Exhaust Gas Treatment Device

Abstract

To provide a small-sized exhaust gas treatment device in which a plurality of catalysts are mounted.SOLUTION: An exhaust gas treatment device 100 includes a TWC 1B for purifying exhaust gas G flowing along a first direction P, a GPF 2 for purifying the exhaust gas G passing through the TWC 1B and flowing along in a second direction Q intersecting with the first direction P, arranged with a center axis O2 offset to a center axis O1 of the TWC 1B, a case 10 storing the TWC 1B and the GPF 2, an air-fuel ratio sensor 3 for measuring the air-fuel ratio of the exhaust gas G passing through the TWC 1B, and a temperature sensor 4 for measuring the temperature of the exhaust gas G passing through the TWC 1B. In the exhaust gas treatment device 100, the air-fuel ratio sensor 3 and the temperature sensor 4 are mounted to the case 10 in the state that their center axes are inclined to each other in view from the first direction P.SELECTED DRAWING: Figure 4

Description

[Technical Field]

[0001] The present invention relates to an exhaust gas treatment device. [Background technology]

[0002] Patent Document 1 discloses a configuration in which an air-fuel ratio sensor is provided in an exhaust passage in which a catalytic converter and a DPF (diesel particulate filter) are arranged in a straight line, to detect the oxygen concentration in the exhaust gas that has passed through the catalytic converter. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Application Laid-Open No. 2008-075458 Summary of the Invention [Problem to be solved by the invention]

[0004] Conventional exhaust gas treatment devices that are placed near internal combustion engines are required to be compact due to space limitations while being equipped with multiple catalysts to comply with exhaust gas regulations.

[0005] The present invention proposes a compact exhaust gas treatment device that can be equipped with a plurality of catalysts. [Means for solving the problem]

[0006] 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; a second catalyst carrier that purifies exhaust gas that has passed through the first catalyst carrier and that flows along a second direction that intersects the first direction and is positioned so that its central axis is offset from the central axis of the first catalyst carrier; a case that houses the first catalyst carrier and the second catalyst carrier; an outer circumferential flow path that is provided between the outer circumferential surface of the first catalyst carrier and the inner circumferential surface of the case and covers the outer periphery of the first catalyst carrier; a first sensor that measures a first characteristic of the exhaust gas that has passed through the first catalyst carrier; and a second sensor that measures a second characteristic of the exhaust gas that has passed through the first catalyst carrier, the second sensor being different from the first characteristic, and the first sensor and the second sensor are attached to the case with their central axes tilted from each other when viewed from the first direction. [Effects of the Invention]

[0007] In the above aspect, when a device other than the exhaust gas treatment device is disposed near the first sensor and the second sensor, the distance between the exhaust gas treatment device and the other device can be reduced. In other words, by adopting such a configuration, the installation space for the exhaust gas treatment device can be reduced, in other words, the exhaust gas treatment device can be made smaller. [Brief explanation of the drawings]

[0008] [Figure 1] FIG. 1 is a side view of an exhaust gas treatment device according to an embodiment of the present invention. [Figure 2] FIG. 2 is a top view showing, in partial cross section, the vicinity of the first catalyst carrier of the exhaust gas treatment device according to the embodiment of the present invention. [Figure 3] FIG. 3 is a cross-sectional view taken along line III-III in FIG. [Figure 4] FIG. 4 is a cross-sectional view of the vicinity of the air-fuel ratio sensor and the temperature sensor of the exhaust gas treatment device according to the embodiment of the present invention. [Figure 5] FIG. 5 is a cross-sectional view of the vicinity of the expanded diameter portion of the exhaust gas treatment device according to the embodiment of the present invention. DETAILED DESCRIPTION OF THE INVENTION

[0009] Hereinafter, an embodiment of the present invention will be described with reference to the accompanying drawings.

[0010] First, an exhaust gas processing device 100 according to an embodiment of the present invention will be described with reference to Fig. 1 to Fig. 5. Fig. 1 is a side view showing the exhaust gas processing device 100 according to this embodiment. Fig. 2 is a top view showing a partial cross section of the vicinity of TWC1B of the exhaust gas processing device 100 according to this embodiment. Fig. 3 is a cross-sectional view of the exhaust gas processing device 100 according to this embodiment taken along line III-III in Fig. 1. 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 processing device 100. Fig. 5 is a cross-sectional view of the vicinity of the expanded diameter portion 15c of the exhaust gas processing device 100.

