U.S. patent application number 14/983931 was filed with the patent office on 2017-07-06 for water muffler of personal watercraft.
The applicant listed for this patent is Kawasaki Jukogyo Kabushiki Kaisha. Invention is credited to Toshio Araki, Kazuma Komura.
Application Number | 20170190406 14/983931 |
Document ID | / |
Family ID | 59227192 |
Filed Date | 2017-07-06 |
United States Patent
Application |
20170190406 |
Kind Code |
A1 |
Araki; Toshio ; et
al. |
July 6, 2017 |
WATER MUFFLER OF PERSONAL WATERCRAFT
Abstract
Please make the following amendments to the abstract. Material
to be inserted in replacement paragraphs or sections is in bold and
underline, and material to be deleted is in and/or in if the
deletion would be difficult to see. Please replace abstract with
the following rewritten abstract: A water muffler of a personal
watercraft comprises: a muffler body; and an inlet pipe which is
connected to the muffler body and guides an exhaust gas and cooling
water to an inner space of the muffler body. The inlet pipe
includes: a center pipe wall; an outer pipe wall provided to
surround the center pipe wall; an exhaust passage which is provided
inside the center pipe wall; and a water passage surrounded by the
center pipe wall and the outer pipe. The center pipe wall has in a
downstream end portion of the inlet pipe, a protruding portion
protruding from the outer pipe wall in an axial direction of the
inlet pipe, and an outlet of the water passage is located to be
apart from an outlet of the exhaust passage in an axial direction
of the inlet pipe.
Inventors: |
Araki; Toshio;
(Kakogawa-shi, JP) ; Komura; Kazuma; (Himeji-shi,
JP) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
Kawasaki Jukogyo Kabushiki Kaisha |
Kobe-shi |
|
JP |
|
|
Family ID: |
59227192 |
Appl. No.: |
14/983931 |
Filed: |
December 30, 2015 |
Current U.S.
Class: |
1/1 |
Current CPC
Class: |
B63H 21/24 20130101;
B63B 34/10 20200201; B63H 21/32 20130101 |
International
Class: |
B63H 21/32 20060101
B63H021/32; B63B 35/73 20060101 B63B035/73; B63H 21/00 20060101
B63H021/00 |
Claims
1. (canceled)
2. A water muffler of a personal watercraft, comprising: a muffler
body having a tubular shape; and an inlet pipe which is connected
to the muffler body and guides an exhaust gas and cooling water to
an inner space of the muffler body, wherein the inlet pipe
includes: a center pipe wall; an outer pipe wall provided to
surround the center pipe wall; an exhaust passage which is provided
inside the center pipe wall and through which the exhaust gas
flows; and a water passage which is surrounded by an outer
peripheral surface of the center pipe wall and an inner peripheral
surface of the outer pipe wall, and through which cooling water
flows, wherein the center pipe wall has in a downstream end portion
of the inlet pipe, a protruding portion protruding from the outer
pipe wall in an axial direction of the inlet pipe, and an outlet of
the water passage is located to be apart from an outlet of the
exhaust passage in the axial direction of the inlet pipe, and
wherein the protruding portion of the center pipe wall is provided
with a radially protruding portion which protrudes in a radial
direction of the inlet pipe.
3. A water muffler of a personal watercraft, comprising: a muffler
body having a tubular shape; and an inlet pipe which is connected
to the muffler body and guides an exhaust gas and cooling water to
an inner space of the muffler body, wherein the inlet pipe
includes: a center pipe wall; an outer pipe wall provided to
surround the center pipe wall; an exhaust passage which is provided
inside the center pipe wall and through which the exhaust gas
flows; and a water passage which is surrounded by an outer
peripheral surface of the center pipe wall and an inner peripheral
surface of the outer pipe wall, and through which cooling water
flows, wherein the center pipe wall has in a downstream end portion
of the inlet pipe, a protruding portion protruding from the outer
pipe wall in an axial direction of the inlet pipe, and an outlet of
the water passage is located to be apart from an outlet of the
exhaust passage in the axial direction of the inlet pipe, and
wherein the inlet pipe is inclined downward toward a downstream
side.
