JPH08108076A - Catalytic converter - Google Patents

Abstract

PURPOSE: To lengthen a heat transfer passage, to suppress the radiation of heat from a honeycomb body and to reduce the quantity of heat radiated by fixing the upper stream side of a protective tube on the upper stream side or downstream side of an exhaust passage and joining the downstream side of the honeycomb body to the inner wall of the downstream side of the protective tube. CONSTITUTION: A flat sheet 113 is superposed on a corrugated sheet 112 and they are spirally wound to form the honeycomb carrier 11 of a catalytic converter 10. At this time, slits 111 are formed in the sheets 113, 112 from the central part of the carrier 11 in the longitudinal direction toward the end on the upper stream side of exhaust gas. The inside diameter of a protective tube 12 covering the periphery of the carrier 11 on the upper stream side of exhaust gas is made larger than that on the downstream side and a gap 100 is ensured around the slits 111. The positional relation between the honeycomb carrier 11 and the protective tube 12 is decided so that the tube 12 protrudes from the end 11a of the carrier 11 on the upper stream side in the axial direction. The tube 12 is then irradiated with laser beams from the outside of the tube 12 except the notches 121 to fix the corrugated sheet 112 and the tube 12 by welding.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a catalytic converter for rendering harmful substances in exhaust gas discharged from an internal combustion engine harmless, for example, a catalytic converter for automobiles.

[0002]

2. Description of the Related Art Heretofore, there has been known a catalytic converter in which a catalyst is supported on a metal carrier in order to convert harmful substances such as HC, CO and NOx discharged from an automobile engine into harmless gas or water. However, according to this type of catalytic converter, the metal carrier does not rise sufficiently to the activation temperature of the catalytic substance for a certain period after the start of the engine, so that the harmful substance in the exhaust gas is discharged without being purified during the certain period. May occur.

Therefore, the electrothermal catalyst carrier disclosed in Japanese Utility Model Laid-Open No. 5-69316 utilizes the phenomenon in which the metal honeycomb carrier itself generates heat when an electric current is applied to the metal honeycomb carrier, and the catalyst substance is used for a short time. The temperature is raised to 0 to accelerate the catalytic reaction. Further, in the plate-shaped catalyst and the method for producing the same disclosed in Japanese Patent Laid-Open No. 2-99144, an expanded metal plate having rhomboid slits is used as a substrate on which a catalytic substance is applied to reduce the heat capacity, and the corrugated shape is obtained. Further, the expanded metal plate is formed by a forming roll having an uneven portion and the surface area of the catalyst substance is increased to improve the reaction rate of the catalyst substance.

[0004]

However, according to the electrothermal catalyst carrier disclosed in Japanese Utility Model Laid-Open No. 5-69316, an electric power supply means or the like is required because the metal honeycomb carrier is forced to generate heat when energized. Therefore, there is a problem that the system configuration becomes complicated. In addition, Japanese Unexamined Patent Publication
According to the plate catalyst and the method for manufacturing the same disclosed in Japanese Patent Publication No. 99144, since the catalyst substance is applied to the entire surface of the expanded metal plate so as to fill the opening of the slit, the amount of the necessary catalyst substance is increased and the cost is reduced. However, there is a problem in that

Further, since the metal carrier is composed of a flat plate having a plate thickness of several tens of microns and a corrugated plate, it may be damaged by a relatively small external force. The problem is that it is difficult to handle without damaging it. Furthermore, since the metal carrier raises the temperature of the catalytic substance to the activation temperature by the heat of the high-temperature exhaust gas, it is mounted in the vicinity of the engine whose exhaust gas temperature is high. For this reason, there is a problem that the joint between the corrugated plate and the flat plate may be damaged (hereinafter referred to as “scoping”) due to vibration and high temperature exhaust gas heat when the vehicle is running.

The present invention has been made in order to solve such a problem, and improves the durability and raises the temperature up to the activation temperature of the catalyst substance in a short time without using electric power to purify the exhaust gas. An object of the present invention is to provide a catalytic converter that can be mounted by a mounting method that can sufficiently exert its ability.

[0007]

A catalytic converter according to a first aspect of the present invention for solving the above-mentioned problems is arranged in an exhaust passage of an internal combustion engine, and metal flat plates and corrugated plates are alternately arranged. A flat plate and the corrugated plate that are adjacent to each other in the radial direction and are joined to each other, and a catalytic converter having a honeycomb body configured by winding or stacking,
A plurality of slits extending in a direction orthogonal to the exhaust gas flow direction, a honeycomb body formed on the exhaust path upstream side of at least one of the flat plate or the corrugated plate, and a downstream side of the honeycomb body that covers the periphery of the honeycomb body A tubular protective cylinder having an inner wall joined to an outer wall is provided, and the upstream side of the protective cylinder is fixed to at least one of the upstream side path and the downstream side path of the exhaust path.

A catalytic converter according to a second aspect of the present invention is the catalytic converter according to the first aspect, wherein:
The honeycomb body is made of heat resistant stainless steel. The catalytic converter according to claim 3 of the present invention is the catalytic converter according to claim 1 or 2, wherein the flange formed on the upstream side of the protective cylinder is an upstream flange formed on the upstream path. It is characterized in that it is sandwiched and fixed between a downstream side flange formed in the downstream side path.

A catalytic converter according to a fourth aspect of the present invention is the catalytic converter according to the third aspect, wherein:
The flange is sandwiched between the upstream side flange and the downstream side flange via a seal member and is fixed by a connecting member. According to a fifth aspect of the present invention, there is provided the catalytic converter according to the fourth aspect, wherein the sealing member is a gasket.

A catalytic converter according to a sixth aspect of the present invention is the catalytic converter according to the fourth aspect, wherein:
The seal member is a heat resistant O-ring. The catalytic converter according to claim 7 of the present invention is the catalytic converter according to claim 4, 5 or 6, wherein a plurality of through holes are formed in the flange, and the plurality of through holes are connected to the connection holes. It is characterized in that it is positioned in the exhaust path by inserting a member.

