U.S. patent application number 15/821949 was filed with the patent office on 2018-05-31 for exhaust system structure of internal combustion engine.
This patent application is currently assigned to MITSUBISHI JIDOSHA KOGYO KABUSHIKI KAISHA. The applicant listed for this patent is MITSUBISHI JIDOSHA KOGYO KABUSHIKI KAISHA. Invention is credited to Sumito HORI, Nobuhiro KAWAKAMI, Yusuke KIDO.
Application Number | 20180149065 15/821949 |
Document ID | / |
Family ID | 60452503 |
Filed Date | 2018-05-31 |
United States Patent
Application |
20180149065 |
Kind Code |
A1 |
KAWAKAMI; Nobuhiro ; et
al. |
May 31, 2018 |
EXHAUST SYSTEM STRUCTURE OF INTERNAL COMBUSTION ENGINE
Abstract
An exhaust system structure of an internal combustion engine,
includes an exhaust manifold which is configured to be connected to
a cylinder of the internal combustion engine, an exhaust pipe which
is provided on a downstream side of an exhaust flow from the
exhaust manifold, a connection member including a flange portion
which connects the exhaust pipe and the exhaust manifold to each
other and a boss portion which is provided integrally with the
flange portion and is fixed to a portion of an outer
circumferential surface of the exhaust pipe, a sensor which is
attached to the boss portion and is configured to detect components
of the exhaust, and a purification device which is connected to a
downstream end of the exhaust pipe and is disposed on a side
opposite to the boss portion with respect to the exhaust pipe.
Inventors: |
KAWAKAMI; Nobuhiro; (Tokyo,
JP) ; KIDO; Yusuke; (Tokyo, JP) ; HORI;
Sumito; (Tokyo, JP) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
MITSUBISHI JIDOSHA KOGYO KABUSHIKI KAISHA |
Tokyo |
|
JP |
|
|
Assignee: |
MITSUBISHI JIDOSHA KOGYO KABUSHIKI
KAISHA
Tokyo
JP
|
Family ID: |
60452503 |
Appl. No.: |
15/821949 |
Filed: |
November 24, 2017 |
Current U.S.
Class: |
1/1 |
Current CPC
Class: |
F01N 13/105 20130101;
F01N 13/10 20130101; F01N 2450/24 20130101; F01N 13/008 20130101;
F01N 2450/22 20130101; F01N 13/1855 20130101; F01N 2260/20
20130101; F01N 2340/02 20130101 |
International
Class: |
F01N 13/00 20060101
F01N013/00; F01N 13/10 20060101 F01N013/10 |
Foreign Application Data
Date |
Code |
Application Number |
Nov 25, 2016 |
JP |
2016-229264 |
Claims
1. An exhaust system structure of an internal combustion engine,
comprising: an exhaust manifold which is configured to be connected
to a cylinder of the internal combustion engine; an exhaust pipe
which is provided on a downstream side of an exhaust flow from the
exhaust manifold; a connection member including a flange portion
which connects the exhaust pipe and the exhaust manifold to each
other and a boss portion which is provided integrally with the
flange portion and is fixed to a portion of an outer
circumferential surface of the exhaust pipe; a sensor which is
attached to the boss portion and is configured to detect components
of the exhaust; and a purification device which is connected to a
downstream end of the exhaust pipe and is disposed on a side
opposite to the boss portion with respect to the exhaust pipe.
2. The exhaust system structure of an internal combustion engine
according to claim 1, wherein the boss portion has a cylindrical
shape which has an axis parallel to a direction in which a cylinder
head and a cylinder block of the internal combustion engine are
arranged in parallel, and wherein the sensor is attached along the
axis of the boss portion.
3. The exhaust system structure of an internal combustion engine
according to claim 1, wherein the purification device has a case
which extends in the same direction as the direction in which the
cylinder head and the cylinder block of the internal combustion
engine are arranged in parallel.
4. The exhaust system structure of an internal combustion engine
according to claim 1, wherein the purification device is provided
to be overhung toward a side of the internal combustion engine from
the connection member.
5. The exhaust system structure of an internal combustion engine
according to claim 1, wherein the exhaust manifold is built in the
cylinder head of the internal combustion engine.
6. The exhaust system structure of an internal combustion engine
according to claim 1, further comprising: a sensor cover for
surrounding the outer circumference of the sensor to block heat,
wherein a portion of the sensor cover is interposed between the
sensor and the boss portion of the connection member.
Description
CROSS REFERENCE TO RELATED APPLICATIONS
[0001] This application is based on Japanese Patent Application
(No. 2016-229264) filed on Nov. 25, 2016, the contents of which are
incorporated herein by reference.
BACKGROUND
[0002] The present invention relates to an exhaust system structure
for compactly disposing an exhaust purification device of an
internal combustion engine, an exhaust pipe provided between the
purification device and an exhaust manifold, and a sensor attached
to the exhaust pipe.
