example, cracks, cracks, etc.) due to an external impact or the like. Specifically, the thickness of the outer peripheral wall 2 is preferably 0.3 mm to 10 mm, more preferably 0.5 mm to 5 mm, and even more preferably 1 mm to 3 mm.

It is preferable that the partition wall 5 and the outer peripheral wall 2 are mainly composed of ceramics. Here, in the present specification, "having ceramics as a main component" means that the mass ratio of ceramics to the mass of all components is 50% by mass or more. Examples of ceramics include cordierite, mullite, silicon nitride, silicon carbide, aluminum titanate and the like. These can be used alone or in combination of two or more. By using such a material, characteristics such as mechanical strength and heat resistance of the honeycomb structure 1 can be ensured.

The partition wall 5 has a porosity of preferably 25% or more, more preferably 30% or more, still more preferably 35% or more. By setting the porosity in such a range, it is possible to secure the ease of flow (filtration rate) of the exhaust gas passing through the partition wall 5 of the honeycomb structure 1. On the other hand, the upper limit of the porosity of the partition wall 5 is not particularly limited, but is generally 50% or less, preferably 45% or less. By setting the porosity in such a range, it is possible to suppress an increase in the pressure loss of the honeycomb structure 1.
Here, the term "porosity" as used herein means a porosity measured by the mercury intrusion method in accordance with JIS R1655: 2003.

The partition wall 5 has an average pore diameter of preferably 5 μm, more preferably 7 μm or more. By setting the average pore diameter in such a range, an increase in pressure loss can be suppressed. In particular, even when the particulate matter is deposited on the honeycomb structure 1, it is possible to suppress an increase in the pressure loss of the honeycomb structure 1. The average pore diameter of the honeycomb structure 1 is preferably 25 μm or less, more preferably 20 μm or less. By setting the average pore diameter in such a range, it is possible to suppress the loss of particulate matter.
Here, in the present specification, the "average pore diameter" means the pore diameter at an integrated value of 50% in the pore distribution obtained by the mercury intrusion method in accordance with JIS R1655: 2003.

A surface layer having an average pore diameter of 5 μm or less may be provided on the surface of the partition wall 5. By providing the surface layer having such an average pore diameter, it is possible to obtain a muffling effect by expanding the flow path cross-sectional area of the intake / exhaust sound even when the exhaust gas passes through the surface layer.
As with the partition wall 5, the surface layer preferably contains ceramics as a main component, and the same type of ceramics as the ceramics used for the partition wall 5 can be used. The average pore diameter of the surface layer can be controlled by adjusting the particle size of the ceramic powder as a raw material, the type of binder, and the like.

When a surface layer is formed on the surface of the partition wall 5 or the surface of the partition wall 5, the catalyst may be supported on the surface of the surface layer. By supporting the catalyst, harmful substances such as NOx, CO and HC contained in the exhaust gas can be purified, so that the function as a catalytic converter can be obtained.
As the catalyst, a catalyst known in the art can be used. Examples of the catalyst include a three-way catalyst for purifying exhaust gas from a gasoline engine, an oxidation catalyst for purifying exhaust gas from a gasoline engine or a diesel engine, an SCR catalyst for purifying NOx selective reduction, and the like. Specifically, precious metals (platinum, rhodium, palladium, ruthenium, indium, silver, and gold), aluminum, nickel, zirconium, titanium, cerium, cobalt, manganese, zinc, copper, tin, iron, niobium, magnesium, lantern. , Samalium, bismuth, and barium, preferably containing at least one element selected from the group. The above element may be contained as a simple substance of a metal, a metal oxide, or another metal compound.

