U.S. patent application number 16/483254 was filed with the patent office on 2019-12-12 for exhaust purification device.
This patent application is currently assigned to HINO MOTORS, LTD.. The applicant listed for this patent is HINO MOTORS, LTD.. Invention is credited to Kuniharu TOBE, Hirofumi TONGU, Tomoyuki TSURUTA.
Application Number | 20190376430 16/483254 |
Document ID | / |
Family ID | 63039831 |
Filed Date | 2019-12-12 |
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United States Patent
Application |
20190376430 |
Kind Code |
A1 |
TSURUTA; Tomoyuki ; et
al. |
December 12, 2019 |
EXHAUST PURIFICATION DEVICE
Abstract
Provided are gas dispersion portion 7C covering entry end face
of selective reduction catalyst 4 (aftertreatment device) and
introducing exhaust gas 1 through exhaust feed port 11 from
direction substantially perpendicular to axis of aftertreatment
device and mixing pipe 7B (exhaust conduit) curved from exhaust
feed port 11 in the gas dispersion portion 7C toward exit side of
the selective reduction catalyst 4 to extend axially of
aftertreatment device. Gas dispersion portion 7C is of crushingly
deformed shape to ensure area from exhaust feed port 11 to vicinity
of extension of axis of the selective reduction catalyst 4 as
fan-likely spreading flow guide space 12, remaining area being flat
throttling space 13 close to entry end face of selective reduction
catalyst 4. Boundary between throttling and flow guide spaces 13
and 12 in crushing deformed shape is formed as arc-like taper slope
14.
Inventors: |
TSURUTA; Tomoyuki;
(Hino-shi, JP) ; TONGU; Hirofumi; (Hino-shi,
JP) ; TOBE; Kuniharu; (Hino-shi, JP) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
HINO MOTORS, LTD. |
Hino-shi |
|
JP |
|
|
Assignee: |
HINO MOTORS, LTD.
Hino-shi
JP
|
Family ID: |
63039831 |
Appl. No.: |
16/483254 |
Filed: |
February 1, 2018 |
PCT Filed: |
February 1, 2018 |
PCT NO: |
PCT/JP2018/003487 |
371 Date: |
August 2, 2019 |
Current U.S.
Class: |
1/1 |
Current CPC
Class: |
Y02T 10/24 20130101;
F01N 3/2066 20130101; F01N 3/2892 20130101; F01N 2470/18 20130101;
F01N 3/24 20130101; F01N 2610/02 20130101; F01N 3/035 20130101;
F01N 3/08 20130101 |
International
Class: |
F01N 3/28 20060101
F01N003/28; F01N 3/20 20060101 F01N003/20 |
Foreign Application Data
Date |
Code |
Application Number |
Feb 3, 2017 |
JP |
2017-018119 |
Claims
1. An exhaust emission control device with an exhaust system
including an aftertreatment device for purifying exhaust gas
passing therethrough and with an adopted layout for turnabout
introduction of the exhaust gas into said aftertreatment device,
characterized in that it comprises a gas dispersion portion for
covering an entry end face of said aftertreatment device and for
introducing the exhaust gas thereinto through an exhaust feed port
from a direction substantially perpendicular to an axis of said
aftertreatment device and an exhaust conduit curved from the
exhaust feed port in said gas dispersion portion toward an exit
side of said aftertreatment device to extend axially of said
aftertreatment device, said gas dispersion portion being of a
crushingly deformed shape to ensure an area from said exhaust feed
port in said gas dispersion portion to a vicinity of an extension
of the axis of said aftertreatment device as a fan-likely spreading
flow guide space, a remaining area being a flat throttling space
close to the entry end face of said aftertreatment device, a
boundary between said throttling and flow guide spaces in the
crushingly deformed shape being formed as an arc-like taper
slope.
