AU2020286337B2

AU2020286337B2 - Exhaust gas purification apparatus

Info

Publication number: AU2020286337B2
Application number: AU2020286337A
Authority: AU
Inventors: Sho Fukuda; Koji Momose
Original assignee: Toyota Industries Corp
Current assignee: Toyota Industries Corp
Priority date: 2020-01-28
Filing date: 2020-12-11
Publication date: 2022-03-31
Anticipated expiration: 2040-12-11
Also published as: JP7327182B2; AU2020286337A1; CN113250791B; CN113250791A; JP2021116762A; DE102021101631A1

Abstract

OF THE DISCLOSURE An exhaust gas purification apparatus configured to purify exhaust gas discharged from an internal combustion engine includes an exhaust passage 5 connected to the internal combustion engine, a fuel-additive valve configured to inject fuel toward the exhaust passage, an internal wall having a cylindrical shape and forming an injection passage that communicates with the exhaust passage and through which the fuel injected from fuel-additive valve passes, and an external wall disposed radially outside the internal wall and cooperating with the 10 internal wall to form an introduction path. The introduction path is configured to introduce the exhaust gas flowing in the exhaust passage into a region of the injection passage on aside close to the fuel-additive valve. The introduction path extends along a circumference of the internal wall. 1/12 CO c',

Description

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EXHAUST GAS PURIFICATION APPARATUS BACKGROUND ART

The present invention relates to an exhaust gas purification apparatus.

As conventional exhaust gas purification apparatuses, a technique disclosed in Japanese Patent Application Publication No. 2009-115057 is known. The exhaust gas purification apparatus disclosed in the above Patent Application Publication includes an exhaust pipe connected to an end of an engine turbocharger on a downstream side of exhaust gas, an oxidation catalyst, an NOx storage catalyst, and a diesel particulate filter (DPF) that are provided inside the exhaust pipe, and a fuel-additive injector (a fuel-additive valve) disposed at a junction section of the exhaust pipe via a support for supplying fuel as an additive to the oxidation catalyst. The support includes, inside thereof, an injection passage through which the fuel injected from the fuel-additive injector passes. The exhaust gas purification apparatus includes a gas flowing-in pipe that connects the support to the exhaust pipe. One end of the gas flowing-in pipe is connected to a gas flowing-in port formed at a position of the injection passage on a side close to the fuel-additive injector. The other end of the gas flowing-in pipe is connected to the junction section of the exhaust pipe.

In the above conventional art, the exhaust gas flows from inside of the exhaust pipe through the gas flowing-in pipe into the injection passage, which reduces a likelihood of the fuel adhering to a wall surface of the injection passage. However, a flow of the exhaust gas may deviate after the exhaust gas is introduced from the gas flowing-in pipe into the injection passage, which may disturb a flow of fuel spray injected from the fuel-additive injector. The disturbed flow of the fuel spray may swirl about and adhere to an injection port of the fuel additive injector, which may cause deposits on the injection port.

The present invention is directed to providing an exhaust gas purification apparatus that reduces adhesion of fuel spray to a fuel-additive valve.

SUMMARY

In accordance with an aspect of the present invention, there is provided an exhaust gas purification apparatus configured to purify exhaust gas discharged from an internal combustion engine. The exhaust gas purification apparatus includes an exhaust passage connected to the internal combustion engine, a fuel additive valve configured to inject fuel toward the exhaust passage, an internal wall having a cylindrical shape and forming an injection passage that communicates with the exhaust passage and through which the fuel injected from the fuel-additive valve passes, and an external wall disposed radially outside the internal wall and cooperating with the internal wall to form an introduction path. The introduction path is configured to introduce the exhaust gas flowing in the exhaust passage into a region of the injection passage on a side close to the fuel additive valve. The introduction path extends along a circumference of the internal wall.

Other aspects and advantages of the disclosure will become apparent from the following description, taken in conjunction with the accompanying drawings, illustrating by way of example the principles of the disclosure.

