U.S. patent application number 14/762272 was filed with the patent office on 2015-12-17 for exhaust gas purification device.
The applicant listed for this patent is FUTABA INDUSTRIAL CO., LTD.. Invention is credited to Naoki Matsumoto, Yoshinobu Nagata, Yasufumi Umeno.
Application Number | 20150361853 14/762272 |
Document ID | / |
Family ID | 51227261 |
Filed Date | 2015-12-17 |
United States Patent
Application |
20150361853 |
Kind Code |
A1 |
Nagata; Yoshinobu ; et
al. |
December 17, 2015 |
EXHAUST GAS PURIFICATION DEVICE
Abstract
An exhaust gas purification device comprises a first channel
member that forms an exhaust gas flow path leading to a catalyst
and a second channel member that forms a reducing agent flow path
guiding a reducing agent injected by an injector to the exhaust gas
flow path upstream of the catalyst. The second channel member is
inserted so as to penetrate a side wall of the first channel member
to protrude into the exhaust gas flow path.
Inventors: |
Nagata; Yoshinobu;
(Okazaki-shi, Aichi, JP) ; Matsumoto; Naoki;
(Okazaki-shi, Aichi, JP) ; Umeno; Yasufumi;
(Okazaki-shi, Aichi, JP) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
FUTABA INDUSTRIAL CO., LTD. |
Okazaki-shi, Aichi |
|
JP |
|
|
Family ID: |
51227261 |
Appl. No.: |
14/762272 |
Filed: |
December 20, 2013 |
PCT Filed: |
December 20, 2013 |
PCT NO: |
PCT/JP2013/084320 |
371 Date: |
July 21, 2015 |
Current U.S.
Class: |
60/303 |
Current CPC
Class: |
Y02T 10/12 20130101;
F01N 3/36 20130101; F01N 2240/20 20130101; F01N 3/2892 20130101;
B01D 2258/012 20130101; B01D 53/90 20130101; F01N 3/2066 20130101;
Y02T 10/24 20130101; F01N 3/2896 20130101; F01N 2610/1453
20130101 |
International
Class: |
F01N 3/28 20060101
F01N003/28 |
Foreign Application Data
Date |
Code |
Application Number |
Jan 25, 2013 |
JP |
2013-012220 |
Claims
1. An exhaust gas purification device comprising: a first channel
member that forms an exhaust gas flow path leading to a catalyst;
and a second channel member that forms a reducing agent flow path
guiding a reducing agent injected by an injector to the exhaust gas
flow path upstream of the catalyst, wherein the second channel
member is inserted so as to penetrate a side wall of the first
channel member to protrude into the exhaust gas flow path.
2. The exhaust gas purification device according to claim 1,
wherein the second channel member is a tubular member, wherein the
second channel member comprises a first end that opens on an
injector side and a second end that is located on an opposite side
from the first end and that opens in the exhaust gas flow path, and
wherein the second channel member forms the reducing agent flow
path from the first end to the second end, the reducing agent flow
path being blocked from the exhaust gas flow path.
3. The exhaust gas purification device according to claim 1,
wherein the exhaust gas flow path is provided, upstream of the
catalyst, with a diffusion member that reduces bias of exhaust gas
flowing into the catalyst, and wherein the second channel member
forms the reducing agent flow path guiding the reducing agent to
the exhaust gas flow path upstream of the diffusion member.
4. The exhaust gas purification device according to claim 1,
wherein part of the second channel member inserted in the exhaust
gas flow path has a function of guiding exhaust gas that has hit an
outer surface of the second channel member to flow around along the
outer surface.
5. The exhaust gas purification device according to claim 1,
wherein part of the exhaust gas flow path in which the second
channel member is inserted is extended so as to be enlarged in a
third direction orthogonal both to a first direction that is a
direction of flow of exhaust gas hitting the outer surface of the
second channel member and to a second direction that is an axial
direction of the second channel member.
6. The exhaust gas purification device according to claim 5,
wherein a cross-sectional shape of the first channel member and a
cross-sectional shape of the second channel member are dissimilar
to each other, and wherein the cross-sectional shape of the first
channel member is wider in the third direction than the
cross-sectional shape of the second channel member.
7. The exhaust gas purification device according to claim 1,
wherein a leading end of the second channel member is located in a
central part of the exhaust gas flow path.
Description
CROSS-REFERENCE TO RELATED APPLICATIONS
[0001] This international application claims the benefit of
Japanese Patent Application No. 2013-12220 filed Jan. 25, 2013 in
the Japan Patent Office, and the entire disclosure of Japanese
Patent Application No. 2013-12220 is incorporated herein by
reference.
