U.S. patent application number 10/370264 was filed with the patent office on 2003-08-14 for watercraft having a closed coolant circulating system with a heat exchanger that constitutes an exterior surface of the hull.
Invention is credited to Bourret, Michel, Lefrancois, Gilbert, Menard, Eric.
Application Number | 20030153219 10/370264 |
Document ID | / |
Family ID | 26857256 |
Filed Date | 2003-08-14 |
United States Patent
Application |
20030153219 |
Kind Code |
A1 |
Menard, Eric ; et
al. |
August 14, 2003 |
Watercraft having a closed coolant circulating system with a heat
exchanger that constitutes an exterior surface of the hull
Abstract
A closed coolant circulating system for a watercraft, for
traveling along a surface of a body of water, containing a supply
of coolant that is caused to flow through the coolant circulating
system. The watercraft comprises a hull and an engine. The
watercraft also comprises a heat exchanger formed from heat
conductive material and having a fluid path defined therein with an
inlet port and an outlet port. The heat exchanger has a heat
exchanging exterior surface and is mounted to the hull such that
the heat exchanging exterior surface constitutes a portion of the
exterior surface of the hull that is normally disposed below the
surface of the body of water. The heat conductive material of the
heat exchanger allows the heat absorbed by the coolant to dissipate
from the coolant to the body of water via the heat exchanging
exterior surface as the coolant flows through the fluid path.
Inventors: |
Menard, Eric; (Rock Forest,
CA) ; Bourret, Michel; (Drummondville, CA) ;
Lefrancois, Gilbert; (Canton Magog, CA) |
Correspondence
Address: |
PILLSBURY WINTHROP, LLP
P.O. BOX 10500
MCLEAN
VA
22102
US
|
Family ID: |
26857256 |
Appl. No.: |
10/370264 |
Filed: |
February 21, 2003 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
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10370264 |
Feb 21, 2003 |
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09691129 |
Oct 19, 2000 |
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6544085 |
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60160819 |
Oct 21, 1999 |
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Current U.S.
Class: |
440/88HE |
Current CPC
Class: |
B63H 21/383 20130101;
B63B 34/10 20200201; F01P 2050/06 20130101; B63H 21/14 20130101;
F28D 1/022 20130101; B63H 21/12 20130101; F01P 3/207 20130101; B63H
21/10 20130101 |
Class at
Publication: |
440/88.0HE |
International
Class: |
B63H 021/10 |
Claims
What is claimed is:
1. A watercraft for travelling along a surface of a body of water,
said watercraft comprising: a hull having an exterior surface; an
engine positioned within the hull; the engine having a heat
absorbing portion positioned to allow heat transfer thereto; a
propulsion system operatively connected to the engine; a closed
coolant circulating system in fluid communication with the engine
heat absorbing portion; a first plate-like heat exchanger having a
fluid path, including an inlet port, and an outlet port, defined
therein, and a heat exchanging exterior surface; a second
plate-like heat exchanger having a fluid path, including an inlet
port, and an outlet port, defined therein, and a heat exchanging
exterior surface; the closed coolant circulating system including
the fluid paths of the first and second heat exchangers; the first
heat exchanger mounted to the hull on a port side thereof such that
the heat exchanging exterior surface constitutes a portion of the
port side exterior surface of the hull; and the second heat
exchanger mounted to the hull on a starboard side thereof such that
the heat exchanging exterior surface constitutes a portion of the
starboard side exterior surface of the hull; wherein the heat
exchanging fluid paths of the first and second heat exchangers
communicate in series within the closed coolant circulating
system.
2. A watercraft according to claim 1, wherein the heat exchanger is
made of aluminum.
3. A watercraft for travelling along a surface of a body of water,
said watercraft comprising: a hull having an exterior surface; an
engine positioned within the hull; the engine having a heat
absorbing portion positioned to allow heat transfer thereto; a
propulsion system operatively connected to the engine; a closed
coolant circulating system in fluid communication with the engine
heat absorbing portion; a first plate-like heat exchanger having a
fluid path, including an inlet port, and an outlet port, defined
therein, and a heat exchanging exterior surface; a second
plate-like heat exchanger having a fluid path, including an inlet
port, and an outlet port, defined therein, and a heat exchanging
exterior surface; the closed coolant circulating system including
the fluid paths of the first and second heat exchangers; the first
heat exchanger mounted to the hull on a port side thereof such that
the heat exchanging exterior surface constitutes a portion of the
port side exterior surface of the hull; and the second heat
exchanger mounted to the hull on a starboard side thereof such that
the heat exchanging exterior surface constitutes a portion of the
starboard side exterior surface of the hull; wherein the heat
exchanging fluid paths of the first and second heat exchangers
communicate in parallel within the closed coolant circulating
system.
4. A watercraft according to claim 3, wherein the heat exchanger is
made of aluminum.
