JP2023083073A - Exhaust gas treatment device - Google Patents

Abstract

A small-sized exhaust gas treatment device equipped with a plurality of catalysts is proposed. An exhaust gas treatment device (100) includes a TWC (1B) for purifying exhaust gas (G) flowing along a first direction (P), and a TWC (1B) for purifying exhaust gas (G) that has passed through the TWC (1B) in a second direction (Q) crossing the first direction (P). A case 10 that purifies the exhaust gas G flowing along and is arranged such that the central axis O2 is offset with respect to the central axis O1 of the TWC1B, a case 10 that houses the TWC1B and the GPF2, and the exhaust gas G that has passed through the TWC1B. and a temperature sensor 4 for measuring the temperature of the exhaust gas G that has passed through the TWC 1B. In the exhaust gas treatment device 100, the air-fuel ratio sensor 3 and the temperature sensor 4 are attached to the case 10 with their central axes tilted with respect to each other when viewed from the first direction P. As shown in FIG. [Selection drawing] Fig. 4

Description

The present invention relates to an exhaust gas treatment device.

Patent Document 1 discloses an air-fuel ratio sensor that detects the concentration of oxygen in the exhaust gas that has passed through the catalytic converter in an exhaust passage in which a catalytic converter and a DPF (diesel particulate filter) are arranged in a straight line. A configuration is disclosed comprising:

JP 2008-075458 A

By the way, a conventional exhaust gas treatment device installed near an internal combustion engine is required to be compact due to restrictions on mounting space while mounting a plurality of catalysts in order to comply with exhaust gas regulations.

The present invention proposes a small-sized exhaust gas treatment device while mounting a plurality of catalysts.

According to one aspect of the present invention, an exhaust gas treatment device includes a first catalyst carrier that purifies exhaust gas flowing along a first direction, and exhaust gas that has passed through the first catalyst carrier and a second catalyst carrier that purifies exhaust gas flowing along a second direction that intersects with the a case that houses a second catalyst carrier; an outer peripheral flow path that is provided between the outer peripheral surface of the first catalyst carrier and the inner peripheral surface of the case and covers the outer periphery of the first catalyst carrier; a first sensor for measuring a first characteristic of the exhaust gas that has passed through the catalyst carrier; and a second sensor for measuring a second characteristic that is different from the first characteristic of the exhaust gas that has passed through the first catalyst carrier. and a second sensor, wherein the first sensor and the second sensor are attached to the case in a state in which central axes thereof are inclined with respect to each other when viewed from the first direction.

In the above aspect, when another device other than the exhaust gas treatment device is arranged in the vicinity of the first sensor and the second sensor, the distance between the exhaust gas treatment device and the other device can be shortened. That is, by adopting such a configuration, it is possible to reduce the mounting space of the exhaust gas treatment device, in other words, to reduce the size of the exhaust gas treatment device.

FIG. 1 is a side view of an exhaust gas treatment device according to an embodiment of the invention. FIG. 2 is a top view showing a partial cross section of the vicinity of the first catalyst carrier of the exhaust gas treatment device according to the embodiment of the present invention. FIG. 3 is a cross-sectional view along line III-III in FIG. FIG. 4 is a cross-sectional view of the vicinity of an air-fuel ratio sensor and a temperature sensor of the exhaust gas treatment device according to the embodiment of the present invention. FIG. 5 is a cross-sectional view of the vicinity of the enlarged diameter portion of the exhaust gas treatment device according to the embodiment of the present invention.

Hereinafter, embodiments of the present invention will be described with reference to the attached drawings.

First, an exhaust gas treatment device 100 according to an embodiment of the present invention will be described with reference to FIGS. 1 to 5. FIG. FIG. 1 is a side view showing an exhaust gas treatment device 100 according to this embodiment. FIG. 2 is a top view partially showing a cross section of the vicinity of TWC 1B of the exhaust gas treatment device 100 according to the present embodiment. FIG. 3 is a cross-sectional view of the exhaust gas treatment device 100 according to the present embodiment taken along line III-III in FIG. FIG. 4 is a cross-sectional view of the vicinity of the air-fuel ratio sensor 3 and the temperature sensor 4 of the exhaust gas treatment device 100. As shown in FIG. FIG. 5 is a cross-sectional view of the exhaust gas treatment device 100 near the enlarged diameter portion 15c.

