U.S. patent application number 14/960008 was filed with the patent office on 2017-06-08 for exhaust structure of vehicle.
This patent application is currently assigned to HONDA MOTOR CO., LTD.. The applicant listed for this patent is HONDA MOTOR CO., LTD.. Invention is credited to Satoru NOJIMA, Katsuaki SHIBUKI, Masaya YAZAKI.
Application Number | 20170159531 14/960008 |
Document ID | / |
Family ID | 58798234 |
Filed Date | 2017-06-08 |
United States Patent
Application |
20170159531 |
Kind Code |
A1 |
SHIBUKI; Katsuaki ; et
al. |
June 8, 2017 |
EXHAUST STRUCTURE OF VEHICLE
Abstract
To elongate an exhaust tail pipe wherein a muffler is covered by
a rear cowl. An exhaust structure of a vehicle including a rear
cowl covering a vehicle rear portion, a rear bank-muffler including
a first and second expansion chamber partitioned by a partition, a
first and second connecting pipe connecting the expansion chambers,
and a tail pipe configured to discharge exhaust air from the rear
bank-muffler. The rear bank-muffler is covered by the rear cowl,
wherein outlines of the rear bank-muffler and the rear cowl are
each formed such that the width decreases toward the vehicle rear.
The tail pipe, the first connecting pipe, and the second connecting
pipe are provided so as to penetrate the partition. A position
where the tail pipe penetrates the partition and positions where
the first connecting pipe and second connecting pipe penetrate the
partition are offset from each other in the vertical direction.
Inventors: |
SHIBUKI; Katsuaki;
(Wako-shi, JP) ; YAZAKI; Masaya; (Wako-shi,
JP) ; NOJIMA; Satoru; (Wako-shi, JP) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
HONDA MOTOR CO., LTD. |
Tokyo |
|
JP |
|
|
Assignee: |
HONDA MOTOR CO., LTD.
Tokyo
JP
|
Family ID: |
58798234 |
Appl. No.: |
14/960008 |
Filed: |
December 4, 2015 |
Current U.S.
Class: |
1/1 |
Current CPC
Class: |
B62J 17/00 20130101;
F01N 3/2885 20130101; Y02A 50/2322 20180101; F01N 13/1838 20130101;
F01N 1/089 20130101; B62K 11/04 20130101; F01N 2340/00 20130101;
F01N 13/082 20130101; Y02A 50/20 20180101; F01N 2230/04 20130101;
F01N 2590/04 20130101 |
International
Class: |
F01N 3/28 20060101
F01N003/28; B62J 17/00 20060101 B62J017/00; B62K 11/04 20060101
B62K011/04; F01N 1/08 20060101 F01N001/08; B62M 7/02 20060101
B62M007/02 |
Claims
1. An exhaust structure of a vehicle comprising: an engine; an
exhaust device operatively connected to the engine; and a rear cowl
covering a vehicle rear portion, said exhaust device including an
exhaust pipe and a muffler connected to a rear portion of the
exhaust pipe, said muffler including a main body formed by a top
wall extending beneath and along a top face of the rear cowl and a
bottom wall extending obliquely upwardly in a rear direction of the
vehicle above and along a bottom face of the rear cowl, a plurality
of expansion chambers partitioned by a partition, connecting pipes
connecting the plurality of expansion chambers, and a tail pipe
configured to discharge exhaust air from said muffler; said muffler
being covered by said rear cowl, wherein: outlines of said muffler
and said rear cowl are each formed such that a width decreases
toward the rear direction of the vehicle; said tail pipe and said
connecting pipes are provided so as to penetrate said partition;
positions where said tail pipe and said connecting pipes penetrate
said partition are offset from each other in the vertical
direction; and an outline of said muffler is formed such that the
bottom wall of the main body that extends obliquely upwardly in the
rear direction of the vehicle above and along the bottom face of
the rear cowl forms a width in a height position where said tail
pipe is arranged that is smaller relative to a width in a height
position where said connecting pipe and a catalyst are
arranged.
2. The exhaust structure of a vehicle according to claim 1,
wherein: one end of said tail pipe is arranged in a foremost
expansion chamber among said expansion chambers of said muffler;
and the other end of said tail pipe is opened to outside air from a
rear portion of said muffler.
3. The exhaust structure of a vehicle according to claim 1,
wherein: said muffler is partitioned into a first expansion chamber
in a rear portion and a second expansion chamber in a front
portion; exhaust air introduced into said muffler from said exhaust
pipe flows into said second expansion chamber through said
connecting pipes; the one end of said tail pipe is arranged in said
second expansion chamber; and the other end of said tail pipe is
opened to outside air from a rear portion of said muffler.
4. The exhaust structure of a vehicle according to claim 2,
wherein: said muffler is partitioned into a first expansion chamber
in a rear portion and a second expansion chamber in a front
portion; exhaust air introduced into said muffler from said exhaust
pipe flows into said second expansion chamber through said
connecting pipes; the one end of said tail pipe is arranged in said
second expansion chamber; and the other end of said tail pipe is
opened to outside air from a rear portion of said muffler.
5. The exhaust structure of a vehicle according to claim 1,
wherein: the catalyst is accommodated inside said muffler and is
supported by said partition; and the catalyst and said connecting
pipe are arranged at substantially the same height in the vertical
direction.
6. The exhaust structure of a vehicle according to claim 2,
wherein: the catalyst is accommodated inside said muffler and is
supported by said partition; and the catalyst and said connecting
pipe are arranged at substantially the same height in the vertical
direction.
7. The exhaust structure of a vehicle according to claim 3,
wherein: the catalyst is accommodated inside said muffler and is
supported by said partition; and the catalyst and said connecting
pipe are arranged at substantially the same height in the vertical
direction.
8. The exhaust structure of a vehicle according to claim 5, wherein
said catalyst is formed into a flat shape whose longitudinal
direction is its width direction.
9.-10. (canceled)
11. The exhaust structure of a vehicle according to claim 1,
wherein: a tubular cover member covers a part of said tail pipe
from outside in the radial direction; ends of said catalyst and
said connecting pipe are opposed to an inner wall of said muffler;
and a space between said cover member and said tail pipe
communicates into said first expansion chamber through a connecting
portion between said cover member and said inner wall.