[0011] The exhaust gas treatment device 100 is mounted on, for example, a vehicle and treats exhaust gas G emitted from an engine (not shown), and in the following embodiment, a structural example is shown as a catalytic converter that is small and has excellent exhaust gas purification performance. Specifically, the exhaust gas treatment device 100 oxidizes hydrocarbons and carbon monoxide contained in the exhaust gas G to carbon dioxide and moisture, reduces nitrogen oxides, and removes fine particulate matter, thereby purifying the exhaust gas G.

[0012] 1 to 5, exhaust gas treatment device 100 includes a case 10 having an inlet flange 11 connected to an exhaust outlet of an exhaust turbine (not shown) and an outlet flange 12 connected to an exhaust pipe (not shown) that guides exhaust gas G to the outside, a pair of TWCs (three-way catalysts) 1A, 1B provided within case 10 to purify exhaust gas G, a gasoline particulate filter (GPF) 2 provided downstream of TWCs 1A, 1B within case 10 as a second catalyst carrier for purifying exhaust gas G that has passed through TWCs 1A, 1A, an air-fuel ratio sensor 3 (see FIG. 4) as a first sensor for measuring the oxygen concentration of exhaust gas G that has passed through TWCs 1A, 1B, and a temperature sensor 4 (see FIG. 4) as a second sensor for detecting the temperature of exhaust gas G. In this embodiment, TWC 1B corresponds to the first catalyst carrier.

[0013] 3 and other figures, the case 10 has an inlet-side tubular portion 13 to which the inlet-side flange 11 is attached, a first casing 14 that houses the TWCs 1A and 1B therein, an intermediate tubular portion 15 that is joined to the first casing 14 and partially houses the first casing 14 therein, a second casing 16 that has one end joined to the intermediate tubular portion 15 and houses the GPF 2 therein, and an outlet-side tubular portion 17 that has one end joined to the second casing 16 and the other end provided with an outlet-side flange 12 for connection to an exhaust-side pipe (not shown). The case 10 is formed of a metal material such as an aluminum alloy.

[0014] 3, the inlet-side cylindrical portion 13 is made of a metal plate member and is formed into a shape whose diameter gradually increases downstream. An inlet-side flange 11 is attached by welding or the like to the outer peripheral surface of an upstream opening 13a of the inlet-side cylindrical portion 13. A downstream opening 13b of the inlet-side cylindrical portion 13 is attached by welding or the like to the outer peripheral surface of the first housing cylindrical portion 14.

[0015] The first cylindrical housing portion 14 is formed into a cylindrical shape using, for example, a metal plate member. The first cylindrical housing portion 14 holds the TWCs 1A and 1B therein via the buffer materials 20A and 20B.

[0016] The intermediate cylindrical portion 15 is configured to bend the flow of exhaust gas G passing through the intermediate cylindrical portion 15 at a predetermined angle (for example, 90°), that is, to form a substantially L-shaped flow path. The intermediate cylindrical portion 15 is formed, for example, by joining two metal plate-shaped members by welding or the like (see FIG. 2).

[0017] 3, the second casing cylindrical portion 16 is formed into a cylindrical shape using, for example, a metal plate member. The outer peripheral surface of the inlet-side opening 16a of the second casing cylindrical portion 16 is joined by welding or the like to the inner peripheral surface of the outlet-side opening 15d of the intermediate cylindrical portion 15. In addition, the outer peripheral surface of the outlet-side opening 16b of the second casing cylindrical portion 16 is joined by welding or the like to the inner peripheral surface of the inlet-side opening 17a of the outlet-side cylindrical portion 17.

[0018] The outlet-side tubular portion 17 is formed of, for example, a metal plate-shaped member. The outlet-side tubular 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. An outlet-side flange 12 is attached to the outer peripheral surface of a downstream opening 17b of the outlet-side tubular portion 17 by welding or the like.

[0019] The TWCs 1A and 1B are formed, for example, by cylindrical honeycomb structures. The outer peripheral surfaces of the TWCs 1A and 1B are fitted into the first cylindrical housing portion 14 via buffer materials 20A and 20B. The TWCs 1A and 1B are housed within the first cylindrical housing portion 14 over the entire axial length.