BRIEF DESCRIPTION OF THE DRAWINGS

The disclosure, together with objects and advantages thereof, may best be understood by reference to the following description of the embodiments together with the accompanying drawings in which:

FIG. 1 is a schematic configuration diagram of an exhaust gas purification apparatus according to a first embodiment of the present invention;

FIG. 2 is a cross-sectional view of a main section of the exhaust gas purification apparatus according to the first embodiment of the present invention;

FIG. 3 is a diagram of the main section of the exhaust gas purification apparatus taken along a line III-III of FIG. 2, indicated with flows of exhaust gas by arrows;

FIG. 4 is a cross-sectional view of the main section of the exhaust gas purification apparatus, indicated with the flows of the exhaust gas in response to fuel injected from a fuel-additive valve shown in FIG. 2;

FIG. 5 is a cross-sectional view of a main section of an exhaust gas purification apparatus as a comparative example;

FIG. 6 is a cross-sectional view of a main section of an exhaust gas purification apparatus according to a second embodiment of the present invention;

FIG. 7 is a diagram of the main section of the exhaust gas purification apparatus taken along a line VII-VII of FIG. 6, indicated with flows of exhaust gas by arrows;

FIG. 8 is a cross-sectional view of the main section of the exhaust gas purification apparatus, indicated with the flows of the exhaust gas in response to fuel injected from a fuel-additive valve shown in FIG. 6;

FIG. 9 is a cross-sectional view of a main section of an exhaust gas purification apparatus according to a third embodiment of the present invention;

FIG. 10 is a cross-sectional view of the main section of the exhaust gas purification apparatus, illustrating a state in which an internal wall and an external wall shown in FIG. 9 are to be assembled;

FIG. 11 is a diagram of the main section of the exhaust gas purification apparatus taken along a line XI-XI of FIG. 9, indicated with flows of exhaust gas by arrows; and

FIG. 12 is a cross-sectional view of the main section of the exhaust gas purification apparatus, indicated the flows of the exhaust gas in response to fuel injected from a fuel-additive valve shown in FIG. 9.

DETAILED DESCRIPTION OF THE EMBODIMENTS

Embodiments of the present invention will now be described in detail with reference to the accompanying drawings. In the description of the embodiments below, descriptions of components identical to those of the previously described embodiment or embodiments will be omitted or simplified by providing the identical reference numerals.

FIG. 1 is a schematic configuration diagram of an exhaust gas purification apparatus according to a first embodiment of the present invention. Referring to FIG. 1, an exhaust gas purification apparatus 1 of the first embodiment is mounted on a vehicle. The exhaust gas purification apparatus 1 purifies exhaust gas discharged from a diesel engine 2 that serves as an internal combustion engine. The diesel engine 2 includes a plurality of injectors configured to inject engine fuel into a plurality of cylinders, respectively, although they are not shown.

The exhaust gas purification apparatus 1 includes an exhaust pipe 3 connected to the diesel engine 2. The exhaust pipe 3 includes an exhaust passage 4 through which the exhaust gas flows. The exhaust passage 4 is thus connected to the diesel engine 2.

The exhaust gas purification apparatus 1 also includes a diesel oxidation catalyst (DOC) 5 and a diesel particulate filter (DPF) 6 that are disposed in the order from upstream to downstream in the exhaust passage 4. The DOC 5 is configured to oxidize and remove particulate matter (PM) contained in the exhaust gas. The DPF 6 collects the PM contained in the exhaust gas.

The exhaust gas purification apparatus 1 further includes a fuel-additive valve 7 disposed at a position between the diesel engine 2 and the DOC 5 in the exhaust passage 4. The fuel-additive valve 7 is configured to inject and add fuel toward the exhaust passage 4. The fuel-additive valve 7 has at a bottom end thereof an injection port 7a through which the fuel is injected in a conical form toward the exhaust passage 4 (see FIG. 2). The fuel added by the fuel-additive valve 7 is mainly used as a reducing agent for recycling the DPF 6.