12. The exhaust structure of a vehicle according to claim 2,
wherein: a tubular cover member covers a part of said tail pipe
from outside in the radial direction; ends of said catalyst and
said connecting pipe are opposed to an inner wall of said muffler;
and a space between said cover member and said tail pipe
communicates into said first expansion chamber through a connecting
portion between said cover member and said inner wall.
13. The exhaust structure of a vehicle according to claim 3,
wherein: a tubular cover member covers a part of said tail pipe
from outside in the radial direction; ends of said catalyst and
said connecting pipe are opposed to an inner wall of said muffler;
and a space between said cover member and said tail pipe
communicates into said first expansion chamber through a connecting
portion between said cover member and said inner wall.
14. The exhaust structure of a vehicle according to claim 11,
wherein: said cover member is connected to said muffler by welding;
and a connecting portion thereof is tapered in side view.
15. An exhaust structure of a vehicle comprising: an engine; an
exhaust device operatively connected to the engine; and an exhaust
pipe and a muffler connected to a rear portion of the exhaust pipe;
a plurality of expansion chambers formed in said muffler, said
plurality of expansion chambers being partitioned by a partition;
connecting pipes connecting the plurality of expansion chambers; a
tail pipe configured to discharge exhaust air from said muffler; a
rear cowl covering a vehicle rear portion, said muffler being
covered by said rear cowl and including a main body formed by a top
wall extending beneath and along a top face of the rear cowl and a
bottom wall extending obliquely upwardly in a rear direction of the
vehicle above and along a bottom face of the rear cowl, wherein:
outlines of said muffler and said rear cowl are each formed such
that a width decreases toward the rear direction of the vehicle;
said tail pipe and said connecting pipes are provided so as to
penetrate said partition; positions where said tail pipe and said
connecting pipes penetrate said partition are offset from each
other in the vertical direction; and an outline of said muffler is
formed such that the bottom wall of the main body that extends
obliquely upwardly in the rear direction of the vehicle above and
along the bottom face of the rear cowl forms a width in a height
position where said tail pipe is arranged that is smaller relative
to a width in a height position where said connecting pipe and a
catalyst are arranged.
16. The exhaust structure of a vehicle according to claim 15,
wherein: one end of said tail pipe is arranged in a foremost
expansion chamber among said expansion chambers of said muffler;
and the other end of said tail pipe is opened to outside air from a
rear portion of said muffler.
17. The exhaust structure of a vehicle according to claim 15,
wherein: said muffler is partitioned into a first expansion chamber
in a rear portion and a second expansion chamber in a front
portion; exhaust air introduced into said muffler from said exhaust
pipe flows into said second expansion chamber through said
connecting pipes; the one end of said tail pipe is arranged in said
second expansion chamber; and the other end of said tail pipe is
opened to outside air from a rear portion of said muffler.
18. The exhaust structure of a vehicle according to claim 15,
wherein: the catalyst is accommodated inside said muffler and is
supported by said partition; and the catalyst and said connecting
pipe are arranged at substantially the same height in the vertical
direction.
19. The exhaust structure of a vehicle according to claim 18,
wherein said catalyst is formed into a flat shape whose
longitudinal direction is its width direction.
20. (canceled)
Description
BACKGROUND OF THE INVENTION
[0001] 1. Field of the Invention
[0002] The present invention relates to an exhaust structure of a
vehicle.
[0003] 2. Description of Background of the Invention
[0004] An exhaust device is known for installation in a vehicle
that includes a muffler in a rear portion of the exhaust device
extending rearwardly from an engine is arranged inside a rear cowl
that covers a vehicle rear portion. See, for example, Japanese
Patent Application Publication No. 2005-83286. In Japanese Patent
Application Publication No. 2005-83286, two tail pipes for
discharging exhaust air to the outside are provided.
[0005] In a case of arranging a muffler inside a rear cowl as in
the aforementioned conventional exhaust structure, the muffler
needs to be formed in correspondence with the shape of the rear
cowl, which limits the shape of the muffler. Even under such a
limitation, it is desirable that the tail pipe be formed as long as
possible to increase the flow velocity of exhaust air in the final
stage, depending on the required output characteristic of an
engine.
SUMMARY AND OBJECTS OF THE INVENTION
[0006] The present invention has been made in view of the
circumstances mentioned above, and aims to elongate a tail pipe in
an exhaust structure of a vehicle whose muffler is covered by a
rear cowl.
[0007] To achieve the above objective, an embodiment of the present
invention provides an exhaust structure of a vehicle comprising an
engine (11); an exhaust device (25) of the engine (11); and a rear
cowl (35) covering a vehicle rear portion. The exhaust device (25)
includes an exhaust pipe (28) and a muffler (29) connected to a
rear portion of the exhaust pipe (28). The muffler (29) includes
multiple expansion chambers (C1, C2) partitioned by a partition
(65), connecting pipes (67, 68) connecting the multiple expansion
chambers (C1, C2), and a tail pipe (69) configured to discharge
exhaust air from the muffler (29). The muffler (29) is covered by
the rear cowl (35), wherein: outlines of the muffler (29) and the
rear cowl (35) are each formed such that the width decreases toward
the vehicle rear. The tail pipe (69) and the connecting pipes (67,
68) are provided so as to penetrate the partition (65) and
positions where the tail pipe (69) and the connecting pipes (67,
68) penetrate the partition (65) are offset from each other in the
vertical direction.
[0008] According to an embodiment of the present invention, the
penetrating positions of the connecting pipes do not interfere with
that of the tail pipe, whereby the tail pipe can be elongated even
when the muffler and rear cowl are formed such that their widths
decrease toward the vehicle rear. In addition, the muffler can be
downsized in the width direction.
[0009] According to an embodiment of the present invention, one end
(69a) of the tail pipe (69) is arranged in a foremost expansion
chamber (C2) among the expansion chambers of the muffler (29); and
the other end (69b) of the tail pipe (69) is opened to outer air
from a rear portion of the muffler (29).
[0010] According to an embodiment of the present invention, it is
possible to elongate the tail pipe by extending it from the
foremost expansion chamber.