The exhaust gas treatment device 100 is mounted on a vehicle, for example, and treats exhaust gas G discharged from an engine (not shown). A structural example as a converter is shown. Specifically, the exhaust gas treatment device 100 oxidizes hydrocarbons and carbon monoxide contained in the exhaust gas G into carbon dioxide and water, reduces nitrogen oxides, and removes fine particulate matter. to purify the exhaust gas G.

As shown in FIGS. 1 to 5, the exhaust gas treatment device 100 includes an inlet-side flange 11 connected to an exhaust outlet of an exhaust turbine (not shown) and an exhaust pipe (not shown) leading exhaust gas G to the outside. ), a pair of TWCs (three-way catalysts) 1A and 1B provided in the case 10 for purifying the exhaust gas G, and downstream of the TWCs 1A and 1B in the case 10 GPF (gasoline particulate filter) 2 as a second catalyst carrier for purifying the exhaust gas G that has passed through the TWCs 1A and 1A, and the oxygen concentration of the exhaust gas G that has passed through the TWCs 1A and 1B is measured. An air-fuel ratio sensor 3 (see FIG. 4) as a first sensor for detecting the temperature of the exhaust gas G and a temperature sensor 4 (see FIG. 4) as a second sensor for detecting the temperature of the exhaust gas G are provided. Note that the TWC 1B of this embodiment corresponds to the first catalyst carrier.

As shown in FIG. 3 and the like, the case 10 includes an inlet-side tubular portion 13 to which an inlet-side flange 11 is attached, a first accommodating tubular portion 14 that accommodates the TWCs 1A and 1B inside, and the first accommodating tubular portion 14. An intermediate tubular portion 15 partially accommodating the first accommodating tubular portion 14 inside, a second accommodating tubular portion 16 having one end joined to the intermediate tubular portion 15 and accommodating the GPF 2 therein, and a second accommodating tubular portion 16 having one end and an outlet-side tubular portion 17 joined to the tubular portion 16 and provided with an outlet-side flange 12 at the other end for connection to an exhaust-side pipe (not shown). Case 10 is made of, for example, a metal material such as an aluminum alloy.

As shown in FIG. 3, the inlet-side tubular portion 13 is formed in a shape whose diameter gradually increases toward the downstream side by a metal plate-like member. The inlet flange 11 is attached to the outer peripheral surface of the upstream opening 13a of the inlet cylindrical portion 13 by welding or the like. The downstream opening 13b of the inlet-side tubular portion 13 is attached to the outer peripheral surface of the first housing tubular portion 14 by welding or the like.

The first housing cylinder part 14 is formed in a cylindrical shape by, for example, a metallic plate member. The first housing cylinder portion 14 internally holds the TWCs 1A and 1B via cushioning materials 20A and 20B.

The intermediate tubular portion 15 is configured to bend the flow of the exhaust gas G passing through the intermediate tubular portion 15 by a predetermined angle (for example, 90°), that is, to form a substantially L-shaped flow path. The intermediate tubular portion 15 is formed, for example, by joining two metal plate-shaped members by welding or the like (see FIG. 2).

As shown in FIG. 3, the second housing cylinder portion 16 is formed in a cylindrical shape, for example, by a metal plate member. The outer peripheral surface of the inlet-side opening 16a of the second housing cylinder portion 16 is joined to the inner peripheral surface of the outlet-side opening 15d of the intermediate tubular portion 15 by welding or the like. Further, the outer peripheral surface of the outlet-side opening 16b of the second housing cylinder 16 is joined to the inner peripheral surface of the inlet-side opening 17a of the outlet-side cylinder 17 by welding or the like.

The outlet-side tubular portion 17 is formed of, for example, a metallic plate member. The outlet-side cylindrical portion 17 guides the exhaust gas G that has passed through the GPF 2 to an exhaust pipe (not shown) that discharges the exhaust gas G to the outside. The outlet-side flange 12 is attached to the outer peripheral surface of the downstream-side opening 17b of the outlet-side cylindrical portion 17 by welding or the like.

The TWCs 1A and 1B are configured by, for example, columnar honeycomb structures. The outer peripheral surfaces of the TWCs 1A and 1B are fitted to the first housing cylinder portion 14 via cushioning materials 20A and 20B. The TWCs 1A and 1B are accommodated in the first tubular accommodating portion 14 over the entire axial direction.