FIG. 2 is a cross-sectional view of a main section of the exhaust gas purification apparatus according to the first embodiment. Referring to FIG. 2, the exhaust gas purification apparatus 1 includes an internal wall 8 that has a cylindrical shape, and an external wall 9 that is disposed radially outside the internal wall 8. Bottom ends of the internal wall 8 and the external wall 9 are fixed to the exhaust pipe 3. An upper end of the external wall 9 is at a position higher than an upper end of the internal wall 8.

The internal wall 8 is configured to protruded from the exhaust pipe 3 towards the fuel-additive valve 7. The internal wall 8 forms an injection passage 10 through which the fuel injected from the fuel-additive valve 7 passes (see FIG. 4). The injection passage 10 communicates with the exhaust passage 4.

The external wall 9 is disposed radially outside the internal wall 8, upstream of the exhaust passage 4 (on a side close to the diesel engine 2). Referring to FIG. 3, the external wall 9 has a substantially arched shape. The external wall 9 includes at the upper end thereof an extending section 11 extending toward the internal wall 8.

The external wall 9 cooperates with the internal wall 8 to form an introduction path 12 that is configured to introduce the exhaust gas flowing in the exhaust passage 4 into a region of the injection passage 10 on a side close to the fuel-additive valve 7. The introduction path 12 communicates with the exhaust passage 4. The introduction path 12 extends along a circumference of the internal wall 8. A communicating port 13 through which the introduction path 12 communicates with the injection passage 10 is formed in a region above the internal wall 8 on a side close to the external wall 9.

A connection wall 14 having a semicircular shape is formed in a region above the internal wall 8 on a side opposite to the external wall 9. An upper end of the connection wall 14 is at a position identical to a position of the upper end of the external wall 9 in a height direction. The fuel-additive valve 7 is attached on the upper ends of the connection wall 14 and the external wall 9. The external wall 9, the internal wall 8, and the connection wall 14 are integrally formed with the exhaust pipe 3, by, for example, casting.

Referring to FIG. 4, a pressure in an upper region (Region X shown in FIG. 4) of the injection passage 10 decreases in response to a flow generated by the fuel injection from the fuel-additive valve 7 during the fuel injection. This generates both an upward flow of the exhaust gas through the injection passage 10 (indicated by Direction A in FIG. 4) and an upward flow of the exhaust gas through the introduction path 12 (indicated by Direction B in FIG. 4).

A width of the introduction path 12 is determined such that the upward flow of the exhaust gas through the introduction path 12 overcomes the upward flow of the exhaust gas through the injection passage 10. The width of the introduction path 12 refers to a maximum length of the introduction path 12 in a radial direction of the internal wall 8. The upward flow of the exhaust gas through the introduction path 12 thus reduces the upward flow of the exhaust gas through the injection passage 10.

Then, as shown in FIG. 3, the exhaust gas located near a circumferential center of the introduction path 12 flows directly toward a radial center of the injection passage 10. The exhaust gas located near circumferential ends of the introduction path 12 flows along the internal wall 8 around toward the radial center of the injection passage 10. This allows the exhaust gas to flow through the injection passage 10 along the circumference of the internal wall 8 uniformly and thus a deviation in the flow of the exhaust gas in a circumferential direction of the internal wall 8 to be comparatively small. This, therefore, hardly affects a direction of a flow of fuel spray F injected from the fuel-additive valve 7.

FIG. 5 is a cross-sectional view of a main section of the exhaust gas purification apparatus as a comparative example. Referring to FIG. 5, an exhaust gas purification apparatus 50 shown as the comparative example includes a wall 51 that has a cylindrical shape and is fixed to the exhaust pipe 3. The wall 51 forms an injection passage 52 through which the fuel injected from the fuel-additive valve 7 passes.

In the exhaust gas purification apparatus 50 having such a configuration, the fuel spray F injected from the injection port 7a of the fuel-additive valve 7 may swirl about in response to an upward flow of the exhaust gas toward the fuel additive valve 7 in the injection passage 52. This may cause fuel drops P of the fuel spray F in surrounding regions of the fuel spray F to adhere to the injection port 7a of the fuel-additive valve 7, resulting in deposits that may clog the injection port 7a.