[0003] Generally, an exhaust system structure of an internal
combustion engine includes an exhaust manifold which is connected
to a cylinder and a purification device which is provided on a
downstream side of an exhaust flow from the exhaust manifold. In
addition, a sensor which detects, for example, an exhaust air-fuel
ratio or NOx concentration (hereinafter, referred to as "exhaust
component") is provided in an exhaust pipe which connects the
exhaust manifold and the purification device to each other, and
information detected by the sensor is used for controlling the
internal combustion engine.
[0004] In the exhaust system structure as described above, since
exhaust flowing out from a plurality of exhaust ports merges in a
process of flowing through the exhaust manifold and mixes with each
other in the exhaust pipe to flow into the purification device, as
the exhaust gets closer to the purification device, the way of flow
is likely to be complicated. Therefore, as the position of the
sensor is on the downstream side of the exhaust pipe (that is,
closer to purification device), the way the exhaust hits the sensor
is likely to vary and the detection accuracy of the sensor is
likely to decrease.
[0005] On the other hand, Patent Document 1 discloses a technique
in which each branch of an exhaust manifold is connected to a
common exhaust gas sensor using a communication passage and
air-fuel ratio of the internal combustion engine is controlled
based on the air-fuel ratio of the exhaust gas of each cylinder
detected by the exhaust gas sensor. According to the technique,
since the exhaust gas sensor is provided at one point where the
downstream ends of the respective communication passages are
gathered, it can be considered that variations in the way the
exhaust hits the exhaust gas sensor can be suppressed.
[0006] [Patent Document 1] JP-A-2006-17081
SUMMARY
[0007] The invention relates to an exhaust system structure of an
internal combustion engine, and an object thereof is to improve a
detection accuracy of a sensor and realize space saving. The
invention is not limited to the object and another object thereof
is also to exhibit operational effects which are derived from each
configuration illustrated in the embodiments for carrying out the
invention to be described below and which cannot be obtained by the
technique of the related art.
[0008] According to the invention, there is provided an exhaust
system structure of an internal combustion engine, including: an
exhaust manifold which is configured to be connected to a cylinder
of the internal combustion engine, an exhaust pipe which is
provided on a downstream side of an exhaust flow from the exhaust
manifold, a connection member including a flange portion which
connects the exhaust pipe and the exhaust manifold to each other
and a boss portion which is provided integrally with the flange
portion and is fixed to a portion of an outer circumferential
surface of the exhaust pipe, a sensor which is attached to the boss
portion and is configured to detect components of the exhaust, and
a purification device which is connected to a downstream end of the
exhaust pipe and is disposed on a side opposite to the boss portion
with respect to the exhaust pipe.
BRIEF DESCRIPTION OF DRAWINGS
[0009] FIG. 1 is an exploded perspective view illustrating an
exhaust system structure together with an internal combustion
engine according to an embodiment.
[0010] FIG. 2 is a cross-sectional view of a main portion of the
exhaust system structure of FIG. 1.
[0011] FIG. 3 is an exploded perspective view for explaining an
attachment structure of a protective member with respect to a
connection member.
[0012] FIG. 4 is a front view of the connection member of FIG. 3
(view seen from side where exhaust pipe is attached).
[0013] FIG. 5 is a side view for explaining the disposition of the
exhaust system structure of FIG. 1.
DETAILED DESCRIPTION OF EXEMPLIFIED EMBODIMENTS
[0014] In the technique of Patent Document 1, since the
communication passage for guiding the exhaust from each branch of
the exhaust manifold to the common exhaust gas sensor is provided
separately from the exhaust pipe between the exhaust manifold and
the purification device, space for installation of the
communication passage is necessary. Therefore, a new structure
which improves the detection accuracy of the sensor and suppresses
the exhaust system structure to be compact is required.
[0015] The invention is invented in view of the problems as
described above, and relates to an exhaust system structure of an
internal combustion engine, and an object thereof is to improve a
detection accuracy of a sensor and realize space saving. The
invention is not limited to the object and another object thereof
is also to exhibit operational effects which are derived from each
configuration illustrated in the embodiments for carrying out the
invention to be described below and which cannot be obtained by the
technique of the related art.
[0016] An exhaust system structure of an internal combustion engine
as an embodiment will be described with reference to the drawings.
The following embodiments are merely examples and there is no
intention to exclude the application of various modifications and
technologies which are not explicitly described in the following
embodiments.
1. Configuration
[0017] [1-1. Engine]
[0018] The exhaust system structure according to this embodiment is
applied to an engine (internal combustion engine) 40 illustrated in
FIG. 1. The engine 40 of this embodiment is a multi-cylinder engine
mounted on a vehicle (not illustrated). In the following
description, a direction of the engine 40 is defined in a state
where the engine 40 is mounted on the vehicle. In other words, a
front-rear direction and a left-right direction thereof are
determined with reference to the vehicle on which the engine 40 is
mounted. In addition, the direction of gravity is defined as
downward, and a direction opposite thereto is defined as upward. In
FIG. 1, a cylinder head 41 and a cylinder block 42 of the engine 40
are illustrated in a simplified manner.