[0011] According to an embodiment of the present invention, the
muffler (29) is partitioned into a first expansion chamber (C1) in
a rear portion and a second expansion chamber (C2) in a front
portion. Exhaust air introduced into the muffler (29) from the
exhaust pipe (28) flows into the second expansion chamber (C2)
through the connecting pipes (67, 68). One end (69a) of the tail
pipe (69) is arranged in the second expansion chamber (C2) and the
other end (69b) of the tail pipe (69) is opened to outside air from
the rear portion of the muffler (29).
[0012] According to an embodiment of the present invention, it is
possible to elongate the tail pipe by extending it from the second
expansion chamber in the front portion to the rear portion of the
muffler.
[0013] According to an embodiment of the present invention, a
catalyst (67) accommodated inside the muffler (29) is supported by
the partition (65); and the catalyst (67) and the connecting pipe
(68) are arranged at substantially the same height in the vertical
direction.
[0014] According to an embodiment of the present invention,
although the catalyst is accommodated inside the muffler in this
configuration, the catalyst can be prevented from interfering with
the tail pipe, and thus the tail pipe can be elongated.
[0015] According to an embodiment of the present invention, the
catalyst (67) is formed into a flat shape whose longitudinal
direction is its width direction.
[0016] According to an embodiment of the present invention, the
catalyst can be downsized in the vertical direction while ensuring
capacity of the catalyst. Consequently, the catalyst does not
interfere with the tail pipe, so that the tail pipe can be
elongated.
[0017] According to an embodiment of the present invention, an
outline of the muffler (29) is formed such that a width (W2) in a
height position where the tail pipe (69) is arranged is smaller
than a width (W1) in a height position where the connecting pipe
(68) and the catalyst (67) are arranged.
[0018] According to an embodiment of the present invention, the
width of the portion of the rear cowl covering the vicinity of the
tail pipe can be reduced, whereby the muffler and rear cowl can be
downsized.
[0019] According to an embodiment of the present invention, a
tubular cover member (70) covers a part of the tail pipe (69) from
outside in the radial direction; ends of the catalyst (67) and the
connecting pipe (68) are opposed to an inner wall of the muffler
(29); and a space between the cover member (70) and the tail pipe
(69) communicates into the first expansion chamber (C1) through a
connecting portion (72) between the cover member (70) and the inner
wall.
[0020] According to an embodiment of the present invention, since
the space between the tubular cover member and tail pipe can be
used as an expansion chamber, the muffler can be downsized while
capacity of the expansion chamber can be ensured.
[0021] According to an embodiment of the present invention, the
cover member (70) is connected to the muffler (29) by welding; and
a connecting portion (73a) of the connection is tapered in side
view.
[0022] According to an embodiment of the present invention, an area
of the welding portion of the cover member can be enlarged, and
rigidity can be enhanced.
[0023] In the exhaust structure of a vehicle according to an
embodiment of the present invention, the tail pipe can be elongated
even when the muffler and rear cowl are formed such that their
widths decrease toward the vehicle rear. In addition, the muffler
can be downsized in the width direction.
[0024] It is also possible to elongate the tail pipe by extending
it from the foremost expansion chamber.
[0025] It is also possible to elongate the tail pipe by extending
it from the second expansion chamber in the front portion to the
rear portion of the muffler.
[0026] Further, the catalyst does not interfere with the tail pipe,
so that the tail pipe can be elongated.
[0027] In addition, the width of the rear cowl can be reduced,
whereby the muffler and rear cowl can be downsized.
[0028] Also, the muffler can be downsized while capacity of the
expansion chamber can be ensured.
[0029] Moreover, an area of the welding portion of the cover member
can be enlarged, and rigidity can be enhanced.
[0030] Further scope of applicability of the present invention will
become apparent from the detailed description given hereinafter.
However, it should be understood that the detailed description and
specific examples, while indicating preferred embodiments of the
invention, are given by way of illustration only, since various
changes and modifications within the spirit and scope of the
invention will become apparent to those skilled in the art from
this detailed description.
BRIEF DESCRIPTION OF THE DRAWINGS
[0031] The present invention will become more fully understood from
the detailed description given hereinbelow and the accompanying
drawings which are given by way of illustration only, and thus are
not limitative of the present invention, and wherein:
[0032] FIG. 1 is a right side view of a motorcycle including an
exhaust structure of a vehicle of the present invention;
[0033] FIG. 2 is a right side view of the periphery of a rear
cowl;
[0034] FIG. 3 is a plan view of the rear cowl as seen from
above;
[0035] FIG. 4 is a plan view of the periphery of the rear cowl as
seen from below;
[0036] FIG. 5 is a perspective view of a rear bank side-exhaust
device;
[0037] FIG. 6 is a plan view of a rear bank-muffler as seen from
above;
[0038] FIG. 7 is a cross-sectional view taken along line VII-VII of
FIG. 6;
[0039] FIG. 8 is a cross-sectional view of the rear bank-muffler as
seen from the left side;
[0040] FIG. 9 is a cross-sectional view of a rear portion of the
rear bank-muffler; and
[0041] FIG. 10 is a front view of a partition as seen from the
vehicle rear side.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS
[0042] Hereinafter, an embodiment of the present invention will be
described with reference to the drawings. Note that in the
description, directions such as front, rear, left, and right
coincide with directions relative to the vehicle body if not stated
otherwise. In addition, in the drawings, reference numeral FR
indicates the front of the vehicle body, UP the upper direction of
the vehicle body, and LE the left of the vehicle.
[0043] FIG. 1 is a right side view of a motorcycle 10 including an
exhaust structure of a vehicle of the present invention.
[0044] The motorcycle 10 is a vehicle in which an engine 11 is
supported by a body frame F; a front fork 12 supporting a front
wheel 2 is steerably supported at the front end of the body frame
F; and a swing arm 13 supporting a rear wheel 3 is provided on the
rear side of the body frame F. The motorcycle 10 is a straddle type
vehicle where a seat 14 on which a rider sits in a straddling
manner is supported on a top portion of the body frame F.
[0045] The body frame F includes a head pipe 15 supporting the
front fork 12 at the front end; paired left and right mainframes 16
extending obliquely downwardly in the rear direction from the head
pipe 15; and paired left and right center frames 17 extending
downwardly from rear portions of the mainframes 16. The body frame
F also includes paired left and right seat frames (not shown)
extending obliquely upwardly from rear portions of the mainframes
16 to a rear portion of the vehicle.