2. The exhaust emission control device as claimed in claim 1,
wherein a step is formed midway on a gradient of the taper slope,
the step being arcuate concentrically of an arc shape of said taper
slope and projecting toward the entry end face of the
aftertreatment device.
3. The exhaust emission control device as claimed in claim 1,
wherein the exhaust conduit has a flow passage cross section
upstream of the exhaust feed port in the form of a rhombus with one
of diagonals thereof being aligned with the curved direction of
said exhaust conduit.
4. The exhaust emission control device as claimed in claim 2,
wherein the exhaust conduit has a flow passage cross section
upstream of the exhaust feed port in the form of a rhombus with one
of diagonals thereof being aligned with the curved direction of
said exhaust conduit.
5. The exhaust emission control device as claimed in claim 1,
wherein a guide depression is formed on the gas dispersion portion,
said guide depression projecting into the throttling space in
position corresponding to a bisectrix of a fan shape of the flow
guide space to suppress and direct a main flow of the exhaust gas
centrally of the entry end face of the aftertreatment device.
6. The exhaust emission control device as claimed in claim 2,
wherein a guide depression is formed on the gas dispersion portion,
said guide depression projecting into the throttling space in
position corresponding to a bisectrix of a fan shape of the flow
guide space to suppress and direct a main flow of the exhaust gas
centrally of the entry end face of the aftertreatment device.
7. The exhaust emission control device as claimed in claim 3,
wherein a guide depression is formed on the gas dispersion portion,
said guide depression projecting into the throttling space in
position corresponding to a bisectrix of a fan-shape of the flow
guide space to suppress and direct a main flow of the exhaust gas
centrally of the entry end face of the aftertreatment device.
8. The exhaust emission control device as claimed in claim 4,
wherein a guide depression is formed on the gas dispersion portion,
said guide depression projecting into the throttling space in
position corresponding to a bisectrix of a fan-shape of the flow
guide space to suppress and direct a main flow of the exhaust gas
centrally of the entry end face of the aftertreatment device.
9. The exhaust emission control device as claimed in claim 5,
wherein a sensor boss is formed on the bisectrix of the fan shape
of the flow guide space between the guide depression and the taper
slope.
10. The exhaust emission control device as claimed in claim 6,
wherein a sensor boss is formed on the bisectrix of the fan shape
of the flow guide space between the guide depression and the taper
slope.
11. The exhaust emission control device as claimed in claim 7,
wherein a sensor boss is formed on the bisectrix of the fan shape
of the flow guide space between the guide depression and the taper
slope.
12. The exhaust emission control device as claimed in claim 8,
wherein a sensor boss is formed on the bisectrix of the fan shape
of the flow guide space between the guide depression and the taper
slope.
Description
TECHNICAL FIELD
[0001] The present invention relates to an exhaust emission control
device.
BACKGROUND ART
[0002] It has been recently proposed that a particulate filter for
capturing particulates in exhaust gas is incorporated in an exhaust
pipe and a selective reduction catalyst capable of selectively
reacting NO.sub.x with ammonia even in the presence of oxygen is
arranged downstream of the particulate filter, urea water as
reducing agent being added at a position between the selective
reduction catalyst and the particulate filter, thereby attaining
lessening of both the particulates and NO.sub.x.
[0003] Such addition of the urea water to the selective reduction
catalyst is conducted at the position between the particulate
filter and the selective reduction catalyst. Thus, in order to
ensure sufficient reaction time for pyrolysis of the urea water
added to the exhaust gas into ammonia and carbon dioxide gas, it is
necessary to prolong a distance between the urea-water added
position and the selective reduction catalyst. However, arrangement
of the particulate filter and the selective reduction catalyst in a
substantially spaced apart relationship will extremely impair the
mountability on a vehicle.
