U.S. patent application number 09/844507 was filed with the patent office on 2002-07-18 for water preclusion system for watercraft exhaust.
Invention is credited to Yamamura, Tadatsugu, Yoshida, Tatsuya.
Application Number | 20020094732 09/844507 |
Document ID | / |
Family ID | 17840047 |
Filed Date | 2002-07-18 |
United States Patent
Application |
20020094732 |
Kind Code |
A1 |
Yoshida, Tatsuya ; et
al. |
July 18, 2002 |
Water preclusion system for watercraft exhaust
Abstract
An exhaust system for a watercraft includes a water trap
arranged on a first side of a hull tunnel, a discharge port
arranged on a second side of the hull tunnel, and a chamber
branched from and communicating with an exhaust passage connecting
the watertrap with the discharge port.
Inventors: |
Yoshida, Tatsuya; (Shizuoka,
JP) ; Yamamura, Tadatsugu; (Shizuoka, JP) |
Correspondence
Address: |
KNOBBE MARTENS OLSON & BEAR LLP
620 NEWPORT CENTER DRIVE
SIXTEENTH FLOOR
NEWPORT BEACH
CA
92660
US
|
Family ID: |
17840047 |
Appl. No.: |
09/844507 |
Filed: |
April 27, 2001 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
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09844507 |
Apr 27, 2001 |
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09422214 |
Oct 19, 1999 |
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6261140 |
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Current U.S.
Class: |
440/89J ;
440/88J; 440/88R; 440/88T; 440/89C; 440/89F; 440/89H |
Current CPC
Class: |
F01N 3/28 20130101; F01N
13/12 20130101; B63B 34/10 20200201; F01N 2590/02 20130101; F01N
2590/022 20130101; F02B 61/045 20130101; B63H 21/32 20130101; F01N
13/004 20130101 |
Class at
Publication: |
440/89 ;
440/88 |
International
Class: |
B63H 021/32 |
Foreign Application Data
Date |
Code |
Application Number |
Oct 19, 1998 |
JP |
10-196932 |
Claims
What is claimed is:
1. A watercraft having a hull defining an engine compartment in
which an engine is provided, said engine including at least one
exhaust port for discharging exhaust gases from said engine to the
atmosphere through an exhaust system, said exhaust system
comprising an exhaust passage extending between an exhaust manifold
of said engine and an exhaust discharge port provided on a first
side of a hull tunnel of said hull, said exhaust passage including
a watertrap device provided on a second side of said hull tunnel
opposite said first side, said exhaust passage including an
intermediate portion extending between said watertrap device and
said discharge port, said intermediate portion extending above a
top of said hull tunnel, and a first chamber branched from and
communicating with said intermediate portion.
2. A watercraft as in claim 1, wherein said first chamber branches
upwardly from said intermediate portion.
3. A watercraft as in claim 1, wherein said first chamber is
provided at a position above said hull tunnel.
4. A watercraft as in claim 3, wherein said first chamber is
provided at a position downstream from an apex of said intermediate
portion.
5. A watercraft as in claim 1, wherein said intermediate portion
includes a throat provided between said first chamber and said
intermediate portion, through which said first chamber and said
intermediate portion communicate, and said throat and said chamber
being tuned so as to form a Hemholtz resonator to attenuate noise
from said engine.
6. A watercraft as in claim 5, wherein said throat and said
Hemholtz resonator are arranged so as to branch upwardly from said
intermediate portion.
7. A watercraft as in claim 1, additionally comprising a second
chamber communicating with said intermediate portion at a position
between said first chamber and said discharge port, said first
chamber having a cross-sectional area larger than a cross-sectional
area of said intermediate portion.
8. A watercraft as in claim 7, wherein said first chamber branches
upwardly from said intermediate portion, and wherein said second
chamber comprises a cavity elongated in a substantially horizontal
direction.
9. A watercraft as in claim 8, wherein said intermediate reservoir
is arranged such that a maximum rated water line of said watercraft
loaded with a maximum rated load is below an upper wall of said
second chamber.
10. A watercraft as in claim 9, wherein said intermediate portion
includes a connector portion extending a predetermined length into
an interior of said second chamber.
11. A watercraft as in claim 10, wherein said second chamber and
said predetermined length are configured such that an amount of
water sufficient to fill said second chamber to the maximum rated
waterline is not sufficient to flow past said connector portion
when said watercraft is inverted.
12. A watercraft as in claim 10, wherein said intermediate portion
includes a throat provided between said chamber and said
intermediate portion, through which said chamber and said
intermediate portion communicate, said throat and said first
chamber being tuned so as to form a Hemholtz resonator and to
attenuate noise from said engine, and said connector portion and
said Hemholtz resonator being tuned so as to provide sound
attenuation of the exhaust of said engine.
13. A watercraft as in claim 1, additionally comprising a cooling
jacket configured to circulate a coolant in thermal communication
with said exhaust passage, a first telltale port and a second
telltale port configured to discharge a stream of the coolant at a
position forward of an operator's seating position of said
watercraft, said first telltale port communicating with said
cooling jacket at a position upstream from said second telltale
port.