4. A water muffler of a personal watercraft, comprising: a muffler
body having a tubular shape; and an inlet pipe which is connected
to the muffler body and guides an exhaust gas and cooling water to
an inner space of the muffler body, wherein the inlet pipe
includes: a center pipe wall; an outer pipe wall provided to
surround the center pipe wall; an exhaust passage which is provided
inside the center pipe wall and through which the exhaust gas
flows; and a water passage which is surrounded by an outer
peripheral surface of the center pipe wall and an inner peripheral
surface of the outer pipe wall, and through which cooling water
flows, wherein the center pipe wall has in a downstream end portion
of the inlet pipe, a protruding portion protruding from the outer
pipe wall in an axial direction of the inlet pipe, and an outlet of
the water passage is located to be apart from an outlet of the
exhaust passage in the axial direction of the inlet pipe, and
wherein a center of the outlet of the exhaust passage is located
above a center of the muffler body.
Description
BACKGROUND OF THE INVENTION
[0001] Field of the Invention
[0002] The present invention relates to a water muffler
incorporated into a personal watercraft.
[0003] Description of Related Art
[0004] In a personal watercraft, a water muffler is used as an
exhaust gas silencer (see U.S. Pat. No. 7,326,093 B2). The water
muffler includes an inlet pipe connected to an exhaust pipe
extending from an engine. This inlet pipe has a double-walled
structure including a center pipe wall, and an outer pipe wall
formed to surround the center pipe wall. The inlet pipe is provided
with an exhaust passage formed inside the center pipe wall, and a
water passage surrounded by the center pipe wall and the outer pipe
wall. The downstream end of the inlet pipe is formed with an outlet
of the exhaust passage and an outlet of the water passage. The
exhaust gas and cooling water flow into the interior of the water
muffler through the outlet of the exhaust passage and the outlet of
the water passage.
[0005] Typically, an exhaust gas outlet and a water outlet are
placed to be coplanar with each other. For this reason, the cooling
water is highly likely to flow into the exhaust passage through the
exhaust gas outlet located inward relative to and close to the
water outlet. As a result, the cooling water may flow back toward
the engine through the exhaust passage.
SUMMARY OF THE INVENTION
[0006] An object of the present invention is to provide a water
muffler which can make it difficult for cooling water to flow back
through an exhaust passage.
[0007] According to an aspect of the present invention, a water
muffler of a personal watercraft comprises a muffler body having a
tubular shape; and an inlet pipe which is connected to the muffler
body and guides an exhaust gas and cooling water to an inner space
of the muffler body, wherein the inlet pipe includes: a center pipe
wall; an outer pipe wall provided to surround the center pipe wall;
an exhaust passage which is provided inside the center pipe wall
and through which the exhaust gas flows; and a water passage which
is surrounded by an outer peripheral surface of the center pipe
wall and an inner peripheral surface of the outer pipe wall, and
through which cooling water flows, wherein the center pipe wall has
in a downstream end portion of the inlet pipe, a protruding portion
protruding from the outer pipe wall in an axial direction of the
inlet pipe, and an outlet of the water passage is located to be
apart from an outlet of the exhaust passage in the axial direction
of the inlet pipe.
[0008] In accordance with this configuration, since the outlet of
the water passage is located to be apart from the outlet of the
exhaust passage in the axial direction of the inlet pipe, the
cooling water does not easily reach the outlet of the exhaust
passage, after the cooling water has flowed through the water
passage and into the inner space of the muffler body. Therefore,
the cooling water does not easily flow back through the exhaust
passage.
BRIEF DESCRIPTION OF THE DRAWINGS
[0009] FIG. 1 is a side view of a personal watercraft according to
an embodiment.