TECHNICAL FIELD
[0002] The present invention relates to an exhaust gas purification
device that purifies exhaust gas in an exhaust gas flow path.
BACKGROUND ART
[0003] Exhaust gas discharged from an internal combustion engine,
such as a diesel engine, contains nitrogen oxides (NO.sub.x) as air
pollutants. As a device for purifying such exhaust gas, an exhaust
gas purification device is known that is configured such that a
catalyst of SCR (Selective Catalytic Reduction) type is provided in
an exhaust gas flow path and that urea water is injected into
exhaust gas upstream of the catalyst. Urea water injected into the
exhaust gas is hydrolyzed by heat of the exhaust gas. Ammonia
(NH.sub.3) generated by the hydrolysis is supplied to the catalyst
with the exhaust gas. Nitrogen oxides in the exhaust gas react with
ammonia in the catalyst and are thereby reduced and purified.
[0004] In this type of exhaust gas purification device, a catalyst
with a large cross-sectional area is generally used in order to
improve exhaust gas purifying effect of the catalyst. Upstream of
the catalyst is formed an enlarged diameter flow path to expand a
diameter of the exhaust gas flow path. However, in a configuration
with such an enlarged diameter flow path, an exhaust gas flow tends
to be biased in the enlarged diameter flow path. Distribution of
the exhaust gas flowing into the catalyst is thus likely to be
biased. Therefore, a configuration has been proposed in which a
diffusion member for diffusing the exhaust gas into the enlarged
diameter flow path is provided upstream of the enlarged diameter
flow path (Patent Document 1).
PRIOR ART DOCUMENTS
Patent Documents
[0005] Patent Document 1: Japanese Unexamined Patent Application
Publication No. 2010-90808
SUMMARY OF THE INVENTION
Problems to be Solved by the Invention
[0006] Inventors of the present invention have found a problem in
which, if distribution of a reducing agent (urea water or ammonia
after the hydrolysis) is biased in the exhaust gas flowing into the
diffusion member, the biased distribution of the reducing agent in
the exhaust gas flowing into the catalyst also is not eliminated.
That is, the diffusion member has a function of reducing the biased
exhaust gas flow in the enlarged diameter flow path, but does not
have a function of dispersing the reducing agent unevenly present
in the exhaust gas. In particular, when the direction in which the
reducing agent is supplied and the direction in which the exhaust
gas flows differ from each other at a merging position where the
reducing agent merges with the exhaust gas, the flow of the
reducing agent is influenced by the flow of the exhaust gas and
thus is likely to be biased. Such biased distribution of the
reducing agent flowing into the catalyst is a factor to decrease
the exhaust gas purifying effect of the catalyst.
[0007] In one aspect of the present invention, it is desirable to
reduce the biased distribution of the reducing agent flowing into
the catalyst.
Means for Solving the Problems
[0008] An exhaust gas purification device in one aspect of the
present invention comprises a first channel member that forms an
exhaust gas flow path leading to a catalyst and a second channel
member that forms a reducing agent flow path guiding a reducing
agent injected by an injector to the exhaust gas flow path upstream
of the catalyst. The second channel member is inserted so as to
penetrate a side wall of the first channel member to protrude into
the exhaust gas flow path.
[0009] Such a configuration can reduce the biased distribution of
the reducing agent in the exhaust gas flow path. According to a
configuration with the second channel member not protruding into
the exhaust gas flow path, the reducing agent guided into the
exhaust gas flow path merges with exhaust gas flowing therein near
a periphery thereof to flow along, and thus the distribution of the
reducing agent in the exhaust gas flow path tends to be biased. In
contrast, the configuration with the second channel member
protruding into the exhaust gas flow path can guide the reducing
agent to a central part of the exhaust gas flow path, thus reducing
the biased distribution of the reducing agent in the exhaust gas
flow path. Accordingly, the exhaust gas purification device in the
one aspect of the present invention can reduce the biased
distribution of the reducing agent flowing into the catalyst.
[0010] According to the above configuration, the second channel
member may be a tubular member, may comprise a first end that opens
on an injector side and a second end that is located on an opposite
side from the first end and that opens in the exhaust gas flow
path, and may form the reducing agent flow path, from the first end
to the second end, that is blocked from the exhaust gas flow path.
According to such a configuration, the reducing agent can be guided
to the central part of the exhaust gas flow path while being hardly
affected by the flow of the exhaust gas in the exhaust gas flow
path.