The catalytic converter according to claim 8 of the present invention is the catalytic converter according to claim 4, 5 or 6, wherein a plurality of cutouts are formed in the flange. It is characterized in that it is positioned in the exhaust path by inserting the connecting member into. According to a ninth aspect of the present invention, there is provided the catalytic converter according to any one of the fourth to eighth aspects, wherein the connecting member is a bolt or a pin.

A catalytic converter according to a tenth aspect of the present invention is the catalytic converter according to any one of the first to ninth aspects, wherein the exhaust passage includes an exhaust manifold, a downstream side catalytic converter, an exhaust pipe and a muffler. And the catalytic converter is located downstream of the exhaust manifold and upstream of the downstream catalytic converter.

The catalytic converter according to an eleventh aspect of the present invention is the catalytic converter according to the tenth aspect, wherein the catalytic converter is located close to a downstream honeycomb body that constitutes the downstream catalytic converter. Is characterized by. A catalytic converter according to a twelfth aspect of the present invention is the catalytic converter according to the eleventh aspect, wherein the downstream outer peripheral edge of the catalytic converter and the downstream outer peripheral edge of the downstream catalytic converter are the downstream from the catalytic converter. It is characterized in that they are connected by a cone portion whose inner diameter increases toward the side catalytic converter, and the downstream end portion of the catalytic converter is attached without protruding into the cone portion.

The catalytic converter according to a thirteenth aspect of the present invention is the catalytic converter according to the twelfth aspect, wherein the divergence angle of the cone portion is 90 ° or less, or the axis between the downstream side catalytic converter and the catalytic converter. The directional spacing is 40 mm or more. Also,
A catalytic converter according to a fourteenth aspect of the present invention is the catalytic converter according to any one of the first to thirteenth aspects, in which a void portion is formed on an upstream side of the honeycomb body, and a downstream side of the honeycomb body and the protection are formed. It is characterized in that it is joined to the inner wall on the downstream side of the cylinder.

The catalytic converter according to a fifteenth aspect of the present invention is the catalytic converter according to the fourteenth aspect, wherein the gap has an inner diameter on the upstream side of the protective cylinder larger than an inner diameter on the downstream side of the protective cylinder. It is characterized by being formed by. The catalytic converter according to claim 16 of the present invention is the catalytic converter according to claim 14, wherein the number of windings or the number of layers of the flat plate and the corrugated plate in the void portion is the honeycomb body from a downstream side of the honeycomb body. It is characterized in that it is formed by having less body upstream side.

A catalytic converter according to a seventeenth aspect of the present invention is the catalytic converter according to any one of the first to sixteenth aspects, wherein the protective cylinder has an upstream end portion of the honeycomb body at an exhaust gas upstream side. It is characterized in that it projects more in the axial direction. The catalytic converter according to claim 18 according to the present invention is the catalytic converter according to any one of claims 1 to 17, wherein an outer diameter of the honeycomb body is larger than an inner diameter of the upstream path. Is characterized by.

According to a nineteenth aspect of the present invention, in the catalytic converter according to the eighteenth aspect, the exhaust gas is provided between the upstream side flange formed in the upstream side route and the upstream side route. It is characterized by interposing a tube element. The catalytic converter according to claim 20 according to the present invention is the catalytic converter according to claim 19, wherein the upstream side is on an extension line extending the axial contour line of the outer peripheral portion of the honeycomb body in the upstream path direction. The side flange or the exhaust pipe element is located.

According to a twenty-first aspect of the present invention, there is provided the catalytic converter according to the twenty-first aspect, wherein the exhaust pipe element is formed by one or more flat surfaces or a cone portion in which at least one of the inner diameter gradually expands. It is characterized by being done. The catalytic converter according to claim 22 according to the present invention is the catalytic converter according to claim 21, wherein the honeycomb body has a separation distance of 1 mm or more between the end surface of the upstream side flange or the exhaust pipe element and the honeycomb body. It is characterized in that it is attached in the exhaust gas flow direction so that the thickness is equal to or less than the thickness of the upstream side flange.

[0019]

According to the catalytic converter of the present invention, the upstream side of the protection tube is fixed to at least one of the upstream path and the downstream path of the exhaust path, and the downstream side of the honeycomb body and the downstream inner wall of the protection tube are fixed. Since and are joined together, it is possible to secure a long heat transfer path through which the heat of the honeycomb body reaches the exhaust path via the protective cylinder. This has the effect of suppressing heat dissipation of the honeycomb body and reducing the amount of heat dissipation.

According to the catalytic converter of the present invention,
Since a plurality of slits extending in the direction orthogonal to the exhaust gas flow direction are formed on the exhaust path upstream side of at least one of the metal flat plate or corrugated plate, the heat capacity of the flat plate or corrugated plate on the exhaust path upstream side becomes small. . Moreover, since the flow of the exhaust gas is disturbed by the plurality of slits, the heat transfer efficiency is increased on the upstream side of the honeycomb body in which the slits are formed. This has the effect of raising the temperature to the activation temperature of the catalyst substance in a short time.

Further, according to the catalytic converter of the present invention, since the outer diameter of the honeycomb body constituting the catalytic converter is set to be larger than the inner diameter of the upstream side passage, the exhaust gas is discharged from the outer peripheral portion of the honeycomb body in the axial center direction. Flows in efficiently. As a result, the exhaust gas flowing into the honeycomb body from the upstream path gathers in the axial center direction of the honeycomb body having a relatively high temperature rising speed. Therefore, the purification of the exhaust gas can be promoted, and the exhaust gas flowing into the outer peripheral portion of the honeycomb body having a slow temperature rising rate can be reduced, so that the honeycomb body can exhibit the exhaust gas purification ability. Further, since the temperature gradient in the outer peripheral portion of the honeycomb body is made gentle and the thermal stress generated between the honeycomb body and the protective cylinder is reduced, scoping caused by the difference in heat capacity between the honeycomb body and the protective cylinder is prevented. , Has the effect of improving durability.