[0019] The engine 40 has the cylinder head 41 and the cylinder
block 42 fixed to each other. In this embodiment, a case where the
cylinder head 41 is provided above the cylinder block 42 and a
crankshaft extends in the left-right direction will be described.
In other words, the engine 40 of this embodiment is a horizontal
placement engine in which the direction in which the cylinder head
41 and the cylinder block 42 are arranged in parallel is an up-down
direction. The direction in which the cylinder head 41 and the
cylinder block 42 are arranged in parallel and an extending
direction of the crankshaft may not be consistent with each of the
up-down direction and the left-right direction strictly and may
have a slight angle with respect to the up-down direction and the
left-right direction, for example.
[0020] A plurality of cylinders are provided in parallel in the
left-right direction inside the engine 40. An exhaust manifold 2
forming an exhaust passage is connected to each of these cylinders.
The exhaust manifold 2 has a shape in which an upstream side of the
exhaust flow branches into a plurality of branches and the
downstream side thereof collects into one. Exhaust discharged from
each cylinder is gathered in one place during flowing through the
exhaust manifold 2.
[0021] The exhaust manifold 2 of this embodiment is built in the
cylinder head 41. Specifically, the exhaust manifold 2 is built in
an overhang portion 41a in which a side surface of the cylinder
head 41 on the exhaust side bulges outward. The cylinder head 41 of
this embodiment is provided such that the overhang portion 41a
bulges rearward. In other words, the exhaust manifold 2 of this
embodiment is positioned behind the cylinder of the engine 40.
[0022] An opening 2h (hereinafter, referred to as exhaust port 2h)
at a downstream end of the exhaust manifold 2 is formed on a side
surface of the overhang portion 41a of the cylinder head 41 (outer
surface facing rearward in this embodiment). In addition, a planar
attachment surface 41b perpendicular to an exhaust flow direction
is formed around the exhaust port 2h. The attachment surface 41b of
this embodiment is provided as a surface that spreads in the
up-down direction and the left-right direction. A plurality of
fastening holes 41h to which fasteners (not illustrated) are
fastened are formed on the attachment surface 41b. In this
embodiment, four fastening holes 41h are arranged at substantially
regular intervals in a circumferential direction of the exhaust
port 2h.
[0023] [1-2. Exhaust System Structure]
[0024] The exhaust system structure according to this embodiment
includes a purification device 3 which purifies exhaust, the
exhaust manifold 2 described above, an exhaust pipe 4 which guides
exhaust from the exhaust manifold 2 to the purification device 3,
and a connection member 1 which is provided at a connection portion
between the exhaust manifold 2 and the exhaust pipe 4. In addition,
the exhaust system structure according to this embodiment further
includes a sensor 5 which is attached to the exhaust pipe 4 via the
connection member 1, a sensor cover 6 for surrounding the outer
circumference of the sensor 5 to block heat, and a heat protector 8
(protection member, see FIG. 3) which covers the exhaust pipe 4 and
the purification device 3.
[0025] The purification device 3 contains a filter (not
illustrated) which traps particulate matter in the exhaust and a
catalyst (not illustrated) which oxidizes or reduces predetermined
components in the exhaust in a case 3A. The case 3A of this
embodiment is configured of a main body portion 3c formed in a
substantially cylindrical shape and an inlet portion 3b and an
outlet portion 3d which are fixed to both ends of the main body
portion 3c, respectively. The main body portion 3c is a portion for
holding a catalyst or the like. In addition, the inlet portion 3b
is a portion forming an inlet of exhaust in the purification device
3. The inlet portion 3b is formed in a hollow shape gradually
reduced in diameter toward the upstream side. The upstream end of
the inlet portion 3b is connected to the exhaust pipe 4. On the
other hand, the outlet portion 3d is a portion forming the outlet
of the exhaust in the purification device 3. The outlet portion 3d
is formed in a hollow shape gradually reduced in diameter toward
the downstream side. The downstream end of the outlet portion 3d is
connected to a pipe 7 connected to another purification device (not
illustrated).
[0026] The exhaust pipe 4 forms an exhaust passage between the
exhaust manifold 2 and the purification device 3. In other words,
the exhaust pipe 4 is provided on the downstream side of the
exhaust flow from the exhaust manifold 2 and on the upstream side
of the exhaust flow relative to the purification device 3. The
exhaust pipe 4 is formed in a curved shape so that the directions
of the openings at both ends thereof are substantially
perpendicular to each other. The exhaust pipe 4 of this embodiment
is provided in such a posture that the exhaust pipe extends
backward from the exhaust port 2h and then bends downward. In other
words, the exhaust pipe 4 has an upstream end opening toward the
front and a downstream end opening downward. The diameter of the
exhaust pipe 4 is substantially uniform in the exhaust flow
direction.