5. A watercraft for travelling along a surface of a body of water,
said watercraft comprising: a hull having an exterior surface with
a recess formed therein; an engine positioned within the hull; the
engine having a heat absorbing portion positioned to allow heat
transfer thereto; a propulsion system operatively connected to the
engine; a closed coolant circulating system in fluid communication
with the engine heat absorbing portion; at least one plate-like
heat exchanger having a fluid path defined therein; the at least
one heat exchanger also having an inlet port, an outlet port, and a
heat exchanging exterior surface; the closed coolant circulating
system including the fluid path of the at least one heat exchanger;
the at least one heat exchanger being mounted in the recess such
that the heat exchanging exterior surface is flush with portions of
the exterior surface of the hull adjacent thereto.
6. A watercraft according to claim 5, wherein the at least one heat
exchanger comprises a base portion and a cover portion coupled to
the base portion to form the heat exchanging fluid path.
7. A watercraft according to claim 6, wherein the cover portion is
adjacent to a portion of exterior of the hull forming the
recess.
8. A watercraft according to claim 5, wherein the watercraft is a
personal watercraft.
9. A watercraft according to claim 5, wherein the watercraft is a
sport boat.
Description
[0001] This is a Continuation Application of pending U.S.
application Ser. No. 09/691,129 filed Oct. 19, 2001, which claims
priority to U.S. Provisional Application No. 60/160,819, filed Oct.
21, 1999, the entirety of both applications is hereby incorporated
into the present application by reference.
1. FIELD OF THE INVENTION
[0002] The present invention relates a watercraft having a closed
loop coolant circulating system with at least one heat exchanger
constituting an exterior surface of the hull.
BACKGROUND OF THE INVENTION
[0003] Many small, recreational watercraft, such as personal
watercraft (PWC), are powered by water-cooled two-stroke internal
combustion engines. These engines use open-loop cooling systems
that draw water through a water intake from the body of water
through which the watercraft is traveling, circulate that water
through the water jacket of the engine to absorb heat from the
engine and then expel the water through an outlet back to the
environment. Typically, the water inlet for such an open-loop
system is located between the impeller and the venturi of the
watercraft propulsion system so that a small volume of pressurized
water is diverted to the engine water jacket and then to the outlet
without the need for a dedicated water pump.
[0004] This open-loop cooling system performs adequately for many
types of engines, including many two-stroke engines, which are not
especially sensitive to temperature for optimal operating
conditions. Nevertheless, an open-loop cooling system has certain
drawbacks.
[0005] First, with an open-loop system, debris or contaminants from
the environment (such as leaves, aquatic plants, mud and even small
insects and marine animals) can enter the open system, thereby
partially or completely obstructing passage(s) and/or reducing the
efficiency of the cooling system.
[0006] Second, when operating the watercraft in salt water, the
cooling system's pipes and water jacket manifold become susceptible
to corrosion due to the presence of salt within the water flowing
through the cooling system. To prevent such corrosion from
occurring, it is necessary to use corrosive-resistant materials
and/or surface treatments on the cooling system components. This
increases the cost of the components and complicates design and
manufacture. Further, even when using such materials or coated
components, it is advisable to flush the seawater from the system
after use to minimize its damaging effects. This is also
time-consuming and inconvenient.
[0007] Furthermore, with an open-loop system the temperature of the
ambient water introduced into the system from the environment can
change considerably, depending on the season and/or location, by as
much as 40.degree. F. or more. This makes it more difficult to
regulate the desired cooling effect of the system and keep the
engine in the desired operating temperature range.
[0008] U.S. Pat. No. 5,507,673 to Boggia (the '673 patent)
discloses a watercraft having an internal combustion engine and a
closed coolant circulating system. Because the coolant circulating
system is closed, the problems discussed above with respect to
open-loop cooling systems are obviated. However, the coolant
circulating systems of the '673 patent does not provide sufficient
heat exchanging surface to properly dissipate engine heat from the
coolant because the coolant is passed only through the tubular
members that constitute the grate covering the impeller tunnel
intake opening. The theory behind this construction is that the
coolant inside the grating tubular members will dissipate heat from
the coolant therein to the water flowing through the grate into the
impeller tunnel. However, in practice this is an impractical
construction because the grate's tubular members fail to provide a
sufficient amount of surface area to allow the coolant therein to
effectively dissipate heat.
[0009] Consequently, there exists a need in the art for a
watercraft with an improved closed coolant circulating system that
provides sufficient heat exchanging surface area to allow heat from
the engine to be dissipated to ambient water in an effective manner
without the drawbacks associated with the system.
SUMMARY OF THE INVENTION
[0010] To meet the above-described need, the present invention
provides a watercraft for travelling along a surface of a body of
water comprising a hull having an exterior surface; an engine
constructed and arranged to generate power, the engine also
generating heat during the generation of power; and a propulsion
system operatively connected to the engine and being constructed
and arranged to propel the watercraft along the surface of the body
of water using the power generated by the engine. The watercraft of
the present invention further comprises a closed coolant
circulating system containing a supply of coolant that is caused to
flow through a fluid path during operation of the engine. The
circulating system has an engine heat absorbing portion through
which the coolant flows. The engine heat absorbing portion is
positioned with respect to the engine such that at least a portion
of the heat generated by the engine is absorbed by the heat
absorbing portion and the coolant flowing therethrough.