[0004] In order to overcome this, an exhaust emission control
device compact in size as shown in FIG. 1 has been proposed. In
such exhaust emission control device, incorporated in an exhaust
pipe 2 through which exhaust gas 1 flows from an engine is a
particulate filter 3 housed in a casing 5 to capture particles in
the exhaust gas 1; arranged downstream of and in parallel with the
particulate filter 3 and housed in a casing 6 is a selective
reduction catalyst 4 having a property capable of selectively
reacting NO.sub.x with ammonia even in the presence of oxygen. An
exit end of the particulate filter 3 is connected to an entry end
of the selective reduction catalyst 4 through an S-shaped
communication passage 7 such that the exhaust gas 1 discharged from
the exit end of the particulate filter 3 is reversely curved back
into the entry end of the adjacent selective reduction catalyst
4.
[0005] The communication passage 7 is the S-shaped structure
comprising a gas gathering portion 7A which covers the exit end of
the particulate filter 3 to gather the exhaust gas 1 just
discharged from the exit end of the particulate filter 3 through
substantially perpendicular turnabout of the gas, a mixing pipe 7B
which extracts the gathered exhaust gas 1 from the gathering
portion 7A in a direction reverse to the exhaust flow in the
particulate filter 3 and a gas dispersing portion 7C which covers
the entry end of the selective reduction catalyst 4 to disperse the
gas 1 guided by the mixing pipe 7B through substantially
perpendicular turnabout of the gas into the entry end of the
selective reduction catalyst 4. The entry end of the mixing pipe 7B
is centrally provided with an injector 8 for addition of the urea
water into the mixing pipe 7B and directed to the exit end of the
mixing pipe 7B.
[0006] In the example illustrated, arranged in the casing 5 and in
front of the particulate filter 3 is an oxidation catalyst 9 for
oxidization treatment of the exhaust gas 1, and arranged in the
casing 6 and behind the selective reduction catalyst 4 is an
ammonia lessening catalyst 10 for oxidization treatment of surplus
ammonia.
[0007] With such construction being employed, the particulates in
the exhaust gas 1 are captured by the particulate filter 3. The
urea water is added downstream of the filter and intermediately of
the mixing pipe 7B into the exhaust gas 1 by the injector 8 and is
pyrolyzed into ammonia and carbon dioxide gas, so that NO.sub.x in
the exhaust gas 1 is favorably reduced and depurated by the ammonia
on the selective reduction catalyst 4. As a result, both the
particulates and NO.sub.x in the exhaust gas 1 are lessened.
[0008] In this case, the exhaust gas 1 discharged from the exit end
of the particulate filter 3 is reversely curved back by the
communication passage 7 into the entry end of the adjacent
selective reduction catalyst 4 so that a long distance is ensured
between the urea-water added position intermediately of the
communication passage 9 and the selective reduction catalyst 4 to
ensure enough reaction time for production of ammonia from the urea
water.
[0009] Moreover, the particulate filter 3 is arranged in parallel
with the selective reduction catalyst 4 and the communication
passage 7 is arranged between and along the particulate filter 3
and selective reduction catalyst 4 so that the whole structure
becomes compact in size to substantially enhance its mountability
on a vehicle.
[0010] As a prior art literature pertinent to this kind of exhaust
emission control device, there already exists, for example, the
following Patent Literature 1.
CITATION LIST
Patent Literature
[0011] Patent Literature 1: JP 2008-196328A
SUMMARY OF INVENTION
Technical Problems
[0012] However, in such turnabout introduction of the exhaust gas 1
into the selective reduction catalyst 4, the exhaust gas 1 tends to
flow biasedly to outward of the curved direction upon the turnabout
of the exhaust gas 1, which may lead to non-uniform introduction of
the exhaust gas 1 into the selective reduction catalyst 4 and
resultant insufficient derivation of catalytic performance to be
inherently exerted.