The upstream opening 14a of the first housing cylinder 14 is inserted into the inner circumference of the downstream opening 13b of the inlet cylinder 13 . The first housing tubular portion 14 is fixed to the inlet-side tubular portion 13 by being joined to the inner peripheral surface of the inlet-side tubular portion 13 by welding or the like. Also, most of the first housing cylinder portion 14 is inserted into the intermediate cylinder portion 15 . It is joined to the inner peripheral surface of the intermediate cylindrical portion 15 by welding or the like at a position spaced apart from the upstream opening portion 14a. The first housing cylinder portion 14 is inserted into the intermediate cylinder portion 15 so that a gap of a predetermined interval W is provided between the first housing cylinder portion 14 and the intermediate cylinder portion 15 . This gap forms an outer peripheral flow path F through which the exhaust gas G flows (see FIG. 5). In this embodiment, the portion of the first housing cylinder portion 14 inserted into the intermediate cylinder portion 15 corresponds to the inner case portion 14c.

GPF2 is composed of, for example, a cylindrical ceramic filter that removes fine particulate matter. GPF2 is fixed in the 2nd accommodation cylinder part 16 by the outer peripheral surface being fitted by the internal peripheral surface of the 2nd accommodation cylinder part 16 through the buffer material 20C. By arranging the TWCs 1A, 1B and the GPF 2 in this way, the TWCs 1A, 1B and the GPF 2 are arranged in a so-called L shape when viewed from the side (see FIG. 3). Further, as shown in FIGS. 3 and 5, in the exhaust gas treatment device 100 of the present embodiment, the GPF 2 is arranged with its central axis O2 offset with respect to the central axis O1 of the TWCs 1A and 1B.

The air-fuel ratio sensor 3 has a rod-shaped member, and a measurement section 3a for measuring the exhaust gas G is provided at the tip of the rod-shaped member. The body portion of the air-fuel ratio sensor 3 is attached from the outside of the intermediate tubular portion 15 so that the measuring portion 3a is positioned on the flow path between the TWC 1B and the GPF 2. As shown in FIG.

The temperature sensor 4 is attached from the outside of the intermediate tubular portion 15 so as to be positioned on the flow path between the TWC 1B and the GPF 2. As shown in FIG. A temperature sensor 4 detects the temperature of the exhaust gas G that has passed through the TWC 1B. The mounting surface (position B) of the intermediate tubular portion 15 to which the air-fuel ratio sensor 3 is mounted is formed so as to be inclined with respect to the mounting surface (position A) to which the temperature sensor 4 is mounted (see FIG. 4).

In the exhaust gas treatment device 100 of the present embodiment, the air-fuel ratio sensor 3 is attached from the outside of the intermediate tubular portion 15 to the mounting surface (position B) inclined with respect to the mounting surface (position A) on which the temperature sensor 4 is mounted. Thus, the air-fuel ratio sensor 3 and the temperature sensor 4 are attached to the intermediate tubular portion 15 with their central axes tilted at an angle θ from each other when viewed from the axial direction of the TWCs 1A and 1B. In other words, the air-fuel ratio sensor 3 and the temperature sensor 4 are attached to the intermediate tubular portion 15 so that their leading ends approach each other toward the inside of the intermediate tubular portion 15 .

Next, a specific configuration of the intermediate tubular portion 15 will be described. In the following description, the direction in which the exhaust gas G passes through the TWCs 1A and 1B, that is, the axial direction of the TWCs 1A and 1B is referred to as the "first direction P." The direction is called "second direction Q" (see FIG. 3). In this embodiment, the case where the first direction P and the second direction Q are orthogonal to each other is taken as an example. It is good if there is

As shown in FIG. 3, the intermediate cylindrical portion 15 covers the outer periphery of the TWC 1B and includes a housing portion 15a that extends cylindrically in the first direction P and a guide portion 15b that guides the exhaust gas G that has passed through the TWC 1B to the GPF 2. have. The guide portion 15b is formed in a shape that expands in diameter toward the GPF 2 (toward the downstream side in the flow direction of the exhaust gas G).

As described above, the intermediate cylindrical portion 15 is arranged such that the central axes O1 and O2 of the TWCs 1A and 1B and the GPF 2 are offset from each other (see FIGS. 4 and 5). It is formed so as to be offset with respect to the portion 15a.

As shown in FIG. 5 and the like, the guide portion 15b has an enlarged diameter portion 15c that is enlarged so as to guide the exhaust gas G to an area in the offset direction of the GPF 2 with respect to the TWCs 1A and 1B on the upstream end surface 2a of the GPF 2.