14. A watercraft as in claim 13, wherein said exhaust passage
additionally comprises an expansion chamber portion including an
expansion chamber and a downstream portion communicating with said
expansion chamber portion through an exhaust passage coupling, and
extending downstream from said expansion chamber portion, said
cooling jacket including a first portion in thermal communication
with said expansion chamber portion and a second portion in thermal
communication with said downstream portion, said first and second
portions of said cooling jacket fluidically communicating through
said exhaust passage coupling, said first telltale port
communicating with said first portion of said cooling jacket and
said second telltale port communicating with said second portion of
said cooling jacket.
15. A watercraft having a hull defining an engine compartment in
which an engine is provided, said engine including at least one
exhaust port for discharging exhaust gases from said engine to the
atmosphere through an exhaust system, said exhaust system
comprising an exhaust passage extending between an exhaust manifold
of said engine and an exhaust discharge port provided on a first
side of a hull tunnel of said hull, said exhaust passage including
a watertrap device provided on a second side of said hull tunnel
opposite said first side, said exhaust passage including an
intermediate portion extending between said watertrap device and
said discharge port, said intermediate portion extending above a
top of said hull tunnel, and a first chamber communicating with
said intermediate portion and having a cross-sectional area larger
than a cross-sectional area of said intermediate portion, said
first chamber provided downstream of an apex of said intermediate
portion, said first chamber being disposed relative to a maximum
rated water line of said watercraft such that an upper wall of said
first chamber lies above said maximum rated waterline.
16. A watercraft as in claim 15, wherein said intermediate portion
includes a connector portion extending a predetermined length into
an interior of said first chamber.
17. A watercraft as in claim 16, wherein said first chamber and
said predetermined length are configured such that an amount of
water sufficient to fill said first reservoir to the maximum rated
water line is not sufficient to flow past said connector portion
when said watercraft is inverted.
18. A watercraft as in claim 16, further comprising a Hemholtz
resonator branched from said intermediate portion at a position
downstream from an apex of said intermediate portion.
19. A watercraft having a hull defining an operator's seating
position and an engine compartment in which an engine is provided,
said engine including at least one exhaust port for discharging
exhaust gases from said engine to the atmosphere through an exhaust
system, said exhaust system comprising an exhaust passage extending
between an exhaust manifold of said engine and an exhaust discharge
port, a cooling jacket configured to circulate coolant in thermal
communication with said exhaust passage, and first and second
telltale ports configured to discharge streams of cooling jacket
liquid at positions forward of the operator's seating position of
said watercraft.
20. A watercraft as in claim 19, wherein said exhaust passage
additionally comprises an expansion chamber portion including an
expansion chamber and a downstream portion communicating with said
expansion chamber portion through an exhaust passage coupling, and
extending downstream from said expansion chamber portion, said
cooling jacket including a first portion in thermal communication
with said expansion chamber portion and a second portion in thermal
communication with said downstream portion, said first and second
portions of said cooling jacket fluidicially communicating through
said exhaust passage coupling, said first telltale port
communicating with said first portion of said cooling jacket and
said second telltale port communicating with said second portion of
said cooling jacket.
21. A watercraft as in claim 19, wherein said first and second
telltale ports are configured to discharge streams of coolant on
opposite sides of said hull.
Description
PRIORITY INFORMATION
[0001] This application is based on and claims priority to Japanese
Patent Application No. 10-296932 filed Oct. 19, 1998, the entire
contents of which is hereby expressly incorporated by
reference.
BACKGROUND OF THE INVENTION
[0002] 1. Field of the Invention
[0003] The present invention is directed to an exhaust system for a
watercraft, and more particularly to a water preclusion and noise
attenuation system employed in a watercraft exhaust system.
[0004] 2. Description of Related Art
[0005] Personal watercraft have become very popular in recent
years. This type of watercraft is quite sporting in nature and
carries a rider and possibly one to three passengers. A relatively
small hull of the personal watercraft commonly defines a riders'
area above an engine compartment. A two-cycle internal combustion
engine frequently powers a jet propulsion unit which propels the
watercraft. The engine lies within the engine compartment in front
of a tunnel formed on the underside of the watercraft hull. The jet
propulsion unit is located within the tunnel and is driven by a
drive shaft. The drive shaft usually extends between the engine and
the jet propulsion device, through a wall of the hull tunnel.
[0006] Because of their small size and high degree of
maneuverability, however, there are certain objections to the use
of these watercraft on some bodies of water. One of these
objections is caused by the fact that this type of watercraft,
primarily because of its small size, has a relatively simple
exhaust system that does not provide a significant degree of
silencing. This result is mandated primarily by the very compact
nature of the watercraft and the relatively small area that is
available for exhaust treatment. Because these watercrafts can be
utilized on quite small bodies of water, the potential noise may be
more objectionable than larger watercraft having unmuffled exhaust
systems but which do not operate on these small bodies of
water.
[0007] An exhaust system of a typical personal watercraft
discharges engine exhaust to the atmosphere either through or close
to the body of water in which the watercraft is operating. Although
submerged discharge of engine exhaust silences exhaust noise,
environmental concerns arise. These concerns are particularly acute
in connection with two-cycle engines because engine exhaust from
two-cycle engines often contains lubricants, unburned fuel, and
other byproducts.
[0008] Such environmental concerns have raised a desire to minimize
exhaustion of hydrocarbons and other exhaust byproducts (e.g.,
carbon monoxide and oxides of nitrogen), and thus reduce pollution
of the atmosphere and the body of water in which the watercraft is
operated. In response to the increased concerns regarding exhaust
emissions, some personal watercraft engines recently have been
equipped with a catalyst to convert exhaust byproducts to harmless
gases.