[0010] FIG. 2 is a plan view of the personal watercraft.
[0011] FIG. 3 is a schematic view showing an exhaust system.
[0012] FIG. 4A is a cross-sectional view showing a part of a
muffler body and a part of an inlet pipe. FIG. 4B is a
cross-sectional view of the inlet pipe which is taken along line
B-B of FIG. 4A. FIG. 4C is a cross-sectional view of the inlet pipe
which is taken along line C-C of FIG. 4A. FIG. 4D is a view taken
in the direction of arrows along line D-D of FIG. 4A (a view
showing the downstream end of the inlet pipe when viewed from a
first chamber in an axial direction).
[0013] FIG. 5 is a cross-sectional view taken along line V-V of
FIG. 4A.
[0014] FIG. 6A is a cross-sectional view of a right deck fin, in a
region which is in the vicinity of a flange of an exhaust system,
when viewed from the front. FIG. 6B is a cross-sectional view of
the right deck fin, in a region which is in the vicinity of a
swelling portion of the exhaust system, when viewed from the
front.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS
[0015] Hereinafter, the embodiment will be described with reference
to the drawings. The stated directions are from the perspective of
a rider riding on a personal watercraft 1.
[0016] As shown in FIGS. 1 and 2, the personal watercraft 1
includes a body 2 including a hull 3 and a deck 4. The deck 4
covers the hull 3 from above, and is connected to the hull 3. A
connection line of the hull 3 and the deck 4 is in some cases
called a gunnel line. An engine room 10 is provided in the interior
of the body 2, is in communication with a maintenance opening 10a
provided in the deck 4, and is opened upward through the
maintenance opening 10a. An engine hood 6 covers the maintenance
opening 10a from above, and is detachably attached to the deck
4.
[0017] The personal watercraft 1 is a stand-up type personal
watercraft which is steered by the rider in a standing posture. A
standing deck 4a, and right and left deck fins 4b, 4c are provided
at the rear portion of the deck 4. The standing deck 4a has a flat
floor surface on which the rider stands. The standing deck 4a is
located rearward relative to the engine room 10. The floor surface
of the standing deck 4a is set to be lower than the upper end of
the engine room 10. The standing deck 4a has on the front side
thereof, a front wall 4d protruding upward and extending in a
rightward and leftward direction. The standing deck 4a is isolated
from the engine room 10 by the front wall 4d. The right and left
deck fins 4b, 4c are provided on the right side and the left side
of the standing deck 4a, respectively, to protrude upward and
extend in a forward and rearward direction. The front end portions
of the right and left standing decks 4b, 4c are continuous with the
front wall 4d. The standing deck 4a is surrounded by the right and
left standing decks 4b, 4c, and the front wall 4d, which have a
U-shape when viewed from above.
[0018] The front end portion of a handle pole 7 is coupled to the
upper surface of the deck 4 in front of the maintenance opening 10a
in such a manner that handle pole 7 is rotatable around the front
end portion. The handle pole 7 is vertically pivotable around the
front end portion thereof. A bar-type steering handle 8 is attached
onto the rear end portion of the handle pole 7. A groove 6a
extending in the forward and rearward direction is provided in the
center portion in the rightward and leftward direction of the upper
surface of the engine hood 6. The handle pole 7 is accommodated in
the groove 6a in a state in which the steering handle 8 is not
gripped by the rider. The rider stands on the standing deck 4a,
grips the steering handle 8, and moves the handle pole 7 upward. In
this state, the rider steers the personal watercraft 1.
[0019] An engine 11 is placed in the engine room 10. The output
shaft of the engine 11 is connected to a propeller shaft 12
extending rearward in the interior of the body 2. A water jet pump
(not shown) is driven by the propeller shaft 12. The water jet pump
pressurizes and accelerates water suctioned through a suction port
provided in the hull 3. The pressurized and accelerated water is
ejected rearward through a jet nozzle 13 attached to the rear end
portion of the body 2. In this way, a forward propulsive force is
generated in the body 2.