[0022]

Embodiments of the present invention will be described below with reference to the drawings. (First Embodiment) A catalytic converter according to a first embodiment of the present invention will be described with reference to FIGS. As shown in FIG. 2, the catalytic converter 10 includes a honeycomb carrier 11 including a flat plate 113 and a corrugated plate 112, a protective cylinder 12 covering the outer periphery of the honeycomb carrier 11, and a flange attached to the outer peripheral wall of the protective cylinder 12. It is composed of 17 and.

The honeycomb carrier 11 includes a flat plate 113 and a corrugated plate 1.
12 and 12 are alternately stacked and wound in a spiral shape. Both the flat plate 113 and the corrugated plate 112 constituting the honeycomb carrier 11 contain, for example, Cr of 18 to 24 wt.
%, Al 4.5 to 5.5 wt%, rare earth element (RE
Fe-C in which M) is 0.1 to 0.2 wt% and the balance is Fe.
A heat-resistant stainless steel foil composed of r-Al.

As shown in FIG. 4, the flat plate 113 and the corrugated plate 112 before winding are formed in a strip shape having a plate width c of 60 mm and a plate thickness of 0.03 to 0.20 mm, for example. FIG.
And as shown in FIG. 4, the flat plate 113 and the corrugated plate 112.
The slit portion 111 is formed in the exhaust gas from the substantially central portion in the axial direction toward the exhaust gas upstream end portion. Here, since the developed corrugated plate 112 and the flat plate 113 have the same shape, FIG. 4 shows the developed shape of the flat plate 113 as a representative. The flat plate 113 and the corrugated plate 112 are provided at one end of the flat plate 113.
A non-slit portion is provided in a width a that becomes a welded portion for joining and. This width a is, for example, 3 mm. A slit portion 111 having a width b is formed at a position adjacent to the non-slit portion. The width b is, for example, 31.2 mm.

As shown in FIG. 5, the rectangular slit formed in the slit portion 111 has, for example, the following dimensions. Slit width w = 3 mm Slit height h = 1.2 mm Orthogonal slit spacing D = 1 mm Axial slit spacing H = 0.8 mm This rectangular slit has a spacing D in the direction orthogonal to the axial direction of the honeycomb carrier 11. Are continuously formed, and are also continuously formed at intervals H in the axial direction. Further, the slits adjacent to each other in the axial direction are positioned so as to be offset from each other by (w + D) / 2.

The corrugated plate 112 has, for example, a repeating pitch of 4.9.
mm, and the height is 1.7 mm, which corresponds to the amplitude of the wave. After winding the flat plate 113 and the corrugated plate 112, the flat plate 113 and the corrugated plate 112 are wound such that the slit portions 111 are located on the upstream side of the exhaust gas. The non-slit portions located on the exhaust gas upstream side and the downstream side of the slit portion 111 of the flat plate 113 and the corrugated plate 112 are laser beam welded simultaneously with this winding,
Joined by resistance welding, brazing, etc. As a result, the flat plate 113 and the corrugated plate 112 are joined together.

As shown in FIGS. 1 to 3, the honeycomb carrier 11 composed of the rolled flat plate 113 and the corrugated plate 112 has a cylindrical protection longer than the honeycomb carrier 11 composed of, for example, heat-resistant stainless steel SUS430 in the axial direction. The circumference is covered by the cylinder 12. The protective cylinder 12 is formed such that the inner diameter of the protective cylinder 12 on the upstream side of the exhaust gas is larger than the inner diameter of the protective cylinder 12 on the downstream side of the exhaust gas.
It is possible to secure the void portion 100 around the honeycomb carrier 11 in which is formed. The void of the void 100 is, for example, 1.5 m
m, which holds a void having a height approximately equal to the height of the corrugated plate 112, and the void 100 forms an air heat insulating portion. The protective cylinder 12 and the honeycomb carrier 11 are connected to each other on the downstream side of the exhaust gas, and the protective cylinder 12 is connected on the upstream side of the exhaust gas.
Since the honeycomb carrier 11 and the honeycomb carrier 11 do not come into contact with each other, a bypass heat transfer path between the honeycomb carrier 11 and the protective cylinder 12 is formed. Therefore, due to the void portion 100 and the bypass heat transfer path, it is possible to lengthen the path through which the heat of the honeycomb carrier 11 is transmitted through the protective cylinder 12 and radiated to the outside, and the heat of the honeycomb carrier 11 that has been heated is transferred to the protective cylinder 12. It has the effect of suppressing escape.

Further, on the upstream side of the exhaust gas, the positions of the honeycomb carrier 11 and the protective tube 12 are arranged so that the end of the protective cylinder 12 projects axially from the upstream end 11a of the honeycomb carrier 11 located upstream of the exhaust gas. The relationship is fixed.
Accordingly, when the honeycomb carrier 11 is stored, transported, attached to an exhaust pipe, or the like, the upstream end 11a does not project to the outside of the protective cylinder 12, so that the honeycomb carrier 11 is less likely to be damaged. .

In a part of the protective cylinder 12 covering the exhaust gas downstream side of the honeycomb carrier 11, notches 121 extending along the axial direction of the honeycomb carrier 11 are formed at eight positions. These eight cutouts 121 are 45 in the circumferential direction of the protective cylinder 12.
Formed at intervals. Honeycomb carrier 11 and protective cylinder 1
2 refers to the corrugated plate 112 of the honeycomb carrier 11 and the protective cylinder 1 by irradiating the circumferential portion of the protective cylinder 12 excluding the eight cutouts 121 with a laser beam from the outside of the protective cylinder 12.
The inner peripheral wall of 2 is welded and fixed. The joining of the honeycomb carrier 11 and the protective cylinder 12 is not limited to laser beam welding, and may be brazing. 2 and 3 show welding marks 32 formed by laser beam welding. When the honeycomb carrier 11 and the protective cylinder 12 are joined, welding cracks may occur on the corrugated plate 112 side due to the difference in heat capacity between the corrugated plate 112 located on the outermost periphery of the honeycomb carrier 11 and the protective cylinder 12. Therefore, in the case of welding by laser beam welding, the corrugated plates 11 are arranged by stacking two corrugated plates 112 on the outermost periphery of the honeycomb carrier 11.
It is possible to prevent weld cracking on the second side. When brazing, it is preferable to position the flat plate 113 on the outermost periphery of the honeycomb carrier 11 in order to secure a sufficient brazing area.