[0009] Catalysts must operate at a relatively high temperature in
order to produce the necessary thermal reaction and burning of the
exhaust byproducts. A catalytic device thus desirably operates
within a specific range of temperature so as to effectively and
efficiently convert engine exhaust into generally harmless
gases.
[0010] Some prior exhaust systems have employed a cooling jacket
about the catalytic device to maintain the catalytic device within
the desired temperature range. In some systems, at least a portion
of the cooling water also is introduced into the stream of the
exhaust gasses discharged from the engine, not only further cool
and silence the exhaust gases, but also to assist the discharge of
exhaust gases. The added water to the exhaust system, however,
gives rise to possible damage to the catalyst.
[0011] In order to prevent water from entering the exhaust system
which could therefore damage the engine and/or catalyst, it is been
known to provide watercraft with a device commonly referred to as a
"watertrap" (a.k.a. "waterlock" or "water box"). A watertrap
typically includes an inlet, an outlet, and a plurality of baffles
defining open chambers which under certain operating conditions
contain water. Typically, the watertrap is arranged in the exhaust
system downstream from the engine exhaust manifold and upstream
from a discharge port of the exhaust system. The exhaust gases and
water flow through the chambers within the watertrap while the
chambers generally prevent water from moving back through the
watertrap and upstream through the exhaust system towards the
engine exhaust manifold and/or the catalyst during abrupt
watercraft movements or if the watercraft is capsized. If a
watercraft is capsized, a significant amount of water may flow into
the watertrap from the portion of the exhaust system piping
downstream from the watertrap, thereby forcing a substantial amount
of water upstream into the exhaust system and fowling and/or
damaging the internal combustion engine and/or shattering the
catalyst bed of the exhaust system.
[0012] Exhaust noise also posses problems for personal watercraft
use. Despite recent attempts to reduce the noise generated by and
emissions discharged from personal watercraft powered by two-cycle
engines, certain recreational facilities have banned the operation
of two-cycle watercraft. Such bans have resulted in a decrease in
popularity of personal watercraft powered by two-cycle engines.
SUMMARY OF THE INVENTION
[0013] A need exists for an exhaust system for a watercraft which
includes a water preclusion system that further reduces the
possibility of water flowing upstream in the exhaust system during
high speed operation and/or capsizing, and which does not cause
undue back pressure in the exhaust system which may reduce the
power output of the engine of the watercraft. Additionally, it is
desirable that such a system further attenuate exhaust noise and is
compact in size, utilizing the relatively compact spaces that are
typically available in the hulls of personal watercraft.
[0014] According to one aspect of the present invention, a
watercraft includes an exhaust system having an exhaust passage
extending between an exhaust manifold of an engine and an exhaust
discharge port provided on a first side of a hull tunnel of a hull
of a watercraft. According to the present aspect of the invention,
the exhaust passage includes a watertrap device provided on a
second side of the hull tunnel opposite the first side and an
intermediate portion extending between the watertrap device and the
discharge port. The intermediate portion extends above a top of the
hull tunnel and includes a chamber branched from and communicating
with the intermediate portion. By providing a chamber branched from
and communicating with the intermediate portion of the exhaust
passage, where the intermediate portion extends above a top of the
hull tunnel of the watercraft, the present aspect of the invention
achieves the conflicting goals of preventing the upstream flow of
water through the exhaust system while avoiding additional back
pressure in the exhaust system.
[0015] For example, by providing the watertrap device on the side
of the hull tunnel opposite the exhaust discharge port and
providing the branched chamber in the portion of the exhaust
passage that extends above a top of the hull tunnel, the exhaust
system provides an additional chamber for trapping water that may
flow into the exhaust discharge port of the watercraft during high
speed maneuvering or capsizing. Furthermore, since the chamber is
branched from the intermediate portion, the chamber does not
generate large back pressures in the exhaust system during
operation of the internal combustion engine. Additionally, the
branched chamber could optionally be tuned so as to form a Hemholtz
resonator, so as to provide additional noise dampening of the
internal combustion engine. Therefore, despite being capsized, the
watercraft can adequately prevent permanent damage to the engine
and/or catalyst bed, provide additional noise suppression of
exhaust, while avoiding the generation of additional back pressures
in the exhaust system.
[0016] Further aspects, features, and advantages of the present
invention will become apparent from the detailed description of the
preferred embodiment which follows.
BRIEF DESCRIPTION OF THE DRAWINGS
[0017] The above-mentioned and other features of the invention will
now be described with reference to the drawings of a preferred
embodiment of the present watercraft exhaust system. The
illustrated embodiments of the watercraft are intended to
illustrate, but not to limit the invention. The drawings contain
the following figures:
[0018] FIG. 1 is a partial sectional, side elevational view of a
personal watercraft including an exhaust system configured in
accordance with a preferred embodiment of the present
invention;
[0019] FIG. 2 is a top plan view of a portion of the exhaust system
included in the personal watercraft of FIG. 1;
[0020] FIG. 3 is a cross-sectional view along line 3-3 of the
watercraft shown in FIG. 2;
[0021] FIG. 4 is a an enlarged perspective view of the exhaust
system shown in FIG. 2;
[0022] FIG. 5 is a top plan view of a chamber provided in the
exhaust system shown in FIG. 4;
[0023] FIG. 6 is a sectional view along line 6-6 shown in FIG.