The amount of the catalyst (catalyst metal + carrier) supported is not particularly limited, but is preferably 10 to 400 g / L. When a catalyst containing a noble metal is used, the amount of the catalyst supported is not particularly limited, but is preferably 0.1 to 5 g / L. By setting the carrying amount of the catalyst (catalyst metal + carrier) to 10 g / L or more, the catalytic action can be easily exhibited. Further, by setting the supported amount of the catalyst (catalyst metal + carrier) to 400 g / L or less, it is possible to suppress the pressure loss and the increase in the manufacturing cost. The carrier is a carrier on which the catalyst metal is supported. As the carrier, one containing at least one selected from the group consisting of alumina, ceria, and zirconia can be used.

The method for producing the honeycomb structure 1 is not particularly limited, and the honeycomb structure 1 can be manufactured according to a method known in the art. For example, the honeycomb structure 1 can be manufactured as follows.
First, the clay containing the ceramic powder is extruded into a desired shape to prepare a honeycomb molded body. At this time, the shape and density of the cell 4, the shape and thickness of the partition wall 5 and the outer peripheral wall 2 can be controlled by selecting an appropriate shape of the base and jig. As the ceramic powder, the above-mentioned ceramic powder, the raw material powder that becomes the above-mentioned ceramic after firing (for example, a cordierite raw material) and the like can be used. In addition, the clay can contain a binder, a pore-forming agent, a dispersant, water, an organic solvent and the like. Then, the honeycomb structure portion 6 can be obtained by drying and firing the obtained honeycomb molded body. The drying method is not particularly limited, and conventionally known drying methods such as hot air drying, microwave drying, dielectric drying, vacuum drying, vacuum drying, and freeze drying can be used. Among these, a drying method that combines hot air drying and microwave drying or dielectric drying is preferable in that the entire honeycomb molded body can be dried quickly and uniformly.

Next, the honeycomb structure 6 is sealed. The sealing may be performed before the honeycomb molded body is fired. The sealing can be performed according to the conventional method of filling the sealing material. For example, a thin film film having an opening corresponding to the cell 4 of the end faces (first end face 3a and second end face 3b) of the honeycomb structure portion 6 on which the mesh sealing portion 7 is to be formed is attached. Then, the end face of the honeycomb structure portion 6 is immersed in a slurry-like eye-sealing material, and the eye-sealing material is allowed to enter the cell 4 of the honeycomb structure portion 6 which is not blocked by the thin film. It is possible to form the eye-sealing portion 7 filled with.

The length of the sealing portion 7 in the cell direction can be adjusted by immersing the end face of the honeycomb structure portion 6 in the sealing material. That is, in order to form the eye-sealing portion 7 so that the length L in the effective flow path direction in the plurality of cells 4 is non-uniform, thin film films having two or more types of opening patterns are prepared, and these thin films are prepared. The film may be sequentially used to change the depth at which the end face of the honeycomb structure 6 is immersed in the sealing material.
As another method, by adjusting the area of the film opening, the sealing portion 7 can be formed so that the length L in the effective flow path direction in the plurality of cells 4 becomes non-uniform. For example, by reducing the area of the film opening, the amount of the eye-sealing material flowing into the cell 4 can be reduced, so that the eye-sealing portion 7 having a short cell-direction length is formed. can do. Therefore, by making the area of the film opening non-uniform, it is possible to form the eye-sealing portions 7 having non-uniform cell-direction lengths in the plurality of cells 4.

The silencer according to the embodiment of the present invention may include a tubular member in addition to the honeycomb structure 1. FIG. 5 shows a cross-sectional view parallel to the axial direction of the tubular member of the silencer having such a structure.
As shown in FIG. 5, the silencer 100 is fitted to the honeycomb structure 1 and the outer peripheral surface of the outer peripheral wall 2 of the honeycomb structure 1 and is axially outside the second end surface 3b which is the outflow side of the fluid. It is provided with a tubular member 10 having a portion extended to the honeycomb. With such a structure, the flow path cross-sectional area of the intake / exhaust sound passing through the second end surface 3b of the honeycomb structure 1 is expanded to the inner diameter of the tubular member 10, so that the sound deadening effect can be improved.