[0011] According to the above configuration, the exhaust gas flow
path may be provided, upstream of the catalyst, with a diffusion
member that reduces bias of the exhaust gas flowing into the
catalyst. The second channel member may form the reducing agent
flow path that guides the reducing agent to the exhaust gas flow
path upstream of the diffusion member. According to such a
configuration, after the biased distribution of the reducing agent
in the exhaust gas flowing into the diffusion member is reduced by
the second channel member, the bias of the exhaust gas flowing into
the catalyst is reduced. Thus, the biased distribution of the
reducing agent flowing into the catalyst can be reduced
effectively.
[0012] According to the above configuration, part of the second
channel member inserted in the exhaust gas flow path may have a
function of guiding exhaust gas that has hit an outer surface of
the second channel member to flow around along the outer surface.
Such a configuration disturbs the flow of the exhaust gas that has
hit the outer surface of the second channel member, so that an
effect of dispersing the reducing agent that has merged from the
second channel member can be obtained.
[0013] According to the above configuration, part of the exhaust
gas flow path in which the second channel member is inserted may be
extended so as to be enlarged in a direction orthogonal both to a
first direction that is a direction of flow of the exhaust gas
hitting the outer surface of the second channel member and to a
second direction that is an axial direction of the second channel
member. Such a configuration facilitates the flow of the exhaust
gas that has hit the outer surface of the second channel member
flowing around along the outer surface, to thereby improve the
effect of dispersing the reducing agent that has merged from the
second channel member.
[0014] In addition to the exhaust gas purification device described
above, the one aspect of the present invention can be implemented
in various forms, such as a reducing agent supply mechanism used in
an exhaust gas purification device, a method of reducing bias of
exhaust gas flowing into a catalyst, etc.
BRIEF DESCRIPTION OF THE DRAWINGS
[0015] FIG. 1A is a top view of an exhaust gas purification device
of an embodiment, and FIG. 1B is a side view of the exhaust gas
purification device of the embodiment.
[0016] FIG. 2A is a cross-sectional view taken along a line IIA-IIA
of FIG. 1A, FIG. 2B is a cross-sectional view taken along a line
IIB-IIB of FIG. 1B, and FIG. 2C is a view highlighting a partial
area of FIG. 2B.
[0017] FIG. 3 is a perspective view of a diffusion member.
[0018] FIG. 4 is a view of the diffusion member seen from
downstream in an exhaust gas flow path.
[0019] FIG. 5 is a view showing a shape of a blade of the diffusion
member.
[0020] FIG. 6A is a cross-sectional view of an exhaust gas
purification device of a comparative example, FIG. 6B is a diagram
showing a simulation result of flow of a reducing agent in the
exhaust gas purification device of the comparative example, and
FIG. 6C is a diagram showing a simulation result of distribution of
the reducing agent in a catalyst end surface of the exhaust gas
purification device of the comparative example.
[0021] FIG. 7A is a diagram showing a simulation result of flow of
the reducing agent in the exhaust gas purification device of the
embodiment, FIG. 7B is a diagram showing a simulation result of
flow of exhaust gas in the exhaust gas purification device of the
embodiment, and FIG. 7C is a diagram showing a simulation result of
distribution of the reducing agent in a catalyst end surface of the
exhaust gas purification device of the embodiment.
[0022] FIG. 8A is a perspective view of a channel member of a first
modified example, FIG. 8B is a top view of the channel member of
the first modified example, FIG. 8C is a side view of the channel
member of the first modified example, and FIG. 8D is a view of the
channel member of the first modified example seen in an axial
direction from downstream.
[0023] FIG. 9A is a perspective view of a channel member of a
second modified example, FIG. 9B is a top view of the channel
member of the second modified example, FIG. 9C is a side view of
the channel member of the second modified example, and FIG. 9D is a
cross-sectional view taken along a line IXD-IXD of FIG. 9C.
[0024] FIG. 10A is a top view of an exhaust gas purification device
of a third modified example, and FIG. 10B is a cross-sectional view
of the exhaust gas purification device of the third modified
example.
[0025] FIG. 11A is a top view of an exhaust gas purification device
of a fourth modified example, FIG. 11B is a cross-sectional view
taken along a line XIB-XIB of FIG. 11A, and FIG. 11C is a
cross-sectional view taken along a line XIC-XIC of FIG. 11B.
EXPLANATION OF REFERENCE NUMERALS
[0026] 1 . . . exhaust gas purification device, 2 . . . first
channel member, 3 . . . second channel member, 4 . . . catalyst, 5
. . . injector, 6 . . . diffusion member
MODE FOR CARRYING OUT THE INVENTION
[0027] Hereinafter, embodiments to which the present invention is
applied will be described with reference to the drawings.