On the outer peripheral wall of the protective cylinder 12 covering the exhaust gas upstream side of the honeycomb carrier 11, for example, heat resistant stainless steel SUS is used.
A flange-shaped flange 17 made of 430 is welded and fixed, and a welding mark 31 is formed. The flange 17 is made of the same material as the protective cylinder 12 in consideration of weldability. In order to secure even higher weldability, the protective cylinder 12 and the flange 1
The flange 17 is welded to the protective cylinder 12 before the γ-Al ₂ O ₃ coat and catalyst support described later are applied to the welding surface with 7.

Next, a method of supporting the catalyst substance will be described. By heating the honeycomb carrier 11 at 800 to 1200 ° C. for 1 to 10 hours, an oxide of aluminum is deposited on the surfaces of the flat plate 113 and the corrugated plate 112 that form the honeycomb carrier 11. This heat treatment is performed for the purpose of suppressing peeling of the γ-Al ₂ O ₃ coat, and the flat plate 113,
Alumina whiskers are generated on the surface of the corrugated plate 112 to increase the surface area. Since this makes it possible to obtain high reliability, it is preferable to perform this heat treatment. After this heat treatment, the honeycomb carrier 11 is impregnated in a slurry containing Al ₂ O ₃ and is baked. As a result, the surfaces of the flat plate 113 and the corrugated plate 112 have γ-Al ₂ O ₃
To be coated. After forming the γ-Al ₂ O ₃ layer, the honeycomb carrier 11 is impregnated with an aqueous solution in which, for example, platinum, rhodium, palladium, etc. are dissolved by a catalyst supporting step and is fired again.

The honeycomb carrier 11 assembled by the above steps functions as a catalytic converter 10 that can be attached to the exhaust path of an automobile. Next, a state in which the catalytic converter 10 is attached to the exhaust path of the automobile will be described with reference to FIG. As shown in FIGS. 6 and 7, V8, 4000 cc
The eight exhaust manifolds derived from the engine 40 of the above are assembled in groups of four, and
The exhaust manifolds 41, 42 of the book are configured as an exhaust path of the engine. The catalytic converter 10 and the start catalyst 13 located downstream of the catalytic converter 10 are disposed in the middle of the exhaust manifolds 41 and 42. The start catalyst 13 is a monolith catalyst made of ceramics having a capacity of 1300 cc, and the start catalyst outer cylinder 2
It is held in 1 via a wire net or a ceramic fiber mat 14.

The downstream flange 21b of the start catalyst outer cylinder 21 and the flange 22a of the exhaust pipe 22 are connected to each other by bolts.
On the downstream side of the exhaust gas, the exhaust pipes 22 are assembled into one and then connected to a main catalyst (not shown) of 1000 cc. In this way, the exhaust manifold 4
By positioning the catalytic converter 10 having a heat capacity lower than that of the start catalyst 13 between the first catalyst 42 and the start catalyst 13, the catalytic converter 10 that heats up in a short time purifies exhaust gas at idling immediately after the engine is started. effective. Further catalytic converter 1
When 0 and the start catalyst 13 are brought close to each other, the heat of reaction of the catalyst substance of the catalytic converter 10 on the exhaust gas upstream side has an effect of promoting activation of the catalyst substance of the start catalyst 13 on the exhaust gas downstream side.

As shown in FIGS. 1 and 3, the flange 17 of the catalytic converter 10 is sandwiched between the exhaust manifold mounting flange 20a and the start catalyst mounting flange 21a via a gasket 18 which is a seal member. It is fixed to the exhaust pipe path by bolts 19. Here, the seal member is not limited to the gasket, and may be, for example, a heat resistant O-ring. The seal member prevents exhaust gas from flowing from the upstream side to the downstream side without passing through the catalytic converter 10.

The outer diameter d of the honeycomb carrier 11 is set to be larger than the inner diameters of the exhaust manifolds 41 and 42. For example, the exhaust manifolds 41, 42
If the inner diameter is larger than the outer diameter d of the honeycomb carrier 11, an exhaust pipe element having a cone shape or the like whose diameter decreases in the exhaust gas flow direction is provided between the exhaust manifolds 41 and 42 and the exhaust manifold mounting flange 20a. On the other hand, when the inner diameters of the exhaust manifolds 41 and 42 are smaller than the outer diameter d of the honeycomb carrier 11,
An exhaust pipe element having a cone shape or the like whose diameter increases in the exhaust gas flow direction may be provided between the exhaust manifolds 41 and 42 and the exhaust manifold mounting flange 20a. With this exhaust pipe element, the exhaust manifolds 41, 42 and the honeycomb carrier 11 are adjusted so as to be in an optimal connected state.

Furthermore, the flat portion 20b of the exhaust manifold mounting flange 20a and the honeycomb carrier 1 are provided.
1 to 10 mm described later between the upstream end 11a
And the catalytic converter 10 is attached to the exhaust path. Due to this interval e, the exhaust gas from the exhaust manifolds 41 and 42 does not directly flow into the void portion 100. Further, since the outer diameter d of the honeycomb carrier 11 is larger than the inner diameters of the exhaust manifolds 41, 42, the exhaust gas flowing into the honeycomb carrier 11 from the exhaust manifolds 41, 42 is directed in the axial center direction of the honeycomb carrier 11 having a relatively high temperature rising speed. get together. Therefore, the purification of the exhaust gas can be promoted, and the exhaust gas flowing into the outermost peripheral portion of the honeycomb carrier 11 having a slow temperature rising speed can be reduced, which has the effect of improving the exhaust gas purification efficiency of the honeycomb carrier 11.