[0027] The upstream end of the exhaust pipe 4 is connected to the
exhaust manifold 2 via the connection member 1 so as to communicate
with the exhaust port 2h. In this embodiment, the upstream end of
the exhaust pipe 4 is connected to the attachment surface 41b of
the cylinder head 41 via the connection member 1. In addition, an
inlet portion 3b of the case 3A of the purification device 3 is
fixed to the downstream end of the exhaust pipe 4, for example, by
welding. As illustrated in FIG. 2, the exhaust pipe 4 has a hole
portion 4h for allowing the tip of the sensor 5 to protrude into
the exhaust pipe 4. The hole portion 4h is formed in the vicinity
of the upstream end of the exhaust pipe 4 and is drilled on the
side opposite to the side where the downstream end is positioned
with respect to the upstream end thereof. The hole portion 4h of
this embodiment is provided on the upper side surface of the outer
circumferential surface of the exhaust pipe 4.
[0028] As illustrated in FIG. 3, the connection member 1 also
serves as three elements which are a flange for connecting the
exhaust pipe 4 to the exhaust manifold 2, a boss for attaching the
sensor 5 to the exhaust pipe 4, and an attachment base for
attaching the heat protector 8. The connection member 1 has a
flange portion 10, a boss portion 20, and an attachment portion 30
which function as the flange, the boss, and the attachment base,
respectively. The flange portion 10, the boss portion 20, and the
attachment portion 30 are integrally formed by casting, for
example, using ductile cast iron as a material.
[0029] The flange portion 10 is a flat plate-shaped portion fixed
to the exhaust manifold 2 and the exhaust pipe 4. The flange
portion 10 has an opening 11 which is passed through the flange
portion in a thickness direction thereof, a plurality of fastening
portions 12 which are fastened and fixed to the exhaust manifold 2
(attachment surface 41b of cylinder head 41 in this embodiment),
and a recessed portion 13 which is provided at the outer edge
portion between the fastening portions 12 adjacent to each other.
As illustrated in FIG. 2, the edge portion of the flange portion 10
surrounding the opening 11 is fixed to the upstream end of the
exhaust pipe 4, for example, by welding. In other words, the flange
portion 10 is fixed to the exhaust pipe 4 in a state where the
opening 11 communicates with the exhaust pipe 4. In addition, the
flange portion 10 is fixed to the exhaust manifold 2 in a state
where the opening 11 and the exhaust port 2h communicate with each
other. Hereinafter, the surface of the outer surfaces of the flange
portion 10, which abuts against the attachment surface 41b of the
cylinder head 41 in a state where the flange portion 10 is fixed to
the exhaust manifold 2, is referred to as a fastening surface 10a
and a surface opposite thereto is referred to as an end surface
10b.
[0030] As illustrated in FIG. 3 and FIG. 4, the fastening portion
12 is provided on an outside of the opening 11 in the radial
direction and two fastening portions 12 are respectively disposed
on the upper side and the lower side of the opening 11 (that is, at
four corners of opening 11). In this embodiment, the four fastening
portions 12 are disposed at substantially regular intervals in the
circumferential direction of the opening 11 and the boss portion 20
is positioned between the two upper fastening portions 12. These
fastening portions 12 have through holes 12h which are provided at
positions corresponding to the fastening holes 41h of the
attachment surface 41b of the cylinder head 41, respectively. The
fastening portion 12 of this embodiment is fixed to the cylinder
head 41 by fastening a fastener (not illustrated) inserted through
the through hole 12h to the fastening hole 41h.
[0031] The recessed portion 13 is a portion recessed toward the
opening 11 side in the outer edge portion of the flange portion 10.
The recessed portion 13 of this embodiment includes two first
recessed portions 13A between which the opening 11 is interposed
and which are disposed facing each other and a second recessed
portion 13B which is disposed on the opposite side to the boss
portion 20 with respect to the opening 11. The first recessed
portion 13A is disposed between the upper and lower fastening
portions 12 positioned on the same side with respect to the opening
11. The second recessed portion 13B is disposed between the two
lower fastening portions 12. In other words, the boss portion 20,
the fastening portion 12, and the recessed portion 13 are provided
at positions deviating from each other in the circumferential
direction of the opening 11. In a state where the connection member
1 is fixed to the exhaust pipe 4, the second recessed portion 13B
is provided adjacent to a downstream end (a connection position
with the inlet portion 3b) of the exhaust pipe 4.
[0032] As illustrated in FIG. 4, the second recessed portion 13B is
formed to have recessed amount larger than that of the first
recessed portion 13A. In other words, the recessed amount Db of the
second recessed portion 13B is set larger than the recessed amount
Da of the first recessed portion 13A (Db>Da). The recessed
amounts Da and Db referred to here are a distance between a portion
most recessed in the recessed portion 13 (closest to opening 11)
and a straight line L which connects between the edge portions
which are positioned on the outermost side of the fastening portion
12 positioned on both sides of the recessed portion 13 (which are
farthest from opening 11 in up-down direction or left-right
direction).
[0033] As illustrated in FIG. 3 and FIG. 4, the boss portion 20 is
a tubular portion to which the sensor 5 is attached. The boss
portion 20 is provided integrally with the flange portion 10. The
boss portion 20 is provided to bulge from the end surface 10b of
the flange portion 10 in the thickness direction on an outside of
the opening 11 of the flange portion 10 in the radial direction.