[0046] The swing arm 13 is supported in a vertically-swingable
manner by a pivot shaft 18 provided in middle portions in the
vertical direction of the left and right center frames 17. The rear
wheel 3 is axially supported by an axle 19 at a rear end portion of
the swing arm 13.
[0047] A steering handle 20 is attached to a top end portion of the
front fork 12 with the front wheel 2 being supported to a bottom
end portion of the front fork 12 through an axle 21.
[0048] A fuel tank 22 is supported by the left and right center
frames 17 behind the head pipe 15. The seat 14 is positioned behind
the fuel tank 22 and supported by the aforementioned seat
frames.
[0049] The engine 11 is a V4 engine in which cylinders are arranged
in a V-shape in the longitudinal direction. The engine 11 includes
a crankcase 23 supporting a crankshaft extending in the vehicle
width direction; a front bank 47F configured of two cylinders
extending to the front from the crankcase 23 in an inclined manner;
and a rear bank 47R configured of two cylinders extending
rearwardly from the crankcase 23 in an inclined manner.
[0050] The engine 11 has a front bank side-exhaust device 24
connected to the front bank 47F, and a rear bank side-exhaust
device 25 (exhaust device) connected to the rear bank 47R.
[0051] The front bank side-exhaust device 24 has an exhaust pipe 26
drawn from front faces of cylinder heads of the cylinders in the
aforementioned front bank 47F and then collected into one pipe on
its rear end side; and a front bank-muffler 27 arranged outside the
swing arm 13 and connected to the rear end of the exhaust pipe
26.
[0052] The rear bank side-exhaust device 25 has an exhaust pipe 28
drawn from rear faces of cylinder heads of the cylinders in the
rear bank 47R and then collected into one pipe on its rear end
side; and a rear bank-muffler 29 arranged in a rear end portion of
the motorcycle 10 and connected to the rear end of the exhaust pipe
28.
[0053] The motorcycle 10 includes a resin body cover 30 covering
the vehicle body. The body cover 30 includes a front side cover 31
covering a front portion of the engine 11, the head pipe 15, and
the mainframes 16; a front cowl 32 covering the head pipe 15 from
the front; and an under cover 33 covering the engine 11 from below.
The body cover 30 also includes a middle cover 34 covering the rear
bank side-exhaust device 25 below the seat 14, and a rear cowl 35
covering the rear bank-muffler 29 behind the seat 14.
[0054] A rear stay 36 extending obliquely downwardly in the rear
direction is provided on a lower face of the rear cowl 35, and a
pair of blinkers 37 projecting to the left and right are provided
at the rear end of the rear stay 36. A plate-shaped license plate
holder 38 extending downwardly in the rear direction is also
provided at the rear end of the rear stay 36.
[0055] A rear wheel cover 39 covering the rear wheel 3 from the
upper front is attached to a front portion of the swing arm 13. A
front fender 40 is attached to the front fork 12.
[0056] FIG. 2 is a right side view of the periphery of the rear
cowl 35. FIG. 3 is a plan view of the rear cowl 35 as seen from
above. FIG. 4 is a plan view of the periphery of the rear cowl 35
as seen from below.
[0057] Referring to FIGS. 2 to 4, the middle cover 34 has an
upwardly-extending portion 34a raised upwardly in the rear
direction from the rear end side of the seat 14. Air introduction
holes 34b, 34b communicating into the inside of the body cover 30
are provided on left and right sides of the upwardly-extending
portion 34a.
[0058] The rear cowl 35 is provided so as to be continuous with the
rear edge of the upwardly-extending portion 34a, and extends to the
rear end of the body cover 30.
[0059] An outline of the rear cowl 35 is formed such that in plan
view, its width increases toward the front end, and gradually
decreases toward the vehicle rear, becoming narrower toward the
rear end. More specifically, the outline of the rear cowl 35 in a
plan view as seen from above includes a front edge portion 35a
extending substantially straight in the width direction along the
rear edge of the upwardly-extending portion 34a; side edge portions
35b, 35b extending rearwardly from left and right ends of the front
edge portion 35a such that a distance therebetween becomes shorter
toward the rear; and a rear edge portion 35c connecting the rear
ends of the side edge portions 35b, 35b.
[0060] The outline of the rear cowl 35 is formed such that in a
side view, its thickness increases in the vertical direction toward
the front end, and gradually decreases toward the vehicle rear,
growing thinner toward the rear end.
[0061] A top face 41 of the rear cowl 35 is curved such that its
center in the vehicle width direction is positioned at the highest
point, and portions continuous therewith become lower toward the
outer sides in the vehicle width direction. The top face is also
formed so as to be slightly inclined downwardly in the rear
direction in side view.
[0062] A bottom face 42 of the rear cowl 35 is inclined upwardly in
the rear direction in a side view. The bottom face 42 of the rear
cowl 35 has a downwardly-bulging portion 42a bulging downwardly in
its center in the vehicle width direction, and has a curved shape
where the center in the vehicle width direction is positioned at
the lowest point, and portions continuous therewith become higher
toward the outer sides in the vehicle width direction. The
downwardly-bulging portion 42a extends from the front end of the
rear cowl 35 to a rear portion thereof.
[0063] A ventilating hole 43 long in the longitudinal direction is
provided on each of left and right side faces of a front portion of
the rear cowl 35. An inward-bulging portion 43a where a part of the
rear cowl 35 bulges inwardly is formed in a front portion of the
ventilating hole 43.
[0064] In addition, in the bottom face 42 of the rear cowl 35,
exhaust holes 44, 44 long in the longitudinal direction are
provided in bottom face-side portions 42b, 42b on left and right
sides of the downwardly-bulging portion 42a. The exhaust holes 44,
44 are positioned behind the ventilating holes 43. A rear opening
45 designed to expose a rear portion of the rear bank-muffler 29 is
provided in a rear end portion of the downwardly-bulging portion
42a.
[0065] The rear bank-muffler 29 is cooled by a flow of air
introduced from the air introduction holes 34b, 34b and discharged
from the exhaust holes 44, 44 as well as the rear opening 45.