Further, the inner diameter of the introduction pipe 21c located on the exhaust gas upstream side of the start catalyst 13 is set to be larger than the outer diameter of the protective cylinder 12 of the catalytic converter 10.
Between the introduction pipe 21c and the start caster outer cylinder 21 having an inner diameter larger than that of the introduction pipe 21c, a tapered cone portion whose inner diameter increases from the introduction pipe 21c side in the direction of the start caster outer cylinder 21 side. 21e is located,
The introduction pipe 21c is connected to the start casterist outer cylinder 21. The divergence angle θ of this cone portion 21e is 9
It is desirable that the angle is 0 ° or less, and the distance f between the catalytic converter 10 and the start caster list 13, the ratio of the outer diameter of the honeycomb carrier 11 and the outer diameter of the start caster list 13, and the spread angle θ are correlated. I have a relationship. The interval f is determined from this ratio and the spread angle θ, and in any case, the interval f is preferably 40 mm or more. When the outer diameter of the honeycomb carrier 11 and the outer diameter of the start caster list 13 are substantially the same, the divergence angle θ of the cone portion 21e is 0.
It becomes °. In this case, the honeycomb carrier 11 and the start caster list 13 may be in contact with each other.

Further, in the catalytic converter 10, the catalytic converter 1 is placed in the space 101 formed by the cone portion 21e.
It is housed in the introduction pipe 21c so that the downstream end of 0 does not fly out. This prevents the exhaust gas from forming a vortex in the space 101. This catalytic converter 10
By setting the accommodating position and the above-mentioned interval f, it becomes possible to cause the high-temperature exhaust gas heated by the honeycomb carrier 11 to flow into the monolith catalyst of the start caster 13 substantially uniformly, and also to start the catalyst 13.
This has the effect of making it easier for the exhaust gas to flow into the outer peripheral portion of the.

Furthermore, the upstream end 11a of the honeycomb carrier 11 and the exhaust manifold mounting flange 2 are provided.
An interval e of 1 mm or more is provided between the flat surface portion 20b of 0a. Due to this interval e, the honeycomb carrier 11
Since the amount of thermal expansion in the axial direction is absorbed, the upstream end 11a does not contact the flat surface portion 20b during thermal expansion,
Damage to the upstream end 11a is prevented. In order to raise the temperature of the honeycomb carrier 11, it is effective to use high temperature exhaust gas, and it is desirable to position the catalytic converter 10 on the exhaust gas upstream side of the exhaust manifold 41. However, since the exhaust manifold mounting flange 20a having a large heat capacity is located on the upstream side of the exhaust gas where the catalytic converter 10 is disposed, the engine 4
The temperature of the exhaust gas discharged from zero sharply decreases on the downstream side of the exhaust manifold mounting flange 20a. Therefore, the distance e between the upstream end portion 11a of the honeycomb carrier 11 and the flat surface portion 20b of the exhaust manifold mounting flange 20a is set to 1 to 10 mm from the balance between the distance e and the thickness of the flange 20a, for example, 10 mm. It is desirable to position the catalytic converter 10 at.

Next, the operation of the catalytic converter 10 will be described with reference to FIGS. 1 and 6. After starting the engine 40,
The exhaust gas discharged from each cylinder in the exhaust stroke of each cylinder reaches the catalytic converter 10 via the exhaust manifolds 41 and 42. The exhaust gas that has reached the catalytic converter 10 has a slit portion 1 located upstream of the honeycomb carrier 11.
In addition to the effect of the slit portion 111 listed below, the temperature of the slit portion 111 rises fastest because the slit portion 111 and the protective cylinder 12 are thermally insulated by the air heat insulating portion of the void portion 100. .

By forming the slit, the slit portion 111
Has a smaller heat capacity. Since the cross-sectional area of the honeycomb carrier 11 in the axial direction of the honeycomb carrier 11 is reduced by forming the slits, heat conduction to the downstream side of the honeycomb carrier 11 is suppressed. Since the heat transfer paths are lengthened by staggering the positions where the slits are formed, heat conduction to the downstream side of the honeycomb carrier 11 is suppressed.

Since the contact area between the flat plate 2 and the corrugated plate 3 is reduced by forming the slits, the heat conduction to the outside in the radial direction of the honeycomb carrier 11 is suppressed. Since the slit has a function of disturbing the flow of exhaust gas, heat transfer efficiency is improved. In addition, the honeycomb carrier 11 and the protective cylinder 12 are joined by welding marks 32 on the downstream side of the honeycomb carrier 11, and the protective cylinder 12 and the exhaust manifold 4 are joined together.
1 and 42 are flanges 17 on the upstream side of the honeycomb carrier 11.
Since the honeycomb carrier 11 is fixed by the exhaust manifolds 41, 4 through the protective cylinder 12,
The heat transfer path reaching 2 can be secured for a long time. Thereby, the heat radiation of the honeycomb carrier 11 is suppressed and the heat radiation amount is extremely reduced.

Further, on the exhaust gas downstream side of the honeycomb carrier 11 in which the slit portion 111 is not formed, the slit portion 1 is provided.
In comparison with the upstream side of the exhaust gas in which 11 is formed, the thermal conductivity is extremely high because the thermal conductivity is large in the radial direction and the axial direction, and the activation temperature of the catalyst is short in the entire exhaust gas downstream side of the honeycomb carrier 11. Up to. Next, FIG. 8 shows the experimental results of examining the temperature rise characteristics of the catalytic converter 10 of the first embodiment and the catalytic converter of Comparative Example 1 due to the exhaust gas.
It will be described based on.

As shown in FIG. 7, an experiment was conducted with a structure in which the catalytic converter 10 or the catalytic converter of Comparative Example 1 was arranged in the middle of the exhaust manifold 41, and the start catalyst 13 was arranged downstream of the exhaust gas. The catalytic converter of Comparative Example 1 had the same structure as that of the catalytic converter 10 except that the flat plate 113 and the corrugated plate 112 of the honeycomb carrier 11 were not provided with slit portions. In addition, when checking the temperature rise of each catalytic converter or start catalyst 13, the catalytic converter or start catalyst 13 corresponding to a position 19 mm axially downstream from the exhaust gas upstream side of each catalytic converter or start catalyst 13 is located.
The temperature condition of the central part of the was measured.