1. CONFIGURATION
[0028] An exhaust gas purification device 1 purifies exhaust gas
discharged from an internal combustion engine (for example, a
diesel engine) of a motor vehicle. The exhaust gas purification
device 1 comprises a first channel member 2, a second channel
member 3, a catalyst 4, an injector 5, and a diffusion member 6. In
the following description, up-down and left-right directions
(vertical and horizontal directions) will be represented relative
to FIG. 2A. However, such a representation is merely for
convenience of description, and orientation of the exhaust gas
purification device 1 is not particularly limited.
[0029] The first channel member 2 forms part of an exhaust gas flow
path for guiding exhaust gas discharged from the internal
combustion engine to outside of the motor vehicle, in particular
the exhaust gas flow path leading to the catalyst 4. The first
channel member 2 comprises, in order from an upstream side of the
exhaust gas flow path (left side in FIG. 2A), a first tube 2A, a
second tube 2B, a third tube 2C, a fourth tube 2D, and a fifth tube
2E. Classification of these first to fifth tubes 2A to 2E are
merely for convenience of description, and classification of parts
that compose the first channel member 2 is not particularly
limited.
[0030] The first tube 2A is a straight circular tube.
[0031] The third tube 2C is a straight circular tube having the
same inner diameter as the first tube 2A. However, the third tube
2C differs from the first tube 2A in direction of flow of the
exhaust gas. Specifically, the first tube 2A forms a flow path in
which the exhaust gas flows diagonally downward, and the third tube
2C forms a flow path in which the exhaust gas flows in a horizontal
direction. Thus, the first tube 2A and the third tube 2C are
connected with each other by the gently-sloping second tube 2B,
which is curved in an arc shape in a side view.
[0032] The second tube 2B is formed, for example, by joining two
pieces of outer covering together one above the other. As shown in
FIG. 1A, the exhaust gas flow path formed of the second tube 2B
(i.e., part of the exhaust gas flow path in which the second
channel member 3 is inserted) is extended so as to be enlarged
(expand) on both sides in a widthwise direction (up-down direction
in FIG. 1A) as compared with the first tube 2A and the third tube
2C in a top view. In other words, a cross-sectional shape of the
second channel member 3 is circular, while a cross-sectional shape
of the part of the first channel member 2 in which the second
channel member 3 is inserted is a laterally elongated shape
(elliptical shape in this example). The widthwise direction here
refers to a direction orthogonal both to a first direction that is
a direction of flow of exhaust gas hitting an outer surface
(specifically an upper face) of the second channel member 3 (i.e.,
a diagonally downward direction) and to a second direction that is
an axial direction of the second channel member 3 (i.e., a
horizontal direction). Further, the first direction is a direction
along a first axis C1 that is a center axis of the first tube 2A,
and the second direction is a direction along a second axis C2 that
is a center axis of the third tube 2C. In the present embodiment,
the first axis C1 and the second axis C2 are positioned to cross
each other.
[0033] The fifth tube 2E is a straight circular tube coaxial to the
third tube 2C (having the second axis C2 as the center axis).
However, the fifth tube 2E is larger than the third tube 2C in
inner diameter in order to accommodate the cylindrical catalyst 4
having an outer diameter larger than the inner diameter of the
third tube 2C. Thus, the third tube 2C and the fifth tube 2E are
connected with each other by the gently-sloping fourth tube 2D,
which is a circular tube having a shape of a truncated cone that
forms an enlarged diameter flow path for gradually expanding the
inner diameter of the exhaust gas flow path. In other words, the
first channel member 2 forms, upstream of the catalyst 4, the
exhaust gas flow path having the enlarged diameter flow path as the
exhaust gas flow path leading to the catalyst 4.
[0034] The second channel member 3 is a tubular member having no
penetrated portions in its side for communication between the
inside and the outside thereof. Of both ends of the second channel
member 3, a first end (upstream-side end) 3A opens on an injector 5
side, and a second end (downstream-side end) 3B located on an
opposite side from the first end 3A opens in the exhaust gas flow
path. That is, the second channel member 3 is a so-called dosing
pipe that forms a reducing agent flow path guiding a reducing agent
injected by the injector 5 (diffused from a small hole 5A arranged
outside the exhaust gas flow path) to the exhaust gas flow path
upstream of the catalyst 4 (more specifically, upstream of the
diffusion member 6). Since the second channel member 3 has no
penetrated portions in its side as described above, the reducing
agent flow path blocked (partitioned) from the exhaust gas flow
path is formed from the first end 3A to the second end 3B.
[0035] The second channel member 3 is a circular tube coaxial to
the third tube 2C (having the second axis C2 as the center axis).