On the first plane S (see the cross section shown in FIG. 5 and FIGS. 2 and 3) passing through the central axis O2 of the GPF 2 and parallel to the downstream end surface 1b of the TWC 1B, the upstream end surface of the GPF 2 (upstream end surface 2a ) and passing through the center line of the TWC 1B is defined as a first virtual line L1, and a line tangential to the inner wall of the enlarged diameter portion 15c and passing through the central axis O1 of the TWC 1B is defined as a second virtual line L2. At this time, the enlarged diameter portion 15c is formed so that the angle α formed by the first virtual line L1 and the second virtual line L2 is 45° or less. If the angle α is greater than 45 degrees, the distance of the flow path between the TWC 1B and the GPF 2 will be long, and the exhaust gas treatment device 100 will be large. Therefore, by setting the angle α to 45 degrees or less, it is possible to prevent the exhaust gas treatment device 100 from increasing in size. Further, by increasing the angle α, it is possible to reduce the angle change of the flow of the exhaust gas G along the inner wall of the enlarged diameter portion 15c from the outer peripheral flow path F, so that the pressure loss can be reduced.

Next, the flow of the exhaust gas G in the exhaust gas treatment device 100 will be described.

As shown in FIG. 3, the exhaust gas G flowing from the inlet-side flange 11 passes through the inlet-side tubular portion 13 and is guided to the TWCs 1A and 1B. In the TWCs 1A and 1B, hydrocarbons and carbon monoxide contained in the exhaust gas G are oxidized and decomposed into carbon dioxide and moisture, and nitrogen oxides are reduced.

The exhaust gas G that has passed through the TWCs 1A and 1B collides with the inner wall facing the downstream side end surface of the TWC 1B of the intermediate cylinder portion 15, passes through the guide portion 15b, and flows directly toward the upstream side end surface 2a of the GPF 2. and a flow toward the outer peripheral flow path F.

The flow directly toward the upstream end face 2a of the GPF 2 forms the main stream of the exhaust gas G. On the other hand, the exhaust gas G that has flowed into the outer peripheral flow path F flows toward the upstream end surface 2a of the GPF 2 along the outer peripheral surface of the first housing cylinder portion 14 (inner case portion 14c) (see FIG. 5). At this time, the exhaust gas G flowing through the outer peripheral passage F heats the TWCs 1A and 1B from the outer periphery via the inner case portion 14c. By guiding the exhaust gas G to the outer peripheral passage F in this way, the temperature of the TWCs 1A and 1B can be raised in a short period of time immediately after the engine is started, so that the activation of the TWCs 1A and 1B can be achieved early. . In particular, since the TWC 1B positioned downstream in the first direction P, where the temperature does not rise, can be heated from the outer circumference, the time for activation of the TWC 1B can be shortened.

The TWCs 1A and 1B are accommodated over the entirety in the first direction P within the first accommodation cylinder portion 14 (inner case portion 14c). Since the entire TWCs 1A and 1B are provided inside the first housing cylinder portion 14 (the inner case portion 14c) in this way, it is possible to suppress the leakage of the exhaust gas G from the outer peripheral surfaces of the TWCs 1A and 1B. The exhaust gas G that has flowed into 1B passes through the entire area of TWCs 1A and 1B. As a result, the purification performance of the TWCs 1A and 1B can be maximized. Further, with such a configuration, the exhaust gas G flowing through the outer peripheral passage F heats the TWCs 1A and 1B from the outer periphery without entering the TWCs 1A and 1B. As a result, the TWC 1A, 1B can be kept warm, and the purification performance can be improved. Furthermore, since the TWCs 1A and 1B are covered with the first housing cylinder portion 14 (inner case portion 14c), the exhaust gas G flowing through the outer peripheral passage F does not enter the TWCs 1A and 1B, so that the exhaust gas G flows from the outer peripheral passage F to the GPF 2. The flow resistance of the exhaust gas G can be reduced.

The exhaust gas G that has passed through the outer peripheral flow path F joins the flow directly directed toward the GPF 2 in the space V inside the guide portion 15 b of the intermediate cylinder portion 15 and flows into the GPF 2 .

The exhaust gas G that has flowed into the GPF 2 has fine particulate matter removed by the GPF 2 and is discharged to the exhaust pipe through the outlet-side cylindrical portion 17 .

Next, the arrangement of the air-fuel ratio sensor 3 and the temperature sensor 4 will be described.