[0011] A heat exchanger is formed from a heat conductive material
and has a heat exchanging fluid path defined therein with an inlet
port and an outlet port. The heat exchanger has a heat exchanging
exterior surface and is mounted to the hull such that the heat
exchanging exterior surface constitutes a portion of the exterior
surface of the hull that is normally disposed below the surface of
the body of water when the watercraft is in an upright position.
The inlet and outlet ports are respectively communicated to the
engine heat absorbing portion such that the heat exchanging fluid
path constitutes a portion of the coolant circulating system with
the coolant flowing into the heat exchanging fluid path from the
heat absorbing portion via the inlet port and from the fluid path
back to the heat absorbing portion via the outlet port. The heat
conductive material of the heat exchanger allows the heat absorbed
from the engine by the coolant to dissipate from the coolant to the
body of water via the heat exchanging exterior surface as the
coolant flows through the fluid path.
[0012] With such a closed coolant circulating system, there is no
opportunity for debris or contaminants from the environment to
enter the system and blocking passages, thereby reducing the
efficiency of the closed coolant circulating system.
[0013] In addition, because the coolant circulating system is
closed, water from the body of water on which the watercraft is
travelling is not allowed to enter the cooling system. Therefore,
it is not necessary to take the special steps discussed above to
prevent corrosion from occurring within the coolant circulating
system due to the watercraft's use in salt water. Nor does the
coolant circulating system need to be flushed when the watercraft
is operated in salt water.
[0014] A particularly advantageous feature of the present invention
is that the heat exchanger is mounted to the hull such that the
heat exchanging exterior surface thereof constitutes a portion of
the exterior surface of the hull that is normally disposed below
the surface of the body of water when the watercraft is in an
upright position. As a result of this construction, the heat
exchanger can be provided with a relatively large heat exchanging
exterior surface, which contacts the body of water. Also, because
the heat exchanging surface constitutes a portion of the hull's
exterior surface, the heat exchanger takes advantage of a large
amount of available surface area in the watercraft that already
exists to provide the heat exchanging surface. Consequently, heat
exchanging can be achieved in a more effective and efficient manner
than in the construction disclosed in the '673 patent discussed
above.
[0015] In one preferred aspect of the invention, the engine is a
four-stroke internal combustion engine. The introduction of more
stringent emissions standards has led watercraft designers to look
for four-stroke engines that run cleaner than two-stroke engines.
In a two-stroke engine, lubricating oil is usually either mixed
with the fuel or injected into the intake tract for lubricating the
pistons, rings, cylinder walls, bearings, etc. This oil entering
the combustion chamber results in a greater amount of incompletely
combusted hydrocarbons in the exhaust of the typical two-stroke
engine. On the other hand, in a four-stroke engine, oil is not
mixed with fuel to lubricate the walls of the cylinders. Instead,
oil is routed through passages in the piston and connecting rod
assembly for lubricating the sides of the piston head. Therefore,
less oil reaches the combustion chamber and hydrocarbon emissions
are reduced.
[0016] The operation of many four-stroke engines is, however, more
sensitive to temperature and requires a reliable cooling system
capable of maintaining the engine operating temperature within an
optimal, narrow range. An open-loop cooling system that simply
circulates water from the body of water through which the
watercraft travels is inadequate for such temperature-sensitive
four-stroke engines because, as discussed above, the temperature of
the water drawn into the open loop cooling system can vary greatly
due to environmental conditions. By using the closed-loop coolant
circulating system of the present invention in combination with a
four-stroke engine, the problems associated with variations in
ambient water conditions can be minimized.
[0017] In another preferred aspect of the present invention, the
heat exchanger has a plate-like configuration and is a ride plate
mounted at an underside stem portion of the hull along a centerline
thereof. In this aspect, the heat exchanger and the ride plate
define an impeller tunnel having a rearward discharge opening at
the stem and a forward intake opening spaced forwardly of the
discharge opening. The propulsion system includes an impeller
assembly mounted to the ride plate/heat exchanger within the
tunnel. The impeller assembly has an impeller with a plurality of
blades, which is connected to the engine so as to rotate under
power from the engine such that the impeller draws water out from
the tunnel through the discharge port is a pressurized stream to
propel the watercraft.
[0018] This preferred aspect is particularly advantageous because
it takes advantage of an existing structure, the ride plate, which
is normally made from heat conductive material. Specifically, the
ride plate of a watercraft is typically made from metal so that it
is rugged enough to withstand impacts with submerged objects during
high speed operation of the watercraft. Modifying the ride plate so
that it also functions as a heat exchanger advantageously allows
the present invention to be implemented without modifying the hull
itself so as to incorporate the heat exchanger on the exterior of
the hull itself.
[0019] Other objects, features, and advantages of the present
invention will become apparent from the following detailed
description, the accompanying drawings, and the appended
claims.