In the present embodiment, the second channel member 3 is shaped as
a truncated cone in which an inner diameter of the reducing agent
flow path is gradually expanded toward the exhaust gas flow path,
and is configured such that the injected reducing agent is less
likely to directly hit (less likely to corrode) an inner surface of
the second channel member 3. The second channel member 3 is
connected to the second tube 2B of the first channel member 2, and
the reducing agent injected by the injector 5 merges with the
exhaust gas flowing in the second tube 2B. Specifically, the second
channel member 3 is inserted so as to penetrate a penetrated
portion (through hole) provided in a side wall of the second tube
2B to protrude into the exhaust gas flow path (to locate a leading
end of the second channel member 3 in a central part of the exhaust
gas flow path). The second channel member 3 is joined (welded), at
an outer peripheral surface thereof, directly to the side wall of
the second tube 2B.
[0036] As described above, the part of the exhaust gas flow path in
which the second channel member 3 is inserted is extended to so as
be enlarged on both sides in a widthwise direction in a top view as
shown in FIG. 1A. Thus, the exhaust gas flow path formed between
the first channel member 2 and the second channel member 3 is
shaped to be wider at its side parts on both sides in the widthwise
direction than at its upper part as shown in FIG. 2B. The exhaust
gas that has flowed from the first tube 2A thus tends to flow
around in an area F (area on both sides of the second channel
member 3 in the widthwise direction) shown in FIG. 2C, to thereby
produce a flow lifting up the reducing agent from the second
channel member 3, as shown in FIG. 7B to be explained later.
[0037] The catalyst 4 is a catalyst of SCR (Selective Catalytic
Reduction) type having a function of reducing nitrogen oxides
(NO.sub.x). The catalyst 4 is provided downstream of the enlarged
diameter flow path in the exhaust gas flow path (specifically
inside the fifth tube 2E).
[0038] The injector 5 functions as a supplier that injects the
liquid reducing agent and supplies the reducing agent to upstream
of the diffusion member 6 in the exhaust gas flow path
(specifically into the second tube 2B) through the second channel
member 3. In the present embodiment, urea water is injected as the
reducing agent. Strictly speaking, urea water injected into the
exhaust gas is hydrolyzed by heat of the exhaust gas to produce
ammonia (NH.sub.3), and the produced ammonia functions as the
reducing agent. However, the state prior to the hydrolysis (i.e.,
urea water) is also referred to as the reducing agent.
[0039] The diffusion member 6 allows the exhaust gas that has
flowed therein from upstream to be diffused to flow out to the
enlarged diameter flow path so as to reduce bias of the exhaust gas
flowing into the catalyst 4 (to bring the exhaust gas distribution
close to a uniform state). The diffusion member 6 is provided
upstream of the enlarged diameter flow path in the exhaust gas flow
path (inside the third tube 2C).
[0040] A specific structure of the diffusion member 6 will be
described as an example. The diffusion member 6 shown in FIG. 3 and
FIG. 4 is formed by bending a single metal plate. The diffusion
member 6 comprises a main body 61, a plurality of blades 62, and a
plurality of supports 63.
[0041] The supports 63 are protruding pieces extending upstream
along a flow direction D of the exhaust gas. The supports 63
protrude radially outward as compared with the main body 61 by
being bent in a stepped manner. Thus, in a state in which the
diffusion member 6 is fitted in the third tube 2C, outer surfaces
of the supports 63 are in contact with an inner surface of the
third tube 2C, resulting in a gap between the main body 61 and the
inner surface of the third tube 2C. When the supports 63 and the
third tube 2C are welded to each other at the interfaces, the main
body 61 is supported by the supports 63. That is, the diffusion
member 6 is fixed to the third tube 2C.
[0042] The plurality of blades 62 are protruding pieces formed
downstream along the flow direction D of the exhaust gas. Each of
the blades 62 is inclined with respect to the flow direction D of
the exhaust gas by being bent at its tip, and guides the exhaust
gas in a direction corresponding to the inclination. The direction
in which each of the blades 62 is inclined and the direction in
which each of the blades 62 guides the exhaust gas are set as
below.