[0020] The upstream opening 14a of the first casing 14 is inserted into the inner periphery of the downstream opening 13b of the inlet-side casing 13. The first casing 14 is fixed to the inlet-side casing 13 by being joined to the inner periphery of the inlet-side casing 13 by welding or the like. A large portion of the first casing 14 is inserted into the intermediate casing 15. A portion of the first casing 14 is joined to the inner periphery of the intermediate casing 15 by welding or the like at a position spaced apart from the upstream opening 14a. The first casing 14 is inserted into the intermediate casing 15 so as to leave a gap of a predetermined distance W between the first casing 14 and the intermediate casing 15. This gap forms an outer peripheral flow passage F through which exhaust gas G flows (see FIG. 5). In this embodiment, the portion of the first casing 14 inserted into the intermediate casing 15 corresponds to the inner case portion 14c.

[0021] The GPF 2 is configured, for example, by a cylindrical ceramic filter that removes fine particulate matter. The GPF 2 is fixed inside the second tubular housing 16 by fitting its outer peripheral surface to the inner peripheral surface of the second tubular housing 16 via a buffer material 20C. By arranging the TWCs 1A and 1B and the GPF 2 in this manner, the TWCs 1A and 1B and the GPF 2 are arranged in a so-called L-shape in side view (see FIG. 3). Furthermore, as shown in FIGS. 3 and 5, in the exhaust gas treatment device 100 of this embodiment, the GPF 2 is arranged such that its central axis O2 is offset from the central axis O1 of the TWCs 1A and 1B.

[0022] The air-fuel ratio sensor 3 has a rod-shaped member, and at the tip of the rod-shaped member is provided a measuring unit 3a that measures the exhaust gas G. The main body of the air-fuel ratio sensor 3 is attached from the outside of the intermediate cylindrical portion 15 so that the measuring unit 3a is positioned on the flow path between the TWC1B and the GPF2.

[0023] The temperature sensor 4 is attached from the outside of the intermediate cylindrical portion 15 so as to be located on the flow path between the TWC 1B and the GPF 2. The temperature sensor 4 detects the temperature of the exhaust gas G that has passed through the TWC 1B. The attachment surface (position B) of the intermediate cylindrical portion 15 on which the air-fuel ratio sensor 3 is attached is formed so as to be inclined with respect to the attachment surface (position A) on which the temperature sensor 4 is attached (see FIG. 4).

[0024] In the exhaust gas processing device 100 of this embodiment, the air-fuel ratio sensor 3 is attached from the outside of the intermediate cylindrical portion 15 to an attachment surface (position B) that is inclined with respect to the attachment surface (position A) to which the temperature sensor 4 is attached, so that the air-fuel ratio sensor 3 and the temperature sensor 4 are attached to the intermediate cylindrical portion 15 with their central axes inclined by angle θ 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 cylindrical portion 15 with their tips approaching each other as they move toward the interior of the intermediate cylindrical portion 15.

[0025] Next, a specific configuration of the intermediate cylindrical portion 15 will be described. Note that, hereinafter, the direction in which the exhaust gas G passes through the TWCs 1A and 1B, i.e., the axial direction of the TWCs 1A and 1B, will be referred to as the "first direction P," and the direction in which the exhaust gas G passes through the GPF 2, i.e., the axial direction of the GPF 2, will be referred to as the "second direction Q" (see FIG. 3). Note that, in this embodiment, the first direction P and the second direction Q are perpendicular to each other, but they do not necessarily have to be perpendicular to each other, and it is sufficient that the first direction P and the second direction Q intersect.

[0026] 3, the intermediate cylindrical portion 15 covers the outer periphery of the TWC 1B and has an accommodating 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. 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).

[0027] As described above, the intermediate cylindrical portion 15 is arranged such that the central axes O1, O2 of the TWC1A, 1B and the GPF2 are offset from each other (see Figures 4 and 5, etc.), and therefore the guide portion 15b is formed to be offset from the accommodating portion 15a.

[0028] As shown in FIG. 5 and other figures, the guide portion 15b has an expanded diameter portion 15c that expands in diameter so as to guide the exhaust gas G to a region on the upstream end face 2a of the GPF 2 in the offset direction of the GPF 2 relative to the TWCs 1A and 1B.