The boss portion 20 of this embodiment has an axis C2 orthogonal to
the center axis C1 of the opening 11 of the flange portion 10. The
center axis C1 is an axis extending in the thickness direction of
the flange portion 10. In other words, the axis C2 of the boss
portion 20 of this embodiment extends in parallel with the
fastening surface 10a and the end surface 10b of the flange portion
10. The boss portion 20 has an inner circumferential surface 23
which surrounds the axis C2, an outer wall surface 24 which is
positioned outside the inner circumferential surface 23 in the
radial direction, a lower end surface 21 and an upper end surface
22 which are provided at both ends of the inner circumferential
surface 23 and the outer wall surface 24.
[0034] A female thread process for fixing the sensor 5 is performed
on the inner circumferential surface 23. In addition, the outer
wall surface 24 is formed in a curved surface shape overhung
rearward (exhaust pipe 4 side) from the end surface 10b of the
flange portion 10. The lower end surface 21 is a surface facing
downward (opening 11 side) and forms a curved surface continuous
with the edge portion of the flange portion 10 in which the opening
11 is formed. In other words, the lower end surface 21 is formed in
a curved surface shape along a portion of the outer circumferential
surface on the upper side of the exhaust pipe 4. On the other hand,
the upper end surface 22 is a surface facing upward (side opposite
to opening 11) and is formed in a plane shape perpendicular to the
axis C2. As illustrated in FIG. 2, in a state where a columnar
space surrounded by the inner circumferential surface 23
communicates with the hole portion 4h of the exhaust pipe 4, the
boss portion 20 is fixed to a portion of the outer circumferential
surface of the exhaust pipe 4 by welding, for example.
[0035] As illustrated in FIG. 3, the attachment portion 30 is a
flat plate-like portion to which the heat protector 8 is attached.
The attachment portion 30 protrudes from the flange portion 10. Two
attachment portions 30 are disposed so as to face each other in a
state where the opening 11 is interposed therebetween. The
attachment portion 30 of this embodiment protrudes outward from the
outer edge portion of each first recessed portion 13A of the flange
portion 10 in the radial direction. In other words, the attachment
portion 30 and the first recessed portion 13A positioned on the
same side with respect to the opening 11 are provided in parallel
in the radial direction of the flange portion 10. Each attachment
portion 30 has a flat welding surface 31 facing the exhaust pipe 4
side. One surface portion of an L-shaped bracket 9 for attaching
the heat protector 8 is welded to the welding surface 31. A
fastening hole 9h is drilled in the other surface portion of the
bracket 9.
[0036] The heat protector 8 is for blocking the heat of the exhaust
flowing through in the exhaust pipe 4 and the purification device 3
from the peripheral devices. The heat protector 8 is formed in a
shape corresponding to the external shape of the exhaust pipe 4 and
the purification device 3. The heat protector 8 has a fastening
hole 8h for fixing and an edge portion 8a which is formed in a
curved shape along the outer wall surface 24 of the boss portion 20
of the connection member 1. The heat protector 8 is attached to the
connection member 1 by a fastener (not illustrated) inserted
through the fastening hole 8h and the fastening hole 9h of the
bracket 9 in a state where the edge portion 8a is brought close to
the outer wall surface 24 of the boss portion 20. The edge portion
8a of the heat protector 8 and the outer wall surface 24 of the
boss portion 20 may be used for positioning the heat protector
8.
[0037] The sensor 5 detects components of the exhaust. Specific
examples of the sensor 5 include a linear air-fuel ratio sensor
(LAFS) which detects the oxygen concentration in the exhaust, a NOx
sensor which detects the NOx concentration in the exhaust, and the
like. The information detected by the sensor 5 is used for
controlling the engine 40, for example. As illustrated in FIG. 2,
the sensor 5 includes a substantially columnar detection portion 5a
which is provided with a detection element, a screw portion 5b
which has an outer circumferential surface subjected to a male
thread process, a seat portion 5c which has a larger radial
dimension than the detection portion 5a and the screw portion 5b,
and an output portion 5d in which an output terminal is built. The
detection portion 5a, the screw portion 5b, the seat portion 5c,
and the output portion 5d are arranged coaxially in this order.
[0038] The sensor 5 is fixed to the boss portion 20 by screwing the
screw portion 5b with the inner circumferential surface 23 of the
boss portion 20 of the connection member 1. In a state where the
sensor 5 is fixed to the boss portion 20, the detection portion 5a
is provided by protruding into the exhaust pipe 4 through the hole
portion 4h of the exhaust pipe 4. The seat portion 5c interposes a
portion (bottom surface portion 6a to be described below) of the
sensor cover 6 between the seat portion 5c and the upper end
surface 22 of the boss portion 20.
