U.S. patent number RE31,989 [Application Number 06/643,411] was granted by the patent office on 1985-09-24 for motorcycle engine exhaust system.
This patent grant is currently assigned to Yamaha Hatsudoki Kabushiki Kaisha. Invention is credited to Satoru Ichikawa, Kazuhiko Nomura.
United States Patent |
RE31,989 |
Nomura , et al. |
September 24, 1985 |
Motorcycle engine exhaust system
Abstract
A motor cycle includes a frame, a front and rear wheel, and an
engine mounted to the frame which has at least two exhaust pipes. A
muffler is mounted to the frame beneath the engine, and both
exhaust pipes discharge into the muffler. At least one tailpipe
exhausts from the muffler. The silencing volume of the muffler can
enable a shorter-than-usual tailpipe to be used, which need not
interfere with access to the rear wheel axle.
Inventors: |
Nomura; Kazuhiko (Iwata,
JP), Ichikawa; Satoru (Hamamatsu, JP) |
Assignee: |
Yamaha Hatsudoki Kabushiki
Kaisha (JP)
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Family
ID: |
26456962 |
Appl.
No.: |
06/643,411 |
Filed: |
August 22, 1984 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
Issue Date |
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78697 |
Sep 25, 1979 |
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Reissue of: |
343020 |
Jan 26, 1982 |
04422519 |
Dec 27, 1983 |
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Foreign Application Priority Data
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Sep 29, 1978 [JP] |
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53-119181 |
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Current U.S.
Class: |
180/219; 180/226;
180/296; 180/89.2; 181/228; 181/238; 181/272 |
Current CPC
Class: |
F01N
1/08 (20130101); F01N 13/08 (20130101); F02B
75/22 (20130101); F02B 61/02 (20130101); F01N
2590/04 (20130101); F02B 2075/1816 (20130101); F02B
2075/027 (20130101) |
Current International
Class: |
F01N
1/08 (20060101); F01N 7/08 (20060101); F02B
61/00 (20060101); F02B 75/00 (20060101); F02B
75/22 (20060101); F02B 61/02 (20060101); F02B
75/02 (20060101); F02B 75/18 (20060101); B62D
061/02 (); F01N 001/08 (); F01N 007/08 () |
Field of
Search: |
;181/204,211,228,229,238-240,262,263,272,275
;180/89.2,218,225,226,229,291,296 ;60/312-314,323,324
;123/52M,52V,198R |
References Cited
[Referenced By]
U.S. Patent Documents
Foreign Patent Documents
Primary Examiner: Tarcza; Thomas H.
Attorney, Agent or Firm: Beutler; Ernest A.
Parent Case Text
This is a continuation of application Ser. No. 78,697, filed Sept.
25, 1979, now abandoned.
Claims
We claim:
1. An engine exhaust system for a motorcycle of the type having a
frame, a front and rear wheel mounted to said frame, a V type
engine with at least two cylinders arranged to form a "V", and
arranged forwardly and rearwardly relative to one another, said
exhaust system comprising: a muffler mounted to said frame
underneath said engine, said muffler having an expansion chamber, a
forward exhaust pipe extending from the forwardmost cylinder
forwardly and downwardly to discharge into said expansion chamber,
a rearward exhaust pipe extending from the rearwardmost cylinder
downwardly to discharge into said expansion chamber, and a tailpipe
having a volume and a dimension of length, exhausting from said
muffler, said forward exhaust pipe and tailpipe, where they
respectively enter and leave said muffler, being substantially
coaxial, said rearward exhaust pipe passing downwardly rearwardly
of said engine and forwardly of said rear wall.
2. An engine exhaust system according to claim 1 in which said
tailpipe extends rearwardly from said muffler, and has a trailing
end which terminates forwardly of the axle of said rear wheel.
3. An engine exhaust system according to claim 1 in which said
muffler includes a first and a second of said expansion chambers,
separated from one another by a partition, there being a
communication pipe interconnecting said first and second expansion
chambers, said exhaust pipes discharging into said first expansion
chamber, and said tailpipe exhausting from said second expansion
chamber.
4. An engine exhaust system according to claim 3 in which said
tailpipe extends rearwardly from said muffler, and has a trailing
end which terminates forwardly of the axle of said rear wheel.