[0066] Stay fixing portions 46, 46 to which the front end of the
rear stay 36 is fastened are provided in a base portion of the
downwardly-bulging portion 42a between the rear opening 45 and the
left and right exhaust holes 44, 44.
[0067] FIG. 5 is a perspective view of the rear bank side-exhaust
device 25.
[0068] As shown in FIG. 5, the exhaust pipe 28 of the rear bank
side-exhaust device 25 includes paired exhaust port connecting
pipes 50, 50 drawn rearwardly from the cylinder heads of the
cylinders of the rear bank 47R; upwardly-extending pipes 51, 51
extending upwardly in the rear direction from the rear ends of the
exhaust port connecting pipes 50, 50; and a junction pipe 52 where
the upwardly-extending pipes 51, 51 are joined into one pipe. The
exhaust pipe 28 extends rearwardly while passing through one side
(right side) in the vehicle width direction on which the front
bank-muffler 27 is arranged.
[0069] The upwardly-extending pipes 51, 51 are not only fitted to
the exhaust port connecting pipes 50, 50, but also connected to the
exhaust port connecting pipes 50, 50 by multiple springs 53 bridged
between the exhaust port connecting pipes 50, 50 and the
upwardly-extending pipes 51, 51.
[0070] The junction pipe 52 has an exhaust valve (not shown)
provided therein to vary an area of its flow path, and an actuator
54 provided on its outer face to activate the exhaust valve. The
rear bank-muffler 29 is connected to the rear end of the junction
pipe 52.
[0071] FIG. 6 is a plan view of the rear bank-muffler 29 as seen
from above. FIG. 6 shows not only the rear bank-muffler 29 but also
the outline of the rear cowl 35 indicated by a two-dot chain
line.
[0072] As shown in FIGS. 5 and 6, the rear bank-muffler 29 includes
a muffler main body 55 formed into a box shape that fits inside the
rear cowl 35, and a tubular tail portion 56 extending rearwardly
from a rear portion of the muffler main body 55.
[0073] The muffler main body 55 is configured by coupling an upper
half body 59a (FIG. 8) and a lower half body (FIG. 8) obtained by
dividing the box shape into upper and lower parts. FIG. 6 shows a
state where the upper half body 59a is separated and removed from
the muffler main body 55 for a clear view of the internal
structure.
[0074] The muffler main body 55 is configured in accordance with
the shape of the rear cowl 35, and is formed such that its width is
maximized on the front end side, and decreases toward the vehicle
rear. An outline of the muffler main body 55 has, in plan view,
side edge portions 55a, 55a following the side edge portions 35b,
35b of the rear cowl 35, and a rear edge portion 55b connecting the
rear ends of the side edge portions 55a, 55a.
[0075] The muffler main body 55 has an exhaust pipe connecting
portion 57 bulging downwardly in the front direction, on one side
(right side) in the vehicle width direction in its front face. The
rear end of the junction pipe 52 is connected to the exhaust pipe
connecting portion 57.
[0076] Muffler fixing stays 58, 58 projecting in the vehicle width
directions are provided on left and right sides of a front portion
of the muffler main body 55. The inward-bulging portion 43a (FIG.
2) of the ventilating hole 43 of the rear cowl 35 is fixed from
outside with a bolt to each of the muffler fixing stays 58, 58.
[0077] The rear stay 36 includes a plate portion 36a positioned
below the tail portion 56. Left and right edge portions of the
plate portion 36a extend so as to be continuous with the rear ends
of the side edge portions 55a, 55a of the muffler main body 55, and
the width of the plate portion 36a decreases toward the rear. The
plate portion 36a is formed so as to have a larger width than the
tail portion 56 of the rear bank-muffler 29, and covers the tail
portion 56 from below.
[0078] FIG. 7 is a cross-sectional view taken along line of FIG. 6.
FIG. 8 is a cross-sectional view of the rear bank-muffler 29 as
seen from the left side. FIG. 9 is a cross-sectional view of a rear
portion of the rear bank-muffler 29.
[0079] As shown in FIGS. 6 to 9, the muffler main body 55 includes
a top wall portion 60 extending along the top face 41 of the rear
cowl 35; a bottom wall portion 61 extending obliquely upwardly in
the rear direction along the bottom face 42 of the rear cowl 35; a
front wall portion 62 where the exhaust pipe connecting portion 57
is provided; and a rear wall portion 63 on which the tail portion
56 is provided.
[0080] The bottom wall portion 61 has a bottom wall-bulging portion
61a bulging downwardly at the center in the vehicle width direction
along the downwardly-bulging portion 42a of the bottom face 42 of
the rear cowl 35 and bottom face-side wall portions 61b, 61b
extending along the bottom face-side portions 42b, 42b of the rear
cowl 35, while connecting the bottom wall-bulging portion 61a to
the left and right side edges of the top wall portion 60. Since the
bottom wall-bulging portion 61a and the bottom face-side wall
portions 61b, 61b bulge downwardly in the form of curved surfaces,
it can also be said that they constitute parts of left and right
side wall portions of the muffler main body 55 in a side view.
[0081] As shown in FIG. 9, the muffler main body 55 is formed such
that a width W2 of the bottom wall-bulging portion 61a is smaller
than a width W1 on the top wall portion 60 side, and that the width
gradually decreases from the top wall portion 60 toward the bottom
wall-bulging portion 61a. More specifically, the sectional shape of
the muffler main body 55 as seen from the rear is a substantially
reverse triangular shape. The substantially reverse triangular
shape is substantially symmetrical with respect to a center line L
in the vehicle width direction.
[0082] In addition, the rear cowl 35 is formed so as to follow the
outline of the muffler main body 55 with a predetermined gap
between itself and the muffler main body 55, and its sectional
shape is similarly a substantially reverse triangular shape. A
plate-shaped insulating member 64 is provided between the top face
41 of the rear cowl 35 and the top wall portion 60 of the muffler
main body 55.
[0083] The muffler main body 55 is a multistage expansion-type
muffler having a plate-shaped partition 65 which partitions the
inside of the muffler main body 55 into front and rear parts. A
first expansion chamber C1 positioned in a rear portion of the
muffler main body 55, and a second expansion chamber C2 positioned
in a front portion thereof are formed inside the muffler main body
55 by use of the partition 65. The partition 65 is provided in the
front portion of the muffler main body 55, and the first expansion
chamber C1 on the rear side has a larger capacity than the second
expansion chamber C2 on the front side.