The tubular member 10 preferably has a structure in which a portion extending outward in the axial direction from the second end surface 3b of the honeycomb structure 1 has an enlarged diameter. FIG. 6 shows a cross-sectional view of the honeycomb structure 1 of the silencer 100 having such a structure parallel to the axial direction.
In the present specification, "a portion of the tubular member 10 extending axially outward from the second end surface 3b of the honeycomb structure 1" is the first portion of the honeycomb structure 1 in the axial direction of the tubular member 10. 2 It means a portion having a length from the end surface 3b to 1/2 of the axial length of the honeycomb structure 1.
As shown in FIG. 6, the tubular member 10 in the silencer 100 has a structure in which a portion extending outward in the axial direction from the second end surface 3b of the honeycomb structure 1 has an enlarged diameter. With such a structure, the cross-sectional area of the flow path of the intake / exhaust sound that has passed through the second end surface 3b of the honeycomb structure 1 is further expanded, so that the sound deadening effect can be further improved.

The maximum inner diameter of the portion of the tubular member 10 extending outward in the axial direction from the second end surface 3b of the honeycomb structure 1 is 1.1 times or more the area of the second end surface 3b of the honeycomb structure 1. It is preferable, and it is more preferable that it is 1.3 times or more. With such a configuration, it is possible to stably obtain a muffling effect due to a rapid expansion of the flow path cross-sectional area of the intake / exhaust sound passing through the second end surface 3b of the honeycomb structure 1.

The material of the tubular member 10 is not particularly limited, but for example, stainless steel, titanium alloy, copper alloy, aluminum alloy, brass and the like can be used. Among these, stainless steel is preferable because of its high durability and reliability and low cost.

The silencer 100 having the above structure can be manufactured according to a method known in the art. For example, the silencer 100 can be manufactured by fitting the tubular member 10 to the outer peripheral surface of the outer peripheral wall 2 of the honeycomb structure 1. The fitting method is not particularly limited, but brazing, welding, diffusion joining and the like can be used in addition to the fixing method by fitting such as clearance fitting, tightening fitting and shrink fitting.

The silencer 100 according to the embodiment of the present invention may further include a fibrous sound absorbing material in addition to the metal can, the honeycomb structure 1 and the tubular member 10. FIG. 7 shows a cross-sectional view of the tubular member 10 of the silencer 100 having such a structure parallel to the axial direction.
As shown in FIG. 7, the silencer 100 includes a fibrous sound absorbing material 20 provided on the outer peripheral side of the tubular member 10 and held between the tubular member 10 and the metal can 30.
The tubular member 10 is provided with a small hole 11, and the sound deadening effect can be enhanced by allowing the fibrous sound absorbing material 20 to absorb the intake / exhaust sound through the small hole 11.

The position of the small hole 11 provided in the tubular member 10 is not particularly limited, but is axially outward from the first end surface 3a and / or the second end surface 3b of the honeycomb structure 1 in the axial direction of the tubular member 10. It is preferably a stretched portion.
The shape and size of the small holes 11 provided in the tubular member 10 are not particularly limited, and may be appropriately adjusted according to the type of the fibrous sound absorbing material 20 to be used.

The fibrous sound absorbing material 20 is not particularly limited, but for example, glass wool, rock wool, steel wool, ceramic wool, or the like can be used. Among these, glass wool is preferable from the viewpoint of sound deadening effect.

The metal can 30 forms a space with the tubular member 10 and holds the fibrous sound absorbing material 20 housed in the space.
The shape of the metal can 30 is not particularly limited as long as it can hold the fibrous sound absorbing material 20 provided on the outer peripheral side of the tubular member 10, and may be, for example, tubular.
The material of the metal can 30 is not particularly limited, and the same material as that of the tubular member 10 can be used.

The silencer 100 according to the embodiment of the present invention may further include a silencer structure known in the art in addition to the above structure. Examples of the known sound deadening structure include a structure (jammer plate) that serves as a barrier.

