CN113272534A

CN113272534A - Tail gas treatment device

Info

Publication number: CN113272534A
Application number: CN201980088064.2A
Authority: CN
Inventors: 菅谷大辅; 三石俊一; 山本隆治; 横岛悟; 久永彻; 岛村大祐
Original assignee: Marilyn Co ltd
Current assignee: Marilyn Co ltd
Priority date: 2019-01-09
Filing date: 2019-12-17
Publication date: 2021-08-17
Anticipated expiration: 2039-12-17
Also published as: CN113272534B; DE112019006601T5

Abstract

In an exhaust gas treatment device (10), an air-fuel ratio sensor (40) is provided such that a measurement portion (41) is located in a region (A1) closer to the GPF (14) side than the center of a TWC (12), the region being surrounded by a downstream-side end surface (12c) of the TWC (12), an upstream-side end surface (14b) of the GPF (14), and an inner wall surface (31c) of a housing (30) that receives exhaust gas (G) that has passed through the TWC (12).

Description

Tail gas treatment device

Technical Field

The invention relates to a tail gas treatment device.

Background

JP2008-075458A discloses a structure in which an air-fuel ratio sensor that detects the oxygen concentration in exhaust gas that has passed through a catalytic converter (catalytic converter) is provided in an exhaust passage in which the catalytic converter and a DPF (diesel particulate filter) are arranged in a straight line.

Disclosure of Invention

However, the conventional exhaust gas treatment device disposed in the vicinity of the internal combustion engine is required to be equipped with a plurality of catalysts in order to meet exhaust emission regulations, and is required to be small in size due to a limitation of a mounting space, and further, an exhaust gas component passing through the catalyst must be measured with high accuracy, and it is difficult to configure an exhaust gas treatment device that satisfies these requirements.

The invention provides a small exhaust gas treatment device which can install a plurality of catalysts and can measure exhaust gas components with high precision.

According to a certain aspect of the present invention, an exhaust gas treatment device includes: a1 st catalyst carrier for purifying exhaust gas flowing in a1 st direction; a 2 nd catalyst carrier for purifying the exhaust gas that has passed through the 1 st catalyst carrier and flows in a 2 nd direction intersecting the 1 st direction; a housing for housing the 1 st catalyst carrier and the 2 nd catalyst carrier; and a sensor having a measurement unit for measuring an exhaust gas passing through the 1 st catalyst carrier, wherein the measurement unit is disposed in a region closer to the 2 nd catalyst carrier side than a center of the 1 st catalyst carrier, the region being surrounded by a downstream-side end surface of the 1 st catalyst carrier, an upstream-side end surface of the 2 nd catalyst carrier, and an inner wall surface of the housing which receives the exhaust gas passing through the 1 st catalyst carrier.

In the above aspect, the measurement portion of the sensor is located in a region on the 2 nd catalyst carrier side from the center of the 1 st catalyst carrier, which is surrounded by the downstream-side end surface of the 1 st catalyst carrier, the upstream-side end surface of the 2 nd catalyst carrier, and the inner wall surface of the housing. In the region where the measuring portion of the sensor is disposed, the exhaust gas passing through the 1 st catalyst carrier is made to collide against the inner wall surface of the housing and constitutes the main flow of the exhaust gas from the 1 st catalyst carrier to the 2 nd catalyst carrier, so that the flow velocity of the exhaust gas becomes fast. Therefore, by disposing the 1 st catalyst carrier and the 2 nd catalyst carrier so that the flow direction of the exhaust gas flowing through the 1 st catalyst carrier and the flow direction of the exhaust gas flowing through the 2 nd catalyst carrier intersect each other, the exhaust gas treatment device can be downsized while sufficiently ensuring the exhaust gas purification performance, and even in this configuration, the exhaust gas can be detected with high accuracy by the sensor for measuring the exhaust gas.

Drawings

Fig. 1 is a side view of an exhaust gas treatment device according to embodiment 1 of the present invention.

Fig. 2 is a rear view of an exhaust gas treatment device according to embodiment 1 of the present invention.

Fig. 3 is a sectional view taken along line iii-iii of fig. 1.

Fig. 4 is a sectional view taken along line IV-IV of fig. 1.

Fig. 5 is a sectional view taken along line V-V of fig. 2.

Fig. 6 is a sectional view taken along line VI-VI of fig. 1.

Fig. 7 is a partial perspective view illustrating a flow of exhaust gas within a housing of the exhaust gas treatment device.

Fig. 8 is a front view of an exhaust gas treatment device according to a modification of embodiment 1 of the present invention.

Fig. 9 is a sectional view taken along line IX-IX of fig. 8.

Fig. 10 is a side view of an exhaust gas treatment device according to a modification of embodiment 1 of the present invention.

Fig. 11 is a sectional view taken along line XI-XI of fig. 10.

Fig. 12 is a side cross-sectional view of an exhaust gas treatment device according to another modification of embodiment 1 of the present invention.

Fig. 13 is a diagram showing the result of simulation of the flow of the exhaust gas from the 1 st catalyst carrier toward the 2 nd catalyst carrier of the exhaust gas treatment device according to embodiment 1 of the present invention.

Fig. 14 is a diagram showing in table form the results of a simulation of the flow of exhaust gas from the 1 st catalyst carrier toward the 2 nd catalyst carrier in each variation of the exhaust gas treatment device.

Fig. 15A is a diagram showing the result of simulating the flow of the exhaust gas from the 1 st catalyst carrier toward the 2 nd catalyst carrier of the exhaust gas treatment device.

Fig. 15B is a diagram showing the result of simulating the flow of the exhaust gas from the 1 st catalyst carrier toward the 2 nd catalyst carrier of the exhaust gas treatment device.

Fig. 16 is a side cross-sectional view of an exhaust gas treatment device according to embodiment 2 of the present invention.

Fig. 17 is a perspective view of an exhaust gas treatment device according to a modification of embodiment 2.

Fig. 18 is a sectional view of an exhaust gas treatment device according to a modification of embodiment 2.

Fig. 19 is a cross-sectional view showing the flow of the exhaust gas in the exhaust gas treatment device according to the modification of embodiment 2.

Fig. 20 is a perspective view showing an exhaust gas treatment device according to another modification of embodiment 2 in a partial cross section.

Fig. 21 is a plan view partially in section showing a state in which a lower cover of an electrode cover for an electrically heated catalyst is attached to an electrode protruding from a case containing the electrically heated catalyst.

Fig. 22 is a perspective view showing a mounted state of the upper cover from which the electrode cover for the electrically heated catalyst is removed.

Fig. 23 is a perspective view showing a mounted state of an electrode cover for an electrically heated catalyst.

Fig. 24 is a plan view of a modification of the electrically heated catalyst electrode cover.

Fig. 25 is a sectional view taken along line XXV-XXV of fig. 24.

Fig. 26 is a front view of a modification of the electrically heated catalyst electrode cover.

Fig. 27 is a bottom view of a modified example of the electrode cover for electrically heated catalyst.

Fig. 28 is an enlarged cross-sectional view showing a main portion of a flow of fluid dropped to an upper cover of a modified example of the electrically heated catalyst electrode cover.

Detailed Description

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

(embodiment 1)

An exhaust gas treatment device 10 according to embodiment 1 of the present invention will be described with reference to fig. 1 to 7. Fig. 1 is a side view showing an exhaust gas treatment device 10 according to embodiment 1. Fig. 2 is a rear view of the exhaust gas treatment device 10. Fig. 3 is a sectional view of the exhaust gas treatment device 10 taken along the line III-III in fig. 1. Fig. 4 is a sectional view of the exhaust gas treatment device 10 taken along the line IV-IV in fig. 1. Fig. 5 is a sectional view of the exhaust gas treatment device 10 taken along the line V-V in fig. 2. Fig. 6 is a cross-sectional view of the exhaust gas treatment device 10 taken along the line VI-VI in fig. 1. Fig. 7 is a partial perspective view showing the flow of the exhaust gas G in the casing 30 of the exhaust gas treatment device 10.

The exhaust gas treatment device 10 is mounted on, for example, a vehicle and treats exhaust gas G discharged from an engine (not shown), and in the following embodiments, a configuration example is shown as a small-sized catalytic converter having excellent exhaust gas purification performance. Specifically, the exhaust gas treatment device 10 oxidizes hydrocarbons (hydrocarbons) and carbon monoxide contained in the exhaust gas G to carbon dioxide and water, and reduces nitrogen oxides and removes fine particulate matter, thereby purifying the exhaust gas G.

As shown in fig. 1 to 5, the exhaust gas treatment device 10 includes: a casing 30 having an inlet-side flange 11 connected to an exhaust outlet portion of an exhaust turbine (not shown) and an outlet-side flange 39 connected to an exhaust pipe (not shown) for guiding exhaust gas G to the outside; a TWC (Three-Way Catalyst)12, which is a1 st Catalyst carrier that purifies the exhaust gas G, disposed in the casing 30; a GPF (gasoline particulate filter) 14, which is a 2 nd catalyst carrier that is disposed on the downstream side of the TWC12 in the casing 30 and purifies the exhaust gas G that has passed through the TWC 12; and an air-fuel ratio sensor 40 for measuring the oxygen concentration of the exhaust gas G having passed through the TWC 12.

The housing 30 has: a Diffuser (Diffuser) portion 25 to which the inlet side flange 11 is attached; an inlet side tube portion 31 which accommodates the TWC12 therein; an intermediate cylinder 37 that is joined to the inlet-side cylinder 31 and accommodates the GPF14 therein; and an outlet side cylinder portion 38 having one end joined to the intermediate cylinder portion 37 and the other end provided with an outlet side flange 39 for connecting an exhaust side pipe line (not shown).

As shown in fig. 4 and 5, the diffuser portion 25 is formed by a conical diffusion plate 26 having a diameter gradually increasing toward the downstream. The inlet-side flange 11 is attached to the outer peripheral surface of the upstream-side opening 26a of the diffuser plate 26 by welding or the like. The downstream opening 26b of the diffuser plate 26 is attached to the inner peripheral surface of the inlet opening 31a of the inlet side tube 31 by welding or the like.