As shown in FIG. 8, in the catalytic converter 10, the temperature reaches 300 ° C. in about 10 seconds after the engine is started. In contrast, the catalytic converter of Comparative Example 1 reached a temperature of 300 ° C. in about 15 seconds, which was about 5 seconds later than in the case of the catalytic converter 10. Furthermore, even in the start catalyst 13 on the exhaust gas downstream side of each catalytic converter, the temperature rises faster in the configuration in which the catalytic converter 10 is arranged on the exhaust gas upstream side of the start catalyst 13. Thus, by forming the slit portion on the exhaust gas upstream side of the honeycomb carrier, it is possible to obtain a rapid temperature rise of the catalytic converter, and in addition to this, connect the catalytic converter and the start catalyst by the cone portion. By this experiment, it was confirmed by this experiment that a rapid temperature rise of the start catalyst can be obtained.

Next, the catalytic converter 10 of the first embodiment,
The experimental results of examining the radial temperature distribution of the honeycomb carrier of each of the catalytic converters of Comparative Example 2 will be described with reference to FIG. As shown in FIG. 7, an experiment was performed by a configuration in which the catalytic converter 10 or the catalytic converter of Comparative Example 2 was disposed in the middle of the exhaust manifold 41, and the start catalyst 13 was disposed downstream of the exhaust gas. Further, in the catalytic converter of Comparative Example 2, the inner diameter of the flange of the exhaust manifold is larger than the outer diameter of the honeycomb carrier 11, and the exhaust gas flowing from the exhaust manifold is formed between the honeycomb carrier 11 and the protective cylinder 12 in a void portion. The one flowing into 100 was used. A radial temperature distribution corresponding to a position 45 mm downstream of the exhaust gas upstream side end portion in the axial direction of the catalytic converter was measured 17 seconds after the engine was started.

As shown in FIG. 9, in the catalytic converter 10, there is a gradual temperature gradient α in the outer peripheral portion of the honeycomb carrier 11 located outside the inner diameter of the exhaust manifold 41. This is because by setting the inner diameter of the exhaust manifold 41 smaller than the inner diameter of the honeycomb carrier 11, the exhaust gas flowing into the outer peripheral part of the honeycomb carrier 11 is suppressed and the catalytic reaction of the outer peripheral part of the honeycomb carrier 11 is suppressed. On the other hand, in the catalytic converter of Comparative Example 2, the temperature gradient β of the outer peripheral portion of the honeycomb carrier 11 is larger than the temperature gradient α. This is because the inner diameter of the exhaust manifold 41 is set to be larger than the inner diameter of the honeycomb carrier 11.
This is because a large amount of exhaust gas has flowed into the void portion 100 of 1 and the outer peripheral portion. Thus, by forming the slit portion on the exhaust gas upstream side of the honeycomb carrier, the honeycomb carrier 1
By setting the inner diameter of 1 to be larger than the inner diameter of the exhaust manifold 41, the temperature gradient of the outer peripheral portion of the honeycomb carrier 11 is made gentle and the honeycomb carrier 11 is
It is possible to reduce the thermal stress generated between the protective cylinder 12 and the protective cylinder 12. This has the effect of preventing scoping caused by the difference in heat capacity between the honeycomb carrier 11 and the protective cylinder 12. Further, due to the difference in heat capacity between the honeycomb carrier 11 and the protective cylinder 12, there is an effect that the cyclic thermal stress generated inside the honeycomb carrier 11 is reduced as the engine speed increases and decreases while the vehicle is running, and the durability of the catalytic converter 10 is improved. .

Further, by setting the inner diameter of the honeycomb carrier 11 to be larger than the inner diameter of the exhaust manifold 41, high-temperature exhaust gas efficiently flows in the axial center direction of the honeycomb carrier 11, so that the catalyst of the catalyst converter of Comparative Example 2 is used. The converter 10 has a higher temperature in the range of about 20 mm from the center of the honeycomb carrier. This allows
This has the effect of further improving the temperature raising performance of the honeycomb carrier 11.

(Second Embodiment) A catalytic converter according to a second embodiment of the present invention will be described with reference to FIGS. 10 and 11. Regarding the substantially same constituent parts as those of the first embodiment,
The same symbols are attached. As shown in FIG. 10, the catalytic converter 50 according to the second embodiment is different from the first embodiment in that a flange 51 is provided with a hole 51a into which a connecting element such as a bolt or a pin can be inserted.

According to the catalytic converter 10 shown in the first embodiment, the protective tube 12 and the introduction tube 21c are fixed without being positioned, so that the introduction tube 21c and the protective tube 12 are coaxial with each other. It is difficult to position it, and the outer peripheral wall of the protective cylinder 12 may locally contact the inner wall of the introduction pipe 21c. As a result, the contact point between the outer peripheral wall of the protective cylinder 12 and the introduction pipe 21c shortens the heat radiation path from the honeycomb carrier 11 to the outside, which may promote the deterioration of the temperature raising performance.

Therefore, in the catalytic converter 50 according to the second embodiment, instead of the flange 17 of the catalytic converter 10 of the first embodiment, a flange 51 having a positionable hole 51a is provided on the outer peripheral wall of the protective cylinder 13. . As shown in FIG. 11, a flange 51 made of, for example, heat resistant stainless steel SUS430 is welded and fixed to the outer peripheral wall of the protective cylinder 13. In this flange 51, holes 51a through which the bolts 19 can pass are formed in the circumferential direction at, for example, six locations at 60 ° intervals. Introducing the catalytic converter 50 into the introducing pipe 21c
The bolt 19 is inserted into the hole 51a and the flange 51 is fastened together with the exhaust manifold mounting flange 20a and the start casterist mounting flange 21a. By thus inserting the connecting elements such as bolts and pins into the holes 51a formed in the flange 51, the catalytic converter 50 can be easily positioned in the exhaust pipe path. Here, the clearance between the bolt 19 and the hole 51a is preferably about 0.5 mm.