[0020] An air cleaner 14, a battery 15, and a fuel tank 16 are
placed in the engine room 10. The air cleaner 14 is connected to
the intake port of the engine 11 through an air-intake pipe 17. The
battery 15 is configured to store electric power to be supplied to
electric components such as a starter motor (not shown) for
starting the engine 1, and a controller (not shown) for controlling
the engine 11. The fuel tank 16 is configured to store fuel to be
supplied to the combustion chamber of the engine 11. The air
cleaner 14 is placed rearward relative to the engine 11 and located
in the rear portion of the engine room 10. The battery 15 is placed
in front of the engine 11. The fuel tank 16 is placed in front of
the engine 11 and the battery 15. The fuel tank 11 is located in
the front portion of the engine room 10. Further, a part of an
exhaust system 20 (see FIG. 3) of the engine 11 is placed in the
engine room 10.
[0021] As shown in FIG. 3, the exhaust system 20 includes a first
exhaust pipe 21, a second exhaust pipe 22, and a water muffler 30.
The first exhaust pipe 21 includes one pipe member or a plurality
of pipe members which are coupled to each other. The second exhaust
pipe 22 has the same structure.
[0022] The first exhaust pipe 21 connects the exhaust port of the
engine 11 to a water muffler 30 and serves to guide an exhaust gas
emitted from the engine 11 to the water muffler 30. The exhaust gas
flows through the water muffler 30, and thereby a noise of the
exhaust gas is reduced. The second exhaust pipe 22 serves to guide
the exhaust gas which has flowed through the water muffler 30
outside of the watercraft. The upstream end of the second exhaust
pipe 22 is connected to the water muffler 30, while the downstream
end of the second exhaust pipe 22 is opened at the stern. The
exhaust gas emitted from the engine 11 flows through the first
exhaust pipe 21, the water muffler 30, and the second exhaust pipe
22 in this order, and is discharged outside of the watercraft.
[0023] The temperatures of the components included in the exhaust
system 20 are elevated by exhaust heat radiated from the engine 11.
The exhaust system 20 includes a cooling water passage through
which cooling water flows, in addition to an exhaust passage
through which the exhaust gas flows. Water surrounding the personal
watercraft 1 is used as the cooling water. The temperatures of the
components included in the exhaust system 20 and the temperature of
the exhaust gas can be lowered by cooling using the water.
[0024] The structure of the water muffler 30 will now be described.
A muffler body 31 of the water muffler 30 has a cylindrical shape.
The muffler body 31 includes a first side wall 31a located on a
first side (one side) in an axial direction, a second side wall 3
lb located on a second side (the other side) in the axial
direction, and a peripheral wall 31c connecting the side walls 31a,
31b to each other, and having a circular cross-section. The muffler
body 31 has an inner space surrounded by the walls 31a to 31c. The
muffler body 31 includes a first separating wall 32 and a second
separating wall 33 which are placed in an inner space thereof to be
spaced apart from each other in the axial direction. The inner
space of the muffler body 31 is separated into three chambers 34 to
36 arranged in the axial direction, by the separating walls 32, 33.
The first chamber 34 is in communication with the second chamber 35
via a first communicating portion 37. The second chamber 35 is in
communication with the third chamber 36 via a second communicating
portion 38.
[0025] The first chamber 34 is placed between the second chamber 35
and the third chamber 36 in the axial direction and surrounded by
the two separating walls 32, 33. The first separating wall 32 and
the third chamber 36 are placed on the first side in the axial
direction. The second separating wall 33 and the second chamber 35
are placed on the second side in the axial direction. The first
communicating portion 37 is constituted by a pipe or a through-hole
provided on the second separating wall 33. The second communicating
portion 38 is constituted by a pipe penetrating the first
separating wall 32 and the second separating wall 33 and extending
through the interior of the first chamber 34.