[0043] Assuming that a vector in the direction in which each of the
blades 62 guides the exhaust gas is a vector E as shown in FIG. 5,
the vector E can be a vector directed from a base to a tip of each
of the blades 62. A component of the vector E in a plane orthogonal
to the flow direction D of the exhaust gas is assumed as a vector
X. When the diffusion member 6 is viewed from downstream in the
flow direction D of the exhaust gas, the vector X of each of the
blade 62 makes a circuit in a given route as a whole as shown in
FIG. 4. Thus, the exhaust gas passing through the diffusion member
6 is guided in the direction of the vector X in each of the blades
62, resulting in a swirling flow produced in the exhaust gas that
has flowed into the diffusion member 6, as a whole in a
counterclockwise direction in FIG. 4. As a result, the exhaust gas
is likely to spread into the enlarged diameter flow path, to
thereby reduce the bias of the exhaust gas flowing in the catalyst
4.
2. OPERATION
[0044] The operation of the exhaust gas purification device 1 will
be described next. The exhaust gas discharged from the internal
combustion engine is guided by the exhaust gas flow path to the
diffusion member 6, passes through the diffusion member 6, and then
is guided into the catalyst 4. The reducing agent injected from the
injector 5 is guided by the reducing agent flow path to the central
part of the exhaust gas flow path and then merges with the exhaust
gas.
[0045] The part of the second channel member 3 inserted in the
exhaust gas flow path has a function of guiding the exhaust gas
that has hit the upper face of the outer surface of the second
channel member 3, from among the exhaust gas flowing from the first
tube 2A to the second tube 2B, to flow around along the outer
surface. Thus, a swirling flow is generated in the vicinity of the
leading end of the second channel member 3, so that the reducing
agent that has flowed out from the second channel member 3 is
lifted up and dispersed in the exhaust gas flow path.
3. EFFECTS
[0046] According to the present embodiment described above, the
following effects can be obtained.
[0047] [A1] In the exhaust gas purification device 1, the second
channel member 3 is inserted so as to penetrate the side wall of
the first channel member 2 to protrude into the exhaust gas flow
path. That is, the second channel member 3 is extended to the
inside of the first channel member 2. Thus, the exhaust gas
purification device 1 can reduce biased distribution of the
reducing agent in the exhaust gas flow path as compared to a
configuration with the second channel member 3 not protruding into
the exhaust gas flow path.
[0048] Here, a reason why such an effect is obtained will be
explained by comparison with the configuration with the second
channel member 3 not protruding into the exhaust gas flow path (an
exhaust gas purification device of a comparative example). As shown
in FIG. 6A, according to an exhaust gas purification device 9 of
the comparative example having the second channel member 3 not
protruding into the exhaust gas flow path, the reducing agent
guided into the exhaust gas flow path merges with exhaust gas
flowing therein near a periphery thereof to flow along, and thus
tends to gather at a lower part of the exhaust gas flow path. This
causes the distribution of the reducing agent flowing into the
diffusion member 6 to be biased largely downward in this example.
The diffusion member 6 has a function of reducing the bias of the
exhaust gas in the enlarged diameter flow path, but its effect of
spreading the reducing agent that has unevenly flowed therein to
the entire exhaust gas flow path is small. Thus, the exhaust gas
that has passed through the diffusion member 6 easily flows into
the catalyst 4 in a state where the distribution of the reducing
agent is biased. In such a state, it is not possible to obtain
sufficient exhaust gas purifying effect of the catalyst 4. In
contrast, according to the exhaust gas purification device 1 of the
present embodiment, the second channel member 3 can guide the
reducing agent to the central part of the exhaust gas flow path as
shown in FIG. 2A, thereby reducing the biased distribution of the
reducing agent in the exhaust gas flow path. Thus, the exhaust gas
purification device 1 can reduce the biased distribution of the
reducing agent flowing into the catalyst 4.
[0049] [A2] The second channel member 3 forms the reducing agent
flow path, from the first end 3A to the second end 3B, that is
blocked from the exhaust gas flow path. According to the exhaust
gas purification device 1, the reducing agent can thus be guided to
the central part of the exhaust gas flow path while being hardly
affected by the flow of the exhaust gas in the exhaust gas flow
path.
[0050] [A3] The second channel member 3 forms the reducing agent
flow path guiding the reducing agent into the exhaust gas flow path
upstream of the diffusion member 6. Accordingly, after the biased
distribution of the reducing agent in the exhaust gas flowing into
the diffusion member 6 is reduced by the second channel member 3,
the bias of the exhaust gas flowing into the catalyst 4 is reduced.
Thus, the exhaust gas purification device 1 can effectively reduce
the biased distribution of the reducing agent flowing into the
catalyst 4.
[0051] [A4] The part of the second channel member 3 inserted in the
exhaust gas flow path has the function of guiding the exhaust gas
that has hit the outer surface of the second channel member 3 to
flow around along the outer surface. Accordingly, in the exhaust
gas purification device 1, the flow of the exhaust gas that has hit
the outer surface of the second channel member 3 is disturbed, and
thus the effect of dispersing the reducing agent that has merged
from the second channel member 3 is obtained.