As shown in fig. 5, the inlet-side tube 31 has an inlet-side opening 31a through which the exhaust gas G flows in and an outlet-side opening 31b through which the exhaust gas G flows out. The inlet-side cylindrical portion 31 is configured to divert the flow of the exhaust gas G passing through the inlet-side cylindrical portion 31 at a predetermined angle (e.g., 90 °), that is, to form a substantially L-shaped flow path. The inlet-side tube portion 31 is formed by joining two metal plate-like members symmetrically formed in the flow direction of the exhaust gas G by welding or the like (see fig. 2 to 4).

As shown in fig. 6, the intermediate cylinder portion 37 is formed in an elliptical cylinder shape from a metal plate-like member. As shown in fig. 5, the outer peripheral surface of the inlet-side opening 37a of the intermediate tube portion 37 is joined to the inner peripheral surface of the outlet-side opening 31b of the inlet-side tube portion 31 by welding or the like. The outer peripheral surface of the outlet-side opening 37b of the intermediate cylindrical portion 37 is joined to the inner peripheral surface of the inlet-side opening 38a of the outlet-side cylindrical portion 38 by welding or the like.

The TWC12 is constituted by, for example, a cylindrical honeycomb structure. The outer peripheral surface 12a of the TWC12 is fitted to a metal cylindrical inner housing 20 via a cushion material 13. The TWC12 is housed in the inner housing 20 throughout the axial direction.

The upstream opening 20b of the inner case 20 is inserted into the inner periphery of the downstream opening 26b of the diffuser plate 26. The inner case 20 is fixed to the case 30 by being joined to the inner peripheral surface of the diffuser plate 26 by welding or the like. At this time, the inner housing 20 is provided in the housing 30 so as to provide a gap of a predetermined interval W between the outer peripheral surface 20a of the inner housing 20 and the inlet side cylindrical portion 31. The gap forms an outer peripheral flow path 35 through which the exhaust gas G flows. As shown in fig. 3, a plurality of spacers 34 for preventing the inner housing 20 from wobbling are provided between the outer peripheral surface 20a of the inner housing 20 and the inlet-side cylindrical portion 31.

In this way, the upstream side opening 20b of the inner housing 20 is joined to the downstream side opening 26b of the diffuser plate 26, whereby all the exhaust gas G flowing in from the exhaust inlet 11a of the inlet side flange 11 can be guided to the TWC 12.

The GPF14 is formed of, for example, an elliptic cylindrical ceramic filter for removing fine particulate matter (see fig. 4 and 6). The GPF14 is fixed in the intermediate tube 37 by fitting the outer peripheral surface 14a thereof to the inner peripheral surface of the intermediate tube 37 via the cushion material 15. Thus, the TWC12 and GPF14 are configured in a so-called T-shape in side view.

Further, the flow path sectional area of the GPF14 is formed larger than the flow path sectional area of the TWC 12. At this time, as shown in fig. 4, the GPF14 is provided in the intermediate cylinder 37 such that the major axis is positioned in the axial direction of the TWC 12. With this arrangement, for example, even when a space cannot be secured in the width direction (vertical direction in fig. 4) of the exhaust gas treatment device 10, the flow path cross-sectional area of the GPF14 can be secured.

The outlet-side cylinder 38 guides the exhaust gas G having passed through the GPF14 to an exhaust pipe (not shown) that discharges the exhaust gas G to the outside. The outlet-side tube portion 38 is formed by joining two metal plate-like members symmetrically formed in the flow direction of the exhaust gas G by welding or the like.

The air-fuel ratio sensor 40 has a rod-like member, and a measurement unit 41 for measuring the exhaust gas G is provided at the tip end thereof. The main body portion of the air-fuel ratio sensor 40 is attached from the outside of the housing 30 to the flat surface portion 31d provided on the inlet-side tube portion 31 in such a manner that the measurement portion 41 is positioned on the flow path between the TWC12 and the GPF 14. The detailed mounting position of the air-fuel ratio sensor 40 is explained in detail below.

Next, a more detailed structure of the inlet side tube portion 31 will be described. Further, hereinafter, the direction in which the exhaust gas G passes through the TWC12, that is, the axial direction of the TWC12 is referred to as "1 st direction P", and the direction in which the exhaust gas G passes through the GPF14, that is, the axial direction of the GPF14 is referred to as "2 nd direction Q" (refer to fig. 5). In the present embodiment, the case where the 1 st direction P and the 2 nd direction Q are orthogonal to each other is taken as an example, but the 1 st direction P and the 2 nd direction Q do not necessarily have to be orthogonal to each other as long as they intersect each other.

The inlet side tube portion 31 further includes: a branching section 33 that is provided on an inner wall surface 31c of the inlet-side tube section 31 for receiving the exhaust gas G that has passed through the TWC12, and that branches the exhaust gas G that has passed through the TWC12 so as to be partially guided to the GPF 14; and a guide unit 32 for guiding the exhaust gas G remaining after being branched by the branching unit 33 to the outer peripheral flow path 35.

The branched portion 33 is formed in a shape in which a part of the pipe wall on the outer side in the flow direction of the exhaust gas G in the inlet side cylindrical portion 31 protrudes in the inner radial direction. Preferably, the angle α formed by the top 33a of the bifurcation 33 is about 70 ° to 120 °. If the angle α is less than 70 °, the processing of the inlet side tube portion 31 becomes difficult. On the other hand, if the angle α is greater than 120 °, there is a risk that the flow rate of the exhaust gas G guided to the outer peripheral flow path 35 cannot be sufficiently ensured.

As shown in fig. 5, the guide portion 32 includes: an inclined portion 32a inclined by a predetermined angle θ from the branching portion 33 toward the downstream side in the 1 st direction P with respect to a plane X orthogonal to the 1 st direction P; and a curved portion 32b that guides the exhaust gas G that has passed through the inclined portion 32a to the outer peripheral flow path 35.

The inclined portion 32a is formed in a substantially planar shape, and an angle θ formed by a plane Y including the inclined portion 32a and the plane X is formed between 3 ° and 20 °. By setting the predetermined angle θ to such an angle, the exhaust gas G branched by the branching portion 33 can be smoothly guided to the curved portion 32b and can be guided to the outer peripheral flow path 35 along the inner wall surface 31c of the casing 30. This allows the exhaust gas G to be smoothly guided to the outer peripheral flow passage 35 without interfering with the flow of the exhaust gas G that passes through the TWC12 and is directed to the branch portion 33.

When the TWC12 and the GPF14 are viewed from a direction (see fig. 4, hereinafter also referred to as "3 rd direction R") orthogonal to the 1 st direction P and the 2 nd direction Q (the state shown in fig. 5), both ends of the TWC12 in the 1 st direction P are positioned between both ends of the GPF14 in the 1 st direction P (see fig. 4 and 5). Accordingly, the TWC12 does not protrude outward in the 1 st direction P from the GPF14, and therefore the exhaust gas treatment device 10 can be downsized.

Next, the flow of the exhaust gas G in the exhaust gas treatment device 10 will be explained.

As shown in fig. 5, the exhaust gas G flowing in from the exhaust inlet 11a of the inlet-side flange 11 is guided to the TWC12 via the diffuser portion 25. The hydrocarbon and carbon monoxide contained in the exhaust gas G flowing into the TWC12 are oxidized and decomposed into carbon dioxide and water, and nitrogen oxides are reduced.

The exhaust gas G having passed through the TWC12 is divided into a flow directly heading toward the upstream end surface 14b of the GPF14 and a flow heading toward the outer peripheral flow path 35 via the guide portion 32 by the branch portion 33 formed on the inner wall surface 31c of the inlet-side tube portion 31.

The flow directed toward the upstream end surface 14b of the GPF14 forms a main flow of the exhaust gas G, and the flow is directed to become approximately 90 ° by the branching portion 33 and directly flows into the upstream end surface 14b of the GPF14 without flowing to the outer peripheral flow passage 35.

The exhaust gas G flowing into the outer peripheral flow path 35 via the guide portion 32 flows along the outer peripheral surface 20a of the inner housing 20 toward the upstream end surface 14b of the GPF14 (see fig. 7). At this time, the exhaust gas G flowing through the outer peripheral flow passage 35 heats the TWC12 from the outer periphery via the inner casing 20. By guiding the exhaust gas G to the outer peripheral flow path 35 in this way, the temperature of the TWC12 can be increased in a short time immediately after the engine start, and thus the TWC12 can be activated. In particular, since the portion on the downstream side in the 1 st direction (the downstream side end surface 12c side) where the temperature of the TWC12 is hard to rise can be heated from the outer periphery, the time required for activating the TWC12 can be shortened.

The TWC12 is housed in an inner housing 20 extending in the 1 st direction P, the inner housing 20 being provided in the housing 30 and facing the inlet side tube portion 31 with an outer peripheral flow path 35 therebetween. Thus, the TWC12 is integrally provided in the inner casing 20, and the exhaust gas G flowing through the outer peripheral flow path 35 does not enter the TWC12, and the TWC12 is heated from the outer periphery. Thereby, the heat retaining effect of the TWC12 can be obtained, and the purification performance of the catalyst can be improved. Further, due to the double-pipe structure constituted by the casing 30 and the inner casing 20, heat escape to the outside of the casing 30 is effectively prevented, and the TWC12 is covered with the inner casing 20 to prevent the exhaust gas G flowing in the outer peripheral flow passage 35 from entering the TWC12, so there is also an effect that the flow passage resistance of the exhaust gas G from the outer peripheral flow passage 35 toward the GPF14 can be reduced. Further, since the exhaust gas G flowing through the outer peripheral flow passage 35 does not enter the TWC12, the flow of the exhaust gas G flowing through the TWC12 in the 1 st direction P is not obstructed. Further, since the TWC12 is integrally provided in the inner casing 20, the exhaust gas G that has flowed into the TWC12 passes through the entire region of the TWC12, and therefore, the exhaust gas G can be better purified. Thus, the overall length of the TWC12 may be shortened.

As described above, in the space 16 between the outer peripheral surface 20a of the inner housing 20 and the upstream end surface 14b of the GPF14 in the inlet side tube portion 31, the exhaust gas G having passed through the outer peripheral flow passage 35 merges with the flow branched by the branching portion 33 and directed toward the upstream end surface 14b of the GPF14, and flows into the GPF 14.

The exhaust gas G having flowed into the GPF14 is removed of fine particulate matter, and then is discharged to the exhaust pipe through the outlet-side cylinder 38.