BRIEF DESCRIPTION OF THE DRAWINGS
[0020] FIG. 1 is a perspective view of a personal watercraft of the
present invention;
[0021] FIG. 2 is a side view of the personal watercraft illustrated
in FIG. 1, with the engine, driveshaft, propulsion system and ride
plate shown in phantom;
[0022] FIG. 3 is a schematic view of the closed loop cooling system
circuit;
[0023] FIG. 4 is a perspective view of a typical ride plate for a
personal watercraft;
[0024] FIG. 5 is a rear view of the personal watercraft illustrated
in FIG. 1;
[0025] FIG. 6A is a bottom view of the personal watercraft
illustrated in FIG. 1;
[0026] FIG. 6B is a cross-sectional view taken along line 6B in
FIG. 6A;
[0027] FIG. 7 is a top view of the ride plate with the top cover in
covering relation to the bottom plate;
[0028] FIG. 8 is a top view of the bottom plate with one embodiment
of the coolant path shown;
[0029] FIG. 9 is a top view of the bottom plate with an alternate
embodiment of the coolant path shown;
[0030] FIG. 10A is a bottom view of the personal watercraft with a
single hull-mounted heat exchanger mounted forward of the ride
plate;
[0031] FIG, 10B is a cross-sectional view taken along line 10B in
FIG. 10A;
[0032] FIG. 11A is a bottom view of the personal watercraft with a
starboard and port heat exchanger mounted forward of the ride
plate; and
[0033] FIG. 11B is a cross-sectional view taken along line 11B in
FIG. 11A;
[0034] FIG. 12 is a top view of the bottom plate shown with
multiple fluid paths;
[0035] FIG. 13 is a top view of the bottom plate with an alternate
embodiment of multiple fluid paths;
[0036] FIG. 14 is a top view of the heat exchanging ride plate with
the top plate in position on the bottom plate, showing two possible
locations for secondary inlet and outlet ports;
[0037] FIG. 15 is a schematic view showing the interaction between
the hull mounted heat exchanger with multiple fluid paths and two
fluid circulation systems of the engine;
[0038] FIG. 16A is a bottom schematic view of a sport boat in
accordance with the invention; and
[0039] FIG. 16B is a back schematic view of the sport boat of FIG.
16A.
DETAILED DESCRIPTION OF THE INVENTION
[0040] FIG. 1 shows a personal watercraft (PWC), generally
indicated at 10, for traveling along a surface of a body of water.
The PWC 10 includes a hull, generally shown at 12, for buoyantly
supporting the PWC 10 on the surface of the body of water. The hull
12 is typically molded from fiberglass material and lined with
buoyant foam material and comprises an exterior surface 14
configured with a V-shaped bow to reduce drag resistance between
the surface of the body of water and the hull 12. The PWC 10
further includes a ride plate 16 that, in cooperation with the hull
12, forms an impeller tunnel 18, as will be described below.
[0041] As shown in FIG. 2, the PWC 10 preferably has an internal
combustion engine, shown schematically at 20, to provide power
generation thereto, which engine 20 is operatively connected to a
propulsion system 22, preferably by a metallic driveshaft 24
(propulsion system 22 and driveshaft 24 are shown schematically in
FIG. 2). The propulsion system 22, which in the illustrated
embodiment is in the form of an impeller assembly, is positioned
within the impeller tunnel 18 and rigidly mounted to the hull 12.
Alternatively, it is contemplated that any suitable propulsion
system, such as an outboard mounted propeller, may be used in place
of the impeller assembly. A forward intake opening 26 of the
impeller tunnel 18 allows the propulsion system 22 to intake water
from the body of water, while a rearward discharge opening 28 in
the impeller tunnel 18 allows water discharged through a steering
nozzle 30 of the propulsion system 22 to be directed in an aft
direction away from the PWC 10, thus propelling the PWC 10 in a
forward direction. The steering nozzle 30 may be pivoted in a
starboard or port direction by an operator to allow steering of the
PWC 10, as is well known in the art. Furthermore, the steering
nozzle 30 may be capable of trim adjustment, as well. Trim
adjustment is well known in the art and allows a rider to adjust
the pitch of the watercraft with respect to the surface of the body
of water and thereby manipulate the contact area between the hull
and the surface of the body of water. A venturi 32 is positioned
between the impeller assembly and the steering nozzle 30 to further
pressurize the water being discharged through the nozzle 30.
[0042] The internal combustion engine 20 affords a relatively high
power-to-weight ratio and, perhaps more important in PWC 10, a high
power-to-space ratio. However, the internal combustion engine 20
produces a significant amount of heat. A closed loop cooling system
is used to remove excess heat from the engine 20.
[0043] A cooling system circuit, for the closed-loop cooling system
of the present invention, is shown schematically in FIG. 3 (also
shown in FIG. 15) and comprises a water pump 34 to circulate a
coolant (preferably a mixture of glycol and water, or any other
suitable liquid coolant), an engine heat absorbing portion 36,
preferably a coolant jacket 38 effectively surrounding the
periphery of the engine 20, and a heat exchanger 40. The coolant is
pumped through the coolant jacket 38 by the water pump 34 to absorb
heat from the engine 20. Coolant exiting the coolant jacket 38 then
returns to the water pump 34 and is directed via flexible hoses or
rigid piping through the heat exchanger 40 where the heat is
dissipated into the body of water on which the PWC 10 is floating.
The coolant cooled by the heat exchanger 40 is then returned to the
water pump 34 via flexible hoses or rigid piping and circulated
back through coolant jacket 38 to repeat the cycle.