The silencer 100 having the above structure can be manufactured according to a method known in the art. For example, the silencer 100 is manufactured by arranging the fibrous sound absorbing material 20 on the outer peripheral side of the tubular member 10 fitted to the outer peripheral surface of the outer peripheral wall 2 of the honeycomb structure 1 and accommodating it in the metal can 30. can do. Further, the tubular member 10 and the metal can 30 may be joined by welding or the like.

Hereinafter, the present invention will be described in more detail with reference to Examples, but the present invention is not limited to these Examples.

(Example 1)
A cylindrical honeycomb molded body was obtained by throwing clay containing a cordierite-forming raw material into an extrusion molding machine and extrusion molding. Next, after drying the honeycomb molded product, both end faces were cut so as to have a predetermined size to obtain a honeycomb dried product. Next, using a plurality of thin films having different opening patterns and a sealing material containing the same components as the honeycomb molded body, the cells on the first end face and the second end face of the honeycomb dried body are sealed with each other. A honeycomb structure made of cordierite was obtained by firing at 1400 ° C. In the sealing of the cells on the first end face, the depth of immersion in the sealing material is the same, and in the sealing of the cells on the second end face, the depth of immersion in the sealing material is changed. went. Further, the mesh sealing has a structure shown in FIGS. 1A to 1C, that is, a cell in which the mesh sealing portion is provided only on the first end surface and a cell in which the mesh sealing portion is provided only on the second end surface. And were arranged alternately in a staggered pattern.

The obtained honeycomb structure had a diameter of 118.4 mm, an axial length of 127 mm, a partition wall thickness of 0.3 mm, an outer peripheral wall thickness of 1 mm, a cell density of 31 cells / cm ² , a porosity of the partition wall of 48%, and an average pore diameter. It was 12 μm. The porosity and the average pore diameter were measured by the above method.

(Example 2)
Similar to Example 1 except that when sealing a part of the cells on the second end face of the honeycomb dried body, the depth of immersing the second end face of the honeycomb dried body in the eye sealing material was increased. A honeycomb structure was obtained.

(Comparative Example 1)
A honeycomb structure was obtained in the same manner as in Example 1 except that the seal was not sealed.
(Comparative Example 2)
When sealing the cells of the first end face and the second end face of the honeycomb dried body, the depth of immersing the first end face and the second end face of the honeycomb dried body in the eye sealing material was the same. A honeycomb structure was obtained in the same manner as in Example 1.

(Length in the effective flow path direction)
The honeycomb structures obtained in the above Examples and Comparative Examples are cut in parallel with the extending direction of the cells of the honeycomb structure, and then the cross-sectional observation thereof is performed to observe the first end surface and the second end surface of the plurality of cells. The length of the sealing portion formed in the cell in the cell direction (the length in the direction in which the cell extends) was measured, and the length in the effective flow path direction was calculated.

(Silencer effect test)
A tubular member was fitted to the outer peripheral surface of the outer peripheral wall of the honeycomb structure obtained in the above Examples and Comparative Examples to produce a silencer. Next, the first muffler of the two mufflers provided in the exhaust system of the 2L gasoline engine was removed, and the silencer produced above was provided at that position. Then, the gasoline engine was operated under the conditions of an engine rotation speed of 2000 rpm and a throttle fully opened (WOT), and the sound pressure level was measured using a sound pressure measuring device at the outlet of the tail pipe downstream of the muffler.
The results of each of the above evaluations are shown in Table 1.

As shown in Table 1, the silencer using the honeycomb structures of Examples 1 and 2 having non-uniform lengths in the effective flow path direction did not form a mesh sealing portion, and the honeycomb structure of Comparative Example 1 was not formed. The sound pressure level was lower than that of the silencer using the body and the silencer using the honeycomb structure of Comparative Example 2 having a uniform length in the effective flow path direction.