[0029] On a first plane S (see the cross section shown in FIG. 5 and FIGS. 2 and 3) that passes through the central axis O2 of the GPF 2 and is parallel to the downstream end face 1b of the TWC 1B, a line that is parallel to the upstream end face (upstream end face 2a) of the GPF 2 and passes through the center line of the TWC 1B is defined as a first imaginary line L1, and a line that is tangent to the inner wall of the expanded diameter section 15c and passes through the central axis O1 of the TWC 1B is defined as a second imaginary line L2. The expanded diameter section 15c is formed so that the angle α between the first imaginary line L1 and the second imaginary line L2 is 45° or less. If the angle α is greater than 45°, the flow path distance between the TWC 1B and the GPF 2 becomes longer, resulting in an increase in the size of the exhaust gas treatment device 100. Therefore, by setting the angle α to 45° or less, an increase in the size of the exhaust gas treatment device 100 can be suppressed. Furthermore, by increasing the angle α, the angle change of the flow of the exhaust gas G from the outer peripheral flow passage F along the inner wall of the expanded diameter portion 15c can be reduced, thereby reducing the pressure loss.

[0030] Next, the flow of the exhaust gas G in the exhaust gas treatment device 100 will be described.

[0031] As shown in Figure 3, exhaust gas G flowing in from the inlet flange 11 is guided to the TWCs 1A and 1B through the inlet tubular portion 13. 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.

[0032] The exhaust gas G that has passed through TWC1A, 1B hits the inner wall of the intermediate cylindrical section 15 that faces the downstream end face of TWC1B, and is divided into a flow that passes through the guide section 15b and heads directly toward the upstream end face 2a of the GPF 2, and a flow that turns back and heads toward the outer peripheral flow path F.

[0033] The flow directly toward the upstream end face 2a of the GPF 2 forms the mainstream of the exhaust gas G. Meanwhile, the exhaust gas G that flows into the outer peripheral flow passage F flows toward the upstream end face 2a of the GPF 2 along the outer peripheral surface of the first housing cylindrical portion 14 (inner case portion 14c) (see FIG. 5). At this time, the exhaust gas G flowing through the outer peripheral flow passage F heats the TWCs 1A and 1B from the periphery via the inner case portion 14c. By guiding the exhaust gas G to the outer peripheral flow passage F in this manner, the temperature of the TWCs 1A and 1B can be increased in a short time immediately after engine start, thereby enabling the TWCs 1A and 1B to be activated quickly. In particular, the TWCs 1B located downstream in the first direction P, where the temperature is less likely to increase, can be heated from the periphery, thereby shortening the time required for the TWCs 1B to be activated.

[0034] The TWCs 1A and 1B are accommodated in the first cylindrical housing portion 14 (inner case portion 14c) throughout the first direction P. By providing the entire TWCs 1A and 1B within the first cylindrical housing portion 14 (inner case portion 14c) in this manner, it is possible to prevent the exhaust gas G from leaking from the outer peripheral surfaces of the TWCs 1A and 1B, and the exhaust gas G that flows into the TWCs 1A and 1B passes through the entire area of ​​the TWCs 1A and 1B. This allows the purification performance of the TWCs 1A and 1B to be maximized. Furthermore, with this configuration, the exhaust gas G flowing through the outer peripheral flow path F heats the TWCs 1A and 1B from the outer periphery without entering the TWCs 1A and 1B. This provides a heat retention effect for the TWCs 1A and 1B, thereby improving the purification performance. Furthermore, by covering TWC1A, 1B with the first housing tube portion 14 (inner case portion 14c), the exhaust gas G flowing through the outer peripheral flow path F does not enter TWC1A, 1B, thereby reducing the flow path resistance of the exhaust gas G traveling from the outer peripheral flow path F to the GPF2.

[0035] The exhaust gas G that has passed through the outer peripheral flow passage F merges with the flow that flows directly toward the GPF 2 in the space V within the guide portion 15b of the intermediate cylindrical portion 15, and flows into the GPF 2.

[0036] The exhaust gas G that has flowed into the GPF 2 has fine particulate matter removed by the GPF 2, and is then discharged into the exhaust pipe through the outlet-side cylindrical portion 17.