5;
[0024] FIG. 7 is a top plan view of the watercraft shown in FIG. 1
schematically representing an arrangement of telltale ports;
[0025] FIG. 8 is a partial top plan view of the watercraft shown in
FIG. 1;
[0026] FIG. 9 is a rear elevational view of the control mast of the
watercraft shown in FIG. 1;
[0027] FIG. 10 is a partial side elevational view of the watercraft
shown in FIG. 1, illustrating the movement of a hatch; and
[0028] FIG. 11 is a partial prospective view of the watercraft
shown in FIG. 1 with the hatch in an open position.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT
[0029] An improved exhaust system for a watercraft is disclosed
herein. The exhaust system includes an enhances noise attenuation
and water preclusion system which does not significantly increase
backpressure within the system. Thus, engine performance is not
significantly impacted despite quieter watercraft operation.
[0030] FIG. 1 illustrates a personal watercraft 10 which includes
an exhaust system 12 configured in accordance with a preferred
embodiment of the present invention. Although the present exhaust
system 12 is illustrated in connection with a personal watercraft,
the illustrated exhaust system can be used with other types of
watercraft as well, such as, for example, but without limitation,
small jet boats and the like. Before describing the exhaust system
12, an exemplary personal watercraft 10 will first be described in
general details to assist the reader's understanding of the
environment of use and the operation of the exhaust system 12.
[0031] The watercraft 10 includes a hull 14 formed by a lower hull
section 16 and an upper deck section 18. The hull sections 16, 18
are formed from a suitable material such as, for example, a molded
fiberglass reinforced resin (e.g., SMC). The lower hull section 16
and the upper deck section 18 are fixed to each other around the
peripheral edges 20 in any suitable manner.
[0032] As viewed in the direction from the bow to the stem of the
watercraft, the upper deck section 18 includes a bow portion 19, a
control mast 20 and a rider's area 22. The bow portion 19 slopes
upwardly toward the control mast 20 and includes at least one air
duct through which air can enter the hull. A hatch cover 24
desirably extends above an upper end of the air duct to inhibit an
influx of water into the hull.
[0033] The hatch cover 24 is preferably attached to the upper deck
section 18 via a hinge 25. Additionally, as shown in FIGS. 8, 10
and 11, pneumatic cylinders 27 are mounted adjacent the hinge 25 so
as to bias the hatch 24 to an open position, thereby enabling a
user to easily open the hatch 24. Furthermore, by providing two
pneumatic cylinders 27, the hatch 24 can be raised, lowered and
maintained in an open position in a stable manner. The cylinders 27
also inhibit twisting of the hatch and thereby strengthen the
hinged coupling. Also as shown in FIG. 11, the hatch 24 provides
access to a access hole 29 which may be used to provide access to a
storage compartment for storing a fuel tank or any other desired
item.
[0034] A fuel tank (not shown) is preferably located within the
hull 14 beneath the hatch over 24. Conventional means, such as, for
example, straps, are preferably used to secure the fuel tank to the
lower hull 16.
[0035] The control mast 20 extends upward from the bow portion 19
and supports a handlebar assembly 28. The handlebar 28 controls the
steering of the watercraft 10 in a conventional manner. The
handlebar assembly 28 also carries a variety of controls of the
watercraft 10, such as, for example, a throttle control, a start
switch and a lanyard switch.
[0036] A display panel (not shown) is desirably located in front of
the control mast 20 on the bow portion 19 and is orientated to be
visible by the rider. The display panel desirably displays a number
of performance characteristics of the watercraft such as for
example, watercraft speed (via a speedometer), engine speed (via a
tachometer), fuel level, oil level, engine temperature, battery
charge level and the like. As shown in FIG. 8, the cowling adjacent
the control mast 20 preferably includes a reverse lever 21a, a fuel
cock 21b, and a choke 21c. These components are arranged to the
sides of the control mast 20 and just forward of the same. The
reverse lever 21a is operatively connected to a conventional
reverse thrust bucket (not shown) which is configured to
selectively divert water discharged from a propulsion device to
cause the watercraft 10 to move in a reversed direction. The fuel
cock 21b and choke knob 21c are arranged on a side of the control
mast 20 opposite the reverse lever 21a. This arrangement of these
components disposes each of them in convenient reach of the
watercraft rider when seated just behind the control mast 20..
[0037] The rider's area 22 lies behind the control mast 20 and
includes a seat assembly 30. In the illustrated embodiment, the
seat assembly 30 has a longitudinally extending straddle-type shape
that may be straddled by an operator and by at least one to three
passengers. The seat assembly 30, at least in principal part, is
formed by a seat cushion 32 supported by a raised pedestal 34. The
raised pedestal 34 has an elongated shape and extends
longitudinally along the center of the watercraft 10. The seat
cushion 32 desirably is removably attached to a top surface of the
pedestal 34 and covers the entire upper end of the pedestal for
rider and passenger comfort.
[0038] An access opening (not shown) is preferably located on an
upper surface of the pedestal 34. The access opening opens into an
engine compartment 38 formed within the hull 14. The seat cushion
32 normally covers and seals an access opening 35. When the seat
cushion 32 is removed, the engine compartment 38, as well as a
storage cavity 36, are accessible through the access opening.