Next, an exhaust gas treatment device 10' according to a modification will be described with reference to fig. 8 to 11. Fig. 8 is a front view of the exhaust gas treatment device 10'. Fig. 9 is a sectional view taken along line IX-IX in fig. 8. Fig. 10 is a side view of the exhaust gas treatment device 10', and fig. 11 is a sectional view taken along line XI-XI in fig. 10.

In the modification shown in fig. 8 to 11, the GPF 14' is formed in a cylindrical shape. As shown in fig. 9 and 10, in this modification, the lengths of the GPF14 ' and the intermediate cylinder 37 ' in the axial direction (1 st direction P) of the TWC12 are shortened, and therefore the exhaust gas treatment device 10 ' can be downsized correspondingly to this. As described above, if the GPF14 ' is formed in a cylindrical shape so that the flow path cross-sectional area of the GPF14 ' can be secured, the exhaust gas treatment device 10 ' can be downsized by such a configuration.

Next, an exhaust gas treatment device 110 according to another modification will be described with reference to fig. 12. Fig. 12 is a side cross-sectional view of an exhaust gas treatment device 10 according to another modification.

The modification shown in fig. 12 is an exhaust gas treatment device 110 in which the angle formed by the 1 st direction P and the 2 nd direction Q is an acute angle. In the modification shown in fig. 12, the GPF14 and the intermediate cylinder 37 may be disposed on the center side of the TWC12 in the axial direction (1 st direction P) of the TWC 12. Accordingly, the length of the TWC12 in the axial direction (the 1 st direction P) is shortened, and therefore the exhaust gas treatment device 10 can be downsized correspondingly.

Next, the detailed mounting position of the air-fuel ratio sensor 40 will be described with reference to fig. 13 and 14.

In the exhaust gas treatment device 10 of the present embodiment, the air-fuel ratio sensor 40 attached to the housing 30 is configured to: the measurement portion 41 included in the air-fuel ratio sensor 40 is located at a position where a region where the flow velocity of the exhaust gas G flowing along the shape of the inner wall surface 31c of the casing 30 is high is formed on the flow path between the TWC12 and the GDP 14 and the flow velocity of the exhaust gas G becomes higher in this region than in other regions.

Here, a more specific mounting position of the air-fuel ratio sensor 40 will be described with reference to fig. 13 and 14. Fig. 13 is a result of simulating the flow of the exhaust gas G from the TWC12 of the exhaust gas treatment device 10 toward the GPF 14. Fig. 13 shows the distribution of flow rates. Fig. 14 is a list of results of simulation of the flow of the exhaust gas G from the TWC12 to the GPF14 in the case where the models corresponding to the exhaust

gas treatment devices

10, 10', and 110 respectively have or do not have the bifurcation 33.

The dark portion and the white portion around the dark portion (region a) in the portion circled with the thick solid line in fig. 13 are portions where the flow rate is particularly fast. The region a as the 2 nd region is located on the downstream side of the branch portion 33 and extends in the tangential direction D of the top portion 33a that protrudes most in the 1 st direction P of the branch portion 33.

Therefore, in the exhaust gas treatment device 10, the air-fuel ratio sensor 40 is attached to the inlet-side tube portion 31 such that the measurement portion 41 is located in the region a. Thus, the oxygen concentration of the exhaust gas G having passed through the TWC12 is measured with high accuracy by the air-fuel ratio sensor 40. Such an air-fuel ratio sensor 40 may be inserted and fixed to the housing 30 at any angle as long as the above-described measuring portion 41 is located in the region a. The air-fuel ratio sensor 40 may be disposed obliquely to the TWC12, or may be disposed obliquely to the GPF 14. However, the air-fuel ratio sensor 40 is preferably disposed along the flow direction of the exhaust gas G, and the measurement unit 41 is preferably disposed toward the gravity direction lower side so as to prevent water droplets and the like from adhering to the measurement unit 41. In the configuration shown in fig. 5 and the like, when the 2 nd direction Q is the vertical direction (up-down direction), the measurement unit 41 is preferably disposed so as to face the GPF 14.

In a case where space is limited and a space for installing the flat surface portion 31d of the air-fuel ratio sensor 40 in the inlet-side cylindrical portion 31 cannot be secured (for example, in a case where the inlet-side cylindrical portion 31 is formed near the joint portion 31e or near the curved surface portion of the inlet-side cylindrical portion 31), the air-fuel ratio sensor 40 may be installed in the inlet-side cylindrical portion 31 such that the measurement portion 41 of the air-fuel ratio sensor 40 is located in the region a1 (the region indicated by the thick broken line in fig. 13 and 14) which is the 1 st region where the flow velocity of the exhaust gas G is high. That is, the measurement unit 41 of the air-fuel ratio sensor 40 is preferably disposed in a region where the flow velocity of the exhaust gas G is high, except for a region where the flow velocity of the exhaust gas G is the slowest, in the space between the TWC12 and the GPF 14. However, the present invention is not limited to this, and the measurement unit 41 of the air-fuel ratio sensor 40 may be disposed in a region where the sensor sensitivity can be secured (for example, a peripheral region near a region where the flow velocity is the fastest, or the like) in consideration of, for example, restrictions on the fixing position of the main body portion of the air-fuel ratio sensor 40, the installation space, and the like.

The region a1 is a region surrounded by the downstream end surface 12c of the TWC12, the upstream end surface 14b of the GPF14, and the inner wall surface 31c of the inlet-side tube portion 31 that receives the exhaust gas G that has passed through the TWC12, and is set closer to the GPF14 side than the center of the TWC 12. The center of the TWC12 is a region of a plane including the center line O of the TWC12 in the 3 rd direction R. In the region a1, since the flow of the exhaust gas G from the TWC12 toward the GPF14 constitutes the main flow, the flow velocity of the exhaust gas G becomes faster. Therefore, by attaching the air-fuel ratio sensor 40 to the inlet-side tube portion 31 so that the measurement portion 41 is positioned in the region a1, the oxygen concentration of the exhaust gas G that has passed through the TWC12 can be accurately measured. In the present embodiment, the region a1 is a flow path (space) of the exhaust gas G that is substantially surrounded by the downstream end surface 12c of the TWC12, the upstream end surface 14b of the GPF14, and the inner wall surface 31c that receives the exhaust gas G (the inner wall surface of the casing 30 that faces the downstream end surface 12c of the TWC12) and flows toward the GPF14 through the exhaust gas G of the TWC12, and more specifically, a flow path that extends toward the upstream end surface 14b of the GPF14 along the planar direction of the downstream end surface 12c of the TWC12 from the space between the lower end surface on the GPF14 side of the downstream end surface 12c of the TWC12 and the inner wall surface 31c of the casing 30. The inner wall surface 31c of the casing 30 is a wall surface facing the downstream end surface 12c of the TWC12, and may include a wall surface extending to the GPF14 side, and the wall surface may be constituted by, for example, only a flat surface or a flat surface and a deformed surface.

Further, since the boss is easily formed at a position avoiding the engaging portion 31e, the air-fuel ratio sensor 40 can be mounted at such a position.

Referring to fig. 15A and 15B, a more specific mounting position of the air-fuel ratio sensor 40 will be described.

Fig. 15A and 15B are the results of simulation of the flow of the exhaust gas G on a cross section along the XV-XV line of fig. 1. In addition, case one, case two, and case three in fig. 15A and 15B are results of simulations in which the engine speed is sequentially low, medium, and high. Fig. 15A is a simulation result of the case where the air-fuel ratio sensor 40 is attached to the position shown in fig. 4, and fig. 15B is a simulation result of the case where the air-fuel ratio sensor 40 is attached to the opposite side of the position shown in fig. 4 with the joint portion 31e interposed therebetween.

As is clear from fig. 15A and 15B, even if the center position in the 3 rd direction R of the inlet side tube portion 31 is deviated, there is a region where the flow velocity of the exhaust gas G is high, that is, a region a 1. Therefore, even when the air-fuel ratio sensor 40 cannot be attached to the center position in the 3 rd direction R of the inlet-side tube portion 31 due to the presence of the joint portion 31e, for example, the oxygen concentration of the exhaust gas G that has passed through the TWC12 can be measured with high accuracy by attaching the air-fuel ratio sensor 40 to the inlet-side tube portion 31 so that the measurement portion 41 is located in the region a 1.

According to embodiment 1 above, the following effects can be obtained.

In the exhaust gas treatment device 10 of the present embodiment, in order to improve the purification performance of the exhaust gas G, the two catalysts (specifically, the TWC12 and the GPF14) are arranged so as to overlap each other to achieve downsizing, the exhaust gas G having passed through the TWC12 is made to collide against the inner wall of the casing 30, the speed (flow velocity) of the main flow of the exhaust gas G flowing toward the GPF14 is increased, and the air-fuel ratio sensor 40 is provided so that the measurement section 41 of the air-fuel ratio sensor 40 is positioned in the region a or the region a1 where the flow velocity of the exhaust gas G between the TWC12 and the GPF14 is high, whereby the air-fuel ratio sensor 40 for measuring the exhaust gas G can detect the value with high accuracy, and the exhaust gas treatment device can be realized which is small and has excellent exhaust gas purification performance.

Further, in the exhaust gas treatment device 10, when the TWC12 and the GPF14 are viewed from the direction orthogonal to the 1 st direction P and the 2 nd direction Q, both ends of the TWC12 in the 1 st direction P are located between both ends of the GPF14 in the 1 st direction P. Accordingly, the TWC12 does not protrude from the GPF14 to the outside in the 1 st direction P, and therefore, the exhaust gas treatment device 10 can be downsized. Further, even in the case where the heater (or the catalyst with a heater) is provided on the upstream side of the TWC12 in the 1 st direction P, the amount of protrusion of the heater (or the catalyst with a heater) in the 1 st direction P can be reduced. That is, in the present embodiment, the exhaust gas treatment device 10 may further include a heater that heats the exhaust gas G on the upstream side of the TWC12, and with this configuration, the TWC12 can be heated using the exhaust gas G as a medium, and the exhaust gas treatment device can exhibit excellent exhaust gas purification performance in a situation such as at the time of engine start. Further, by arranging the TWC12 so as to overlap the GPF14 in the 1 st direction P, even if the TWC12 is configured to slightly protrude from the GPF14, an exhaust gas treatment device that is small in size as a whole and has excellent exhaust gas purification performance can be realized.