[0044] As shown in FIG. 3, engine 20 includes an engine block
portion 42 having cylinder bores 44. An engine cylinder head
portion 46 (shown separate from engine block portion 42 for display
of the coolant jacket 38) is mounted to an upper surface 48 of
engine block portion 42. A combustion chamber is formed in each
cylinder bore 44, defined by respective cylinder walls 50 provided
by the cylinder bore 44, a lower surface (not shown) of the
cylinder head portion 46 and an upper surface of a piston (not
shown) disposed within each cylinder bore 44. Cylinder head portion
46 includes exhaust and intake valves 52, which allow air from an
external environment to enter each combustion chamber and exhaust
fumes to exit therefrom at intervals determined by engine
speed.
[0045] The coolant jacket 38 is configured to partially surround
each combustion chamber to remove heat therefrom produced by the
ignition of a fuel, (introduced into each combustion chamber by an
associated fuel injector) and mechanical friction between moving
components within the engine 20. It is noted that engine 20 may
also be normally aspirated (as opposed to the use of fuel injectors
described above), wherein a carburetor (not shown) will form a
fuel/air mixture, which is introduced to the combustion chambers
via the intake valves 52. A coolant opening 54 within the engine
block portion 42 defined by the coolant jacket 38 provides a
coolant path 56 within the engine 20 (indicated by arrows within
the engine block portion 42) that partially surrounds the periphery
of each cylinder bore 44. The coolant opening 54 extends upwardly
along the length of the cylinder bores 44 where a communicating
opening 58 within the cylinder head portion 46 defined by the
coolant jacket 38 provides an additional coolant path 60
therethrough (indicated by arrows within the cylinder head portion
46). Inlet ports 62 in the engine block portion 42 allows the
coolant to enter the coolant jacket 38. The coolant then flows
through the coolant path 56 around the cylinder bores 44. The
coolant then enters the communicating opening 58 where it flows
through the cylinder head portion 46 and exits from an outlet port
64 in the cylinder head portion 46.
[0046] A coolant thermostat (not shown) allows coolant to bypass
the heat exchanger and circulate through the coolant jacket 38
until the coolant temperature reaches a predetermined relatively
high temperature. At this point the coolant thermostat allows an
increasing amount of coolant to flow through the heat exchanger as
the coolant temperature increases. The closed loop system, as above
described, maintains a relatively constant engine temperature by
recirculating the relatively cooler coolant through the coolant
jacket 38 and directing the relatively warmer coolant through the
heat exchanger 32 to be cooled therein. A bypass 66 allows coolant
of a predetermined relatively high temperature to dispense into a
coolant expansion tank 68 to prevent a high-pressure build-up
within the cooling system due to the thermal expansion of the
coolant.
[0047] Heat is dissipated from the heat exchanger 40 due to a
temperature variance between heat conductive material of the heat
exchanger 40 and the body of water. The abundance of relatively
cooler water provided by the body of water allows a great deal of
heat to be absorbed by the body of water from the heat exchanger
40. Furthermore, the process of convection, wherein warmer,
relatively lower density, water molecules proximate the heat
exchanger 40 are displaced by cooler, relatively higher density,
water molecules, ensures that the heat exchanger 40 may effectively
cool the engine 20 even when the PWC 10 is not in motion across the
surface of the body of water.
[0048] The ride plate 16, shown in FIG. 4, is formed from a rigid
material, preferably a metal such as aluminum, steel, or magnesium.
The ride plate 16 is positioned at the aft end of the PWC 10, such
that an exterior downwardly facing surface 70 of the ride plate 16
is flush with and forms a portion of the exterior surface 14 of the
hull 12. As described above and shown in FIGS. 2 and 5, the ride
plate 14 mounts to the hull 12 to form the impeller tunnel 18.
Specifically, a partial intake opening 72 (FIG. 4) is provided on
the forward edge of the ride plate 16. This partial opening 72
cooperates with a corresponding partial intake opening 74 in the
hull 12 to form the forward intake opening 26 (FIG. 6A) through
which water is brought into the propulsion system 22. An aft edge
of the ride plate 16 forms a partial periphery of the rearward
discharge opening 28. The remainder of the periphery of the
rearward discharge opening 28 is formed by respective aft edges of
the hull 12 associated with the impeller tunnel 18. Water brought
in through the forward intake opening 26 is pressurized by the
propulsion system 22 and then discharged under pressure by the
steering nozzle 30 through the rearward discharge opening 28.
[0049] The ride plate 16 includes a plurality of upwardly opening
threaded openings 78, as shown in FIG. 6B. A plurality of threaded
fasteners 80, in the form of threaded bolts, pass through
associated openings 82 in the hull 12, from the interior thereof
and threadedly engage openings 78, securing the ride plate 16 to
the hull 12.
[0050] It is noted that the propulsion system 22 is mounted to the
hull 12 such that it is disposed above the ride plate 16, within
the impeller tunnel 18. The propulsion system 22 may have a
plurality of connecting portions 84 extending radially outwardly
from a forward portion thereof, as shown in FIG. 6B. It may be
preferable for a corresponding plurality of threaded fasteners 86
to secure the propulsion system 22 to the hull 12. In this case
each threaded fastener 86 passes through respective openings
provided within each of the connecting portions 84 and through the
hull 12 (at corresponding locations).