[0039] The pedestal 34 also desirably includes at least one air
duct (not shown) located behind the access opening. The air duct
communicates with the atmosphere through a space formed between the
pedestal 34 and the cushion 32, which is formed behind the access
opening. Air can pass through the rear duct in both directions.
[0040] As shown in FIGS. 3 and 8, the upper deck section 18 of the
hull 12 advantageously includes a pair of raised gunnels 39
positioned on opposite sides of the aft end of the upper deck
assembly 18. The raised gunnels 39 define a pair of foot areas 40,
as shown in FIG. 8, that extend generally longitudinally and
parallel to the sides of the pedestal 34. In this position, the
operator and any passengers sitting on the seat assembly 30 can
place their feet in the foot areas 40 with the raised gunnels 39
shielding the feet and lower legs of the riders. A non-slip (e.g.,
rubber) mat desirably covers the foot areas 40 to provide increased
grip and traction for the operator and the passengers.
[0041] The lower hull portion 16 principally defines the engine
compartment 38. Except for the air ducts, the engine compartment 38
is normally substantially sealed so as to enclose an engine of the
watercraft 10 from the body of water in which the watercraft is
operated.
[0042] The lower hull 16 is designed such that the watercraft 10
planes or rides on a minimum surface area at the aft end of the
lower hull 16 in order to optimize the speed and handling of the
watercraft 10 when up on plane. For this purpose, as shown in FIG.
3, the lower hull section generally has a V-shaped configuration
formed by a pair of inclined sections that extend outwardly from a
keel line 16a of the hull to the hull's side walls at a dead rise
angle. Each inclined section desirably includes at least one strake
16c, and the strakes 16c of the hull preferably are symmetrically
disposed relative to the keel line of the watercraft 10. The
inclined sections also extend longitudinally from the bow toward
the transom of the lower hull 14. The side walls are generally flat
and straight near the stem of the lower hull and smoothly blend
towards the longitudinal center of the watercraft at the bow. The
lines of intersection between the inclined sections and the
corresponding side walls form the outer chines 16b of the lower
hull section.
[0043] Toward the transom of the watercraft, the inclined sections
of the lower hull 16 extend outwardly from a recessed channel or
tunnel 42 that extends upward toward the upper deck portion 16. As
used hereinafter, "recessed channel," "tunnel," and "hull tunnel"
are used interchangeably to refer to the portion of the transom end
of the watercraft hull that is formed to accommodate a jet of water
generated by the watercraft for propulsion purposes. For example,
the watercraft 10 includes a jet pump unit 44 which generates a
generally rearward directed jet of water to generate a propulsion
force to cause forward and/or reverse movement of the watercraft
10.
[0044] The jet pump unit 44 is mounted within the tunnel 42 formed
on the underside of the lower hull section 16 by a plurality of
bolts. An intake duct of the jet pump unit 44 defines an inlet
opening 45 that opens into a gullet. The gullet leads to an
impeller housing assembly in which the impeller of the jet pump 44
operates. An impeller housing assembly also acts as a
pressurization chamber and delivers the water flow from the
impeller housing to a discharge nozzle housing.
[0045] A steering nozzle 46 is supported at the downstream end of a
discharge nozzle 48 by a pair of vertically extending pivot pins.
In an exemplary embodiment, the steering nozzle 46 has an integral
lever on one side that is coupled to the handlebar assembly 28, for
example, a bowden-wire actuator, as known in the art. In this
manner, the operator of the watercraft can move the steering nozzle
46 to effect directional changes of the watercraft 10.
[0046] A ride plate 50 preferably covers a portion of the tunnel 42
behind the inlet opening 45 to enclose the pump assembly and a
nozzle assembly 60 of the propulsion unit. The aft end of an
impeller shaft 52 is suitably supported and journaled within the
engine chamber of the assembly in a known manner. The impeller
shaft 52 extends in the forward direction through a front wall 54
of the tunnel 42 as well as through a bulkhead 56.
[0047] An internal combustion engine 60 of the watercraft powers
the impeller shaft 52 to drive the impeller of the jet pump unit
44. The engine 60 is positioned within the engine compartment 38
and is mounted primarily beneath the control mast 20.
Vibration-absorbing engine mounts (not shown) are preferably used
to secure the engine 60 to the lower hull portion 16 in a known
manner. The engine 60 is mounted in approximately a central
position in the watercraft 10.
[0048] In the illustrated embodiment, the engine 60 includes three
in-line cylinders and operates on a two-stroke, crankcase
compression principle. The engine 60 is positioned such that the
row of cylinders lies parallel to a longitudinal axis of the
watercraft 10, running from bow to stern. The axis of each cylinder
may be skewed or inclined relative to a vertical central plane of
the watercraft 10, in which the longitudinal axis lies. This engine
type, however, is merely exemplary. Those skilled in the art will
readily appreciate that the present exhaust system can be used with
any of a variety of engine types having other number of cylinders,
having other cylinder arrangements and operating on other
combustion principles (e.g., four-stroke principle).
[0049] Preferably, the jet pump 44 supplies cooling water through a
conduit (not shown) to an engine cooling jacket. For this purpose,
an outlet port may be formed on the housing of the jet pump 44. The
conduit is coupled to an outlet port and extends to an inlet port
for supplying coolant, such as water to the engine cooling jacket.