(embodiment 2)

Referring to fig. 16, an exhaust gas treatment device 210 according to embodiment 2 of the present invention will be described. Fig. 16 is a side cross-sectional view of the exhaust gas treatment device 210, which corresponds to a cross-section taken along the line V-V in fig. 2. Hereinafter, the differences from embodiment 1 will be mainly described, and the same components as those of the exhaust gas treatment device 10 according to embodiment 1 will be denoted by the same reference numerals and their descriptions will be omitted. In fig. 16, the inlet-side flange 11, the diffuser portion 25, and the outlet-side cylindrical portion 38 are not shown.

The embodiment 2 is different from the embodiment 1 in that it includes an EHC (electrically heated catalyst) 250. Specifically, the exhaust gas treatment device 210 further includes an EHC250 for purifying the exhaust gas G on the upstream side of the TWC 212 for purifying the exhaust gas G. In the exhaust gas treatment device 210, a flat surface portion 231d is provided in the vicinity of the branch portion 233, and the air-fuel ratio sensor 40 is attached to the flat surface portion 231 d. This can effectively prevent water droplets and the like from adhering to the measurement portion 41 of the air-fuel ratio sensor 40 in the casing 30.

The EHC250 includes: a heater portion 251 having

electrodes

252a, 252 b; and an electrode support 253 that is formed of a honeycomb structure and supports the heater portion 251 and the

electrodes

252a and 252 b.

The heater portion 251 is a heater that generates heat by the current applied to the

electrodes

252a and 252b, and has, for example, a spiral shape. The heater portion 251 holds the

electrodes

252a and 252b in the extended cylinder portion 236 by welding the

electrodes

252a and 252b to the extended cylinder portion 236, which is fixed to the outer peripheral surface 20a of the inner housing 20 by welding.

The outer peripheral surface 253a of the electrode support 253 holds the electrode support 253 in the inner case 20 via the buffer material 215 so as to be positioned on the upstream side of the TWC 12.

A plurality of pins 254 for maintaining the interval between the heater portion 251 and the electrode supporter 253 and for holding the heater portion 251 and the

electrodes

252a and 252b are provided between the heater portion 251 and the electrode supporter 253. The plurality of pins 254 are disposed between the heater portion 251 and the electrode supporter 253 so as to be inserted into the heater portion 251 and the electrode supporter 253, respectively.

In the exhaust gas treatment device 210, at the time of cold start (cold start) at the time of engine start, current is caused to flow to the heater portion 251 through the

electrodes

252a and 252b, whereby the temperature of the exhaust gas G flowing in the extension cylinder portion 236 is heated to 200 to 300 ℃, and the TWC 212 is heated by the heated exhaust gas G. This enables the catalyst component of the TWC 212 to reach the activation temperature in a short time. In this way, in the exhaust gas treatment device 210, the catalyst component of the TWC 212 can be activated in a short time, and therefore, the purification performance at the time of engine start can be improved.

Further, as shown in fig. 16, in the exhaust gas treatment device 210, when the TWC 212 and the GPF14 are viewed from the 3 rd direction R, both ends of the TWC 212 in the 1 st direction P are located between both ends of the GPF14 in the 1 st direction P. Thereby, even in a case where a space for installing the exhaust gas treatment device 210 is limited, a space for installing the EHC250 can be secured. In other words, the above configuration can suppress an increase in size of the exhaust gas treatment device 210.

In the above embodiment, the configuration in which one heater portion 251 is provided has been described as an example, but a plurality of heater portions 251 may be provided in the exhaust gas treatment device 210.

According to embodiment 2 above, the following effects can be obtained.

Since the EHC250 is provided in the exhaust gas treatment device 210, the catalyst component of the TWC 212 can be activated in a short time. This can improve the purification performance at the time of engine start.

In the exhaust gas treatment device 210, when the TWC 212 and the GPF14 are viewed from the 3 rd direction R, both ends of the TWC 212 in the 1 st direction P are located between both ends of the GPF14 in the 1 st direction P. Thereby, even in a case where a space for installing the exhaust gas treatment device 210 is limited, a space for installing the EHC250 can be secured. In addition, the EHC250 may not be provided when there is a restriction on a space for installing the exhaust gas treatment device 210. For example, the TWC 212 or the GPF14 may be directly heated by providing a metal layer on the outer peripheral surface of the TWC 212 or the GPF14 and applying electric current from the outside. This saves the space for installing the EHC250, and activates the catalyst component in a short time by heating the TWC 212 or the GPF 14. In this case, the TWC 212 or the GPF14 may be made of, for example, a honeycomb-shaped carrier having conductivity, and may be made of a metal or a ceramic as long as the material is provided with conductivity (forms a current path).

Next, an exhaust gas treatment device 310 as a1 st modification of the exhaust gas treatment device 210 will be described with reference to fig. 17 to 19.

Fig. 17 is a perspective view showing an exhaust gas treatment device 310 according to modification 1, fig. 18 is a sectional view of the exhaust gas treatment device 310, and fig. 19 is a sectional view showing a flow of exhaust gas in a casing of the exhaust gas treatment device 310.

As shown in fig. 19, the exhaust gas treatment device 310 includes: a pair of

TWCs

323 and 325 for flowing the exhaust gas G in the 1 st direction P and purifying the exhaust gas G; a1 st Electrically Heated Catalyst (EHC)322 and a 2 nd Electrically Heated Catalyst (EHC)324 for flowing the exhaust gas G in the 1 st direction P and purifying the exhaust gas G; a1 st inner tube 320 for holding an EHC 322 and an EHC 324; a 2 nd three-way catalyst (TWC)337 as a 2 nd catalyst carrier for allowing the exhaust gas G to flow in the 2 nd direction Q and purifying the exhaust gas having passed through the pair of

TWCs

323, 325; and a1 st outer tube 330 and a 2 nd outer tube 336 as housings for housing the EHC 322 and the EHC 324, the pair of

TWCs

323, 325, and the TWC 337.

Specifically, as shown in fig. 17 to 19, the exhaust gas treatment device 310 includes: a metal inlet pipe 311 that is positioned on the upstream side of the exhaust passage on the exhaust turbine side of the turbocharger and is attached to an inlet-side flange, not shown; a metal diffusion pipe 312; a1 st inner tube 320 as a metallic and cylindrical inner housing and a 2 nd inner tube 321 as a metallic and cylindrical inner housing; a1 st outer tube 330 as a metal shell covering the 1 st and 2 nd

inner tubes

320 and 321; a 2 nd outer tube 336 as a metallic and cylindrical case; and a metal outlet pipe 339.

As shown in fig. 17 and 18, the inlet pipe 311 has: an inlet-side pipe portion 311a formed in a conical stepped surface shape with a diameter gradually decreasing; and an outlet-side pipe portion 311b formed in a flat elliptic cylindrical shape from the inlet-side pipe portion 311 a. Further, the diffuser pipe 312 has: an inlet-side pipe portion 312a formed in a flat elliptic cylindrical shape; an outlet-side pipe portion 312b which is rotated by 90 ° with respect to the inlet-side pipe portion 312a and is formed in a large-diameter cylindrical shape; and an inclined curved surface portion 312c formed between the inlet-side pipe portion 312a and the outlet-side pipe portion 312b, and deflecting the exhaust gas G entering from the inlet pipe 311 by 90 ° to flow toward the 1 st inner pipe 320 side. Further, an end of the outlet-side pipe portion 311b of the inlet pipe 311 is fitted into and welded to the inlet-side pipe portion 312a of the diffuser pipe 312.

As shown in fig. 18, an end portion of the outlet side pipe portion 312b of the diffuser pipe 312 is fitted into and welded to the inlet side open end portion 320a of the 1 st inner pipe 320, which is made of metal and cylindrical. The outlet-side open end 320b of the 1 st inner tube 320 is fitted into and welded to the inlet-side open end 321a of the 2 nd inner tube 321, which is made of metal and cylindrical. The outlet-side open end 321b of the 2 nd inner pipe 321 is formed to have a diameter slightly larger than that of the inlet-side open end 321 a.

The 1 st inner tube 320 contains and holds a1 st electrically heated catalyst 322 in a disc shape whose activity is increased by heating the electrically heated catalyst carrier 322a for purifying the exhaust gas G by allowing the electric current flowing from the + electrode 322c to the-electrode 322d to flow through the electrically heated catalyst carrier 322 a. Further, a cylindrical 1 st three-way catalyst (TWC)323 for purifying the exhaust gas G is housed and held in the center of the 1 st inner tube 320. Further, the 2 nd electrically heated catalyst 324 having a disk shape is housed and held in the 1 st inner tube 320 on the side of the outlet-side open end 320b (downstream side), and the 2 nd electrically heated catalyst 324 heats the electrically heated catalyst carrier 324a for purifying the exhaust gas G by flowing a current from the + electrode 324c to the-electrode 324d, thereby increasing the activity. The gaps S1 insulate the 1 st electrically heated catalyst 322 and the 1 st three-way catalyst 323, and the gaps S1 between the 1 st three-way catalyst 323 and the 2 nd electrically heated catalyst 324 from each other.

Further, a cylindrical 1 st three-way catalyst (TWC)325 serving as a TWC for purifying the exhaust gas G is accommodated and held in the downstream 2 nd inner pipe 321 by a cylindrical cushion 326. That is, the 1 st electrically heated catalyst 322, the 1 st (upstream) third-way catalyst 323, the 2 nd electrically heated catalyst 324, and the 1 st (downstream) third-way catalyst 325 are provided in this order from the upstream side of the exhaust passage of the pipe member constituted by the 1 st inner pipe 320 and the 2 nd inner pipe 321. Thus, the 2 nd electrically heated catalyst 324 is provided between the pair of 1 st three-

way catalysts

323, 325.