[0084] The rear bank-muffler 29 includes an introduction pipe 66
provided in the exhaust pipe connecting portion 57 to introduce
exhaust air into the muffler main body 55; a first communication
pipe 67 (connecting pipe, catalyst) introducing exhaust air
introduced into the introduction pipe 66 to the first expansion
chamber C1 and a second communication pipe 68 (connecting pipe)
through which the first expansion chamber C1 communicates into the
second expansion chamber C2. The rear bank-muffler 29 also has a
tail pipe 69 extending rearwardly from the second expansion chamber
C2, and through which the second expansion chamber C2 communicates
to the outside of the rear bank-muffler 29; and a tubular cover 70
(cover member) covering a rear portion of the tail pipe 69.
[0085] The bottom wall portion 61 of the muffler main body 55 is
inclined upwardly in the rear direction along the bottom face 42 of
the rear cowl 35, and the partition 65 is provided so as to be
substantially perpendicular to the bottom wall portion 61.
Accordingly, the partition 65 is arranged while being tilted in a
forward direction with respect to the vertical direction, in
proportion to the inclination amount of the bottom wall portion
61.
[0086] FIG. 10 is a front view of the partition 65 as seen from the
vehicle rear side.
[0087] The partition 65 has a substantially reverse triangular
shape in accordance with the shape of the muffler main body 55, and
its periphery is coupled with the inner wall of the muffler main
body 55.
[0088] The partition 65 has a supporting hole portion 65a into
which the first communication pipe 67 is fitted, a supporting hole
portion 65b into which the second communication pipe 68 is fitted,
and a supporting hole portion 65c into which the tail pipe 69 is
fitted.
[0089] Each of the supporting hole portions 65a, 65b, 65c has a rib
portion formed by bending the inner edge of the hole, and the first
communication pipe 67, the second communication pipe 68, and the
tail pipe 69 are each supported by being fitted to the inner face
of the rib portion.
[0090] The supporting hole portion 65a is arranged close to one
side (right side) of the center line L in an upper portion of the
partition 65. The supporting hole portion 65b is arranged on the
other side (left side) of the center line L in the upper portion of
the partition 65. The supporting hole portion 65c is arranged in a
position overlapping with the center line L in a lower portion of
the partition 65.
[0091] Diameters of the supporting hole portion 65b and supporting
hole portion 65c are substantially the same. The supporting hole
portion 65a is formed so as to have a larger diameter than the
supporting hole portion 65b or supporting hole portion 65c in
correspondence with the shape of the first communication pipe 67,
and has a flat shape longer in the vehicle width direction than in
the vertical direction.
[0092] Referring to FIGS. 6 to 10, the first communication pipe 67
is arranged close to one side (right side) of the center line L in
an upper portion inside the muffler main body 55. The first
communication pipe 67 is supported by being fitted in the
supporting hole portion 65a in a direction substantially orthogonal
to the partition 65, and extends substantially straight in an
obliquely upwardly manner in the rear direction, along the bottom
wall portion 61.
[0093] The first communication pipe 67 is a pipe formed flat being
longer in its width direction than its thickness direction, and
tapered such that its diameter expands toward its rear end.
[0094] A front end 67a of the first communication pipe 67 is
connected to the rear end of the introduction pipe 66 inside the
second expansion chamber C2. A rear end 67b of the first
communication pipe 67 is positioned in a middle portion in the
longitudinal direction inside the first expansion chamber C1. A
catalyzer in which a catalyst material is carried by a honeycomb
type support (not shown) is fitted and supported to an inner
circumference of the first communication pipe 67. The catalyzer is
provided along substantially the entire length of the first
communication pipe 67. More specifically, the first communication
pipe 67 not only is a pipe configured to introduce exhaust air into
the first expansion chamber C1, but also is a catalyst for
purifying exhaust air.
[0095] The second communication pipe 68 is arranged on the other
side (left side) of the center line L in the upper portion inside
the muffler main body 55. The second communication pipe 68 is
supported by being fitted in the supporting hole portion 65b in a
direction substantially orthogonal to the partition 65, and extends
substantially straight in an obliquely upward manner in the rear
direction, along the bottom wall portion 61.
[0096] The second communication pipe 68 is a pipe having a
substantially fixed diameter along its entire length, and having a
substantially circular cross section. A front end 68a of the second
communication pipe 68 is positioned inside the second expansion
chamber C2. A rear end 68b of the second communication pipe 68
extends further rearwardly than the rear end 67b of the first
communication pipe 67, and is positioned in a rear portion inside
the first expansion chamber C1.
[0097] A rear portion of the second communication pipe 68 is fitted
to and supported by a supporting wall 71 provided in the first
expansion chamber C1.
[0098] The second communication pipe 68 is provided adjacent to the
side of the first communication pipe 67 with the center line L in
between, and is arranged in substantially the same height position
as the first communication pipe 67 inside the muffler main body 55.
As shown in FIG. 7, the diameter of the second communication pipe
68 is smaller than the thickness of the first communication pipe 67
in the vertical direction, and in side view, a part of the second
communication pipe 68 except for its rear end portion overlaps with
the first communication pipe 67.
[0099] The width W1 of the muffler main body 55 corresponds to its
width in a height position where the first communication pipe 67
and the second communication pipe 68 are arranged. The width W2 of
the muffler main body 55 corresponds to its width in a height
position where the tail pipe 69 is arranged.
[0100] The tail pipe 69 is provided in the center in the vehicle
width direction in a lower portion inside the muffler main body 55,
and is arranged such that the position of its center substantially
coincides with the center line L. In other words, the tail pipe 69
is arranged so as to be offset downwardly from the first
communication pipe 67 and second communication pipe 68.
[0101] The supporting hole portions 65a, 65b, 65c of the partition
65 are penetrating positions through which the first communication
pipe 67, the second communication pipe 68, and the tail pipe 69
penetrate, respectively. The supporting hole portions 65a, 65b are
provided in substantially the same height positions, and the
supporting hole portion 65c is arranged so as to be offset
downwardly from the supporting hole portions 65a, 65b.