The engine cooling jacket extends through the exhaust manifold,
through the cylinder block, about the cylinders, and through the
cylinder head assembly. Either the cylinder head assembly or the
exhaust manifold can include a coolant discharge port through which
the cooling water exits the engine 60 and thence flows through at
least a portion of the exhaust system 12.
[0050] The personal watercraft 10 so far described represents only
an exemplary watercraft on which the present exhaust system 12 can
be employed. A further description of the personal watercraft 10 is
not believed necessary for an understanding and an appreciation of
the present exhaust system 12. The exhaust systems will now be
described in detail.
[0051] The exhaust system 12 discharges exhaust byproducts from the
engine 60 to the atmosphere and/or to the body of water in which
the watercraft 10 is operated. The exhaust system 12 is fed exhaust
gasses from an exhaust manifold (not shown) that is affixed to the
side of the cylinder block of engine 60 and which receives exhaust
gases from the combustion chambers through exhaust ports in a
well-known manner. For this purpose, the exhaust manifold desirably
includes a number of runners equal in number to the number of
cylinders. Each runner communicates with the exhaust port(s) of the
respective cylinder. The runners of the exhaust manifold thence
merge together to form a common exhaust path that terminates at an
outlet end of the manifold.
[0052] The exhaust manifold may have a dual shell construction
formed by an inner wall and an outer wall. A cooling jacket is
formed between the two walls and communicates with one or more
water passages within the engine block 60. In the illustrated
embodiment, coolant flows from the engine block 60 into the cooling
jacket of the exhaust manifold; such coolant, however, can be
supplied from a different location of the cooling system (e.g.,
from a location upstream of the engine cooling jacket). This dual
wall construction desirably is formed along each runner of the
manifold, as well as about the common flow section of the
manifold.
[0053] As shown in FIG. 7, an expansion chamber 72 has a generally
tubular shape with an enlarged cross-sectional flow area to allow
the exhausts gases to expand and silence, as known in the art. The
upstream end of the expansion chamber 72 has a diverging
configuration and the downstream has a converging configuration, as
is conventional. A thick-wall, which is defined between an inner
surface and an outer surface forms the tubular shape of the
expansion chamber 72. The inner surface defines the exhaust flow
passage through the expansion chamber 72. A plurality of cooling
passages (not shown) extend along side the flow passage through the
thick wall of the expansion chamber 72. The passages are desirably
spaced around the inner surface.
[0054] As shown in FIG. 1, the expansion chamber 72 has a reduced
cross-sectional outlet portion 74 which directs exhaust gases into
a catalytic device 76. The catalytic device 76 desirably includes
the catalyst bed 78 which changes at least a portion of the exhaust
gases into harmless gases (e.g., carbon dioxide and water). The
catalyst bed 78 lies within the exhaust gas flow through the
exhaust system 12 at a position that mandates that all exhaust
gases must pass through the catalyst bed 78. The catalyst bed 78
reduces the emissions of hydrocarbons and other exhaust products
(e.g., carbon monoxide and oxides of nitrogen) from the watercraft
engine.
[0055] For this purpose, the catalyst bed 78 is formed of a
catalytic material, which is designed to render harmless either all
or some of the exhaust byproducts. For example, the catalyst bed 78
can be made of a metal catalyst material, such as, for example,
platinum. The catalyst bed 78, however, can be made of different
types of catalytic materials for treating different exhaust
byproducts or lubricants.
[0056] The catalyst device 76 is jacketed by a cooling jacket. In
the illustrated embodiment, the cooling jacket receives coolant
flow from the cooling jacket in thermal contact with the expansion
chamber. Other coolant flow path arrangements of course are also
possible, as well known in the art.
[0057] As shown in FIG. 1, an exhaust passage 68 extends downwardly
from the catalytic device 76 and is coupled to a watertrap device
80 by a flexible conduit.
[0058] As shown in FIGS. 1 and 2, the watertrap 80 is connected to
the exhaust passage 68 via a connector pipe 82. Preferably, the
watertrap device 80 is provided with a plurality of internal
baffles arranged to retain a predetermined volume of water and to
generally suppress the back flow of water toward the catalytic
device 76. In order to further inhibit significant flows of water
into the watertrap 80 during high speed maneuvering or capsizing,
the watercraft 10 is provided with a water preclusion system
90.
[0059] The present water preclusion system 90 inhibits a flow of
significant volume of water through watertrap 80, and into the
catalytic bed 78 and/or the expansion chamber 72. As noted above,
if water reaches the catalytic bed 78 during operation of the
watercraft 10, the catalytic bed 78 can shatter under some
operating condition. Additionally, if water, especially sea water,
enters the expansion chamber 72, the exhaust manifold or the
combustion chambers of the engine 60, accelerated and/or severe
corrosion can occur which often requires expensive and invasive
repairs. The present water preclusion system 90 thus inhibits a
significant backflow of water through the exhaust system and
thereby reduces the likelihood that such repairs to the catalyst
device, to the engine, and/or to the balance of the exhaust system
will be required.
[0060] As shown in FIGS. 1 through 4, the water preclusion system
90 includes an intermediate exhaust passage 92 which extends
between the watertrap device 80 and an exhaust discharge 94.