[0052] [A5] The part of the exhaust gas flow path in which the
second channel member 3 is inserted is extended so as to be
enlarged in the direction orthogonal both to the first direction
that is the direction of the flow of the exhaust gas hitting the
outer surface of the second channel member 3 and to the second
direction that is the axial direction of the second channel member
3. Since the exhaust gas purification device 1 facilitates the flow
of the exhaust gas that has hit the outer surface of the second
channel member 3 flowing around along the outer surface, it is
possible to improve the effect of dispersing the reducing agent
that has merged from the second channel member 3.
4. SIMULATION RESULTS
[0053] Now, simulation results will be described. According to the
exhaust gas purification device 9 of the comparative example, as
shown in FIG. 6B, the reducing agent (streamlines in the figure)
guided into the exhaust gas flow path merges with the exhaust gas
flowing therein near a periphery thereof to flow along, and thus
the reducing agent is less likely to reach the central part of the
exhaust gas flow path and gathers at a lower part thereof. This
causes the distribution of the reducing agent (ammonia) (dots in
the figure) in an end surface of the catalyst 4 to be biased as
shown in FIG. 6C. FIG. 6C corresponds to a VIC-VIC cross-sectional
view of FIG. 6B.
[0054] In contrast, according to the exhaust gas purification
device 1 of the present embodiment, as shown in FIG. 7A, the second
channel member 3 guides the reducing agent to the central part of
the exhaust gas flow path, and thus a phenomenon in which the
reducing agent gathers at the lower part of the exhaust gas flow
path is less likely to occur. Moreover, the exhaust gas that has
hit the upper face of the second channel member 3 is guided to
branch to left and right so as to flow around along the outer
surface thereof. Thus, a swirling flow with a high flow velocity is
generated as shown in FIG. 7B and the reducing agent that has
flowed out from the second channel member 3 is lifted up and
dispersed in the exhaust gas flow path. This allows the
distribution of the reducing agent (ammonia) (dots in the figure)
in the end surface of the catalyst 4 to be less biased than that of
the comparative example as shown in FIG. 7C. FIG. 7B corresponds to
a VIIB-VIIB cross-sectional view of FIG. 7A, and FIG. 7C
corresponds to a VIIC-VIIC cross-sectional view of FIG. 7A.
5. OTHER EMBODIMENTS
[0055] The embodiment of the present invention has been described
above. However, it goes without saying that the present invention
is not limited to the above embodiment and may be embodied in
various forms.
[0056] [B1] The second channel member 3 is not limited to the shape
exemplified in the above embodiment. FIG. 8A is a perspective view
of a channel member 31 of a first modified example that can be used
in place of the second channel member 3 described above, FIG. 8B is
a top view (plan view) thereof, FIG. 8C is a side view thereof, and
FIG. 8D is a view seen in an axial direction from downstream. The
channel member 31 of the first modified example differs from the
second channel member 3 of the above embodiment in that the channel
member 31 is shaped to have part other than an upper face 31A of a
leading end thereof removed (cut out). Even with such a shape, the
protruding upper face 31A guides the reducing agent to the central
part of the exhaust gas flow path, and the swirling flow produced
by the exhaust gas that has hit the upper face 31A lifts up and
disperses the reducing agent in the exhaust gas flow path. Thus,
the channel member 31 provides effects similar to those of the
above embodiment.
[0057] [B2] FIG. 9A is a perspective view of a channel member 32 of
a second modified example that can be used in place of the second
channel member 3 described above, FIG. 9B is a top view (plan view)
thereof, FIG. 9C is a side view thereof, and FIG. 9D is an IXD-IXD
cross-sectional view of FIG. 9C. The channel member 32 of the
second modified example differs from the second channel member 3 of
the above embodiment in that the channel member 32 has a penetrated
portion 32A and a blade 32B provided on an upper face thereof. The
penetrated portion 32A and the blade 32B are formed by processing
the upper face. The blade 32B has a shape bent inward along a bend
line in an axial direction of the reducing agent flow path and has
a function of guiding the exhaust gas that has flowed in from the
penetrated portion 32A to flow along an inner surface of the
reducing agent flow path. Part of the exhaust gas is taken into the
reducing agent flow path through the penetrated portion 32A, and
thus an effect of reducing the phenomenon in which the exhaust gas
is blown back at an outlet of the reducing agent flow path is
obtained, in addition to effects similar to those of the above
embodiment. Moreover, since the exhaust gas that has flowed in from
the penetrated portion 32A is guided to flow along the inner
surface of the reducing agent flow path, it is possible to reduce
the influence of the exhaust gas on the flow of the reducing agent.