In the first embodiment of the present invention in contrast to the above described comparative example, the exhaust gas flowing from the diesel engine 2 through the introduction path 12 is introduced into the region of the injection passage 10 on the side close to the fuel-additive valve 7, in a state in which the fuel is injected from the fuel-additive valve 7 toward the exhaust passage 4. This suppresses the flow of the exhaust gas toward the fuel-additive valve 7 in the injection passage 10. The introduction path 12 extends along the circumference of the internal wall 8. In other words, the introduction path 12 expands in the circumferential direction of the internal wall 8. This configuration reduces the deviation in the flow of the exhaust gas in the circumferential direction of the internal wall 8 in response to the exhaust gas being introduced from the introduction path 12 into the region of the injection passage 10 on the side close to the fuel-additive valve 7, and also reduces the disturbance in the flow of the fuel spray F injected from the fuel-additive valve 7. This therefore reduces the swirls of the fuel spray F caused by a flow of the fuel spray F itself, and thus reduces adhesion of the fuel spray F to the fuel-additive valve 7. As a result, generation of the deposits on the fuel-additive valve 7 is reduced, and thus clogging of the injection port 7a of the fuel-additive valve 7 is reduced.

In the first embodiment, the external wall9 is disposed radially outside the internal wall 8, upstream of the exhaust passage 4. However, the exhaust gas purification apparatus according to the present invention is not limited to the above-described configuration. The external wall 9 may be disposed, for example, radially outside the internal wall 8, downstream of the exhaust passage 4.

FIG. 6 is a cross-sectional view of a main section of the exhaust gas purification apparatus according to a second embodiment of the present invention. Referring to FIG. 6, the exhaust gas purification apparatus 1 of the second embodiment includes an internal wall 20 that has a cylindrical shape, and the external wall 9 that is disposed radially outside the internal wall 20.

Referring to FIGS. 6 and 7, the internal wall 20 includes a wall body 21 that has a structure identical to the internal wall 8 of the first embodiment, and an upper wall 22 that has a circular shape, is disposed at an upper end of the wall body 21, and partially covers an inside of the internal wall 20. Theupperwall22 is disposed at an upper end of the internal wall 20 (on a side close to the fuel additive valve 7). The upper wall 22 has an opening 22a that has a circular shape and through which the fuel injected from the fuel-additive valve 7 passes. The opening 22a cooperates with the communicating port 13 to form a communication path by which the introduction path 12 communicates with the injection passage 10.

In the exhaust gas purification apparatus 1 having such a configuration, in a state in which the fuel is not injected from the fuel-additive valve 7 (as shown in FIG. 6), the exhaust gas hits the upper wall 22 even though the exhaust gas flowing in the exhaust passage 4 flows into the injection passage 10 toward the fuel-additive valve 7. Thus, the exhaust gas is unlikely to reach the fuel-additive valve 7.

On the other hand, in the state in which the fuel is injected from the fuel additive valve 7, even though the fuel spray F injected from the fuel-additive valve 7 swirls about in response to an upward flow of the exhaust gas present in the injection passage 10 to some extent and the fuel drops P in a surrounding region of the fuel spray F swirl up toward the fuel-additive valve 7 during the fuel injection, the fuel drops P hit the upperwall 22, as shown in FIG. 8. Thus, the fuel drops P in the surrounding region of the fuel spray F are unlikely to reach the fuel-additive valve 7.

In the exhaust gas purification apparatus 1 of the second embodiment, in the state in which the fuel is not injected from the fuel-additive valve 7 toward the exhaust passage 4, the exhaust gas hits the upper wall 22 even though the exhaust gas flows into the injection passage 10 toward the fuel-additive valve 7. This reduces the exhaust gas that reaches the fuel-additive valve 7. Ontheother hand, in the state in which the fuel is injected from the fuel-additive valve 7 toward the exhaust passage 4, even though the fuel spray F swirls up toward the fuel additive valve 7 in response to the upward flow of the exhaust gas present in the injection passage 10 to some extent toward the fuel-additive valve 7, the fuel spray F hits the upperwall 22. This further reduces the adhesion of the fuel spray F to the fuel-additive valve 7.