[0026] The water muffler 30 includes an inlet pipe 41 and an outlet
pipe 42. The upstream end portion of the inlet pipe 41 is connected
to the downstream end portion of the first exhaust pipe 21. The
downstream end portion of the inlet pipe 41 is opened in the first
chamber 34. The upstream end portion of the outlet pipe 42 is
opened in the third chamber 36. The downstream end portion of the
outlet pipe 42 is connected to the upstream end portion of the
second exhaust pipe 22. The exhaust gas emitted from the first
exhaust pipe 21 flows through the inlet pipe 41, the first chamber
34, the first communicating portion 37, the second chamber 35, the
second communicating portion 38, the third chamber 36, and the
outlet pipe 42, and into the second exhaust pipe 22.
[0027] The inlet pipe 41 penetrates the first side wall 31a and the
first separating wall 32 and extends through the interior of the
third chamber 36. The inlet pipe 41 protrudes from the first side
wall 31a in a first direction (one direction) of the axial
direction and is connected to the first exhaust pipe 21 in a
location that is apart from the muffler body 31 in the first
direction of the axial direction. The outlet pipe 42 protrudes
radially from the peripheral wall 31c and is connected to the
second exhaust pipe 22 in a location that is radially apart from
the muffler body 31. Since the inlet pipe 41 penetrates the first
side wall 31a located on the first side in the axial direction and
the third chamber 36 is located on the first side in the axial
direction, the outlet pipe 42 is close to the inlet pipe 41 in the
axial direction. For example, in a case where the water muffler 30
is placed in the interior of the body 2 in such a manner that the
axial direction of the water muffler 30 conforms to the forward and
rearward direction, the inlet pipe 41 and the outlet pipe 42 are
placed in the front portion of the water muffler 30.
[0028] As shown in FIG. 4A, the inlet pipe 41 has a double-walled
pipe structure. The inlet pipe 41 includes a center pipe 43 and an
outer pipe 44. The center pipe 43 has a center pipe wall 45. The
outer pipe 44 has an outer pipe wall 46. An exhaust passage 47
through which the exhaust gas flows is provided inside the center
pipe wall 45. A water passage 48 through which the cooling water
flows is provided between the outer peripheral surface of the
center pipe wall 45 and the inner peripheral surface of the outer
pipe wall 46. As shown in FIG. 4B, the center pipe 43 and the outer
pipe 44 are circular pipes, respectively, and are disposed
coaxially with each other. The common axis of the pipes 43, 44 is a
center C41 of the inlet pipe 41. The exhaust passage 47 has a
circular cross-section. The water passage 48 has a ring-shaped
cross-section.
[0029] The downstream end portion of the inlet pipe 41 is formed
with an outlet 49 (hereinafter referred to as an exhaust gas outlet
49) of the exhaust passage 47, and an outlet 50 (hereinafter
referred to as a water outlet 50) of the water passage 48. The
downstream end of the center pipe 43 is opened to form the exhaust
gas outlet 49. The downstream end of the outer pipe 44 (the
downstream end of the water passage 48) is closed by a ring-shaped
closing plate 51. The water outlet 50 includes at least one
through-hole formed to penetrate the closing plate 51. The
through-hole (the water outlet 50) is, for example, a circular
hole. In a case where the water outlet 50 includes a plurality of
through-holes, the plurality of through-holes are arranged at equal
intervals in the circumferential direction of the closing plate
51.