[0039] The sensor cover 6 is for blocking the heat from the
surroundings of the sensor 5. The sensor cover 6 is formed in a cup
shape having such a size so as to surround the sensor 5 with a gap
between the sensor cover 6 and the sensor 5. The sensor cover 6 has
a circular bottom surface portion 6a which has a hole formed at the
center and a side surface portion 6b which stands from the outer
edge of the bottom surface portion 6a. The bottom surface portion
6a of the sensor cover 6 abuts against the upper end surface 22 of
the boss portion 20. The side surface portion 6b of the sensor
cover 6 surrounds the output portion 5d side from the seat portion
5c of the sensor 5. The sensor cover 6 is fixed by inserting the
sensor 5 into the hole of the bottom surface portion 6a and
interposing the bottom surface portion 6a between the seat portion
5c of the sensor 5 and the upper end surface 22 of the boss portion
20.
[0040] [1-3. Disposition]
[0041] As illustrated in FIG. 5, the exhaust system structure
according to this embodiment is disposed behind the cylinder of the
engine 40. In addition, as described above, the connection member 1
is provided so that the boss portion 20 is positioned above the
exhaust pipe 4. In addition, the purification device 3 is provided
on the lower side of the exhaust pipe 4. In other words, the
purification device 3 is provided on the side opposite to the boss
portion 20 with respect to the exhaust pipe 4. In other words, the
exhaust pipe 4 is positioned between the boss portion 20 of the
connection member 1 and the purification device 3 in the radial
direction of the exhaust pipe 4. In this way, the sensor 5, the
exhaust pipe 4, and the purification device 3 are provided in
parallel in the radial direction of the exhaust pipe 4 in this
order. In this embodiment, these sensors 5, the exhaust pipe 4, and
the purification device 3 are provided in parallel in the up-down
direction.
[0042] The purification device 3 is provided in a state where a
portion thereof is entered into a space below (that is, below the
exhaust manifold 2) the overhang portion 41a of the cylinder head
41. In other words, the purification device 3 is provided to toward
a side of the engine 40 from the connection member 1. In addition,
the purification device 3 of this embodiment is provided in such a
posture that the axis C3 of the case 3A extends in the up-down
direction. In other words, the case 3A according to this embodiment
extends in the same direction as the parallel arrangement direction
of the cylinder head 41 and the cylinder block 42. Here, the axis
C3 of the case 3A is the axis C3 of the main body portion 3c of the
case 3A.
[0043] Similarly, the connection member 1 is provided in such a
posture that the axis C2 of the boss portion 20 extends in the
up-down direction. In other words, the boss portion 20 of the
connection member 1 has an axis C2 parallel to the direction in
which the cylinder head 41 and the cylinder block 42 are arranged
in parallel. In addition, the sensor 5 of this embodiment is
attached along the axis C2 of the boss portion 20 of the connection
member 1. Therefore, the sensor 5 also has an axis parallel to the
parallel arrangement direction of the cylinder head 41 and the
cylinder block 42. In this way, in this embodiment, both the
purification device 3 and the sensor 5 are provided along the
direction in which the cylinder head 41 and the cylinder block 42
are arranged in parallel.
2. Action and Effect
[0044] [2-1. Exhaust System Structure]
[0045] (1) In the exhaust system structure described above, the
connection member 1 having the flange portion 10 for connecting the
exhaust manifold 2 and the exhaust pipe 4 to each other and the
boss portion 20 integrated with the flange portion 10 is provided
and the sensor 5 is attached to the boss portion 20 of the
connection member 1. In addition, a purification device 3 connected
to the downstream end of the exhaust pipe 4 is provided on the side
opposite to the boss portion 20 with respect to the exhaust pipe 4.
Therefore, the sensor 5, the exhaust pipe 4, and the purification
device 3 can be disposed compactly and space saving can be
achieved. In other words, in this embodiment, since the sensor 5,
the exhaust pipe 4, and the purification device 3 are provided in
parallel in the up-down direction, in the direction orthogonal to
the up-down direction (for example, the front-rear direction and
the left-right direction), the installation space of the sensor 5,
the exhaust pipe 4, and the purification device 3 can be suppressed
to be kept small.
[0046] In addition, since the sensor 5 is attached to the boss
portion 20 of the connection member 1 provided immediately
downstream of the exhaust manifold 2, variations in the way the
exhaust hits the sensor 5 can be suppressed. Therefore, the
detection accuracy of the sensor 5 can be improved.
[0047] (2) Since the boss portion 20 of the connection member 1 has
the axis C2 parallel to the direction in which the cylinder head 41
and the cylinder block 42 are arranged in parallel and the sensor 5
is attached along the axis C2, the sensor 5 can be arranged along
the direction in which the cylinder head 41 and the cylinder block
42 are arranged in parallel. Accordingly, since the installation
space of the sensor 5 with respect to the engine 40 can be
suppressed to be kept small, it can contribute to space saving. For
example, as compared with the configuration in which the sensor 5
is fixed to the outer circumferential surface of the curve of the
exhaust pipe 4 and at a position close to the purification device
3, since the installation space of the sensor 5 can be made smaller
according to the above configuration, space saving can be likely to
be realized.
[0048] (3) Since the case 3A of the purification device 3 extends
in the same direction as the parallel arrangement direction of the
cylinder head 41 and the cylinder block 42, the purification device
3 is disposed along the parallel arrangement direction of the
cylinder head 41 and the cylinder block 42. Accordingly, since the
installation space of the purification device 3 with respect to the
engine 40 can be suppressed to be kept small, it can contribute to
space saving.