As shown in fig. 17, the metal 1 st outer tube 330 is formed by dividing it into left and right parts, and is formed in a cylindrical shape having an L-shaped side surface by overlapping and fusion-welding the central parts 330a to each other. In detail, as shown in fig. 17 and 18, the 1 st outer tube 330 has: a cylindrical small-diameter tube portion 331 extending to the vicinity of the inlet-side open end portion 320a of the 1 st inner tube 320 and welded to the outer peripheral surface 320c of the 1 st inner tube 320; a large-diameter tube portion 332 extending downstream from the small-diameter tube portion 331 and forming an outer peripheral flow path 335 through which the exhaust gas G flows, with a gap S2 interposed between the center of the outer peripheral surface 320c of the 1 st inner tube 320 and the outlet-side open end 321b of the outer peripheral surface 321c of the 2 nd inner tube 321; an inclined curved surface part 333 that guides a part of the exhaust gas G having passed through the pair of 1 st three-way catalysts 323, 325 to the outer peripheral flow path 335, and that deflects the remaining exhaust gas G having passed through the pair of 1 st three-way catalysts 323, 325 toward a cylindrical 2 nd three-way catalyst (TWC)337 as a 2 nd catalyst carrier described later; and an outlet-side cylindrical portion 334 having a large diameter, which is fitted around and welded to an inlet-side opening end portion 336a of a 2 nd outer tube 336 to be described later. The large-diameter outlet-side cylindrical portion 334 is provided at a position rotated by 90 ° with respect to the small-diameter cylindrical portion 331.

As shown in fig. 18 and 19, the large diameter cylindrical portion 332 of the 1 st outer pipe 330 extends substantially parallel to the outer peripheral surface 320c of the 1 st inner pipe 320 and the outer peripheral surface 321c of the 2 nd inner pipe 321 to form a double-layer structure (so-called double pipe structure), and an outer peripheral flow passage 335 is formed between the outer peripheral surface 320c of the 1 st inner pipe 320 and the outer peripheral surface 321c of the 2 nd inner pipe 321. The outer peripheral flow path 335 communicates with the entire circumference of the gap S3 from the downstream end face 325a of the 1 st three-way catalyst 325 on the downstream side to the outlet-side cylindrical portion 334 through which the main flow of exhaust gas G flows, and extends cylindrically upstream of the main flow of exhaust gas in the opposite direction from the position of the downstream end face 325a of the 1 st three-way catalyst 325.

As shown in fig. 18 and 19, the surfaces (front surfaces) of the outer

peripheral surfaces

320c and 321c of the 1 st and 2 nd

inner tubes

320 and 321 that do not form the outer peripheral flow path 335 are positioned at positions facing the upstream end surface 337a of the 2 nd three-way catalyst 337, as will be described later, with a gap S4 therebetween, and the 1 st and 2 nd three-

way catalysts

325 and 337 on the downstream side are arranged in a so-called T-shape, and a part of the exhaust gas G that has passed through the pair of 1 st and 2 nd three-

way catalysts

323 and 325 circulates through the outer peripheral flow path 335 and flows into the upstream end surface 337a of the 2 nd three-way catalyst 337. That is, a part of the exhaust gas G having passed through the pair of 1 st three-

way catalysts

323, 325 is guided to the outer peripheral flow channel 335 along the upper side of the inclined curved surface portion 333. Further, the main flow of the exhaust gas G having passed through the pair of 1 st three-

way catalysts

323, 325 turns around substantially 90 ° in the gap S3 below the inclined curved surface portion 333 through which the main flow of the exhaust gas flows, and flows directly into the upstream end surface 337a of the 2 nd three-way catalyst 337 without circulating to the outer circumferential flow path 335.

As shown in fig. 18, the 2 nd outer tube 336 is formed in a cylindrical shape made of metal, and a cylindrical 2 nd three-way catalyst (TWC)337 as a 2 nd catalyst carrier is accommodated and held in the inside thereof via a cylindrical buffer material 338. Further, an outlet-side opening end 336b of the 2 nd outer pipe 336 is fusion-welded to the large-diameter cylindrical portion 339a of the metal outlet pipe 339. Further, a small-diameter cylindrical portion 339b of an outlet pipe 339 is fusion-welded to the outlet-side flange 340.

Further, as shown in fig. 17 to 19, the + electrode 322c and the-electrode 322d protruding from the outer peripheral surface 322b of the electrically heated catalyst carrier 322a of the 1 st electrically heated catalyst 322 penetrate the 1 st inner tube 320 and the 1 st outer tube 330 to protrude to the outside. Further, the + electrode 324c and the-electrode 324d protruding from the outer peripheral surface 324b of the electrically heated catalyst carrier 324a of the 2 nd electrically heated catalyst 324 penetrate the 1 st inner tube 320 and the 1 st outer tube 330 to protrude to the outside.

According to the above exhaust gas treatment device 310, at the time of cold start (cold start) at the time of engine start, until the temperature of the exhaust gas G flowing in from the inlet pipe 311 reaches 200 to 300 ℃, electric current from the +

electrodes

322c, 324c to the-

electrodes

322d, 324d flows through the respective electrically

heated catalyst carriers

322a, 324a of the 1 st and 2 nd electrically

heated catalysts

322, 324 to heat the respective electrically

heated catalyst carriers

322a, 324a, respectively. By this heat generation, the catalyst components of the electrically

heated catalyst carriers

322a and 324a reach the activation temperature in a short time. That is, the catalyst components of the electrically heated catalyst supports 322a and 324a can be activated in a very short time, and the catalyst temperature raising performance at the time of cold start can be greatly improved.

As shown in fig. 19, the exhaust gas G having passed through the pair of 1 st three-

way catalysts

323, 325 is guided along the curved shape below the inclined curved surface portion 333 of the 1 st outer tube 330 to the upstream end surface 337a of the downstream 2 nd three-way catalyst 337, and passes through the 2 nd three-way catalyst 337 to go from the large-diameter cylindrical portion 339a to the small-diameter cylindrical portion 339b of the outlet tube 339.

On the other hand, a part of the exhaust gas G having passed through the pair of 1 st three-

way catalysts

323, 325 returns to the outer circumferential flow path 335 in the opposite direction along the curved shape above the inclined curved surface portion 333 of the 1 st outer tube 330, flows through the outer circumferential flow path 335 in the circumferential direction, and is directed from the side of the gap S4 between the 2 nd inner tube 321 and the 2 nd three-way catalyst 337 toward the upstream end surface 337a of the 2 nd three-way catalyst 337. That is, a part of the exhaust gas G having passed through the pair of 1 st three-

way catalysts

323, 325 circulates in the outer peripheral flow path 335 and flows into the 2 nd three-way catalyst 337, and the remaining exhaust gas G having passed through the pair of 1 st three-

way catalysts

323, 325 directly flows into the 2 nd three-way catalyst 337 without passing through the outer peripheral flow path 335.

In this way, the exhaust gas G can sufficiently flow into the outer peripheral flow path 335 along the outer

peripheral surfaces

320c and 321c of the 1 st inner tube 320 and the 2 nd inner tube 321, which are the tube members, and a part of the exhaust gas G having passed through the pair of 1 st three-

way catalysts

323 and 325 flows along the curved shape of the inclined curved surface portion 333 of the 1 st outer tube 330, thereby heating the pair of 1 st three-

way catalysts

323 and 325 from the surroundings. Therefore, after the engine is started, for example, the temperature of the pair of 1 st three-

way catalysts

323, 325 rises at an early stage, and rapid activation of the catalysts is achieved. In particular, since the downstream side portion of the 1 st three-way catalyst 325 on the downstream side is heated from the surroundings, it contributes to the temperature rise of the 1 st three-way catalyst 325.

Further, the front side surface of the outer peripheral surface 321c of the 2 nd inner pipe 321, which does not form the outer peripheral flow path 335, is positioned at a position facing the upstream side end surface 337a of the 2 nd three-way catalyst 337 housed and fitted in the 2 nd outer pipe 336 by the gap S4, the downstream side end surface 325a of the 1 st three-way catalyst 325 and the upstream side end surface 337a of the 2 nd three-way catalyst 337 on the downstream side are arranged in a T-shape, and a part of the exhaust gas G having passed through the 1 st three-way catalyst 325 is circulated in the outer peripheral flow path 335 and flows into the downstream side end surface 325a of the 1 st three-way catalyst 325, whereby the space required for arranging the catalysts can be saved.

In the 1 st modification, the small diameter cylindrical portion 331 of the 1 st outer tube 330 (housing) is welded to the 1 st inner tube 320 (inner housing) at a portion on the upstream side of the 1 st electric heating catalyst 322 and avoiding the outer periphery of the 1 st electric heating catalyst 322, but the small diameter cylindrical portion 331 of the 1 st outer tube 330 and the 1 st inner tube 320 may be welded to the first inner tube 320 at a portion on the downstream side of the 1 st electric heating catalyst 322 and avoiding the outer periphery of the 1 st electric heating catalyst 322.

In addition, in the 1 st modification example, the 1 st electrically heated catalyst 322 and the 2 nd electrically heated catalyst 324 are provided so as to sandwich the TWC 323 on the upstream side, but the 2 nd electrically heated catalyst 324 may be omitted, or the 3 rd electrically heated catalyst may be further provided on the downstream side of the 2 nd electrically heated catalyst 324.

In addition, in the 1 st modification example, the inner case for holding the 1 st electrically heated catalyst 322 and the like is formed by the 1 st inner tube 320 and the 2 nd inner tube 321, but the inner case may be formed by one inner tube.

Further, in the 1 st modification example, the gap is provided between the 2 nd electrically heated catalyst 324 and the downstream TWC 325, but the 2 nd electrically heated catalyst 324 and the downstream TWC 325 may be provided in contact with each other without a gap.

Further, in modification 1, the TWC (three-way catalyst) 325 is used as the 2 nd catalyst carrier, but a Gasoline Particulate Filter (GPF), a Diesel Particulate Filter (DPF), or the like may be used.

Next, an exhaust gas treatment device 410 as a 2 nd modification of the exhaust gas treatment device 210 will be described with reference to fig. 20. Fig. 20 is a perspective view showing an exhaust gas treatment device 410 according to modification 2 in a partial cross section.

The exhaust gas treatment device 410 is a device in the form of an Electrically Heated Catalyst (EHC) disposed under the floor of a vehicle, and has a catalyst housing 51 of one-layer structure. That is, the catalyst case 51 includes: a metal front housing 52 having a cylindrical shape on the inlet side (upstream side) of the exhaust gas G and a conical surface shape with a gradually increasing diameter on the downstream side; a metal middle case 53 which is cylindrical and fusion-welded to the downstream end side of the front case 52; and a rear case 54 made of metal, which is fusion-welded to the downstream end of the middle case 53, and has a conical surface shape with a gradually decreasing diameter on the upstream side and a cylindrical shape on the outlet side (downstream side) of the exhaust gas G.

As shown in fig. 20, a columnar adsorbent 55 holding hydrocarbons that temporarily adsorb (capture) the exhaust gas G is accommodated in the front housing 52 side of the middle housing 53 via a cylindrical buffer 56.