[0030] The center pipe wall 45 has a protruding portion 45a
protruding from the outer pipe wall 46, at a downstream end portion
of the inlet pipe 41. In this structure, the water outlet 50 is
located to be apart from the exhaust gas outlet 49 in the axial
direction of the inlet pipe 41. A distance from the first
separating wall 32 to the exhaust gas outlet 49 is set to be longer
than a distance from the first separating wall 32 to the water
outlet 50. The outer peripheral surface of the center pipe 43
includes an exposed portion which is exposed in the first chamber
34. The ring-shaped closing plate 51 is externally fitted to the
center pipe 43. The inner peripheral edge of the closing plate 51
is integrated with the outer peripheral surface of the center pipe
43. The outer surface of the closing plate 51 is exposed in the
first chamber 34. The outer surface of the closing plate 51 is made
closer to the first separating wall 32 than the downstream end of
the center pipe 43 is.
[0031] As shown in FIGS. 4A and 4D, the center pipe 43 has a
radially protruding portion 52 which radially protrudes, at the
downstream end portion thereof. The radially protruding portion 52
is placed to overlap with the water outlet 50 when viewed from the
axial direction of the inlet pipe 41.
[0032] As shown in FIG. 4A, in a state in which the water muffler
30 is incorporated into the body 2, the inlet pipe 41 is inclined
downward toward a downstream side. As shown in FIG. 5, the center
C41 of the exhaust gas outlet 49 is placed above the center C31 of
the muffler body 31. Also, the center C41 of the exhaust gas outlet
49 is apart from the center C31 of the muffler body 31 in the
rightward and leftward direction. In the present embodiment, the
first exhaust pipe 21 is placed on the left side of the engine 11.
In the same manner, the center C41 of the exhaust gas outlet 49 is
apart from the center C31 of the muffler body 31, to the left.
Alternatively, in a case where the first exhaust pipe 21 is placed
at the right side, the center C41 of the exhaust gas outlet 49 may
be apart from the center C of the muffler body 31, to the
right.
[0033] In the water muffler 30 having the above-described
configuration, the center pipe wall 45 has the protruding portion
45a protruding from the outer pipe wall 46, at the downstream end
portion of the inlet pipe 41. The water outlet 50 is placed to be
apart from the exhaust gas outlet 49 in the axial direction of the
inlet pipe 41. Since the water outlet 50 is placed to be apart from
the exhaust gas outlet 49 in the axial direction of the inlet pipe
41, the cooling water does not easily reach the exhaust gas outlet
49 after the cooling water has flowed through the water passage 48
and into the inner space (the first chamber 34) of the muffler body
31 through the water outlet 50. Therefore, the cooling water does
not easily flow back through the exhaust passage 47.
[0034] In particular, the protruding portion 45a is provided with
the radially protruding portion 52 which radially protrudes. In
this structure, even when the cooling water which has passed
through the water outlet 50 flows toward the exhaust gas outlet 49
along the outer peripheral surface of the protruding portion 45a,
this cooling water can be caused to collide with the radially
protruding portion 52. Thus, the cooling water does not reach the
exhaust gas outlet 49 and can be diffused in the radial direction
of the inlet pipe 41. As a result, the cooling water does not
easily flow back through the exhaust passage 47. In the present
embodiment, the radially protruding portion 52 overlaps with the
water outlet 50 in the axial direction of the inlet pipe 41. The
radially protruding portion 52 can suitably prevent the back flow
of the cooling water through the exhaust passage 47.
[0035] Further, the inlet pipe 41 is inclined downward toward the
downstream side. Even if the cooling water flows into the exhaust
passage 47, the cooling water can be discharged from the exhaust
passage 47 by a gravitational force. This makes it possible to
prevent the backflow of the cooling water. The center C41 of the
exhaust gas outlet 49 is placed above the center C31 of the muffler
body 31. In this structure, even if the cooling water ejected from
the water outlet 50 is accumulated in the interior of the water
muffler 30, it becomes possible to prevent the back flow of the
accumulated cooling water through the exhaust passage 47.