[0013] It has been also proposed as an improved measure that the
gas dispersion portion 7C has a depression in a position opposite
to an introduction side of the exhaust gas 1 and directed toward an
entry end face of the selective reduction catalyst 4 to suppress
the flow of the exhaust gas 1. Nevertheless, it is a fact that any
depression shapes proposed up to the present may correct
longitudinal bias in flow along the introduced direction of the
exhaust gas 1 into the gas dispersion portion 7C, but cannot
concurrently contribute to improved dispersion in a lateral
direction (direction substantially parallel to the entry end face
of the selective reduction catalyst 4 and substantially
perpendicular to the introduced direction of the exhaust gas
1).
[0014] The invention was made in view of the above. Upon turnabout
introduction of exhaust gas into a selective reduction catalyst or
other aftertreatment device, the invention has its object to
correct more effectively than ever before a tendency of the exhaust
gas flowing biasedly and relatively much to outward of a curved
direction to thereby attain improvement in catalytic
performance.
Solution to Problems
[0015] The invention is directed to an exhaust emission control
device with an exhaust system including an aftertreatment device
for purifying exhaust gas passing therethrough and with an adopted
layout for turnabout introduction of the exhaust gas into said
aftertreatment device, characterized in that it comprises a gas
dispersion portion for covering an entry end face of said
aftertreatment device and for introducing the exhaust gas thereinto
through an exhaust feed port from a direction substantially
perpendicular to an axis of said aftertreatment device and an
exhaust conduit curved from the exhaust feed port in said gas
dispersion portion toward an exit side of said aftertreatment
device to extend axially of said aftertreatment device, said gas
dispersion portion being of a crushingly deformed shape to ensure
an area from said exhaust feed port in said gas dispersion portion
to a vicinity of an extension of the axis of said aftertreatment
device as a fan-likely spreading flow guide space, a remaining area
being a flat throttling space close to the entry end face of said
aftertreatment device, a boundary between said throttling and flow
guide spaces in the crushingly deformed shape being formed as an
arc-like taper slope.
[0016] In this way, the exhaust gas guided through the exhaust
conduit is changed in direction into the direction substantially
perpendicular to the axis of the aftertreatment device and is
introduced into the exhaust feed port. Thus, during its flowing
from said exhaust feed port through the fan-likely spreading flow
guide space, dispersibility in the lateral direction (direction
substantially parallel to the entry end face of the aftertreatment
device and substantially perpendicular to the introduced direction
of the exhaust gas into the exhaust feed port) is enhanced while
the flow of the exhaust gas is uniformly suppressed by the
arc-shaped taper slope. As a result, the tendency of the exhaust
gas flowing biasedly and relatively much to outward of the curved
direction is effectively corrected without causing lateral
bias.
[0017] Further, it is preferable in the invention that a step is
formed midway on a gradient of the taper slope, said step being
arcuate concentrically of an arc shape of said taper slope and
projecting toward the entry end face of the aftertreatment device.
Then, when the exhaust gas contains an additive having greater
specific gravity than the exhaust gas, the additive flowing along
an inner wall surface of the flow passage outward of the curved
direction by a centrifugal force is caused to run onto said step,
whereby the additive is broken away from the inner wall surface of
the flow passage and is diffused toward the entry end face of the
aftertreatment device. Thus, the additive whose bias has been
difficult to be corrected can be substantially improved in
dispersibility.
[0018] Further, it is preferable in the invention that the exhaust
conduit has a flow passage cross section upstream of the exhaust
feed port in the form of a rhombus with one of diagonals thereof
being aligned with the curved direction of said exhaust conduit.
Then, the flow of the exhaust gas upstream of the exhaust feed port
can be guided centrally of the exhaust conduit and be persuaded to
form a main flow substantially centrally of the exhaust conduit to
thereby further suppress generation of lateral bias upon the
turnabout of the flow.