[0037] Next, the arrangement of the air-fuel ratio sensor 3 and the temperature sensor 4 will be described.

[0038] As described above, in the exhaust gas treatment device 100 of this embodiment, the air-fuel ratio sensor 3 and the temperature sensor 4 are attached to the intermediate cylindrical portion 15 with their central axes inclined by the angle θ when viewed from the axial direction of the TWCs 1A, 1B, more specifically, with their tips approaching each other as they move toward the interior of the intermediate cylindrical portion 15 (see FIG. 4 ). By arranging the air-fuel ratio sensor 3 and the temperature sensor 4 with their central axes inclined to each other when viewed from the axial direction of the TWCs 1A, 1B in this way, for example, when another device other than the exhaust gas treatment device 100 is disposed near the air-fuel ratio sensor 3 and the temperature sensor 4, the distance between the exhaust gas treatment device 100 and the other device can be reduced. In other words, with this configuration, the installation space for the exhaust gas treatment device 100 can be reduced, in other words, the exhaust gas treatment device 100 can be made smaller. Furthermore, if there are layout restrictions due to another device near the positions where the air-fuel ratio sensor 3 and the temperature sensor 4 are attached, for example, in a case where a sensor (air-fuel ratio sensor 3 in FIG. 4) attached at position B on a projection plane seen from the central axis direction of the intermediate cylindrical portion 15 (FIG. 4) would protrude radially from the intermediate cylindrical portion 15, then by arranging the larger of the two sensors in the height direction at position A, it is possible to prevent the sensor from protruding from the intermediate cylindrical portion 15. This allows the exhaust gas treatment device 100 to be further miniaturized.

[0039] The air-fuel ratio sensor 3 and the temperature sensor 4 may be disposed in front of and behind each other in the flow direction of the exhaust gas G.

[0040] The configuration, operation, and effects of the embodiment of the present invention configured as above will be described below.

[0041] The exhaust gas treatment device 100 includes a first catalyst carrier (TWC1B) that purifies exhaust gas G that flows along a first direction P, a second catalyst carrier (GPF2) that purifies exhaust gas G that has passed through the first catalyst carrier (TWC1B) and flows along a second direction Q that intersects with the first direction P, and is disposed so that a central axis O2 of the first catalyst carrier (TWC1B) is offset from a central axis O1 of the first catalyst carrier (TWC1B), and a housing that accommodates the first catalyst carrier (TWC1B) and the second catalyst carrier (GPF2). The exhaust gas treatment device 100 includes a case 10 having a first catalyst carrier (TWC1B) and an outer peripheral flow path F provided between the outer peripheral surface of the first catalyst carrier (TWC1B) and the inner peripheral surface of the case 10 (intermediate cylindrical portion 15) and covering the outer periphery of the first catalyst carrier (TWC1B), a first sensor (air-fuel ratio sensor 3) for measuring a first characteristic of the exhaust gas G that has passed through the first catalyst carrier (TWC1B), 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 relative to each other when viewed from a first direction P.

[0042] With this configuration, when another device other than the exhaust gas processing device 100 is disposed near the first sensor (air-fuel ratio sensor 3) and the second sensor (temperature sensor 4), the distance between the exhaust gas processing device 100 and the other device can be reduced. In other words, with this configuration, the installation space for the exhaust gas processing device 100 can be reduced, in other words, the exhaust gas processing device 100 can be made smaller.

[0043] In the exhaust gas treatment device 100, the case 10 has an expanded diameter portion 15c that expands in diameter so as to guide the exhaust gas G to a region of the upstream end face 2a of the second catalyst carrier (GPF2) in the offset direction of the second catalyst carrier (GPF2). On a first plane that passes through the central axis O2 of the second catalyst carrier (GPF2) and is parallel to the downstream end face of the first catalyst carrier (TWC1B), when a first imaginary line L1 is defined as a line that is parallel to the upstream end face 2a of the second catalyst carrier (GPF2) and passes through the central axis O1 of the first catalyst carrier (TWC1B), and a second imaginary line L2 is defined as a line that is tangent to the inner wall of the expanded diameter portion 15c and passes through the central axis O1 of the first catalyst carrier (TWC1B), the angle α formed by the first imaginary line L1 and the second imaginary line L2 is 45° or less.