[0051] One purpose for the ride plate 16 is to provide a skimming
surface for the PWC 10. At high speeds, a substantial portion of
the hull 12 is lifted out of the body of water. In this situation
the downwardly facing surface 70 of the ride plate 16 forms the
skimming surface on which the PWC 10 travels. The rigidity of the
ride plate 16 serves to protect the propulsion system 22 from
damage caused by impacts with floating and/or submerged debris
during such operating conditions.
[0052] One embodiment of the cooling system of the invention is
directed toward an integration of the heat exchanger 40 and the
ride plate 16 into a heat exchanging ride plate 90. As shown in
FIG. 7 and 8, a heat exchanging ride plate 90 includes a coolant
path 92 (FIG. 8) formed therein between a top plate 94 (FIG. 7) and
a bottom plate 96. The integration of the heat exchanger 40 and the
ride plate 16 is advantageous because the heat exchanging ride
plate 90 is situated at the aft end of the PWC 10 and generally
remains in contact with the body of water at all times (except
during roll-over) as the PWC 10 travels along the surface of the
body of water.
[0053] It is noted that the rider is often separated from the PWC
10 during roll-over. As such, it is customary in the art to provide
an engine shut-off switch to shut-off the engine when the rider is
separated from the PWC. Therefore, during roll-over, damage to the
engine due to insufficient cooling caused by ride plate or heat
exchanger exposure to the atmosphere is substantially
prevented.
[0054] The heat exchanging ride plate 90 includes a heat exchanger
body, which comprises the top and bottom plates 94, 96. The top
plate 94 is positioned in covering relation to the bottom plate 96
and secured, for example, with threaded fastening devices around
the periphery thereof to the bottom plate 96. It may be preferable
to provide a seal between the top plate 94 and the bottom plate 96
to prevent leakage of the coolant from there between. It is
contemplated that any of various heat-resistant sealants, such as
high temperature resistant silicone-based sealant, or a gasket may
be positioned between the top and bottom plates 94, 96 prior to
fastening them together in order to from a seal therebetween. It is
noted that it may be especially preferable to provide a seal
between the plates 94, 96 when the coolant system utilizes a
coolant such as a glycol-based fluid. The top plate 94 further
includes an inlet port 98 and an outlet port 100, both disposed at
a forward end thereof. The inlet and outlet ports 98, 100 provide
upwardly extending circular flanges 102 that extend through the
hull 12 at associated openings therein. Coolant hoses or pipes are
fastened over the flanges 102 with associated clamping devices,
connecting the heat exchanging ride plate 90 to the cooling system.
The bottom plate 96 provides the downwardly facing surface 70,
which when the heat exchanging ride plate 90 is mounted to the hull
12, is generally flush with and cooperates with the exterior
surface 14 of the hull 12 to constitute a portion thereof, as shown
in FIG. 6B.
[0055] The bottom plate 96 includes a plurality of upwardly
extending channel walls 104 that interrelate to form the coolant
path 92, as shown in FIG. 8. As indicated by arrows A through E (A
represents inlet port location and E represents outlet port
location), the coolant path 92 has a serpentine configuration with
a plurality of U-shaped bends 106. In this manner, the coolant has
a relatively long duration within the coolant path 92 with which to
transfer heat to the heat exchanging ride plate 90. A series of
parallel ribs 108 extend upwardly from the bottom plate 96
partially into the coolant path 92. The ribs 108 provide additional
surface area for heat absorption by the heat exchanging ride plate
90 from the coolant and produces turbulence within the coolant flow
that further expedites heat transfer. Heat dissipates from the
coolant to the body of water by exterior surfaces of the heat
exchanging ride plate 90 (especially from the downwardly facing
exterior surface), such that a temperature T2 of the coolant
exiting the heat exchanging ride plate 90 (at E in FIG. 8, prior to
entering the coolant jacket 38) is lower than the temperature T1 of
the coolant entering the heat exchanging ride plate 90 (at A in
FIG. 8, after exiting the coolant jacket 38), so that T1>T2.
[0056] Another embodiment of a coolant path through the heat
exchanging ride plate 90 is shown in FIG. 9. A coolant path 92',
defined by a plurality of upwardly protruding channel walls 104'
(as in the above-described embodiment), has a spiraled
configuration, which also provides a long duration for the heat
exchanging ride plate 90 to absorb heat from the coolant.
Additionally, the coolant path 92', indicated by arrows A-G (A
represents inlet port location and G represents outlet port
location), includes bends 106' that are predominantly 90.degree. to
minimize head loss within the heat exchanging ride plate 90 due to
resistance in coolant flow through bends of larger angles, as in
the U-shaped (180.degree.) bends 106 (FIG. 8) of the
above-described embodiment.