[0019] Further, it is preferable in the invention that a guide
depression is formed on the gas dispersion portion, said guide
depression projecting into the throttling space in position
corresponding to a bisectrix of a fan shape of the flow guide space
to suppress and direct the main flow of the exhaust gas centrally
of the entry end face of the aftertreatment device. Then, when the
flow rate of the exhaust gas is lowered, the main flow of the
exhaust gas is effectively suppressed and guided centrally of the
entry end face of aftertreatment device by said guide
depression.
[0020] Further, it is preferable in the invention that a sensor
boss is formed on the bisectrix of the fan shape of the flow guide
space between the guide depression and the taper slope. Then, the
sensor boss can be utilized to position the sensor, which
contributes to direct detection of temperature or other various
information on the main flow of the exhaust gas.
Advantageous Effects of Invention
[0021] The above-mentioned exhaust emission control device
according to the invention can exhibit various excellent effects as
mentioned in the below.
[0022] (I) Upon turnabout introduction of the exhaust gas into the
aftertreatment device, the tendency of the exhaust gas flowing
relatively much and to outward of the curved direction can be
effectively corrected to an extent unattainable ever before, so
that a full volume of the aftertreatment device can be effectively
utilized to sufficiently derive the catalytic performance to be
inherently exhibited.
[0023] (II) When employed is the construction that the step is
formed midway on the gradient of the taper slope, is arcuate
concentrically of an arc shape of said taper slope and projects
toward the entry end face of the aftertreatment device, even if the
exhaust gas contains the additive having greater specific gravity
than the exhaust gas, the additive flowing along the inner wall
surface of the flow passage outward of the curved direction by the
centrifugal force can be caused to run onto the step, whereby the
additive is broken away from the inner wall surface of the flow
passage and is diffused toward the entry end face of the
aftertreatment device. Thus, the dispersibility of the additive
contained in the exhaust gas can be substantially improved to
further effectively derive the catalytic performance of the
aftertreatment device.
[0024] (III) When employed is the construction that the exhaust
conduit has the flow passage cross section upstream of the exhaust
feed port in the form of the rhombus with one of the diagonals
thereof being aligned with the curved direction of said exhaust
conduit, the formation of the flow passage cross section upstream
of the exhaust feed port in the exhaust conduit in the form of the
rhombus guides the flow of the exhaust gas upstream of the exhaust
feed port centrally of the exhaust conduit to persuade formation of
the main flow thereof substantially centrally of the exhaust
conduit, thereby further suppressing generation of lateral bias
upon turnabout of the flow, leading to further effective derivation
of the catalytic performance of the aftertreatment device.
[0025] (IV) When employed is the construction that the guide
depression is formed on the gas dispersion portion and projects
into the throttling space in position corresponding to the
bisectrix of the fan-shape of the flow guide space to suppress and
direct the main flow of the exhaust gas centrally of the entry end
face of the aftertreatment device, even if the flow rate of the
exhaust gas is lowered to lower the suppressive effect of the taper
slope, the main flow of the exhaust gas can be effectively
suppressed by the guide depression to guide the same centrally of
the entry end face of the aftertreatment device to thereby
compensate lowering of the catalytic performance due to lowering in
flow rate of the exhaust gas.
[0026] (V) When employed is the construction that the sensor boss
is formed on the bisectrix of the fan shape of the flow guide space
between the guide depression and the taper slope, the sensor boss
can be utilized to position the sensor, which contributes to direct
detection of temperature or other various information on the main
flow of the exhaust gas, leading to substantial enhancement of the
detection accuracy and realization of easily arranging the sensor
in position.
BRIEF DESCRIPTION OF DRAWINGS
[0027] FIG. 1 is a schematic diagram showing an example of a
conventional exhaust emission control device;
[0028] FIG. 2 is a perspective view showing an embodiment of the
invention;
[0029] FIG. 3 is a front view of a gas dispersion portion shown in
FIG. 2;
[0030] FIG. 4 is a view looking in a direction of arrows IV in FIG.