[0049] (4) Since the purification device 3 is provided to be
further overhung toward the engine 40 side than the connection
member 1, the purification device 3 can be brought closer to the
engine 40. Therefore, it can further contribute to space
saving.
[0050] (5) Since the exhaust manifold 2 is built in the cylinder
head 41, the installation space of the exhaust manifold 2 can be
suppressed to be kept small. Therefore, it is possible to make the
exhaust system structure more compact and further contribute to
space saving.
[0051] (6) Since the sensor 5 interposes a portion of the sensor
cover 6 between the sensor 5 and the boss portion 20 of the
connection member 1, the sensor cover 6 can be attached at the same
time as attaching the sensor 5 to the boss portion 20 of the
connection member 1. Therefore, the attachment work of the sensor
cover 6 can be simplified. In addition, since a component (for
example, screw, adhesive, or the like) for attaching the sensor
cover 6 is not required, it can contribute to reduction in the
number of parts.
[0052] [2-2. Connection Member]
[0053] (1) The connection member 1 described above includes the
flange portion 10 which is fixed to the exhaust pipe 4 in a state
where the opening 11 communicates with the exhaust pipe 4, the boss
portion 20 to which the sensor 5 is attached, and an attachment
portion 30 to which the heat protector 8 is attached. In other
words, the connection member 1 also serves as three elements which
include a flange for connecting the exhaust pipe 4 to the exhaust
manifold 2, a boss for attaching the sensor 5, and an attaching
base for attaching the heat protector 8. Therefore, by connecting
the exhaust pipe 4 to the exhaust manifold 2 using the connection
member 1, the sensor 5 and the heat protector 8 can be attached to
the exhaust pipe 4 via the connection member 1. Therefore, compared
to a case where the boss portion 20 and the attachment portion 30
are provided separately from the flange portion 10, the number of
parts can be reduced and it can be contribute to reduction in the
manufacturing cost.
[0054] In addition, since the boss portion 20 is provided so as to
bulge from the flange portion 10 on the outer side of the opening
11 of the flange portion 10 in the radial direction, the sensor 5
attached to the boss portion 20 can be positioned immediately
downstream of the exhaust manifold 2. Accordingly, since variations
in the way the exhaust hits the sensor 5 can be suppressed, the
detection accuracy of the sensor 5 can be improved.
[0055] (2) Since the flange portion 10 has the recessed portion 13
recessed toward the opening 11 side at the outer edge portion
between the plurality of fastening portions 12, the volume of the
flange portion 10 can be reduced by the volume lost by the recessed
portion 13. In addition, since the boss portion 20, the fastening
portion 12, and the recessed portion 13 are provided so as to
deviate from each other in the circumferential direction of the
opening 11, the connection member 1 can be formed in a compact
shape. Accordingly, it is possible to contribute to space saving
and it is possible to reduce the weight of the connection member
1.
[0056] (3) Since the attachment portion 30 protrudes outward from
the recessed portion 13 in the radial direction, the protrusion
amount of the attachment portion 30 in the radial direction can be
reduced. Therefore, it is possible to make the connection member 1
more compact and further contribute to space saving.
[0057] (4) The connection member 1 described above is provided with
a first recessed portion 13A in which the attachment portion 30
protrudes and a second recessed portion 13B on which a larger
recessed amount is formed than that of the first recessed portion
13A. In addition, the second recessed portion 13B is provided to be
adjacent to the downstream end of the exhaust pipe 4. Therefore,
access to the downstream end of the exhaust pipe 4 is facilitated
by the second recessed portion 13B. Therefore, the work of welding
the other tubular member (inlet portion 3b of case 3A in this
embodiment) to the downstream end of the exhaust pipe 4 can be
likely to be performed.
[0058] (5) Since the attachment portion 30 has the flat welding
surface 31 to which the bracket 9 for attaching the heat protector
8 is welded, for example, compared to a case where the heat
protector 8 is fastened and fixed directly to the attachment
portion 30, the attachment portion 30 can be made thinner and the
protrusion amount of the attachment portion 30 can be suppressed.
If the attachment portion 30 is provided with a female threaded
hole, in a case where the heat protector 8 is attached by screwing
a fastener such as a bolt into the female threaded hole, there is a
need to secure the thickness of the attachment portion 30 according
to the length of the screw portion of the fastener. In addition, in
this case, in order to secure a clearance between the heat
protector 8 and the exhaust pipe 4, there is a need to increase the
protrusion amount of the attachment portion 30 from the flange
portion 10. On the other hand, in a case where the heat protector 8
is attached via the bracket 9 as described above, since it is
sufficient to provide the flat welding surface 31 on the attachment
portion 30, the attachment portion 30 can be made thin and the
protrusion amount of the attachment portion 30 can be suppressed.
Therefore, the weight of the connection member 1 can be
reduced.
3. Modification Example
[0059] Regardless of the embodiment described above, various
modifications can be made without departing from the spirit of the
invention. The respective configurations of this embodiment can be
selected as required or may be combined appropriately.