[0057] Head loss within the heat exchanging ride plate 90 is the
reduction in pressure of the coolant therein. More specifically,
the amount of head loss in the heat exchanging ride plate 90 is
defined by the difference, .DELTA.P, between a pressure P1 of the
coolant entering the heat exchanging ride plate 90 (at A in FIG. 9,
after exiting the engine heat absorbing portion 30) and a pressure
P2 of the coolant exiting the heat exchanging ride plate 90 (at G
in FIG. 9, prior to entering the coolant jacket 38), or
P1-P2=.DELTA.P. Substantial head loss may significantly reduce flow
rate of the coolant through the heat exchanging ride plate 90,
which may increase power necessary to circulate coolant through the
cooling system or require use of a more powerful water pump 34 to
maintain sufficient coolant flow through the cooling system,
therefore it is advantageous to limit the amount of head loss
through the heat exchanging ride plate 90. Head loss in the
embodiment of FIG. 9 is reduced by providing the coolant path 92'
that is predominately straight with bends 106' of smaller angles
(e.g. 90.degree. or less), such that resistance to coolant flow is
limited. Furthermore, as shown in FIG. 9, the bends 106' in the
coolant path 92' are arcuately configured, such that the bends 106'
provide smooth transitions between altering directions of the
coolant path 92'.
[0058] Other coolant paths through the heat exchanging ride plate
90 are contemplated, however preferable embodiments include those
that produce a relatively long duration of exposure of the coolant
to the heat exchanger, have a relatively large surface area and
effect a minimal head loss on the coolant.
[0059] Referring to FIG. 6B, the propulsion system 22 may include a
plurality of nozzles 109 that serve to direct water from the
propulsion system 22 onto a top surface of the heat exchanging ride
plate 90. As shown, nozzles 109 divert water from the high pressure
stream generated by the impeller through a fluid path provided by
the nozzles and direct that water onto the top surface of the ride
plate 90. This arrangement facilitates cooling of the engine 20,
especially at high speeds when the top surface of the ride plate 90
may not be immersed under the surface of the body of water and the
propulsion system 22 generates a relatively large amount of water
flow through nozzles 109.
[0060] Another embodiment of the heat exchanger, shown in FIG. 10A,
is a single hull-mounted heat exchanger 110 that conforms to the
exterior surface 14 of the hull 12 and is secured in a downwardly
facing recess 112 (FIG. 10B), so as to be flush with the hull 12.
As shown in FIG. 10B, the single hull-mounted heat exchanger 110
conforms to the exterior surface of the hull 14 and is secured
thereto by, for example, threaded fastening devices 114, which
extend through openings 116 in the hull 12 and threadedly engage
within upwardly opening threaded recesses 118 within the single
hull-mounted heat exchanger 110 (similar to the upwardly opening
threaded recesses 78 in the ride plate heat exchanger 90). The
single hull-mounted heat exchanger 110 of this embodiment may be
located at any position on the hull 12. However, in order to cool
the engine 20 properly, it may be advantageous for the single
hull-mounted heat exchanger 110 to be positioned such that an
exterior surface 120 is predominantly submerged in the body of
water. Additionally, this embodiment will allow use of the single
hull-mounted heat exchanger 110 with a larger surface area relative
to the heat exchanging ride plate 90, since the single hull-mounted
heat exchanger 110 is not confined to the ride plate 16. It may be
advantageous for the single hull-mounted heat exchanger 110 to
utilize one of the coolant paths 92, 92', as described herein
above.
[0061] Yet another embodiment of the invention is directed toward
the use of port and starboard side hull-mounted heat exchangers 122
(FIG. 11A), which may be mounted within associated recesses 124 in
the hull and integrated in series or parallel with each other and
with or without the heat exchanging ride plate 90 described herein
above. Shown in FIG. 11A, the port and starboard side hull-mounted
heat exchangers 122 may be used in series or parallel to provide
cooling for the engine 20. Shown in FIG. 11B, the port and
starboard side hull-mounted heat exchangers 122 of this embodiment
are mounted to the hull 12 in a similar manner as that for the
above-described single hull-mounted heat exchanger 110 and may also
utilize one of the coolant paths 92, 92', as described herein
above. Threaded fastening devices 126 extend through openings 128
in the hull 12 and threadedly engage corresponding upwardly opening
threaded recesses 130 in the port and starboard side hull-mounted
heat exchangers 122.
[0062] It is contemplated that watercraft other than PWC may
effectively utilize the present invention herein described.
Additionally, a heat exchanger of any of the above-described
embodiments may be used as a cooling system for other mediums that
become heated during engine operation, for example, engine oil. For
this purpose, engine oil may be directed through the heat
exchanger, as described herein above for the coolant, which
provides additional cooling for the engine and maintains a higher
viscosity of the oil (since oil exiting the heat exchanger is lower
in temperature than oil entering the heat exchanger), which may be
advantageous in watercraft with large engines. It is also
contemplated that a plurality of fluid paths may be provided in a
single heat exchanger to provide heat exchanging for a plurality of
fluids within a single heat exchanger.