3;
[0031] FIG. 5 is a sectional view looking in a direction of arrows
V in FIG. 4; and
[0032] FIG. 6 is a sectional view of the gas dispersion portion
shown in FIG. 4.
DESCRIPTION OF EMBODIMENT
[0033] An embodiment of the invention will be described in
conjunction with the drawings.
[0034] FIGS. 2-6 show the embodiment of the invention. In the
embodiment relating to an exhaust emission control device
constructed similar to that explained in the above with respect to
FIG. 1, a gas dispersion portion 7C providing a downstream portion
of the communication passage 7 is constructed such that it covers
an entry end face of a selective reduction catalyst 4 as
aftertreatment device and that the exhaust gas 1 is introduced
through an exhaust feed port 11 from a direction substantially
perpendicular to an axis of the catalyst 4 (see FIG. 4). A mixing
pipe 7B guiding the exhaust gas 1 into the exhaust feed port 11 of
the gas dispersion portion 7C provides an exhaust conduit curved
from the exhaust feed port 11 toward an exit side of the selection
reduction catalyst 4 to extend axially of the selection reduction
catalyst 4. The gas dispersion portion 7C is of a crushingly
deformed shape to ensure an area extending from the exhaust feed
port 11 to a vicinity of an extension of the axis of the selective
reduction catalyst 4 in the gas dispersion portion 7C as a
fan-likely spreading flow guide space 12, a remaining area being a
flat throttling space 13 close to the entry end face of the
selective reduction catalyst 4, a boundary between the throttling
and flow guide spaces 13 and 12 in the crushingly deformed shape
being formed as an arc-like taper slope 14.
[0035] Especially in the embodiment, formed midway on a gradient of
the taper slope 14 is a step 15 which is arcuate concentrically of
an arc shape of the taper slope 14 and projects or jetties toward
the entry end face of the selective reduction catalyst 4; and the
mixing pipe 7B has a flow passage cross section upstream of the
exhaust feed port 11 in the form of a rhombus with one of diagonals
thereof being aligned with the curved direction of the mixing pipe
7B (see FIG. 5).
[0036] Formed on the gas dispersion portion 7C is a guide
depression 16 which projects into the throttling space 13 in
position corresponding to a bisectrix X of the fan shape of the
flow guide space 12 (see FIG. 3) to suppress and direct a main flow
of the exhaust gas 1 centrally of the entry end face of the
selective reduction catalyst 4. Formed on the bisectrix X (see FIG.
3) of the fan shape of the flow guide space 12 and between the
guide depression 16 and the taper slope 14 is a sensor boss 17 into
which a sensor 18 is fitted to detect a temperature of the exhaust
gas 1.
[0037] In this way, the exhaust gas 1 guided through the mixing
pipe 7B is changed in direction into the direction substantially
perpendicular to the axis of the selective reduction catalyst 4 and
is introduced into the exhaust feed port 11. While flowing from the
exhaust feed port 11 into the flow guide space 12 widened
fan-likely, the exhaust gas 1 is enhanced in dispersibility in the
lateral direction (direction substantially parallel to the entry
end face of the selective reduction catalyst 4 and substantially
perpendicular to the introduction direction of the exhaust gas 1)
and is evenly suppressed in flow by the arc-shaped taper slope 14.
Thus, the tendency of the exhaust gas 1 flowing biasedly and
relatively much to outward of the curved direction is corrected
effectively without causing any lateral bias.
[0038] In a case of an exhaust emission control device having, as
the aftertreatment device, the selective reduction catalyst 4 as
disclosed in the embodiment, the exhaust gas 1 contains misty urea
water (additive) added upstream. The misty urea water, which has
greater specific gravity than the exhaust gas 1, tends to be
prominently biased to outward of the curved direction. However, the
formation, midway on the gradient of the taper slope 14, of the
step 15 which is arcuate concentrically of the arc shape of the
taper slope 14 and projects or jetties toward the entry end face of
the selective reduction catalyst 4 causes the misty urea water
flowing along an inner wall surface of the flow passage outward of
the curved direction by a centrifugal force to run onto the step
15, whereby the misty urea water is broken away from the inner wall
surface of the flow passage and is diffused toward the entry end
face of the selective reduction catalyst 4. Thus, the misty urea
water whose bias has been difficult to be corrected can be
substantially enhanced in dispersibility.