[0060] In the embodiment described above, although a case where the
parallel arrangement direction of the cylinder head 41 and the
cylinder block 42 is the up-down direction is exemplified, the
parallel arrangement direction thereof is not particularly limited.
In addition, the orientation (posture) in which the engine 40 is
disposed and the position of the exhaust system structure with
respect to the engine 40 are not limited to those described above.
For example, the cylinder head 41 may be provided so that the
overhang portion 41a bulges forward or leftward and rightward. In
other words, the exhaust manifold 2 may be positioned in front of
or on the left and right of the cylinder of the engine 40. In
addition, along with this, the connection member 1, the exhaust
pipe 4, the purification device 3, or the like may be disposed in
front of or on the left and right of the engine 40.
[0061] In the embodiment described above, although a case where the
exhaust manifold 2 is built in the cylinder head 41 is exemplified,
the exhaust manifold 2 may be provided separately from the cylinder
head 41. In a case where the exhaust manifold 2 is separate from
the cylinder head 41, the attachment base of the flange portion 10
of the connection member 1 may not be the cylinder head 41 but may
be a flange portion provided at the downstream end of the exhaust
manifold 2, for example.
[0062] This exhaust system structure is applicable not only to the
multi-cylinder engine like the engine 40 but also to a single
cylinder engine. In a case where this exhaust system structure is
applied to a single cylinder engine, the exhaust manifold is
connected to each of a plurality of exhaust ports provided in the
cylinder.
[0063] In the embodiment described above, although a case where the
boss portion 20 of the connection member 1 has a cylindrical shape
and has the axis C2 parallel to the direction in which the cylinder
head 41 and the cylinder block 42 are arranged in parallel is
exemplified, the shape of the boss portion 20 and the direction of
the axis C2 are not limited to the those described above. The boss
portion 20 may be any boss portion as long as the boss portion can
be attached so that at least the sensor 5 can detect the components
of the exhaust in the exhaust pipe 4. Similarly, the shape and the
extending direction (the direction of the axis C3) of the case 3A
of the purification device 3 are not limited to those described
above.
[0064] The sensor 5 may be attached along the direction crossing
the axis C2 of the boss portion 20 of the connection member 1, with
respect to the direction in which the cylinder head 41 and the
cylinder block 42 are arranged in parallel. However, it is
preferable that the sensor 5 is provided so as not to be further
overhung than the purification device 3 in a direction orthogonal
to the axis C3 of the case 3A. In other words, as illustrated in
FIG. 5, it is preferable that the sensor 5 is installed so as to be
accommodated in an area E where the maximum outer diameter portion
of the purification device 3 is extended in the direction of the
axis C3. In other words, it is preferable that the entire sensor 5
is provided so as to overlap with the purification device 3 in the
direction of the axis C3. By installing the sensor 5 in this
manner, since it is possible to suppress the installation space of
the sensor 5 with respect to the purification device 3 in a
direction orthogonal to the axis C3 of the purification device 3,
it can contribute to space saving.
[0065] In addition, in a case where it is unnecessary for the
connection member 1 to serve as an element which is an attachment
base of the heat protector 8, the attachment portion 30 may be
omitted from the connection member 1. Even in a case where the
attachment portion 30 is omitted, since the sensor 5, the exhaust
pipe 4, and the purification device 3 can be disposed compactly as
described above according to the exhaust system structure, space
saving can be achieved and the detection accuracy of the sensor 5
can be improved. In addition, if the attachment portion 30 is
omitted, the weight of the connection member 1 can be reduced by
the amount of the omitted attachment portion 30.
[0066] Similarly, the fastening portion 12 and the recessed portion
13 may be omitted from the connection member 1. For example, the
fastening portion 12 may be omitted from the connection member 1
and the fastening surface 10a of the flange portion 10 may be
welded and fixed to the exhaust manifold 2. In addition, the
recessed portion 13 may be omitted from the connection member 1 and
the flange portion 10 may be formed in a simple shape such as a
circle or a rectangle.
[0067] The sensor 5 may be any sensor as long as the sensor detects
components of exhaust and the specific type thereof is not
particularly limited. Similarly, the purification device 3 may
contain a filter, a catalyst or the like for purifying exhaust and
the specific type thereof is not particularly limited.
[0068] In the exhaust system structure described above, the
connection member having the flange portion for connecting the
exhaust manifold and the exhaust pipe to each other and the boss
portion integrated with the flange portion is provided and the
sensor 5 is attached to the boss portion of the connection member.
In addition, a purification device connected to the downstream end
of the exhaust pipe is provided on the side opposite to the boss
portion with respect to the exhaust pipe. Therefore, the sensor,
the exhaust pipe, and the purification device can be disposed
compactly and space saving can be achieved. In addition, since the
sensor is attached to the boss portion of the connection member
provided immediately downstream of the exhaust manifold, variations
in the way the exhaust hits the sensor can be suppressed.
Therefore, the detection accuracy of the sensor can be
improved.
* * * * *