According to the catalytic converter 50 of the second embodiment, the flange 51 of the catalytic converter 50 fixed to the introduction pipe 21c is formed with holes 51a at equal intervals in the circumferential direction. When attached to the introduction pipe 21c, the introduction pipe 21c and the protective cylinder 12 can be easily positioned coaxially with each other, and the accuracy of attachment of the catalytic converter 50 can be improved. As a result, the protective cylinder 12
This has the effect of preventing the outer peripheral wall of the above from locally contacting the inner wall of the introduction pipe 21c. As a result, contact between the outer peripheral wall of the protective cylinder 12 and the inner wall of the introduction pipe 21c is prevented, and thus there is an effect of preventing heat radiation from the contact point between the outer peripheral wall of the protective cylinder 12 and the introduction pipe 21c.

In the second embodiment, the catalytic converter 5
Although the bolt 19 is used for positioning 0, the present invention is not limited to this, and a pin or other shaft-shaped member may be used for positioning. Further, in the second embodiment, the holes 51a are formed in the flange 51 of the catalytic converter 50 at six locations at 60 ° intervals, but the present invention is not limited to this, and four locations at 90 ° intervals, eight locations. It may be at 45 ° intervals.

Further, although the hole 51a is used for positioning the catalytic converter 50 in the second embodiment, the present invention is not limited to this, and one place where a bolt, a pin and other shaft-like members can be locked. You may form the above notch in a flange. (Third Embodiment) A catalytic converter according to a third embodiment of the present invention will be described with reference to FIG. The same components as those in the first embodiment are designated by the same reference numerals.

As shown in FIG. 12, the catalytic converter 60 according to the third embodiment differs from the first embodiment in that the introduction pipe 61 and the protective cylinder 121 are fixed by welding because the flange is removed. A welding fixing member 63 is formed on the exhaust gas upstream side of the outer peripheral wall of the protective cylinder 12. By welding the welding fixing member 63 and the start casterist mounting flange 61a, the catalytic converter 6
0 is fixed to the introduction pipe 61. At the time of welding, the catalyst supported on the honeycomb carrier 11 is damaged by the heat generated by the welding because it is thermally insulated by the air heat insulating layer of the void 100 formed between the protective cylinder 12 and the honeycomb carrier 11. Can be joined without

The upstream end 11 of the honeycomb carrier 11
A space g of 1 mm or more is provided between a and the flat surface portion 62b of the exhaust manifold mounting flange 62a. According to the catalytic converter 60 of the third embodiment,
Since the protective cylinder 12 and the introduction pipe 61 are welded to each other without using a flange for fixing the catalytic converter 60 and the introduction pipe 61, the number of parts can be reduced. This has the effect of reducing the cost of the catalytic converter 60.

Further, according to the catalytic converter 60 of the third embodiment, the upstream end 11a of the honeycomb carrier 11 and the flat portion 62 of the exhaust manifold mounting flange 62a are provided.
Since the gap g of 1 mm or more is provided between the honeycomb substrate 11 and the substrate b, the thermal expansion amount of the honeycomb carrier 11 in the axial direction can be absorbed. Accordingly, the upstream end 11a does not come into contact with the flat surface portion 62b when the honeycomb carrier 11 is thermally expanded, and there is an effect of preventing damage to the upstream end 11a.

(Fourth Embodiment) A catalytic converter according to a fourth embodiment of the present invention will be described with reference to FIG. The same components as those in the first embodiment are designated by the same reference numerals. As shown in FIG. 13, the catalytic converter 70 according to the fourth embodiment is different from the first embodiment in that the number of windings or the number of layers of the flat plate 113 and the corrugated plate 112 constituting the honeycomb carrier 71 is changed.

The catalytic converter 70 comprises a honeycomb carrier 71 consisting of a flat plate 113 and a corrugated plate 112, and a protective cylinder 72 covering the outer periphery of the honeycomb carrier 71. The honeycomb carrier 71 has a shape in which flat plates 113 and corrugated plates 112 are alternately overlapped and wound in a spiral shape, and is wound so that the exhaust gas upstream side has a smaller number of windings than the downstream side.

The air insulating layer can be provided by reducing the number of windings on the upstream side of the exhaust gas of the honeycomb carrier 71 to form the void portion 73 on the outermost peripheral side on the upstream side of the honeycomb carrier 71. This eliminates the need to make the inner diameter of the exhaust gas upstream side larger than the inner diameter of the downstream side unlike the protection cylinder 12 of the catalytic converter 10 of the first embodiment, and has a simple cylindrical shape with the same diameter from the exhaust gas upstream side to the downstream side. A protective cylinder 72 consisting of

According to the catalytic converter 70 of the fourth embodiment, the flat plate 113 and the corrugated plate 11 constituting the honeycomb carrier 71 are formed.
The outer diameter of the honeycomb carrier 71 on the upstream side of the exhaust gas can be reduced by setting the number of windings with 2 on the upstream side of the exhaust gas to be smaller than on the downstream side thereof. Therefore, even if the protective cylinder 72 having a simple cylindrical shape is used, the void portion 73 can be formed in the outermost periphery on the upstream side of the honeycomb carrier 71. As a result, when the protection cylinder 72 is assembled to the honeycomb carrier 71, it is not necessary to consider the directionality of the protection cylinder 72, so that the assembly time can be reduced and the cost can be reduced.

[Brief description of drawings]

FIG. 1 is a schematic cross-sectional view showing a state in which a catalytic converter according to a first embodiment of the present invention is attached to an exhaust path.

FIG. 2 is a view on arrow II in FIG.

FIG. 3 is a half sectional view of the catalytic converter according to the first embodiment.

FIG. 4 is a development view of a flat plate used for the honeycomb carrier of the catalytic converter according to the first embodiment.

FIG. 5 is a schematic explanatory view of a slit portion of the catalytic converter according to the first embodiment.

FIG. 6 is an overall configuration diagram showing a state in which the catalytic converter according to the first embodiment is mounted in an exhaust path of an engine.

FIG. 7 is a view taken in the direction of the arrow VII in FIG. 6;

FIG. 8 is a temperature raising performance characteristic diagram showing experimental results of the catalytic converter according to the first embodiment.