FIG. 9 is a cross-sectional view of a main section of the exhaust gas purification apparatus according to a third embodiment of the present invention. Referring to FIG. 9, the exhaust gas purification apparatus 1 according to the third embodiment includes an internal wall 30 that has a cylindrical shape, and an external wall 31 that has a cylindrical shape and is disposed radially outside the internal wall 30. The external wall 31 is integrally formed with the exhaust pipe 3. An upper end of the external wall 31 is at a position higher than an upper end of the internal wall 30.

The internal wall 30 forms an injection passage 32 through which the fuel injected from the fuel-additive valve 7 passes. The injection passage 32 communicates with the exhaust passage 4. The internal wall 30 includes a wall body 33, and an upper wall 34 that has a circular shape, is disposed at an upper end of the wall body 33, and partially covers an inside of the internal wall 30. The upper wall 34 has an opening 34a that has a circular shape and through which the fuel injected from the fuel-additive valve 7 passes.

The external wall 31 is disposed to surround an entire circumference of the internal wall 30. The external wall 31 cooperates with the internal wall 30 to form an introduction path 35 that is configured to introduce the exhaust gas flowing in the exhaust passage 4 into a region of the injection passage 32 on a side close to the fuel-additive valve 7. The introduction path 35 extends along the entire circumference of the internal wall 30. The opening 34a of the upper wall 34 serves as a communicating port through which the injection passage 32 communicates with the introduction path 35.

The external wall 31 includes a wall body 36, and an extending section 37 that has an annular shape, is disposed at an upper end of the wall body 36, and extends radially inward from the external wall 31. Referring to FIG. 10, the extending section 37 forms an opening 37a, having a circular shape, in a region radially inside the extending section 37. A diameter of the opening 37a is larger than an outer diameter of the internal wall 30. The fuel-additive valve 7 is attached to the extending section 37.

The external wall 31 includes a protrusion 38 protruding radially inward from the external wall 31 at a bottom end of the external wall 31. The protrusion 38 is formed such that a circumference of the protrusion 38 is longer than a half of an entire circumference of the external wall 31, as shown in FIGS. 10 and 11. A length of the protrusion 38 extending along the circumference of the external wall 31 is, for example, approximately three quarters of the entire circumference of the external wall 31.

The protrusion 38 includes, on an end surface 38a thereof, an internally threaded portion 39. The wall body 33 of the internal wall 30 includes an externally threaded portion 40 on an outer circumferential surface 33a of the wall body 33 at a bottom portion of an outer circumferential surface 33a. The externally threaded portion 40 of the internal wall 30 is configured to be screwed into the internally threaded portion 39 of the protrusion 38. The externally threaded portion 40 is formed along an entire circumference of the outer circumferential surface 33a of the wall body 33 of the internal wall 30.

To assemble the internal wall 30 into the external wall 31, the internal wall 30 is inserted through the opening 37a of the external wall 31 into an inside of the external wall 31, screwed into the protrusion 38 of the external wall 31 so that the externally threaded portion 40 of the internal wall 30 is screwed into the internally threaded portion 39 of the external wall 31, and tightened, as shown in FIG. 10. This causes the internal wall 30 to be fixed to the protrusion 38 of the external wall 31 as shown in FIG. 9.

In the exhaust gas purification apparatus 1 of the third embodiment as described above, the introduction path 35 extends along the entire circumference of the internal wall 30. This allows the exhaust gas from the exhaust passage 4 to flow in the introduction path 35 along the entire circumference of the internal wall 30, as shown in FIGS. 11 and 12. The exhaust gas flowing in the introduction path 35 along the entire circumference of the internal wall 30 is introduced into the injection passage 32.