5. An engine exhaust system according to claim 1 in which at least
one of said exhaust pipes extends into said muffler for providing
additional length of exhaust pipe from said engine.
6. An engine exhaust system according to claim 1 in which the
engine is a four-cylinder V-type with two cylinders formed in two
banks arranged forwardly and rearwardly relative to one another,
and in which there is a said exhaust pipe for each said cylinder,
said exhaust pipes from said forward bank curving forwardly and
downwardly on opposite sides to said muffler, and said exhaust
pipes from said rear bank extending rearwardly, downwardly and then
forwardly to said muffler, said tailpipes extending rearwardly.
7. An engine exhaust system according to claim 6 in which said
tailpipe extends rearwardly from said muffler, and has a trailing
end which terminates forwardly of the axle of said rear wheel.
8. An engine exhaust system according to claim 7 in which there are
two of said tailpipes, one at each side of said motorcycle.
9. An engine exhaust system according to claim 8 in which said
muffler includes a first and a second of said expansion chambers,
separated from one another by a partition, there being a
communication pipe interconnecting said first and second expansion
chambers, said exhaust pipes discharging into said first expansion
chamber, and said tailpipes exhausting from said second expansion
chamber.
10. An engine exhaust system according to claim 9 in which said
exhaust pipes from said rear bank of exhaust pipes extend into said
first expansion chamber.
11. An engine exhaust system according to claim 1 in which said
rear wheel is mounted to said frame by a pair of laterally
spaced-apart rearwardly extending arms which are pivoted to said
frame by a pivot, said rearward exhaust pipe passing downwardly
between the lanes of said arms.
12. An engine exhaust system according to claim 1 in which said
rearward exhaust pipe, when it passes downwardly between the planes
of said arms, passes rearwardly of the pivot which joins said arms
to said frame.
13. An engine exhaust system for a motorcycle of the type having a
frame, a front and rear wheel mounted to said frame, said rear
wheel being mounted to said frame by a pair of laterally
spaced-apart rearwardly extending arms which are pivoted to said
frame by a pivot, a V type engine with at least two cylinders
arranged to form a "V", and arranged forwardly and rearwardly
relative to one another, said exhaust system comprising: a muffler
mounted to said frame underneath said engine, said muffler having
an expansion chamber, a forward exhaust pipe extending from the
forwardmost cylinder forwardly and downwardly to discharge into
said expansion chamber, a rearward exhaust pipe extending from the
rearwardmost cylinder downwardly between said rearwardly extending
arms, rearwardly of said pivot and forwardly of said rear wheel, to
discharge into said expansion chamber, and a tailpipe having a
volume and dimension of length, exhausting from said muffler.
14. An engine exhaust system according to claim 13 in which said
tailpipe extends rearwardly from said muffler, and has a trailing
end which terminates forwardly of the axle of said rear wheel.
.Iadd.
15. In combination with a motorcycle of the type having a frame
portion, a front wheel dirigibly supported by said frame, a V-type
engine supported by said frame with its crankshaft axis extending
transversely to said frame, trailing arm means pivotally connected
to said frame for pivotal movement about a transversely extending
pivot axis, and a rear wheel journaled by said trailing arm means,
an exhaust system comprising an exhaust device extending
transversely across said frame for substantially the entire width
of said frame and juxtaposed at a level below that of said engine
and in proximity to said trailing arm pivot axis, a front bank
exhaust pipe extending from the front bank of said engine
downwardly and terminating in said exhaust device, a rear bank
exhaust pipe extending downwardly into said exhaust device, said
rear bank exhaust pipe being positioned ahead of the said rear
wheel, and a tailpipe discharging rearwardly from said exhaust
device. .Iaddend. .Iadd.16. A combination according to claim 15
wherein the engine overlies at least in part the exhaust device.
.Iaddend. .Iadd.17. A combination according to claim 15 wherein the
front bank exhaust pipe enters the exhaust device at one side
thereof and the rear bank exhaust pipe enters the exhaust device at
a central position therein. .Iaddend. .Iadd.18. A combination
according to claim 17 wherein there is a second front bank exhaust
pipe extending from said front bank rearwardly and entering the
other side of said exhaust device and a second rear bank exhaust
pipe extending rearwardly and downwardly forwardly of the rear
wheel and entering said exhaust device at the center thereof.