Although the passage 92 may be formed monolithically with chambers
100 and 110 (discussed in detail below), the passage 92 is
preferably formed of portions 91, 93, and 95, which are constructed
from an appropriate material, such as, for example, high
temperature rubber or plastic. Depending on which components are
included in the system 90, portions 91, 93, and 95, or various
combination thereof, are connected via couplings 97 in an known
manner.
[0061] As shown in FIG. 3, the watercraft 10 floats, in an unloaded
state, such that the water line is approximately at the level of an
unloaded water line 96. When the watercraft 10 is loaded with the
maximum rated weight, the watercraft 10 floats at a depth of
approximately the maximum rated water line 98. As shown in FIG. 3,
the intermediate exhaust passage 92 extends from the watertrap
device 80 at a position below the maximum rated water line 98 above
the tunnel 42, and to a position above the maximum rated water line
98, then to a position below the water line 98 and the water line
96 to discharge the port 94. Therefore, when the watercraft 10 is
at rest with the maximum rated load, water will flow into the
exhaust discharge 94 and up into the intermediate passage 92 only
up to the water line 98. Therefore, at least when the watercraft 10
is at rest with the maximum rated load, water should not flow into
the watertrap 80.
[0062] However, as shown in FIGS. 1-4, the water preclusion system
90 includes the chamber 100 which is branched from and communicates
with the intermediate passage 92. As shown in the figures, the
chamber 100 communicates with the passage 92 via a throat 104.
Preferably, the chamber 100 is in the form of a tuned resonator
chamber 102 configured to form a Hemholtz resonator with the throat
portion 104, so as to attenuate noise from the engine 60. As shown
in FIG. 3, the chamber 100 is arranged so as to communicate with
the intermediate passage 92 at a position above the tunnel 42
and/or above the maximum rated water line 98. As an example, the
intermediate passage 92 may be formed monolithically with the
chamber 100, or, as shown in the figures, the intermediate passage
may be formed with the detachable portions 91, 93, and 95 formed of
high temperature rubber or plastic and connected via the couplings
97. In this embodiment, the portion 91 connects a watertrap outlet
80b with an inlet 100a, and the portion 93 connects an outlet 100b
with an discharge port inlet 94a.
[0063] As shown in FIGS. 3 and 4, the chamber 100 preferably
extends upwardly from the intermediate passage 92. If the
watercraft 10 is capsized, thereby causing water to flow towards an
apex 106 of the intermediate passage 92, as viewed in FIG. 3, the
water will flow into the chamber 100 and will be stored there at
least temporarily while the watercraft 10 remains capsized, thereby
preventing the water from flowing directly into the watertrap
80.
[0064] The chamber 100 preferably communicates with the
intermediate passage 92 at a position downstream from the apex 106
of the intermediate passage 92. Arranged as such, the chamber 100
will tend to direct water, which flowed into the chamber 100 during
the capsizing of the watercraft 10, downstream from the apex 106
towards the exhaust discharge port 94 after the watercraft 10 has
been righted. Therefore, even if the watercraft 10 is capsized with
a significant amount of water in the intermediate passage 92, the
chamber 100 will temporarily store and return water to the portion
of the intermediate passage 92 which is downstream from the apex
106. By providing the chamber 100 as such, the water preclusion
system 90 achieves the dual goals of preventing a damaging back
flow of water in the exhaust system of a watercraft, and avoiding
the power sapping back pressure in the exhaust system. Furthermore,
if the chamber 100 is tuned so as to form a Hemholtz resonator with
the throat portion 104, the system 90 additionally reduces the
noises generated by the engine 60 without a significant increase in
backpressure.
[0065] The water preclusion system 90 may, in addition or in lieu
of the chamber 100, include the chamber 110 which communicates with
the intermediate passage 92 via an inlet 112 and an outlet 114. As
shown in FIG. 3, the chamber 110 has a cross-sectional area that is
larger than a cross sectional area of the intermediate passage 92,
by virtue of its elongation generally in a horizontal direction.
Preferably, a connector 116 extends into the reservoir 110 a
predetermined distance 118. As shown in FIG. 6, the connector 116
is preferably formed monolithically with the reservoir 110.
However, it is conceived that the connector 116 may be formed
separately and sealably engaged with the reservoir 110. With the
chamber 110 included in the intermediate passage 92, the inlet 110a
of the chamber 110 preferably communicates with the intermediate
passage 92 via the portion 93 while the chamber 100 and the outlet
110b is connected to discharge the inlet 94a.
[0066] As shown in FIG. 6, the reservoir 110 includes a lower
surface 120 and an upper surface 122. Preferably, the chamber 100
is arranged such that the maximum rated water line 98 falls below
the upper surface 122. Therefore, a volume of water fills the
chamber 110 up to the water line 98 when the watercraft is loaded
with its maximum rated load.
[0067] Preferably, the chamber 110 and the predetermined distance
118 are configured such that when the chamber 110 is inverted, such
as when the watercraft is capsized, the volume of water urged into
the chamber 110 when the watercraft 10 is loaded with its maximum
rated load, fills the inverted chamber 110 to a depth equal to or
less than the predetermined distance 118. Therefore, when the
watercraft 10 is capsized, the volume of water trapped within the
chamber 110 is not sufficient to flow upstream the past inlet 112.