[0039] Thus, according to the above-mentioned embodiment, upon
turnabout introduction of the exhaust gas 1 into the selective
reduction catalyst 4, the tendency of the exhaust gas 1 flowing
relatively much to outward of the curved direction thereof can be
effectively corrected to an extent unattainable ever before, so
that a full volume of the selective reduction catalyst 4 can be
effectively utilized to sufficiently derive the catalytic
performance to be inherently exhibited. Even if the misty urea
water, which has greater specific gravity than the exhaust gas 1,
is contained in the exhaust gas 1, the misty urea water flowing
along the inner wall surface of the flow passage outward of the
curved direction by the centrifugal force is caused to run onto the
step 15 so that the misty urea water can be broken away from the
inner wall surface of the flow passage and be diffused toward the
entry end face of the selective reduction catalyst 4. Thus, the
dispersibility of the misty urea water contained in the exhaust gas
1 can be also substantially enhanced, leading to further effective
derivation of the catalytic performance of the selective reduction
catalyst 4.
[0040] Further, in the embodiment, the mixing pipe 7B has the flow
passage cross section upstream of the exhaust feed port 11 in the
form of the rhombus with one of the diagonals thereof being aligned
with the curved direction of the mixing pipe 7B. Thus, the flow of
the exhaust gas 1 upstream of the exhaust feed port 11 can be
guided centrally of the mixing pipe 7B and persuaded to form a main
flow substantially centrally thereof to thereby further suppress
generation of lateral bias upon turnabout of the flow, leading to
further effective deviation of the catalytic performance of the
selective reduction catalyst 4.
[0041] Moreover, the guide depression 16 is formed in the gas
dispersion portion 7C, so that, even if the flow rate of the
exhaust gas 1 is lowered to lower the suppressive effect of the
taper slope 14, the main flow of the exhaust gas 1 can be
effectively suppressed by the guide depression 16 to guide the same
centrally of the entry end face of the selective reduction catalyst
4 to thereby compensate lowering of the catalytic performance due
to lowering in flow rate of the exhaust gas 1.
[0042] Further, in the embodiment, the sensor boss 17 is formed on
the bisectrix of the fan shape of the flow guide space 12 between
the guide depression 16 and the taper slope 14 so that the sensor
boss 17 can be utilized to position the sensor 18, which
contributes to direct detection of the temperature of the main flow
of the exhaust gas 1, leading to substantial enhancement of the
detection accuracy and realization of easily arranging the sensor
18 in position.
[0043] It is to be understood that an exhaust emission control
device according to the invention is not limited to the above
embodiment and that various changes and modifications may be made
without departing from the scope of the invention. For example,
though the embodiment illustrated is application to an entry side
of a selective reduction catalyst in an arrangement thereof in
parallel with a particulate filter, the invention may be similarly
applied to any aftertreatment device other than the selective
reduction catalyst; alternatively, the invention may be applied to
a variety of types of exhaust emission control devices with adopted
layout of turnabout introduction of exhaust gas into an
aftertreatment device.
REFERENCE SIGNS LIST
[0044] 1 exhaust gas [0045] 4 selective reduction catalyst
(aftertreatment device) [0046] 7B mixing pipe (exhaust conduit)
[0047] 7C gas dispersion portion [0048] 11 exhaust feed port [0049]
12 flow guide space [0050] 13 throttling space [0051] 14 taper
slope [0052] 15 step [0053] 16 guide depression [0054] 17 sensor
boss
* * * * *