.Iaddend. .Iadd.19. A combination according to claim 18 wherein the
engine overlies at least in part the exhaust device.
.Iaddend. .Iadd.20. A combination according to claim 18 wherein the
engine drives a drive shaft that extends to one side of said frame
for driving said rear wheel, one of the rear bank exhaust pipes
being offset relative to the other of said rear bank exhaust pipes
away from said drive shaft for providing clearance therebetween.
.Iaddend. .Iadd.21. A combination according to claim 20 wherein a
pair of tailpipes extend from the opposite sides of the exhaust
device and rearwardly on opposite sides of the rear wheel.
.Iaddend.
Description
FIELD OF THE INVENTION
This invention relates to engine exhaust systems, and in particular
to an exhaust system for an engine that includes a plurality of
exhaust pipes.
BACKGROUND OF THE INVENTION
In order sufficiently to silence its exhaust noise, a motorcycle
driven by an engine having a large displacement must have a muffler
with a large capacity. When engine displacements increased
conventional, motorcycles have had to increase the volume of their
mufflers. However because the exhaust system usually extends its
tailpipe in the vicinity of the rear wheel axle of the motorcycle,
access to the rear axle and rear wheel has been impeded, thereby
rendering maintenance and repair much more difficult. With this in
mind, some motorcycles are designed to have their tailpipe
shortened so its trailing end terminates forwardly of the rear
axle. Then the difficulty arises that the capacity of the tailpipe
may become insufficient, and the desired silencing performance
cannot be attained.
It is an object of this invention to provide an exhaust system with
a suitably short tailpipe, and a suitably large muffling
capacity.
BRIEF DESCRIPTION OF THE INVENTION
An exhaust system according to this invention has a muffler
disposed below an engine having at least two exhaust pipes. The
engine exhaust gases are introduced into the muffler through the
exhaust pipes. A tailpipe exhausts to atmosphere from the muffler,
and the necessary capacity and length of the tailpipes are so
reduced as to provide adequate access to the rear wheel of the
motorcycle, while still providing a sufficiently large capacity in
the exhaust muffler system as a whole.
According to a preferred but optional feature of the invention the
muffler is multiply-chambered, with the exhaust pipes discharging
into one chamber, and the tailpipes exhausting from another. The
chamber are interconnected.
The above and other features of this invention will be fully
understood from the following detailed description and the
accompanying drawings, in which:
FIG. 1 is a side elevation showing a motorcycle, to which one
embodiment of the present invention is applied;
FIG. 2 is a top plan view of FIG. 1 showing the exhaust system of
the motorcycle;
FIGS. 3 and 4 are respectively a partially sectional top plan view
and side elevation showing a muffler; and
FIG. 5 is a perspective view showing an engine and its
surroundings.
DETAILED DESCRIPTION OF THE INVENTION
FIG. 1 shows a main frame 1 which is equipped with a steering head
pipe 2, a pair of right and left tank rails 3 and a pair of right
and left side tubes 4. A front fork 5 is held rotatably to head
pipe 2. Front and rear wheels 6 and 7 respectively are shown. Rear
wheel 7 is supported by rear arms 8. Rear arms 8 are supported on
said main frame 1 by means of a pivot pin 9 in a manner to rock up
and down.
As better seen in FIG. 5, a drive shaft 10 is arranged to extend
through one arm 8a of rear arms 8. Drive shaft 10 is used to
transmit the driving force of a later-described engine to rear
wheel 7. In short, the motorcycle under consideration is equipped
with the so-called "power transmission mechanism of shaft drive
type".
A gusset 11 is welded between the rear arms 8 in the vicinity of
the pivot pin 9. The gusset 11 thus welded is formed with a hole
11a, through which later-described exhaust pipes 20 pass.
A V-type four-cycle four-cylinder water-cooled engine 12 is mounted
to the frame. The banks of the engine are arranged between side
tubes 4 at an inclination with respect to the longitudinal
direction of the motorcycle body. Engine 12 is installed on the
motorcycle with its sides suspended between the side tubes 4.
Intake pipes 15 of engine 12 are located inside of the banks 13 and
14, and extend substantially vertically upward. The upper ends of
the respective intake pipes open into a not-shown intake manifold
which is arranged beneath a fuel tank 16. A connecting pipe 17
extends downwardly from the intake manifold. A air cleaner 18 is
mounted in pipe 17. Each of intake pipes 15 is equipped with a
carburetor of conventional type.