Further, the center of the middle case 53 accommodates and holds a disk-shaped Electrically Heated Catalyst (EHC)57 whose activity is increased by flowing electric power flowing from the + electrode 57c to the-electrode 57d through an electrically heated catalyst carrier 57a for purifying the exhaust gas G.

Further, the rear case 54 side of the middle case 53 accommodates a cylindrical three-way catalyst (TWC)58 as a catalyst carrier for purifying the exhaust gas G, which is held by a cylindrical cushion member 59.

Further, the + electrode 57c and the-electrode 57d protruding from the outer peripheral surface 57b of the electrically heated catalyst carrier 57a of the electrically heated catalyst 57 penetrate the middle case 53 to protrude to the outside.

In the exhaust gas treatment device 410 of this modification, the concentration of the hydrocarbon component in the exhaust gas G tends to increase because the three-way catalyst 58 does not fully function during the start from the engine cold state. At this time, when hydrocarbons are once adsorbed on the adsorbent 55 and the three-way catalyst 58 is warmed and activated, the hydrocarbons are treated and discharged. Therefore, strict exhaust emission control can be met.

At the time of cold start of the engine, the electric current from the + electrode 57c to the-electrode 57d is caused to flow through the electrically heated catalyst carrier 57a of the electrically heated catalyst 57 to heat the electrically heated catalyst carrier 57a until the temperature of the exhaust gas G flowing in from the front case 52 reaches 200 to 300 ℃. The catalyst component of the electrically heated catalyst carrier 57a can be brought to the activation temperature in a short time by the heat generation.

Next, the electrically heated catalyst electrode cover 60 will be described with reference to fig. 21 to 23.

Fig. 21 is a plan view, partially in section, showing a state in which the lower cover 61 of the electrically heated catalyst electrode cover 60 is attached to the electrode 72 protruding from the metal case 70 containing the electrically heated catalyst, fig. 22 is a perspective view showing an attached state of the upper cover 65 with the electrically heated catalyst electrode cover 60 removed, and fig. 23 is a perspective view showing an attached state of the electrically heated catalyst electrode cover 60.

As shown in fig. 21 to 23, the electrically heated catalyst electrode cover 60 is a member for covering an electrode 72 that protrudes from a metal case 70 that houses an electrically heated catalyst 71 and is exposed to the outside, and that allows electric current to flow through the electrically heated catalyst 71. The electrically heated catalyst electrode cover 60 includes: a metal lower cover 61 for covering the lower side of the electrode 72; and a metal upper cover 65 for covering the upper side of the electrode 72. The electrically heated catalyst electrode cover 60 is a member used to cover the + electrodes 22c, 24c, 22d, and 24d of the exhaust gas treatment device 310 and the +

electrode

57c, and 57d of the exhaust gas treatment device 410, and thus has a function of preventing electric shock to the case body and the electrodes.

The lower cover 61 and the upper cover 65 each have:

concave electrode holders

62, 66 for covering the electrode 72; and concave

wire housing portions

63 and 67 for housing the distal end side of the insulating film 81 of the harness (harness)80 for supplying power to the electrode 72, and the

electrode housing portions

62 and 66 and the

wire housing portions

63 and 67 are formed in an L shape.

Circular holes 64 and 68 serving as openings of heat dissipation passages are formed in the electrode housing portion 62 of the lower cover 61 and the electrode housing portion 65 of the upper cover 65 at positions on the tip side of the electrode 72. The hole 64 of the lower cover 61 is formed to have a larger diameter than the hole 68 of the upper cover 65 and a hole 69, which is an opening portion of a passage for heat dissipation, formed between the lower cover 61 and the upper cover 65, which will be described later. The heat radiation passage broadly means a passage for communicating the portion of the screw portion 72a of the electrode 72 as the heat source and the outside air. That is, the heat radiation passage is constituted by the space in which the electrode 72 is covered with the electrode housing portion 62 of the lower cover 61 and the electrode housing portion 66 of the upper cover 65, and the

holes

64, 68, and 69 serving as openings for opening the space to the outside air. The

holes

64, 68, and 69 are provided at positions facing a screw fastening portion of a nut 86 for fixing the relay terminal 85 by screwing (screwing) the screw portion 72a of the electrode 72 to a screw portion 72a of the nut 86, which will be described later.

As shown in fig. 23, the

flat end edges

62a, 66a on the

electrode receiving portions

62, 66 side of the lower cover 61 and the upper cover 65 are joined to the

flat end edges

63a, 67a, 63b, 67b on the

wire receiving portions

63, 67 side of the lower cover 61 and the upper cover 65 by caulking (calking). A circular hole 69 serving as an opening of a heat radiation passage is formed between the joined lower cover 61 and upper cover 65.

Further, as shown in fig. 22, a metal sleeve 73 is fitted into the center of the electrode 72, and a screw portion 72a is formed on the tip end side of the electrode 72 exposed from the sleeve 73. The screw portion 72a is fastened and fixed by a nut 86 to an annular distal end portion 85b of an L-shaped relay terminal 85, which is press-fitted and fixed to the core wire 82 exposed at the distal end side of the insulating film 81 of the wire harness 80. Further, heat insulating sheets 75 are interposed between the sleeve 73 and the concave

electrode receiving portions

62 and 66 of the lower cover 61 and the upper cover 65, and between the base end portion 85a of the relay terminal 85 and the concave

wire receiving portions

63 and 67 of the lower cover 61 and the upper cover 65, respectively.

A cylindrical wall portion 70a is integrally formed so as to protrude from the periphery of the case 70 where the electrode 72 is exposed, so that the electrically heated catalyst electrode cover 60 does not contact the metal case 70.

According to the electrically heated catalyst electrode cover 60, the lower cover 61 and the upper cover 65 constituting the electrically heated catalyst electrode cover 60 have the three

hole portions

64, 68, and 69 serving as openings of a plurality of heat radiation passages, whereby heat generated from the electrodes 72 protruding to the outside from the case 70 containing the electrically heated catalyst 71 can be radiated to the outside, and the heat can be prevented from being collected between the concave electrode receiving portion 62 of the lower cover 61 and the concave electrode receiving portion 66 of the upper cover 65.

That is, the heat transferred to the electrode 72 by the heat transfer can be released downward to the outside through the hole portion 64 formed in the lower cover 61, and in addition, water, dust, and the like can be released to the outside. Further, the heat transferred to the electrode 72 by the heat transfer can be released upward to the outside through the hole portion 68 formed in the upper cover 65. Further, the heat transferred to the electrode 72 by the heat transfer can be released to the outside to the side through the hole 69 formed by the lower cover 61 and the upper cover 65, and in addition, the screwing and fastening state of the screw portion 72a of the electrode 72 and the nut 86 for fixing the annular distal end portion 85b of the relay terminal 85 can be confirmed.

Further, since the outer periphery of the electrode 72 is thermally insulated by the thermal insulation structure of the thermal insulation sheet 75 provided inside the lower cover 61 and the upper cover 65, heat is transferred to the tip end portion of the electrode 72 (the protruding portion of the screw portion 72 a), the concave

electrode housing portions

62 and 66 are provided in the lower cover 61 and the upper cover 65 so as to cover the tip end portion of the electrode 72, and the heat is released therefrom, and further, the heat is radiated from the hole portions (through holes) 64, 68, and 69, which are the opening portions of the heat radiation passage, to the outside air. Since the hole 64 and the like face the distal end portion of the electrode 72 in this manner, the fastening portion (screw fastening portion) of the electrode 72 located inside the

hole

64, 68, 69 can be easily visually recognized.

Further, the heat insulating sheet 75 is interposed between the sleeve and the concave

electrode housing portions

62 and 66 of the lower cover 61 and the upper cover 65, and between the concave

wire housing portions

63 and 67 of the lower cover 61 and the upper cover 65 and the base end portion 85a of the relay terminal 85, respectively, thereby insulating heat radiation from the exhaust pipe (exhaust) member.

In the electrically heated catalyst electrode cover 60, three hole portions (through holes) 64, 68, 69, which are openings of a heat radiation passage, are provided between the lower cover 61 and the upper cover 65. The hole 69 may be set to a size (outer diameter) at which the screw portion 72a of the electrode 72 can be nut-fastened after the upper and lower side covers 65 and 61 are fastened, or may be set to a size at which the screw portion 72a of the electrode 72 can be confirmed to be nut-fastened.

In the electrode cover 60 for an electrically heated catalyst, the heat insulating sheet 75 is provided inside the space between the upper and

lower covers

65 and 61, but the heat insulating sheet 75 may not be provided, and in this case, a layer (insulating layer) made of an insulating material may be provided on the inner surfaces of the upper and lower side covers 65 and 61 instead of the heat insulating sheet 74. That is, an insulating layer made of an insulating material may be provided on the inner surfaces of the upper and lower side covers 65 and 61 opposed to the electrode 72 (portions other than the surfaces joined to the upper and lower side covers 65 and 61), or an insulating coating may be applied to the entire opposed inner surfaces of the upper and lower side covers 65 and 61 including the joint surfaces where the upper side cover 65 and the lower side cover 61 are joined. Further, the insulating coating is preferably formed of a material having heat resistance.

Next, an electrically heated catalyst electrode cover 60' as a modification of the electrically heated catalyst electrode cover 60 will be described with reference to fig. 24 to 28.

Fig. 24 is a plan view of the electrically heated catalyst electrode cover 60 ', fig. 25 is a sectional view taken along line XXV-XXV of fig. 24, fig. 26 is a front view of the electrically heated catalyst electrode cover 60 ', fig. 27 is a bottom view of the electrically heated catalyst electrode cover 60 ', and fig. 28 is an enlarged sectional view of a main portion showing a flow of fluid dropped onto the upper cover 65 ' of the electrically heated catalyst electrode cover 60 '.

As shown in fig. 24 to 28, similarly to the electrically heated catalyst electrode cover 60, the electrically heated catalyst electrode cover 60' is an electrode 72 for covering the metal case 70 containing the electrically heated catalyst 71 so as to protrude and be exposed to the outside, and for allowing an electric current to flow through the electrically heated catalyst 71, and includes: a metal lower cover 61' for covering the lower side of the electrode 72; and an upper cover 65' made of metal for covering the upper side of the electrode 72.