[0036] Turning back to FIGS. 1 to 3, the water muffler 30 is placed
at the left part of the body 2 with respect to a center line C of
the body 2, in a rightward and leftward direction. The first
exhaust pipe 21 is placed on the left side of the engine 11 and
extends rearward from the engine 11. The water muffler 30 is placed
rearward relative to the engine room 10. More specifically, the
water muffler 30 is placed to overlap with the left deck fin 4c
when viewed from above (see FIG. 1). The water muffler 30 is placed
below the left deck fin 4c and accommodated in the interior of the
hull 3 (see FIG. 2). The first side wall 31a faces the front, while
the second side wall 31b faces the rear (see FIGS. 2 and 3). The
inlet pipe 41 protrudes forward from the first side wall 31a (see
FIGS. 2 and 3). The downstream end portion of the first exhaust
pipe 21 is connected to the inlet pipe 41 from the front (see FIGS.
2 and 3).
[0037] The outlet pipe 42 protrudes upward from a first portion
(i.e., front portion) of the water muffler 30 in the axial
direction (see FIG. 1). The second exhaust pipe 22 includes a
transverse pipe member 23 connected to the water muffler 30, and a
downstream pipe member 24 connected to the downstream end portion
of the transverse pipe member 23 (see FIGS. 1 to 3). The downstream
end portion of the transverse pipe member 23 and the upstream end
portion of the downstream pipe member 24 are connected to each
other by a flange 25 as a pipe joint (see FIGS. 1 to 3). The outer
diameter of the flange 25 is set to be larger than that of the
transverse pipe member 23 and that of the downstream pipe member
24.
[0038] The transverse pipe member 23 is connected to the downstream
end portion of the outlet pipe 42, and extends in the rightward and
leftward direction in the interior of the engine room 10 (see FIGS.
1 and 2). More specifically, the transverse pipe member 23 extends
in the rightward and leftward direction within a slight clearance
in the forward and rearward direction, which is formed between the
front wall which isolates the standing deck 4a from the engine room
10, and the air cleaner placed rearward relative to the engine 11
in the interior of the engine room 10. The transverse pipe member
23 is made of rubber and has an elasticity. The downstream end
portion of the transverse pipe member 23 is connected to the
upstream end portion of the downstream pipe member 24 via the
flange 25. The downstream pipe member 24 extends rearward and is
placed in the interior of the right deck fin 4b. The inner spaces
of the right and left deck fins 4b, 4c cannot be accessed easily by
a user, but are spatially in communication with the engine room 10.
Since the exhaust system 20 includes the transverse pipe member
which allows the left part and right part of the body 2 to be in
communication with each other, it becomes possible to prevent the
backflow of the water toward the engine through the exhaust pipe,
even if the personal watercraft 1 is inverted to the left or to the
right.
[0039] The second exhaust pipe 22 includes a swelling portion 22a
protruding upward. Because of the presence of the swelling portion
22a, it becomes possible to prevent a situation in which the water
reaches a portion of the second exhaust pipe 22 which is upstream
of the swelling portion 22a even when the water outside the
watercraft flows forward through the downstream end portion of the
second exhaust pipe 22 as backflow. In this way, the water muffler
30 and the engine 11 can be protected.
[0040] The swelling portion 22a is provided at the downstream pipe
member 24. The upstream end portion of the downstream pipe member
24 and the flange 25 are placed below the top portion of the
swelling portion 22a (see FIG. 1). The upstream portion of the
second exhaust pipe 22 has an inverted-U shape.
[0041] The swelling portion 22a is accommodated in the interior of
the right deck fin 4b. The upstream end portion of the downstream
pipe member 24 is placed in front of the top portion of the
swelling portion 22a. The upstream end portion of the downstream
pipe member 24 and the flange 25 are placed at the front end
portion of the right deck fin 4b or slightly in front of the front
end portion of the right deck fin 4b.