FIG. 9 is a radial temperature distribution characteristic diagram of a honeycomb carrier showing experimental results of the catalytic converter according to the first example.

FIG. 10 is a schematic cross-sectional view showing a state in which a catalytic converter according to a second embodiment of the present invention is attached to an exhaust path.

FIG. 11 is a plan view of a flange of the catalytic converter according to the second embodiment.

FIG. 12 is a schematic cross-sectional view showing a state in which a catalytic converter according to a third embodiment of the present invention is attached to an exhaust path.

FIG. 13 is a schematic sectional view of a catalytic converter according to a fourth embodiment of the present invention.

[Explanation of symbols]

10, 50, 60, 70 Catalytic converter 11, 71 Honeycomb carrier (Honeycomb body) 11a Upstream end (Upstream end of honeycomb body) 12 Protective cylinder 13 Start caster list (Downstream catalytic converter) 17, 51 Flange 51a Hole (through hole) 18 Gasket (seal member) 19 Bolt (connecting member) 20a, 62a Exhaust manifold mounting flange (upstream side flange) 20b, 62b Flat part (upstream side flange end face) 21 Start caster outer cylinder 21a , 61a Start caster mounting flange (downstream flange) 21c, 61 Introducing pipe (downstream path) 21e Cone 22 Exhaust pipe 40 Engine (internal combustion engine) 41, 42, 62 Exhaust manifold (upstream path, exhaust manifold) 73, 10 Void portion 111 slits 112 wave plate 113 flat

─────────────────────────────────────────────────── ─── Continuation of the front page (51) Int.Cl. ⁶ Identification code Internal reference number FI Technical indication B01D 53/94 F01N 3/28 ZAB 301 U

Claims (22)

[Claims] 1. A flat plate and a corrugated plate made of metal, which are disposed in an exhaust path of an internal combustion engine, are alternately superposed on each other, and the flat plate and the corrugated plate which are adjacent to each other in a radial direction are joined to each other. A catalytic converter having a honeycomb body configured by stacking, wherein a plurality of slits extending in a direction orthogonal to an exhaust gas flow direction are formed on an exhaust path upstream side of at least one of the flat plate and the corrugated plate. And a tubular protective cylinder having an inner wall that covers the periphery of the honeycomb body and has an inner wall joined to the downstream outer wall of the honeycomb body, and the protection is provided on at least one of the upstream path or the downstream path of the exhaust path. A catalytic converter characterized in that the upstream side of the cylinder is fixed. 2. The catalytic converter according to claim 1, wherein the honeycomb body is made of heat resistant stainless steel. 3. A flange formed on the upstream side of the protective cylinder is sandwiched and fixed between an upstream flange formed on the upstream path and a downstream flange formed on the downstream path. The catalytic converter according to claim 1 or 2, characterized in that: 4. The catalytic converter according to claim 3, wherein the flange is sandwiched between the upstream side flange and the downstream side flange via a seal member and is fixed by a connecting member. 5. The catalytic converter according to claim 4, wherein the seal member is a gasket. 6. The catalytic converter according to claim 4, wherein the seal member is a heat resistant O-ring. 7. The flange is formed with a plurality of through holes, and is positioned in the exhaust path by inserting the connecting member into the plurality of through holes. 5. The catalytic converter according to 5 or 6. 8. The flange is formed with a plurality of notches, and the flange is positioned in the exhaust path by inserting the connecting member into the notches. 5. The catalytic converter according to 5 or 6. 9. The catalytic converter according to claim 4, wherein the connecting member is a bolt or a pin. 10. The exhaust path is an exhaust manifold,
10. A downstream side catalytic converter, an exhaust pipe, and a silencer, wherein the catalytic converter is located downstream of the exhaust manifold and upstream of the downstream side catalytic converter. The catalytic converter according to the item. 11. The catalytic converter according to claim 10, wherein the catalytic converter is located close to a downstream honeycomb body that constitutes the downstream catalytic converter. 12. The downstream outer peripheral edge of the catalytic converter and the downstream outer peripheral edge of the downstream catalytic converter are connected by a cone portion whose inner diameter increases from the catalytic converter toward the downstream catalytic converter, The catalytic converter according to claim 11, wherein the downstream end portion of the converter is mounted in the cone portion without protruding. 13. The catalytic converter according to claim 12, wherein a divergence angle of the cone portion is 90 ° or less, or an axial distance between the downstream side catalytic converter and the catalytic converter is 40 mm or more. 14. A void portion is formed on the upstream side of the honeycomb body, and the downstream side of the honeycomb body and the downstream side inner wall of the protection cylinder are joined together. The catalytic converter according to one item. 15. The catalytic converter according to claim 14, wherein the void portion is formed by making an upstream inner diameter of the protection cylinder larger than a downstream inner diameter of the protection cylinder. 16. The void portion is formed when the number of windings or the number of layers of the flat plate and the corrugated plate is smaller on the upstream side of the honeycomb body than on the downstream side of the honeycomb body. Item 14. The catalytic converter according to Item 14. 17. The catalytic converter according to claim 1, wherein the protection cylinder projects axially from an upstream end of the honeycomb body on the exhaust gas upstream side. 18. The catalytic converter according to claim 1, wherein an outer diameter of the honeycomb body is larger than an inner diameter of the upstream path. 19. The catalytic converter according to claim 18, wherein an exhaust pipe element is interposed between the upstream side flange formed in the upstream side path and the upstream side path. 20. The upstream flange or the exhaust pipe element is located on an extension line extending an axial contour line of an outer peripheral portion of the honeycomb body in the upstream path direction. The catalytic converter described. 21. The catalytic converter according to claim 20, wherein the exhaust pipe element is formed by a cone portion in which at least one of at least one flat surface or at least one inner diameter gradually expands. 22. The exhaust gas so that the honeycomb body has a separation distance of 1 mm or more between an end surface of the upstream side flange or the exhaust pipe element and the honeycomb body and not more than a wall thickness of the upstream side flange. 22. Catalytic converter according to claim 21, characterized in that it is mounted in the flow direction.