As shown in fig. 25, the base end portion 65a of the lower cover 61 'and the base end portion 65a of the upper cover 65' are arranged to be inserted into a cylindrical wall portion 70a of the housing 70 that houses the electrically heated catalyst 71. The middle portion 61b of the lower cover 61 'is formed to rise in a step shape, and the middle portion 65b of the upper cover 65' is formed to fall in a step shape. Further, the distal end portion 65c of the upper cover 65 'is formed in a curved shape in an eaves shape (shade shape) so as to cover the distal end portion 61c of the lower cover 61' with a space therebetween.

As shown in fig. 25 and 27, a space between the eave-shaped front end portion 65c of the upper cover 65 'and the front end portion 61c of the lower cover 61' and a space covering the electrode 72 with the electrode receiving portion 62 of the lower cover 61 'and the electrode receiving portion 66 of the upper cover 65' serves as a passage S for heat dissipation connecting a portion of the screw portion 72a of the electrode 72 and the outside air. As shown in fig. 27, a plurality of circular small hole portions 64a serving as openings of heat dissipation passages are provided in the lower cover 61' at positions where the heat insulating sheet 75 is not provided. Further, as shown in fig. 27, a part of the flat end edge portion 66a of the lower cover 61 ' of the upper cover 65 ' on the electrode receiving portion 66 side and a part of the flat

end edge portions

67a and 67b of the lower cover 61 ' of the upper cover 65 ' on the wire receiving portion 67 side are bent toward the lower cover 61 ' side and then joined by press working.

According to the electrically heated catalyst electrode cover 60 'of embodiment 4, as shown in fig. 28, even if a fluid such as oil O or water W drips from the cylindrical wall portion 70a of the case 70 onto the upper cover 65', the fluid flows from the upper cover 65 'to the outside through the intermediate portion 65b formed in the upper cover 65' so as to descend in a stepped manner. At this time, since the base end portion 65a of the upper cover 65' is disposed so as to be inserted into the cylindrical wall portion 70a of the housing 70, it is possible to reliably prevent the fluid such as the oil O and the water W from entering the housing 70 through the cylindrical wall portion 70 a. Further, since the distal end portion 65c of the upper cover 65 'is formed in a curved shape in an eaves shape so as to cover the distal end portion 61c of the lower cover 61', it is possible to reliably prevent the fluid such as the oil O or the water W from entering the space between the concave electrode receiving portion 62 of the lower cover 61 'and the concave electrode receiving portion 66 of the upper cover 65' from the heat radiation passage S.

Further, the heat transferred to the electrode 72 can be laterally released to the outside by the heat radiation passage S constituted by the space between the eave-shaped front end portion 65c of the upper cover 65 'and the front end portion 61c of the lower cover 61' and the space covering the electrode 72 with the electrode receiving portion 62 of the lower cover 61 'and the electrode receiving portion 66 of the upper cover 65'. Further, the heat transferred to the electrode 72 by the heat transfer can be released downward to the outside through the plurality of small hole portions 64a formed in the lower cover 61', and in addition, water, dust, and the like can be released to the outside.

The structure, operation, and effects of the embodiments of the present invention configured as described above will be collectively described.

The exhaust

gas treatment device

10, 10', 110, 210 includes: a1 st catalyst carrier (TWC12) for purifying exhaust gas G flowing in a1 st direction P; a 2 nd catalyst carrier (GPF14) for purifying the exhaust gas G that has passed through the 1 st catalyst carrier (TWC12) and flows in a 2 nd direction Q intersecting the 1 st direction P; a casing 30 for housing a1 st catalyst carrier (TWC12) and a 2 nd catalyst carrier (GPF 14); and a sensor (air-fuel ratio sensor 40) having a measuring portion 41 that measures the exhaust gas G, for measuring the exhaust gas G that has passed through the 1 st catalyst carrier (TWC 12). The measurement portion 41 included in the sensor (air-fuel ratio sensor 40) is disposed in a region (region a1) on the 2 nd catalyst carrier (GPF14) side from the center of the 1 st catalyst carrier (TWC12), which is surrounded by the downstream-side end surface 12c of the 1 st catalyst carrier (TWC12), the upstream-side end surface 14b of the 2 nd catalyst carrier (GPF14), and the inner wall surface 31c of the casing 30 that receives the exhaust gas G that has passed through the 1 st catalyst carrier (TWC 12).

According to this structure, the measurement portion 41 of the sensor (air-fuel ratio sensor 40) is located in a region (region a1) on the 2 nd catalyst carrier (GPF14) side from the center of the 1 st catalyst carrier (TWC12), which is surrounded by the downstream-side end surface 12c of the 1 st catalyst carrier (TWC12), the upstream-side end surface 14b of the 2 nd catalyst carrier (GPF14), and the inner wall surface 31c of the housing 30. In this region (region a1), the main flow of the exhaust gas G from the 1 st catalyst carrier (TWC12) to the 2 nd catalyst carrier (GPF14) is constituted, and therefore the flow velocity of the exhaust gas G becomes high. Therefore, in the case where the flow direction of the exhaust gas G flowing through the 1 st catalyst carrier (TWC12) and the flow direction of the exhaust gas G flowing through the 2 nd catalyst carrier (GPF14) intersect, it is possible to realize highly accurate numerical value detection by the sensor (air-fuel ratio sensor 40) that measures the exhaust gas G. Therefore, it is possible to provide a small exhaust

gas treatment device

10, 10', 110, 210 in which a plurality of catalysts are mounted and exhaust gas components can be measured with high accuracy.

Further, even when the inflow condition of the exhaust gas G flowing into the exhaust gas treatment device 10 changes depending on the number of cylinders of the engine, the mounting of the turbocharger, or the like, or depending on the driving state of the engine, for example, the measurement of the exhaust gas G by the sensor (the air-fuel ratio sensor 40) can be performed with high accuracy and stability by forming an exhaust gas flow path (a flow path which is a main flow and has a flow velocity faster than other portions) flowing toward the 2 nd catalyst carrier (GPF14) side while the exhaust gas G having passed through the 1 st catalyst carrier (TWC12) is made to collide with the inner wall surface 31c of the housing 30. That is, the exhaust gas treatment device 10 can be realized that can be adapted to various engine specifications and changes in engine driving conditions.

The casing 30 has a branching portion 33 that branches off the exhaust gas G that has passed through the 1 st catalyst carrier (TWC12) and guides a part of the exhaust gas G to the 2 nd catalyst carrier (GPF14), and the measurement portion 41 is disposed in a region (region a) where the flow velocity of the exhaust gas G that is branched off by the branching portion 33 and guided to the 2 nd catalyst carrier (GPF14) is increased.

Further, the housing 30 has a diverging portion 33 that is provided on the inner wall surface 31c and that diverges so as to guide a part of the exhaust gas G that has passed through the 1 st catalyst carrier (TWC12) to the 2 nd catalyst carrier (GPF 14). The measurement unit 41 is disposed in a region (region a) where the exhaust gas G branched by the branching unit 33 and flowing to the 2 nd catalyst carrier (GPF14) flows in the tangential direction D of the crest portion 33a projecting most in the 1 st direction P in the branching unit 33.

In these structures, a part of the exhaust gas G that has passed through the 1 st catalyst carrier (TWC12) collides with the diverging portion 33 formed on the inner wall surface 31c of the housing 30, turns in the tangential direction D of the top portion 33a of the diverging portion 33, and flows toward the 2 nd catalyst carrier (GPF 14). In the region (region a) where the exhaust gas G flowing toward the 2 nd catalyst carrier (GPF14) flows, the exhaust gas G that has collided with the bifurcation 33 and has been turned is guided, and therefore the flow velocity of the exhaust gas G is also high in the region a 1. Therefore, by providing the sensor (air-fuel ratio sensor 40) in the region a, the sensor (air-fuel ratio sensor 40) for measuring the exhaust gas G can detect the value with high accuracy. In the above embodiment, the configuration in which the manifold 33 is provided in the housing 30 has been described, but the manifold 33 may not be provided, and only the flow velocity of the exhaust gas G flowing toward the 2 nd catalyst carrier (GPF14) side may be adjusted by the shape of the inner wall surface 31c of the housing 30, for example.

Further, the main body portion of the sensor (air-fuel ratio sensor 40) is attached to the flat surface portion 31d provided in the housing 30 from the outside of the housing 30.

According to this configuration, since the boss is more easily formed on the flat surface portion 31d provided on the housing 30 than the curved surface portion, the boss for mounting the sensor (air-fuel ratio sensor 40) can be easily formed.

The housing 30 has a joint portion 31e where the plate-like members are joined to each other, and the sensor (air-fuel ratio sensor 40) is attached at a position avoiding the joint portion 31 e.

According to this configuration, since it is not easy to form a boss on the joining portion 31e of the plate-like member, it is possible to easily form a boss for mounting the sensor (air-fuel ratio sensor 40) by avoiding the joining portion 31 e. Further, by disposing a sensor (air-fuel ratio sensor 40) at a portion avoiding the joint portion 31e of one of the plate-like members of the split case 30, the strength of the joint portion 31e can be ensured.

Further, when the 1 st catalyst carrier (TWC12) and the 2 nd catalyst carrier (GPF14) are viewed from the direction orthogonal to the 1 st direction P and the 2 nd direction Q, both ends of the 1 st catalyst carrier (TWC12) in the 1 st direction P are located between both ends of the 2 nd catalyst carrier (GPF14) in the 1 st direction P.

According to this structure, the 1 st catalyst carrier (TWC12) does not protrude from the 2 nd catalyst carrier (GPF14) to the outside in the 1 st direction P, and therefore, the exhaust gas treatment device 10 can be downsized. Further, even in the case where the heater or the catalyst with a heater is provided on the upstream side of the 1 st catalyst carrier (TWC12) in the 1 st direction P, the amount of protrusion of the heater or the catalyst with a heater in the 1 st direction P can be reduced.

Further, the housing 30 has: a cylindrical portion (inlet side cylindrical portion 31) having an outer peripheral flow path 35 formed between the outer peripheral surface of the 1 st catalyst carrier (TWC12) and the cylindrical portion, through which the exhaust gas G flows; a branching section 33 formed on the inner wall surface 31c and branching off the exhaust gas G that has passed through the 1 st catalyst carrier (TWC12) so as to be partially guided to the 2 nd catalyst carrier (GPF 14); and a guide unit 32 for guiding the remaining exhaust gas G branched by the branching unit 33 to the outer peripheral flow path 35.