[0042] FIG. 6A is a cross-sectional view of the right deck fin 4b,
in a region which is in the vicinity of the flange 25, when viewed
from the front. FIG. 6B is a cross-sectional view of the right deck
fin 4b, in a region which is in the vicinity of the top portion of
the swelling portion 22a, when viewed from the front. As shown in
FIG. 6B, the top portion of the swelling portion 22a is close to
the inner surface of the top portion of the right deck fin 4b. In
contrast, the upstream end portion of the downstream pipe member 24
is vertically apart from the inner surface of the top portion of
the right deck fin 4b. The width of the right deck fin 4b is
reduced in the rightward and leftward direction as the right deck
fin 4b extends upward. In a case where the deck 4 is manufactured
by molding, the right deck fin 4b is designed to have the
above-described width, because it is necessary to provide a draft
angle.
[0043] If the transverse pipe member 23 and the downstream pipe
member 24 are connected to each other at the top portion of the
swelling portion 22a, the top portion of the right deck fin 4b is
required to have a great lateral width so that the flange 25 can be
accommodated therein. Since the right deck fin 4b is required to be
provided with the draft angle, the lower portion of the right deck
fin 4b is expanded. This may lead to reduction of the width of the
standing deck 4a. In the present embodiment, the flange 25 is
placed at the lower portion of the right deck fin 4b. This makes it
possible to reduce the width of the right deck fin 4b, and increase
the width of the standing deck 4a. As a result, the stand-up type
personal watercraft 1 which can be steered easily by the rider can
be realized.
[0044] The water muffler 30 is placed rearward relative to the
engine 11 (see FIG. 1). The inlet pipe 41 is provided on the first
side wall 31a (front wall) of the muffler body 31 so that the inlet
pipe 41 can be linearly connected to the first exhaust pipe 21. On
the front side of the muffler body 31, the third chamber 36, which
is a furthest downstream chamber of the chambers 34 to 36, is
placed (see FIG. 3). For this reason, the outlet pipe 42 is also
placed at the front portion of the water muffler 30. Since the
outlet pipe 42 is placed at the front portion of the water muffler
30, the upstream portion of the second exhaust pipe 22 is made
close to the engine 11. In this layout, the water muffler 30 can be
placed below the right deck fin 4b, and the upstream portion of the
second exhaust pipe 22 can be placed in front of the standing deck
4a. Also, the upstream portion of the second exhaust pipe 22 can be
placed in the engine room 10. In the rear end portion of the engine
room 10, a gap is formed between the separating wall and the air
cleaner 14. The transverse pipe member 23 can be extended through
this gap. In this way, the transverse pipe member 23 can be placed
while avoiding interference with the propeller shaft 12. The
transverse pipe member 23 is made of rubber, and is bendable.
Therefore, the transverse pipe member 23 can be easily placed in a
narrow space. In addition, an operation for connecting the water
muffler 30 and the downstream pipe member 24 to each other can be
performed easily by use of the transverse pipe member 23.
[0045] The above-described configuration and illustration are
merely exemplary, and can be changed within the scope of the
invention. Although in the example of FIG. 4A, the closing plate 51
is located to be apart from the first separating wall 32 in the
axial direction, in the interior of the first chamber, the closing
plate 51 may be coplanar with the first separating wall 32. In the
example of FIG. 4D, the radially protruding portion 52 protrudes
radially from the entire periphery of the protruding portion 45 and
has the ring-shape, when viewed from the axial direction of the
inlet pipe 41. However, it is sufficient that the radially
protruding portion 52 overlaps with the water outlet 50, when
viewed from the axial direction of the inlet pipe 41. As shown in
FIGS. 4A and 4D, in the case where the plurality of water outlets
50 are arranged to be spaced apart from each other in the
circumferential direction, a plurality of radially protruding
portions 52 may be provided to protrude from a plurality of
locations, respectively, on the outer peripheral surface of the
protruding portion 45a. The cross-section of each of the muffler
body 31 and the inlet pipe 41 need not have a circular shape. The
configuration in which the exhaust gas outlet is placed above the
center of the muffler body is merely exemplary. Alternatively, the
exhaust gas outlet may be placed below the center of the muffler
body.
* * * * *