[0102] The tail pipe 69 is supported by being fitted in the
supporting hole portion 65c in a direction substantially orthogonal
to the partition 65, and extends substantially straight in an
obliquely upwardly manner in the rear direction, along the bottom
wall portion 61.
[0103] The tail pipe 69 is a pipe having a substantially fixed
diameter along its entire length and having a substantially
circular cross section, formed so as to have a smaller diameter but
longer full length than the second communication pipe 68. The tail
pipe 69 has its front end 69a (one end) fitted to and supported by
the supporting hole portion 65c.
[0104] The rear wall portion 63 of the muffler main body 55 has a
perpendicular portion 63a opposed to the rear end 67b and rear end
68b, and an inclined portion 63b extending obliquely downwardly in
the front direction from the bottom end of the perpendicular
portion 63a and connecting with the bottom wall-bulging portion
61a. More specifically, the inclined portion 63b is formed by
welding, to the rear wall portion 63, a plate member disposed so as
to close an opening formed in the rear wall portion 63.
[0105] The inclined portion 63b has an opening 72 (connecting
portion to be connected to the inner wall) having a larger diameter
than the outer diameter of the tail pipe 69. The tail pipe 69 has a
tail pipe rear portion 69c extending to the outside of the muffler
main body 55 and extending to the outside in the rear direction
through the opening 72.
[0106] The tubular cover 70 covering the tail pipe rear portion 69c
from its outer peripheral side is provided in the rear wall portion
63 of the muffler main body 55. The tubular cover 70 includes a
tubular portion 73 having a larger diameter than the tail pipe 69,
and a cap 74 closing the rear end of the tubular portion 73.
[0107] The tubular portion 73 has, at its tip end, a tapered
portion 73a which is formed by cutting the tubular portion 73 at an
oblique angle, and the tapered portion 73a is connected to the
periphery of the opening 72. The tubular cover 70 is welded to the
inclined portion 63b by a welding bead (not shown) formed on the
periphery of the tapered portion 73a. The tubular portion 73 is
tapered such that its diameter increases toward the rear.
[0108] The cap 74 has a rear end-supporting hole 74a fitted to a
rear end 69b (other end) of the tail pipe 69, and an annular lid
member 74b closing a gap between an outer circumference of the rear
end 69b and an inner circumference of the tubular portion 73. The
lid member 74b is tapered so as to extend rearwardly from the rear
end 69b and such that its diameter increases toward the rear.
[0109] The tail portion 56 has a double pipe structure where the
tail pipe 69 is covered by the tubular cover 70. The tubular cover
70 is arranged so as to be substantially coaxial with the tail pipe
69, and a rear expansion chamber 75 communicating into the first
expansion chamber C1 through the opening 72 is formed between the
tubular cover 70 and tail pipe 69. This ensures a large capacity of
the first expansion chamber C1.
[0110] Exhaust air G1 introduced into the rear bank-muffler 29
through the junction pipe 52 flows into the first communication
pipe 67 inside the first expansion chamber C1 from the introduction
pipe 66 on one side of the muffler main body 55, and after being
purified by the catalyst in the first communication pipe 67, flows
into the first expansion chamber C1 in the rear portion and
expands. Exhaust air G2 having expanded in the first expansion
chamber C1 turns around, flows into the second expansion chamber C2
through the second communication pipe 68, and expands in the second
expansion chamber C2 in the front portion. In addition, a part of
the exhaust air G2 flows into the rear expansion chamber 75 and
expands. Since the rear end 67b of the first communication pipe 67
is opposed to the rear expansion chamber 75, exhaust air flows into
the rear expansion chamber 75 easily, and the rear expansion
chamber 75 can be used effectively as an expansion chamber. Exhaust
air G3 having expanded in the second expansion chamber C2 turns
around, passes through the tail pipe 69, and is discharged to the
outside from the rear end 69b.
[0111] While the first communication pipe 67 is a pipe for directly
introducing exhaust gas from the exhaust pipe 28 to the first
expansion chamber C1 in the rear portion, it can also be said that
the first communication pipe is a connecting pipe supported by the
partition 65 to connect the first expansion chamber C1 and second
expansion chamber C2.
[0112] In this embodiment, inside the muffler main body 55 formed
into a substantially reverse triangular shape projecting
downwardly, the first communication pipe 67 and second
communication pipe 68 are provided side by side in the upper
portion, and the tail pipe 69 is provided so as to be offset
downwardly from the first communication pipe 67 and second
communication pipe 68. Accordingly, the first communication pipe 67
and second communication pipe 68 can be prevented from interfering
with the tail pipe 69, so that the tail pipe 69 can be formed as
long as possible to allow the engine 11 to have a desired engine
characteristic. Moreover, since the first expansion chamber C1 is
provided in the rear portion of the muffler main body 55 and the
second expansion chamber C2 in the front portion thereof, the tail
pipe 69 can be extended from the front to rear portions of the
muffler main body 55, achieving a long tail pipe 69.
[0113] In addition, since the tail pipe 69 is offset downwardly
from the first communication pipe 67 and second communication pipe
68 at the center in the vehicle width direction, the muffler main
body 55 can be formed into the substantially reverse triangular
shape, and the rear cowl 35 covering the muffler main body 55 can
also be formed into the substantially reverse triangular shape
having a small air resistance. Thus, while adopting the
configuration where the tail pipe 69 can be elongated, air
resistance of the motorcycle 10 can be reduced. Further, since air
flows smoothly along the bottom face 42 of the rear cowl 35, hot
air can be discharged efficiently from the exhaust holes 44,
44.
[0114] Since the first communication pipe 67 as the catalyst is
formed flat and longer in its width direction than its thickness
direction the capacity of the catalyst can be ensured while a space
can be secured below the first communication pipe 67. Thus, the
first communication pipe 67 does not interfere with the tail pipe
69, so that the tail pipe 69 can be arranged below the first
communication pipe 67 to elongate the first communication pipe 67.
In addition, since the catalyst is provided in the muffler main
body 55, there is no need to provide a catalyst in the exhaust pipe
28, whereby exhaust air can pass through the exhaust pipe 28 at a
higher flow velocity, and exhaust efficiency can be enhanced.