As described above, in the exhaust gas treatment device 100 of the present embodiment, the air-fuel ratio sensor 3 and the temperature sensor 4 are in a state in which the central axes are inclined by an angle θ when viewed from the axial direction of the TWCs 1A and 1B. are attached to the intermediate tubular portion 15 so that their tips approach each other toward the inside of the intermediate tubular portion 15 (see FIG. 4). By arranging the air-fuel ratio sensor 3 and the temperature sensor 4 in such a manner that the central axes thereof are inclined to each other when viewed from the axial direction of the TWCs 1A and 1B, for example, exhaust gas processing is performed in the vicinity of the air-fuel ratio sensor 3 and the temperature sensor 4. When another device other than the device 100 is arranged, the distance between the exhaust gas treatment device 100 and the other device can be shortened. That is, by adopting such a configuration, the mounting space of the exhaust gas treatment device 100 can be reduced, in other words, the exhaust gas treatment device 100 can be miniaturized. Also, if there is a layout restriction near the position where the air-fuel ratio sensor 3 and the temperature sensor 4 are attached from another device, for example, on the projection plane viewed from the central axis direction of the intermediate cylindrical portion 15 (FIG. 4), If the sensor (the air-fuel ratio sensor 3 in FIG. 4) attached to position B protrudes radially from the intermediate cylindrical portion 15, the sensor that is larger in the height direction out of the two sensors should be positioned. By arranging it at A, it is possible to prevent it from jumping out of the intermediate cylindrical portion 15 . Thereby, the exhaust gas treatment device 100 can be further miniaturized.

It should be noted that the air-fuel ratio sensor 3 and the temperature sensor 4 may be arranged such that they are arranged one behind the other in the direction in which the exhaust gas G flows.

The configuration, action, and effect of the embodiment of the present invention configured as described above will be collectively described.

The exhaust gas treatment device 100 includes a first catalyst carrier (TWC1B) that cleans the exhaust gas G flowing along the first direction P, and the exhaust gas G that has passed through the first catalyst carrier (TWC1B) in the first direction P. A second catalyst carrier (GPF2) arranged such that the central axis O2 is offset from the central axis O1 of the first catalyst carrier (TWC1B) by purifying the exhaust gas G flowing along the second direction Q that intersects with and the case 10 that houses the first catalyst carrier (TWC1B) and the second catalyst carrier (GPF2), and the outer peripheral surface of the first catalyst carrier (TWC1B) and the inner peripheral surface of the case 10 (intermediate cylindrical portion 15). An outer peripheral flow path F provided between and covering the outer periphery of the first catalyst carrier (TWC1B); A fuel ratio sensor 3) and a second sensor (temperature sensor 4) for measuring a second characteristic different from the first characteristic of the exhaust gas G that has passed through the first catalyst carrier (TWC1B). In the exhaust gas treatment device 100 , the first sensor (air-fuel ratio sensor 3 ) and the second sensor (temperature sensor 4 ) are attached to the case 10 with their central axes tilted from each other when viewed from the first direction P.

With this configuration, when another device other than the exhaust gas treatment device 100 is arranged in the vicinity of the first sensor (air-fuel ratio sensor 3) and the second sensor (temperature sensor 4), the exhaust gas treatment device 100 and another device You can get closer to the device. That is, by adopting such a configuration, the mounting space of the exhaust gas treatment device 100 can be reduced, in other words, the exhaust gas treatment device 100 can be miniaturized.

In the exhaust gas treatment device 100, the case 10 has an enlarged diameter portion that is enlarged in diameter so as to guide the exhaust gas G to a region in the offset direction of the second catalyst carrier (GPF2) on the upstream end face 2a of the second catalyst carrier (GPF2). 15c. On a first plane passing through the central axis O2 of the second catalyst carrier (GPF2) and parallel to the downstream end face of the first catalyst carrier (TWC1B), parallel to the upstream end face 2a of the second catalyst carrier (GPF2) and the first A line passing through the central axis O1 of the first catalyst carrier (TWC1B) is defined as a first imaginary line L1, and a line tangential to the inner wall of the enlarged diameter portion 15c and passing through the central axis O1 of the first catalyst carrier (TWC1B) is defined as a first imaginary line L1. Assuming the second virtual line L2, the angle α formed by the first virtual line L1 and the second virtual line L2 is 45° or less.

In this configuration, since the angle α is set to 45 degrees or less, it is possible to suppress an increase in the distance of the flow path between the TWC 1B and the GPF 2, thereby suppressing an increase in the size of the exhaust gas treatment device 100. Further, by setting the angle α to 45 degrees or less, the outer peripheral flow path F can be formed along the outer peripheral surface of the first catalyst carrier (TWC1B) longer.