However, it is to be noted that, depending on the events leading to
capsizing, more or less water may actually be trapped in the
exhaust passage 92 when the watercraft 10 is capsized. However,
with the chamber 110 and the predetermined distance 118 configured
as such, it has been found that a sufficient amount of water can be
prevented from causing a damaging back flow of water from
occurring.
[0068] Furthermore, if the chamber 110 is used in conjunction with
the chamber 100, the chamber 100 may trap any water that may flow
past the inlet 112 during capsizing of the watercraft 10.
Therefore, by providing the chamber 100 and the chamber 110 to the
intermediate portion 92, the exhaust system prevents damaging
upstream flow of water that has heretofore plagued personal
watercraft. Additionally, if the chambers 100 and 110 are provided
together, further tuning, in a known manner, of the chambers 100
and 110, can produce additional attenuation of engine noise.
[0069] According to a further aspect of the present invention, a
watercraft, such as the watercraft 10, is provided with at least
two telltale ports configured to discharge a stream of water to a
position forward of the rider's seating area. For example, as shown
in FIG. 7, the internal combustion engine 60 includes the exhaust
passage 68 which is connected to an exhaust manifold (not shown) at
a first end and to a water trap (not shown) at a second end. In
order to provide a desired cooling of the exhaust passage 68, a
cooling jacket 69 is formed around the exhaust passage 68. A first
portion 71 of the cooling jacket 69 is fed with a coolant from a
cooling jacket formed in the engine 60 via runners 73.
[0070] As shown in FIG. 7, the first portion 71 of the cooling
jacket 69 is configured to circulate coolant in thermal contact
with the expansion chamber 72. Preferably, the expansion chamber 72
is constricted at the portion 74. Downstream from the portion 74,
the expansion chamber 72 is coupled to a downstream portion 75 of
the exhaust passage 68. The downstream portion 75 may include a
catalytic device such as the catalyst bed 78 for removing
pollutants from the exhaust gases in a known manner. As noted
above, the cooling jacket 69 extends over the downstream portion
175 of the exhaust passage 68 to cool the catalytic bed 78.
Communication between the first portion 71 of the cooling jacket 69
and the downstream portion 75 is accomplished through a known
coupling between the portion 71 and the portion 75.
[0071] Although it has been known to provide a telltale port on a
watercraft in order to verify that coolant is flowing through the
appropriate cooling jackets and channels of the engine and the
exhaust system, it has been found that a leak or a blockage may be
caused at various places within a cooling jacket which may not
cause a change in the appearance of the telltale stream sufficient
to capture the attention of the user. Therefore, the watercraft 10
is preferably provided with at least two telltale ports configured
to discharge a stream of coolant from the cooling jackets 69.
[0072] As shown in FIG. 7, the telltale ports 120, 122 are arranged
at a position forward of the handle bar 28. As is apparent from
FIG. 7, the telltale ports 120, 122 are arranged as sufficiently
forward of the handle bar 28 so as to be clearly visible to a user
seated in the rider's seating position 22.
[0073] The telltale ports 120 and 122 are connected to the cooling
jacket 69 via conduits 124, 126, respectively. Arranged as such,
the telltale ports 120, 122 are clearly visible to a user seated in
the rider's seating area 22 regardless of whether a user is looking
toward the user's left or toward the user's right. Therefore, the
user will be apprised at all times of the operating condition of
the cooling system of the watercraft 10.
[0074] One of the telltale ports 120,122 preferably is connected to
the cooling jacket 69 at a position 128 which is upstream from a
position 130 at which the other of the telltale ports 120, 122 is
attached to the cooling jacket 69. For example, the positions 128,
130 may be spaced by a distance 132. Preferably, the position 128
is provided on an upstream side of the coupling between the portion
71 and the downstream portion 75 while the position 130 is provided
downstream of the coupling. Arranged as such, a user is provided
with an indicator of the coolant pressure in two distinct portions
of the cooling jacket 69. For example, when a user is operating the
watercraft 10, the telltale streams of the coolant are continuously
discharged from the ports 120, 122. However, if a leak forms, for
example, in the coupling between the upstream portion 71 of the
cooling jacket 69 and in the downstream portion 75, the telltale
stream discharged from the port 122 will become weaker or
non-existent. Therefore, by comparing the appearance of the water
streams discharged from the ports 120, 122, a user can identify a
leak in the cooling system. This is particularly useful since the
exhaust systems of watercrafts, and in particular, those systems
that include a catalytic device, operate at high temperature which
should be controlled to a particular operating range. Therefore, by
providing the user with a reference for detecting a leak in an
early stage, severe damage to the catalytic bed and to other
components of the watercraft can be prevented. This arrangement
provides an improvement over a system with a single telltale port.
For example, if a watercraft such as the watercraft 10 is provided
only with the telltale port 122, a user can not determine that a
blockage in the exhaust system has occurred downstream of the point
of the cooling system to which the telltale port is connected.
Thus, the user can not determine that coolant flow to a critical
component (e.g., a catalyst device) is diminished or stopped. In
contrast, by providing at least two telltale ports 120, 122, a user
can readily view the two telltale streams and proper coolant flow
within this critical section of the cooling system.
[0075] Although this invention has been described in terms of a
certain preferred embodiment, other embodiments apparent to those
of ordinary skill in the art are also within the scope of this
invention. Accordingly, the scope of the invention is intended to
be defined only by the claims that follow.
* * * * *