The locations, shapes, numbers, etc. of the penetrated portion 32A
and the blade 32B are not particularly limited.
[0058] [B3] In the above embodiment, the configuration in which the
part of the exhaust gas flow path in which the second channel
member 3 is inserted is extended so as to be enlarged on both sides
in a widthwise direction in a top view has been illustrated, but
the disclosed embodiment is not limited thereto. FIG. 10A is a top
view (plan view) of an exhaust gas purification device 13 of a
third modified example, and FIG. 10B is a cross-sectional view
thereof (cross-sectional view thereof showing a position
corresponding to FIG. 2B). The exhaust gas purification device 13
of the third modified example has a basic configuration similar to
that of the above embodiment, but differs therefrom in that the
part of the exhaust gas flow path in which the second channel
member 3 is inserted is extended so as to be enlarged on one side
in a widthwise direction in a top view. Thus, as shown in FIG. 10B,
the exhaust gas flow path formed between the first channel member 2
and the second channel member 3 is shaped to be wider at its side
part on one side in the widthwise direction (the right side in this
example) than at its upper part. The exhaust gas that has hit the
upper face of the second channel member 3 is thus guided to flow
around to the right along the outer surface thereof. As a result, a
swirling flow is generated to lift up and disperse the reducing
agent that has flowed out from the second channel member 3, so that
effects similar to those of the above embodiment are obtained.
[0059] [B4] The above embodiment assumes that the exhaust gas flow
path comprises a curved flow path, but the disclosed embodiment is
not limited thereto and may be applied to a linear-shaped exhaust
gas flow path. FIG. 11A is a top view (plan view) of an exhaust gas
purification device 14 of a fourth modified example, FIG. 11B is an
XIB-XIB cross-sectional view of FIG. 11A, and FIG. 11C is an
XIC-XIC cross-sectional view of FIG. 11B. According to the
configuration with the second channel member 3 not protruding into
the exhaust gas flow path, even if a linear-shaped exhaust gas flow
path is employed, the reducing agent guided into the exhaust gas
flow path merges with the exhaust gas flowing therein near a
periphery thereof to flow along, and thus the reducing agent is
biased in the exhaust gas flow path. However, according to the
exhaust gas purification device 14 of the fourth modified example,
the reducing agent is guided by the second channel member 3 to the
central part of the exhaust gas flow path, and also dispersed by
the swirling flow produced by the exhaust gas that has hit the
outer surface of the second channel member 3. Thus, effects similar
to those of the above embodiment are obtained.
[0060] [B5] The exhaust gas flow path and the reducing agent of the
above embodiment are merely examples, and the disclosed embodiment
is not limited thereto. For example, in the above embodiment, part
of the first channel member 2 has a laterally elongated shape to
form, between the first channel member 2 and the second channel
member 3, an exhaust gas flow path that is wider at its side parts
than at its upper part (the hitting side). However, at least part
of the second channel member 3 may have a vertically elongated
shape. The first channel member 2 and the second channel member 3
thus having cross-sectional shapes dissimilar to each other, with
the cross-sectional shape of the first channel member 2 being wider
in the widthwise direction than that of the second channel member
3, allow the exhaust gas to easily flow around both sides of the
second channel member 3 in the widthwise direction. For further
example, the first tube 2A and the third tube 2C may have inner
diameters different from each other, and the third tube 2C, the
fifth tube 2E, and the second channel member 3 are not necessarily
coaxial with one another. For further example, the exhaust gas flow
path and the reducing agent flow path may not have circular cross
sections. For further example, the enlarged diameter flow path and
the reducing agent flow path may have shapes other than a truncated
cone shape. For further example, the exhaust gas flow path is not
limited to the configuration with an enlarged diameter flow path,
and may have no enlarged diameter flow path.
[0061] [B6] In the above embodiment, the configuration in which the
diffusion member 6 is provided upstream of the enlarged diameter
flow path in the exhaust gas flow path has been illustrated.
However, the disclosed embodiment is not limited to this
configuration, and may be configured without the diffusion member
6.
[0062] [B7] The reducing agent is not limited to urea water as long
as it contributes to purification of the exhaust gas in the
catalyst.
[0063] [B8] Each component of the present invention is merely
conceptual, and is not limited to that of the above embodiment. For
example, the function of one component may be distributed to a
plurality of components or the functions of multiple components may
be integrated in one component. Also, at least a portion of the
configuration of the above embodiment may be replaced by a
well-known configuration having a similar function.
* * * * *