[0044] In this configuration, the angle α is set to 45 degrees or less, which prevents the flow path distance between the TWC1B and the GPF2 from becoming too long and prevents the exhaust gas treatment device 100 from becoming too large. Furthermore, by setting the angle α to 45 degrees or less, the outer circumferential flow path F can be formed to extend longer along the outer circumferential surface of the first catalyst carrier (TWC1B).

[0045] In the exhaust gas treatment device 100, the exhaust gas G flowing through the outer peripheral flow passage F is guided to the second catalyst carrier (GPF2) by the expanded diameter portion 15c.

[0046] In this configuration, even if the second catalyst carrier (GPF2) is positioned so as to be offset from the central axis O1 of the first catalyst carrier (TWC1B), the exhaust gas G that has passed through the first catalyst carrier (TWC1B) can be guided by the expanded diameter portion 15c to a region in the offset direction of the second catalyst carrier (GPF2).

[0047] 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 circumferential flow path F. The first catalyst carrier (TWC1B) is accommodated in the inner case portion 14c over the entire length in the first direction P.

[0048] This configuration prevents exhaust gas G passing through TWC1A, 1B from leaking from the outer peripheral surfaces of TWC1A, 1B. This allows exhaust gas G flowing into TWC1A, 1B to pass through the entire area of ​​TWC1A, 1B, maximizing the purification performance of TWC1A, 1B. Furthermore, this configuration allows exhaust gas G flowing through outer peripheral flow path F to heat TWC1A, 1B from the outer periphery without entering TWC1A, 1B, thereby achieving a heat retention effect for TWC1A, 1B and improving purification performance.

[0049] Although the embodiments of the present invention have been described above, the above embodiments merely illustrate some of the application examples of the present invention, and it is not intended that the technical scope of the present invention be limited to the specific configurations of the above embodiments.

[0050] 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, but the first sensor and the second sensor may be any sensors that measure the characteristics of the exhaust gas G.

[0051] Furthermore, in the above embodiment, an example has been described in which two TWCs 1A and 1B are provided, but these may also be configured as one three-way catalyst. [Explanation of symbols]

[0052] 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) 10 cases 11 Inlet flange 12 Outlet flange 13 Inlet side cylinder part 14 First housing tube 15 Intermediate cylinder part 15a Storage section 15b Guide part 15c Expanded section 16 Second housing tube 17 Outlet side cylinder part

Claims

1. An exhaust gas treatment device, a first catalyst carrier that purifies exhaust gas flowing in a first direction; a second catalyst carrier that purifies exhaust gas that has passed through the first catalyst carrier and flows in a second direction that intersects with the first direction, and that is disposed so that its central axis is offset from the central axis of the first catalyst carrier; a case that houses the first catalyst support and the second catalyst support; an outer circumferential flow path provided between an outer circumferential surface of the first catalyst carrier and an inner circumferential surface of the case, the outer circumferential flow path 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 support; a second sensor for measuring a second characteristic of the exhaust gas that has passed through the first catalyst support, the second characteristic being different from the first characteristic; the first sensor and the second sensor are attached to the case with their central axes inclined to each other when viewed from the first direction; Exhaust gas treatment device.

2. The exhaust gas treatment device according to claim 1, the case has an expanded diameter portion that expands in diameter at an upstream end surface of the second catalyst carrier so as to guide the exhaust gas to a region of the second catalyst carrier in the offset direction, On a first plane that passes through the central axis of the second catalyst carrier and is parallel to the downstream end face of the first catalyst carrier, a first imaginary line that is parallel to the upstream end face of the second catalyst carrier and passes through a center line of the first catalyst carrier; When a line tangent to the inner wall of the expanded diameter portion and passing through the center line of the first catalyst carrier is defined as a second virtual line, The angle between the first virtual line and the second virtual line is 45° or less. Exhaust gas treatment device.

3. 3. The exhaust gas treatment device according to claim 2, The exhaust gas flowing through the outer peripheral flow passage is guided to the second catalyst carrier by the expanded diameter portion. Exhaust gas treatment device.

4. 4. An exhaust gas treatment device according to claim 1, the case has an inner case portion provided between the first catalyst carrier and the outer peripheral flow path, The first catalyst carrier is accommodated in the inner case portion over the entire area in the first direction. Exhaust gas treatment device.

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