As can be seen from the above results, according to the present invention, there is provided a muffler and a honeycomb structure for a muffler that have a good muffling function and can also have a function as a dust collecting filter or a catalytic converter. Can be done.

1 Honeycomb structure 2 Outer wall 3a 1st end face 3b 2nd end face 4 Cell 5 Partition 6 Honeycomb structure 7th Sealing part 10 Cylindrical member 11 Small hole 20 Fibrous sound absorbing material 30 Metal can 100 Silencer

Claims

A silencer with a honeycomb structure inside a metal can
The honeycomb structure
A honeycomb structure having a outer peripheral wall and a porous partition wall provided inside the outer peripheral wall and partitioning a plurality of cells serving as a flow path for a fluid extending from a first end face to a second end face.
It has a mesh sealing portion provided on at least one of the first end surface and the second end surface of the plurality of cells.
A silencer having a non-uniform length in the effective flow path direction in the plurality of cells.
The silencer according to claim 1, wherein the plurality of cells have a ratio (L max / L min ) of a maximum value L max to a minimum value L min of the length in the effective flow path direction of 1.25 or more.
The silencer according to claim 2, wherein the ratio is 1.30 or more.
The honeycomb structure includes the cell in which the second end surface is opened and the eye sealing portion is provided on the first end surface, and the first end surface is opened and the eye sealing portion is provided on the second end surface. The silencer according to any one of claims 1 to 3, wherein the cells provided with the cells and the cells are arranged alternately so as to be staggered.
In the honeycomb structure, the central region of the first end face and the second end face has the staggered arrangement.
The fourth aspect of the present invention, wherein in the outer peripheral region located on the outer peripheral side of the central region, the eye-sealing portion is provided on at least one of the first end surface and the second end surface of the plurality of cells. Silencer.
In the outer peripheral region located on the outer peripheral side of the central region, the sealing portions are provided on all of the second end faces of the plurality of cells.
The silencer according to claim 5, wherein the first end face is the inflow side of the fluid and the second end face is the outflow side of the fluid.
The silencer according to claim 5 or 6, wherein the area of the second end face is 1.1 times or more the area of the central region of the second end face.
The silencer according to claim 7, wherein the area of the second end face is 1.3 times or more the area of the central region of the second end face.
The partition wall is mainly composed of one or more selected from cordierite, mullite, silicon nitride, silicon carbide and aluminum titanate, has a porosity of 25% or more, and has an average pore diameter of 5 to 25 μm. The silencer according to any one of 8 to 8.
The silencer according to any one of claims 1 to 9, wherein a surface layer having an average pore diameter of 5 μm or less is provided on the surface of the partition wall.
The silencer according to any one of claims 1 to 10, wherein a catalyst is supported on the surface of the partition wall or, when the surface layer is formed on the surface of the partition wall, on the surface of the surface layer. ..
Claims 1 to 11 further include a tubular member fitted to the outer peripheral surface of the outer peripheral wall of the honeycomb structure and having a portion extending axially outward from the second end surface which is the outflow side of the fluid. The silencer described in any one item.
The silencer according to claim 12, wherein the maximum value of the inner diameter of the stretched portion of the tubular member is 1.1 times or more the area of the second end surface of the honeycomb structure.
The silencer according to claim 13, wherein the maximum value of the inner diameter of the stretched portion of the tubular member is 1.3 times or more the area of the second end surface of the honeycomb structure.
The silencer is provided on the outer peripheral side of the tubular member, and further includes a fibrous sound absorbing material held between the tubular member and the metal can, according to any one of claims 12 to 14. Described silencer.
A honeycomb structure having a outer peripheral wall and a porous partition wall provided inside the outer peripheral wall and partitioning a plurality of cells serving as a flow path for a fluid extending from a first end face to a second end face.
A honeycomb structure for a silencer, which has a sealing portion provided on at least one of the first end surface and the second end surface of the plurality of cells, and has a non-uniform length in the effective flow path direction in the plurality of cells. body.