[0063] FIGS. 12 and 13 show two exemplary embodiments of a
secondary fluid path, indicated at 132 and 132', respectively. The
embodiments illustrated in FIGS. 12 and 13 show secondary fluid
paths 132, 132' used in conjunction with coolant paths 92, 92',
respectively. It is noted that these illustrated embodiments are
for clarity only, and are not meant to be limiting. It is
contemplated that the fluid paths may have any configuration
enabling sufficient heat reduction of the fluid therein, as
described hereinabove. FIG. 14 shows the top plate 94 mated to the
bottom plate 96. As shown, the top plate 94 may have a secondary
inlet port 134 and a secondary outlet port 136. The secondary inlet
and outlet ports 134, 136 are communicated to either end of the
secondary fluid path 132. As such, fluid from a system (an example
is given below) may flow through the secondary fluid path 132 to be
cooled within the hull-mounted heat exchanger of the present
invention. FIG. 14 also shows secondary inlet and outlet ports 134'
and 136', which may be communicated to fluid path 132' when used in
conjunction with the appropriate corresponding bottom plate, shown
in FIG. 13. It is noted that the top plate 94 of FIG. 14 shows both
sets of inlet and outlet ports (134, 136 and 134', 136') for
clarity only and is not meant to be limiting. Furthermore, it is
contemplated that the top plate 94 may need more than one set of
secondary inlet and outlet ports (134, 136 or 134', 136') only in
an instance when there are more than one secondary fluid paths
incorporated into the bottom plate 96. However, in the case where
alternate fluid paths or multiple secondary fluid paths are
possible, the top plate 94 may utilize more than one set of
secondary inlet and outlet ports. It is of course possible and
within the scope of the present invention, to incorporate multiple
secondary fluid paths and inlet and outlet ports into any possible
embodiment of the hull-mounted heat exchanger, including those
embodiments described herein.
[0064] An exemplary use of the hull mounted heat exchanger 40
utilizing a secondary fluid path may be used for cooling both
engine coolant and, for example, engine oil, as shown schematically
in FIG. 15. A four-stroke type engine 20 utilizes a closed circuit
oil circulation system to deliver lubricant (oil) to various
locations throughout the engine. The oil circulation system
includes a lubrication delivery portion, an oil pump, and a filter
and may include an oil pan or reservoir. The lubrication delivery
portion (constructed and arranged to deliver lubrication to various
components of the engine), the oil pump (constructed and arranged
so as to cause the oil to flow through the oil circulation system),
filter and oil pan are shown in FIG. 15 as an engine heat absorbing
portion 138. Due to the proximity and interaction of the oil and
engine components, the oil is exposed to and absorbs a large amount
of heat. The relatively increased temperature of the oil reduces
its viscosity, which may cause excessive wear between some
interacting components of the engine. For this reason, it may be
useful to cool the oil in order to maintain a relatively high
viscosity of the oil. The engine heat absorbing portion 138 has
inlet and outlet ports 140, 142 that are communicated to the
secondary outlet and inlet ports 136, 134, respectively (shown in
FIG. 12) with flexible hoses or rigid piping such that oil may flow
through the secondary fluid path 132, 132'. While the oil flows
through the secondary fluid path, some of the heat is absorbed by
the conductive material of the heat exchanger 90, 110, 122 and may
be dissipated in the body of water, as described previously for the
engine coolant. As such, the temperature of the oil upon exit from
the heat exchanger 90, 110, 122 (as might be measured at the outlet
port 136, 136') is relatively lower than the temperature at which
it entered (as might be measured at the inlet port 134, 134'),
therefore the viscosity of the oil upon exit from the secondary
fluid path is relatively greater than the viscosity at which it
entered. By retaining a relatively higher viscosity of the engine
oil, excessive wear of certain engine components may be reduced or
prevented. Furthermore, cooling the engine oil also contributes to
lowering the overall temperature of the engine, which may be
advantageous, as described above. It is noted that the any
embodiment of the hull mounted heat exchanger having a secondary
fluid path may be used to cool engine oil.
[0065] The secondary fluid paths 132, 132' may be used to cool
other various types of fluids including hydraulic fluid, when
applicable (such as with larger watercraft). It is noted that any
embodiment of the hull mounted heat exchanger of the present
invention may utilize one or more secondary coolant paths to cool
one or more fluids. It is further noted that the illustrated
embodiments of fluid paths 92, 92', 132 and 132' are examples of
varying configurations of fluid paths that are possible within the
heat exchanger of the present invention, and are not meant to be
limitations.
[0066] Additionally, it is contemplated that a drain pathway (not
shown) may be provided in any embodiment of the hull mounted heat
exchanger of the present invention, such that fluid present in the
hull mounted heat exchanger (and those fluid systems that are
communicated thereto) may be removed. It is noted that for
embodiments of the hull mounted heat exchanger including multiple
fluid paths, multiple drain pathways may be provided to
independently drain fluid therefrom. Preferably, the drain
pathway(s) is(are) threaded openings wherein a threaded drain plug
may be inserted and threadedly secured therein. It is noted that
providing drain pathways within the hull mounted heat exchanger may
be advantageous since, in the various embodiments, the hull mounted
heat exchanger is located at a relatively low position on the PWC
and may facilitate draining those systems with which the fluid
pathway(s) is(are) communicated.
[0067] FIGS. 16A and 16B show a sport boat 200 in accordance with
this invention with a heat exchanger in the form of a ride plate
210, which has the same construction as ride plate 16 described
above.
[0068] It will be appreciated that numerous modifications to and
departures from the embodiments of the invention described above
will occur to those having skill in the art. Such further
embodiments are deemed to be within the scope of the following
claims.
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