To the outer sides of the respective banks 13 and 14 of the engine
12, there are connected exhaust pipes 19 and 20 which correspond to
the respective engine cylinders. There is arranged below the engine
12 a muffler 21 which is connected with exhaust pipes 19 and 20.
More specifically, the two exhaust pipes 19 of front bank 13 extend
around the front of the engine 12 until they are connected with
muffler 21. The two exhaust pipes 20 of rear bank 14 extend through
hole 11a until they are connected with muffler 21.
The inside of the muffler 21 (see FIGS. 3 and 4) is divided into
front and rear chambers 21a and 21b by means of a partition 22,
which in turn fixedly supports both two conduits 23 for introducing
the engine exhaust gases from exhaust pipes 20 of rear bank 14 and
two communication pipes 24 for providing communication between
front and rear chambers 21a and 21b. Exhaust pipes 19 of front bank
13 are connected with front chamber 21a. Two tailpipes 25 are
connected with the right and left sides of the rear chamber 21b and
extend rearwardly. It should be noted here that the trailing ends
of tailpipes 25 terminate forwardly of the axle of rear wheel
7.
The operation of the embodiment is as follows. Exhaust gases from
engine 12 are introduced through the exhaust pipes 19 and 20 into
front chamber 21a of muffler 21, where they expand. The exhaust
gases thus introduced into front chamber 21a additionally expand in
rear chamber 21b after they pass through communication pipes 24.
Then the exhaust gases are discharged to atmosphere backwardly
through the tailpipes, while their noises are further reduced.
Thus, the exhaust gases introduced through exhaust pipes 19 and 20
expand in muffler 21 and in tailpipes 25, which together have a
sufficient capacity that the silencing performance obtainable is
sufficient. Since, moreover, the sufficient capacity required by
the exhaust muffler system is shared between muffler 21 and tail
pipes 25, tail pipes 25 may have a relatively small size.
Since in the foregoing embodiment the four exhaust pipes 19 and 20
of the four-cylinder engine are gathered at muffler 21, and since
the exhaust gases are discharged by way of two tail pipes 25, it is
sufficient that two tailpipes 25 having only a relatively small
capacity be provided in the vicinity of the rear wheel 7. Contrary
to the conventional construction it is unnecessary to provide four
tailpipes, nor to provide such a muffler having a large capacity as
has a plurality of exhaust pipes gathered thereat. As a result
access to rear wheel 7 can be remarkably improved, and maintenance
and repair are facilitated. Since, moreover, the trailing ends of
tailpipes 25 terminate forwardly of the rear wheel axle, the
maintenance and repair are still further improved.
In the foregoing embodiment, moreover, since exhaust pipes 20 of
rear bank 14 are connected with muffler 21 through hole 11a which
is formed in gusset 11 of rear arms 8, exhaust pipes 20 can be
shortened and arranged compactly. However, engine performance may
be deteriorated if exhaust pipes 19 and 20 are excessively
shortened, because their length is known to have a close
relationship with the engine performance. But in this invention,
the length of exhaust pipes 20 can substantially be adjusted with
conduits 23. The length of the other exhaust pipes 19 can also
substantially be adjusted by providing conduits extending therefrom
into the front chamber 21a, as the case may be. As a result, the
length of exhaust pipes 19 and 20 can be selected so that the most
proper performance may be attained.
As has been described hereinbefore, according to the present
invention, the muffler is arranged beneath an engine having at
least two exhaust pipes, and the engine exhaust gases are
introduced through the exhaust pipes into the muffler and then
through the tailpipes into the atmosphere from the muffler. As a
result, the capacity of the exhaust muffler system can be shared
between the muffler and the tailpipes so that the capacity of the
tailpipes can be reduced. As a result, the size and length of the
tailpipes can be reduced remarkably to facilitate maintenance and
repair in the vicinity of the rear wheel, such as removal of the
rear axle. Moreover it is possible to provide a muffler having a
sufficient capacity while still reducing the size of the tailpipes
to provide a silencing performance.
This invention is not to be limited by the embodiment shown in the
drawings and described in the description, which is given by way of
example and not of limitation, but only in accordance with the
scope of the appended claims.
* * * * *