According to this configuration, the remaining exhaust gas G not guided to the 2 nd catalyst carrier (GPF14) of the exhaust gas G branched by the branching portion 33 is guided to the outer peripheral flow passage 35, flows in the outer peripheral flow passage 35 in the circumferential direction, and is directed to the 2 nd catalyst carrier (GPF 14). At this time, the exhaust gas G guided to the outer peripheral flow passage 35 heats the 1 st catalyst carrier (TWC12) from the outer periphery. Therefore, immediately after the engine is started, the temperature of the 1 st catalyst carrier (TWC12) is increased in a short time, and the activation of the 1 st catalyst carrier (TWC12) can be achieved. In particular, the downstream side portion in the 1 st direction P, at which the temperature of the 1 st catalyst carrier (TWC12) is heated from the outer periphery, is less likely to rise, whereby the time required for activating the entire 1 st catalyst carrier (TWC12) can be shortened.

The guide portion 32 has an inclined portion 32a inclined at a predetermined angle θ from the branching portion 33 to the downstream side in the 1 st direction P with respect to the plane X orthogonal to the 1 st direction P.

According to this configuration, the guide portion 32 has the inclined portion 32a inclined from the branch portion 33 toward the downstream side in the 1 st direction P. By providing the inclined portion 32a, the exhaust gas G branched by the branching portion 33 can be smoothly diverted and guided to the outer peripheral flow path 35 along the inner wall surface 31c of the casing 30. Therefore, the exhaust gas G can be guided to the peripheral flow path 35 without obstructing the flow of the exhaust gas G that passes through the 1 st catalyst carrier (TWC12) and is directed toward the branch portion 33.

Further, the housing 30 has: a cylindrical portion (inlet side cylindrical portion 31) of an outer peripheral flow path 35 through which exhaust gas G flows is formed between the outer peripheral surface 12a of a1 st catalyst carrier (TWC12), the 1 st catalyst carrier (TWC12) is housed in an inner housing 20 throughout the 1 st direction P, and the inner housing 20 is provided in the housing 30 and opposed to the cylindrical portion (inlet side cylindrical portion 31) with the outer peripheral flow path 35 therebetween.

According to this structure, by providing the inner casing 20, the exhaust gas G flowing through the outer peripheral flow path 35 is heated from the outer periphery of the 1 st catalyst carrier (TWC12) without entering the inside of the 1 st catalyst carrier (TWC 12). Therefore, the flow path resistance of the exhaust gas G from the outer peripheral flow path 35 toward the 2 nd catalyst carrier (GPF14) can be reduced. Further, since the exhaust gas G flowing through the outer peripheral flow path 35 does not enter the 1 st catalyst carrier (TWC12), the flow of the exhaust gas G flowing through the 1 st catalyst carrier (TWC12) in the 1 st direction P is not obstructed. In the above-described embodiment, the double pipe structure in which the 1 st catalyst carrier (TWC12) covered with the inner casing 20 is disposed in the casing 30 is employed, but the present invention is not limited to this, and for example, two catalysts may be disposed directly in one casing. That is, the present invention also includes the following structure: the 1 st catalyst and the 2 nd catalyst are arranged in one casing, only a flow path for guiding the exhaust gas G having passed through the 1 st catalyst to the 2 nd catalyst is provided, and a casing wall surface which constitutes the flow path and receives the exhaust gas G flowing out of the 1 st catalyst is designed in a shape (shape of the casing 30 shown in fig. 16) such that the casing wall surface is partially separated from the 1 st catalyst, whereby a region having a high flow velocity is created in the flow path of the exhaust gas G, and a detection point (contact point of the exhaust gas G) of the sensor (air-fuel ratio sensor 40) is provided in the region.

Although the embodiments of the present invention have been described above, the above embodiments are merely some 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.

In the above embodiment, the air-fuel ratio sensor 40 was described as an example, but other sensors for measuring the value of the exhaust gas G may be applied as the sensor.

The position where the flat surface portion 231d is provided may be any position as long as the measurement portion 41 is located in the region a1 or the region a when the air-fuel ratio sensor 40 is attached.

The application claims priority based on the application of the patent application 2019-.

Claims

1. An exhaust gas treatment device comprising:

a1 st catalyst carrier for purifying exhaust gas flowing in a1 st direction;

a 2 nd catalyst carrier for purifying the exhaust gas that has passed through the 1 st catalyst carrier and flows in a 2 nd direction intersecting the 1 st direction;

a housing for housing the 1 st catalyst carrier and the 2 nd catalyst carrier; and

a sensor having a measuring section for measuring an exhaust gas, which measures the exhaust gas passing through the 1 st catalyst carrier,

the measurement unit of the sensor is disposed in a region closer to the 2 nd catalyst carrier side than the center of the 1 st catalyst carrier, the region being surrounded by a downstream-side end face of the 1 st catalyst carrier, an upstream-side end face of the 2 nd catalyst carrier, and an inner wall face of the housing that receives the exhaust gas that has passed through the 1 st catalyst carrier.

2. The exhaust gas treatment device according to claim 1,

the housing has a diverging portion that is provided on the inner wall surface and that diverges so as to guide a part of the exhaust gas that has passed through the 1 st catalyst carrier to the 2 nd catalyst carrier,

the measurement portion is disposed in a region in which the exhaust gas branched by the branching portion and flowing toward the 2 nd catalyst carrier flows in a tangential direction of a top portion that protrudes most in the 1 st direction in the branching portion.

3. The exhaust gas treatment device according to claim 1 or 2,

the body portion of the sensor is attached to a flat surface portion provided in the housing from the outside of the housing.

4. The exhaust gas treatment device according to any one of claims 1 to 3,

the housing has an engaging portion where the plate-like members are engaged in abutment,

the sensor is mounted at a position avoiding the joint portion.

5. The exhaust gas treatment device according to any one of claims 1 to 4,

when the 1 st catalyst carrier and the 2 nd catalyst carrier are viewed from a direction orthogonal to the 1 st direction and the 2 nd direction, both ends of the 1 st catalyst carrier in the 1 st direction are positioned between both ends of the 2 nd catalyst carrier in the 1 st direction.

6. The exhaust gas treatment device according to any one of claims 1 to 5,

the housing has:

a cylindrical portion forming an outer peripheral flow path through which exhaust gas flows between the cylindrical portion and an outer peripheral surface of the 1 st catalyst carrier;

a branching portion formed on the inner wall surface and configured to branch off a part of the exhaust gas that has passed through the 1 st catalyst carrier so as to be guided to the 2 nd catalyst carrier; and

and a guide portion that guides the remaining exhaust gas branched by the branch portion to the outer peripheral flow path.

7. The exhaust gas treatment device according to claim 6,

the guide portion has an inclined portion inclined at a predetermined angle from the branching portion to a downstream side in the 1 st direction with respect to a plane orthogonal to the 1 st direction.

8. The exhaust gas treatment device according to any one of claims 1 to 7,

the housing has: a cylindrical portion forming an outer peripheral flow path through which exhaust gas flows with an outer peripheral surface of the 1 st catalyst carrier,

the 1 st catalyst carrier is housed in an inner case extending through the entire 1 st direction, and the inner case is provided in the case and opposed to the cylindrical portion with the outer peripheral flow path therebetween.

9. The exhaust gas treatment device according to any one of claims 1 to 8, further comprising:

a1 st electrically heated catalyst housed in the housing, configured to flow exhaust gas in the 1 st direction and purify the exhaust gas; and

an inner housing for holding the 1 st electrically heated catalyst and the 1 st catalyst carrier,

the housing is welded to the inner housing at a position on a downstream side or an upstream side of the 1 st electrically heated catalyst and avoiding an outer periphery of the 1 st electrically heated catalyst.

10. The exhaust gas treatment device according to claim 9,

the shell and the outer peripheral surface of the inner shell are separated by a gap and provided with an outer peripheral flow path for tail gas to flow.

11. The exhaust gas treatment device of claim 10, further comprising:

the 2 nd electrically heats the catalyst,

the outer circumferential flow path is formed so as to surround respective outer circumferences of the 2 nd electrically heated catalyst and the 1 st catalyst carrier.

12. The exhaust gas treatment device according to claim 11,

the 2 nd electrically heated catalyst is disposed between a pair of the 1 st catalyst carriers.

13. The exhaust gas treatment device according to any one of claims 9 to 12, further comprising:

an electrode cover for an electrically heated catalyst for covering an electrode protruding from the housing to the outside and supplying power to the 1 st electrically heated catalyst.

14. The exhaust gas treatment device according to claim 13,

the electrode cover for the electrically heated catalyst has a lower cover for covering the lower side of the electrode and an upper cover for covering the upper side of the electrode,

and a heat insulating sheet interposed between the electrode and the lower and upper covers.

15. The exhaust gas treatment device according to claim 14,

the lower cover and the upper cover each have: an electrode housing portion for covering the electrode; and an electric wire housing portion for housing a distal end side of a wire harness for supplying electric power to the electrode,

the electrode housing portion and the wire housing portion are formed in an L-shape.

16. The exhaust gas treatment device according to claim 14,

the lower cover has a hole portion formed at a predetermined position as an opening of a heat dissipation passage.

17. The exhaust gas treatment device according to claim 14,

the lower cover and the upper cover are formed with hole portions as openings of heat dissipation passages at respective portions, and a hole portion as an opening of a heat dissipation passage is formed between the lower cover and the upper cover, and the hole portion formed in the lower cover is formed to have a larger hole diameter than the other hole portions.

18. The exhaust gas treatment device according to claim 17,

the hole portion, which is an opening portion of the heat dissipation passage, is provided at a portion facing the screw portion of the electrode and a screw fastening portion of a nut screwed to the screw portion to fix the relay terminal.

19. The exhaust gas treatment device according to claim 13,

at least a base end portion of the upper cover out of the lower cover and the upper cover is disposed so as to be inserted into a cylindrical wall portion of the housing,

the middle part of the upper cover is formed to descend in a stepped shape,

the front end of the upper cover is bent to cover the front end of the lower cover to form an eaves shape.

20. The exhaust gas treatment device of claim 19,

the lower cover is provided with a plurality of small hole portions serving as openings of heat dissipation passages at positions where the heat insulating sheet is not provided.