[0115] As shown in FIG. 2, in a side view, the tail portion 56 has
its bottom face extending rearwardly so as to be continuous with
the bottom face of the downwardly-bulging portion 42a, and its rear
end positioned slightly closer to the front than the rear edge
portion 35c of the rear cowl 35. Thus, the tail portion 56 appears
as though it is integrated with the rear cowl 35, which improves
the appearance.
[0116] Moreover, since the stay fixing portions 46, 46 are provided
in the base portion of the downwardly-bulging portion 42a on inner
sides of the exhaust holes 44, 44 in the vehicle width direction,
the stay fixing portions 46, 46 do not interfere with the exhaust
holes 44, 44, and thus the rear bank-muffler 29 can be cooled
efficiently.
[0117] As has been described, according to the embodiment to which
the present invention is applied, the outlines of rear bank-muffler
29 and rear cowl 35 covering the rear bank-muffler 29 are each
formed such that the width decreases toward the vehicle rear; the
tail pipe 69, first communication pipe 67, and second communication
pipe 68 are provided so as to penetrate the partition 65; and the
supporting hole portion 65c is the position where the tail pipe 69
penetrates the partition 65. The supporting hole portions 65a, 65b
are positions wherein the first communication pipe 67 and second
communication pipe 68 penetrating the partition 65 are offset from
each other in the vertical direction. As a result, the penetrating
positions of the first communication pipe 67 and second
communication pipe 68 do not interfere with that of the tail pipe
69, whereby the tail pipe 69 can be elongated even when the rear
bank-muffler 29 and rear cowl 35 are formed such that their widths
decrease toward the vehicle rear. In addition, the rear
bank-muffler 29 can be downsized in the width direction.
[0118] The front end 69a of the tail pipe 69 is arranged in the
foremost second expansion chamber C2 among the expansion chambers
of the rear bank-muffler 29, and the rear end 69b of the tail pipe
69 is opened to outside air from the rear portion of the rear
bank-muffler 29. Thus, the tail pipe 69 can be extended from the
foremost second expansion chamber C2, so that the tail pipe 69 can
be elongated.
[0119] The rear bank-muffler 29 is partitioned into the first
expansion chamber C1 in the rear portion and the second expansion
chamber C2 in the front portion; exhaust air introduced into the
rear bank-muffler 29 from the exhaust pipe 28 flows into the second
expansion chamber C2 through the first communication pipe 67 and
second communication pipe 68; the front end 69a of the tail pipe 69
is arranged in the second expansion chamber C2; and the rear end
69b thereof is opened to outside air from the rear portion of the
rear bank-muffler 29. Thus, it is possible to elongate the tail
pipe 69 by extending it from the second expansion chamber C2 in the
front portion to the rear portion of the rear bank-muffler 29.
[0120] The first communication pipe 67 as the catalyst accommodated
inside the rear bank-muffler 29 is supported by the partition 65,
and the first communication pipe 67 and second communication pipe
68 are arranged at substantially the same height in the vertical
direction. For this reason, although the first communication pipe
67 functioning as the catalyst is accommodated inside the rear
bank-muffler 29 in this configuration, the catalyst can be
prevented from interfering with the tail pipe 69, and thus the tail
pipe 69 can be elongated.
[0121] In addition, since the first communication pipe 67 as the
catalyst is formed into a flat shape whose longitudinal direction
is its width direction, the first communication pipe 67 can be
downsized in the vertical direction while ensuring capacity of the
catalyst. Consequently, the first communication pipe 67 does not
interfere with the tail pipe 69, so that the tail pipe 69 can be
elongated.
[0122] Furthermore, the outline of the rear bank-muffler 29 is
formed such that the width W2 in the height position where the tail
pipe 69 is arranged is smaller than the width W1 in the height
position where the first communication pipe 67 and second
communication pipe 68 are arranged. Thus, the width of the portion
of the rear cowl 35 covering the vicinity of the tail pipe 69 can
be reduced, whereby the rear bank-muffler 29 and the rear cowl 35
can be downsized.
[0123] Moreover, there is provided the tubular cover 70 covering
the tail pipe rear portion 69c from outside in the radial
direction; the rear ends 67b, 68b of the first communication pipe
67 and second communication pipe 68 are opposed to the inner wall
of the rear wall portion 63 of the rear bank-muffler 29; and the
space between the tubular cover 70 and tail pipe rear portion 69c
communicates into the first expansion chamber C1 through the
opening 72 being the connecting portion between the tubular cover
70 and rear wall portion 63. More specifically, since the space
between the tubular cover 70 and tail pipe rear portion 69c can be
used as the rear expansion chamber 75, the rear bank-muffler 29 can
be downsized while capacity of the first expansion chamber C1 can
be ensured.
[0124] The tubular cover 70 is connected to the muffler main body
55 by welding with the tapered portion 73a being the connecting
portion is tapered in a side view. Thus, an area of the welding
portion of the tubular cover 70 can be enlarged, and rigidity can
be enhanced.
[0125] Note that the above embodiment is one aspect to which the
present invention is applied, and the present invention is not
limited to the above embodiment.
[0126] Although the above embodiment has been described by citing
the first communication pipe 67 and second communication pipe 68 as
examples of connecting pipes, the present invention is not limited
to this. It suffices that the tail pipe 69 is offset in the
vertical direction at least from the second communication pipe 68.
In this case, exhaust air is introduced into the first expansion
chamber C1 through a pipe provided in a position different from the
first communication pipe 67, for example.
[0127] Although in the description of the above embodiment the
catalyzer is provided in the first communication pipe 67, the
present invention is not limited to this. The first communication
pipe 67 may be a simple pipe not provided with the catalyzer.
[0128] Although the above embodiment has been described by citing
the V4 engine 11 as an example, the present invention is not
limited to this. It suffices that at lest the rear bank-muffler 29
is covered by the rear cowl 35, and the invention is applicable
regardless of whether the engine is a single cylinder, parallel,
horizontally opposed, or other type.
[0129] The invention being thus described, it will be obvious that
the same may be varied in many ways. Such variations are not to be
regarded as a departure from the spirit and scope of the invention,
and all such modifications as would be obvious to one skilled in
the art are intended to be included within the scope of the
following claims.
* * * * *