In the exhaust gas purification apparatus 1 of the third embodiment, the exhaust gas flows in the introduction path 35 along the entire circumference of the internal wall 30. This reduces the deviation in the flow of the exhaust gas in the circumferential direction of the internal wall 30 in response to the exhaust gas being introduced from the introduction path 35 into the region of the injection passage 32 on the side close to the fuel-additive valve 7, which reduces the disturbance in the flow of the fuel spray F injected from the fuel-additive valve 7. This even further reduces the adhesion of the fuel spray F to the fuel-additive valve 7.

In the exhaust gas purification apparatus 1 of the third embodiment, the internal wall 30 is easily assembled into the external wall 31 by screwing the internal wall 30 into the protrusion 38 of the external wall 31. This simplifies a production process of the exhaust gas purification apparatus 1.

In the above-described third embodiment, the upper wall 34 having the circular shape is formed on the side close to the fuel-additive valve 7 of the internal wall 30. However, the exhaust gas purification apparatus according to the present invention is not limited to the above-described configuration. The upper wall 34 may be removed, instead.

In the above-described third embodiment, the external wall 31 is integrally formed with the exhaust pipe 3. However, the internal wall 30 may be integrally formed with the exhaust pipe 3, instead.

In the above-described third embodiment, the internal wall 30 is screwed into the external wall 31. However, the external wall 31 disposed to surround the entire circumference of the internal wall 30 may, for example, be fastened with the internal wall 30 at multiple points by screws, instead.

The embodiments disclosed herein are illustrative and the exhaust gas purification apparatus according to the present invention is not limited to the embodiments described above in every respect. For example, the exhaust gas purification apparatus 1 of the above-described embodiments includes the DPF 6. However, the exhaust gas purification apparatus may be configured to include a diesel particulate-NOx reduction system (DPNR) and so forth as a filter, instead.

The exhaust gas purification apparatus is applicable, not only to a diesel engine, but also to a gasoline engine to purify exhaust gas discharged from the gasoline engine.

In the claims which follow and in the preceding description of the disclosure, except where the context requires otherwise due to express language or necessary implication, the word "comprise" or variations such as "comprises" or "comprising" is used in an inclusive sense, i.e. to specify the presence of the stated features but not to preclude the presence or addition of further features in various embodiments of the disclosure.

It is to be understood that, if any prior art publication is referred to herein, such reference does not constitute an admission that the publication forms a part of the common general knowledge in the art, in Australia or any other country.

Claims

What is claimed is:

1. An exhaust gas purification apparatus configured to purify exhaust gas discharged from an internal combustion engine, comprising: an exhaust passage connected to the internal combustion engine; a fuel-additive valve configured to inject fuel toward the exhaust passage; an internal wall having a cylindrical shape and forming an injection passage that communicates with the exhaust passage and through which the fuel injected from the fuel-additive valve passes; and an external wall disposed radially outside the internal wall and cooperating with the internal wall to form an introduction path, the introduction path being configured to introduce the exhaust gas flowing in the exhaust passage into a region of the injection passage on a side close to the fuel-additive valve, wherein the introduction path extends along a circumference of the internal wall.

2. The exhaust gas purification apparatus according to claim 1, wherein the internal wall includes an upper wall on a side, of the internal wall, close to the fuel-additive valve, the upper wall partially covering an inside of the internal wall, and the upper wall includes an opening through which the fuel injected from the fuel-additive valve passes.

3. The exhaust gas purification apparatus according to claim 1 or 2, wherein the external wall is disposed to surround an entire circumference of the internal wall, and the introduction path extends along the entire circumference of the internal wall.

4. The exhaust gas purification apparatus according to claim 3, wherein the external wall includes a protrusion protruding radially inward from the external wall so as to extend along a circumference of the external wall, the protrusion includes an internally threaded portion on an end surface of the protrusion, and the internal wall includes an externally threaded portion on an outer circumferential surface of the internal wall, the externally threaded portion of the internal wall being configured to be screwed into the internally threaded portion of the protrusion.