In the exhaust gas treatment device 100, the exhaust gas G flowing through the outer peripheral passage F is guided to the second catalyst carrier (GPF2) by the enlarged diameter portion 15c.

In this configuration, even if the second catalyst carrier (GPF2) is arranged to be offset with respect to the central axis O1 of the first catalyst carrier (TWC1B), the exhaust gas G that has passed through the first catalyst carrier (TWC1B) is The expanded diameter portion 15c can lead to a region in the offset direction of the second catalyst carrier (GPF2).

In the exhaust gas treatment device 100, the case 10 has an inner case portion 14c provided between the first catalyst carrier (TWC1B) and the outer peripheral flow path F. As shown in FIG. The first catalyst carrier (TWC1B) is accommodated over the entire first direction P in the inner case portion 14c.

In this configuration, the exhaust gas G passing through the TWCs 1A, 1B can be prevented from leaking from the outer peripheral surfaces of the TWCs 1A, 1B. As a result, the exhaust gas G that has flowed into the TWCs 1A and 1B passes through the entire TWCs 1A and 1B, so that the purification performance of the TWCs 1A and 1B can be maximized. In addition, in this configuration, the exhaust gas G flowing through the outer peripheral passage F heats the TWCs 1A and 1B from the outer periphery without entering the TWCs 1A and 1B. can be enhanced.

Although the embodiments of the present invention have been described above, the above embodiments merely show a part of application examples of the present invention, and the technical scope of the present invention is not limited to the specific configurations of the above embodiments. do not have.

In the above embodiment, the air-fuel ratio sensor 3 is used as the first sensor, and the temperature sensor 4 is used as the second sensor. Any sensor may be used.

Moreover, in the above embodiment, the case where two TWCs 1A and 1B are provided has been described as an example, but these may be configured as one three-way catalyst.

100 Exhaust gas treatment device 1A TWC
1B TWC (first catalyst carrier)
2 GPF (second catalyst carrier)
3 air-fuel ratio sensor (first sensor)
4 temperature sensor (second sensor)
REFERENCE SIGNS LIST 10 case 11 inlet side flange 12 outlet side flange 13 inlet side tubular portion 14 first accommodating tubular portion 15 intermediate tubular portion 15a accommodating portion 15b guide portion 15c enlarged diameter portion 16 second accommodating tubular portion 17 outlet side tubular portion

Claims (4)

An exhaust gas treatment device,
a first catalyst carrier that purifies exhaust gas flowing along a first direction;
Exhaust gas that has passed through the first catalyst carrier and that flows in a second direction that intersects with the first direction is purified such that the central axis is offset with respect to the central axis of the first catalyst carrier. a second catalyst carrier disposed in
a case accommodating the first catalyst carrier and the second catalyst carrier;
an outer peripheral flow path provided between the outer peripheral surface of the first catalyst carrier and the inner peripheral surface of the case and covering the outer periphery of the first catalyst carrier;
a first sensor for measuring a first characteristic of exhaust gas that has passed through the first catalyst carrier;
a second sensor for measuring a second characteristic different from the first characteristic of the exhaust gas that has passed through the first catalyst carrier;
The first sensor and the second sensor are attached to the case in a state in which central axes are tilted with respect to each other when viewed from the first direction.
Exhaust gas treatment device. An exhaust gas treatment device according to claim 1,
The case has an enlarged diameter portion that expands in diameter so as to guide the exhaust gas to the region of the second catalyst carrier in the offset direction on the upstream end surface of the second catalyst carrier,
On a first plane passing through the central axis of the second catalyst carrier and parallel to the downstream end face of the first catalyst carrier,
A line parallel to the upstream end surface of the second catalyst carrier and passing through the center line of the first catalyst carrier is defined as a first virtual line,
When a line that is tangential to the inner wall of the enlarged diameter portion and passes through the center line of the first catalyst carrier is defined as a second virtual line,
The angle formed by the first virtual line and the second virtual line is 45° or less,
Exhaust gas treatment device. An exhaust gas treatment device according to claim 2,
Exhaust gas flowing through the outer peripheral channel is guided to the second catalyst carrier by the enlarged diameter portion.
Exhaust gas treatment device. An exhaust gas treatment device according to any one of claims 1 to 3,
The case has an inner case portion provided between the first catalyst carrier and the outer peripheral flow path,
The first catalyst carrier is housed in the inner case portion over the entire first direction,
Exhaust gas treatment device.

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