U.S. patent application number 12/247177 was filed with the patent office on 2009-02-12 for water jet propulsion system.
This patent application is currently assigned to OCOR CORPORATION. Invention is credited to Brian J. O'Connor.
Application Number | 20090042464 12/247177 |
Document ID | / |
Family ID | 42100896 |
Filed Date | 2009-02-12 |
United States Patent
Application |
20090042464 |
Kind Code |
A1 |
O'Connor; Brian J. |
February 12, 2009 |
WATER JET PROPULSION SYSTEM
Abstract
A highly efficient watercraft propulsion system that relies on a
positive displacement pump to generate a water jet. The pump is
fully submerged at all times and its inlet is positioned so as to
cause water to be forced into the pump as the watercraft moves
through the water. The pump is preferably combined with a variable
area pump opening which is configured, positioned and oriented so
as to maximize the hydraulic reaction between the water jet stream
and the surrounding body of water.
Inventors: |
O'Connor; Brian J.; (San
Diego, CA) |
Correspondence
Address: |
FULWIDER PATTON LLP
HOWARD HUGHES CENTER, 6060 CENTER DRIVE, TENTH FLOOR
LOS ANGELES
CA
90045
US
|
Assignee: |
OCOR CORPORATION
San Diego
CA
|
Family ID: |
42100896 |
Appl. No.: |
12/247177 |
Filed: |
October 7, 2008 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
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11771035 |
Jun 29, 2007 |
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12247177 |
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11103318 |
Apr 11, 2005 |
7238067 |
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11771035 |
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Current U.S.
Class: |
440/38 |
Current CPC
Class: |
Y02T 70/56 20130101;
Y02T 70/50 20130101; B63H 11/06 20130101; B63H 11/103 20130101;
B63H 11/08 20130101 |
Class at
Publication: |
440/38 |
International
Class: |
B63H 11/08 20060101
B63H011/08 |
Claims
1. A water jet propulsion system for a watercraft, comprising a
non-pulsating positive displacement pump.
2. The water jet propulsion system of claim 1, wherein said
non-pulsating positive displacement pump comprises a
counter-rotating helical lobe pump.
3. The water jet propulsion system of claim 1, further comprising
an inlet opening, a discharge opening and wherein said inlet
opening, discharge opening and pump are arranged in a straight
line.
4. The water jet propulsion system of claim 1, further comprising
an inlet opening, a discharge opening and wherein said inlet
opening, discharge opening and pump are fully submerged at all
times.
5. The water jet propulsion system of claim 4, further comprising a
variable area discharge opening.
6. The water jet propulsion system of claim 5, wherein said
watercraft includes a hull and wherein said discharge opening is
positioned such that a discharged jet of water flows along a
submerged portion of said hull.
7. The water jet propulsion system of claim 4, wherein said inlet
opening is positioned so as to cause water to be forced directly
into said pump when said watercraft is moving through said
water.
8. A water jet propulsion system for a watercraft, comprising a
counter-rotating lobe pump.
9. The water jet propulsion system of claim 8, wherein said lobes
have a helical shape extending along their axes of rotation.
10. The water jet propulsion system of claim 8, further comprising
an inlet opening, a discharge opening and wherein said inlet
opening, discharge opening and pump are arranged along a common
axis.
11. The water jet propulsion system of claim 8, further comprising
an inlet opening, a discharge opening and wherein said inlet
opening, discharge opening and pump are fully submerged at all
times.
12. The water jet propulsion system of claim 11, further comprising
a variable area discharge opening.
13. The water jet propulsion system of claim 11, wherein said
watercraft includes a hull and wherein said discharge opening is
positioned such that a discharged jet of water flows along a
submerged portion of said hull.
14. The water jet propulsion system of claim 8, wherein said inlet
opening is positioned so as to cause water to be forced directly
into said pump when said watercraft is moving through said
water.
15. A water jet propulsion system for a watercraft having a hull,
comprising: a counter-rotating helical lobe pump; an inlet conduit
for conducting water directly into said pump; an outlet opening for
conducting water discharged water from said pump; a housing for
said pump, inlet conduit and outlet orifice, wherein said housing
is configured for attachment to said hull.
16. The water jet propulsion system of claim 15, further comprising
a power transfer box for transferring rotation from a prime mover
to said pump, wherein said transfer box extends from said housing
and through said hull.
17. The water jet propulsion system of claim 16, further comprising
a gear set for transferring rotation from said prime mover to said
pump.
18. The water jet propulsion system of claim 15, further comprising
an inlet opening, a discharge opening and wherein said inlet
opening, discharge opening and pump are arranged along a common
longitudinal axis.
19. The water jet propulsion system of claim 15, wherein said
outlet orifice has a variable cross-sectional area.
20. The water jet propulsion system of claim 15, wherein said lobe
pump is reversible so as to enable water to be pumped from said
outlet opening to said inlet opening and thereby enable a reversing
of said watercraft.
Description
CROSS-REFERENCES TO RELATED APPLICATIONS
[0001] This application is a continuation-in-part of U.S. Ser. No.
11/771,035, filed on Jun. 29, 2007, which is a divisional of U.S.
Ser. No. 11/103,318 filed on Apr. 11, 2005, now U.S. Pat. No.
7,238,067.
BACKGROUND
[0002] The present invention generally relates to water jet
propulsion systems for watercraft and more particularly pertains to
the use of a particular type of pump configuration and its
adaptation to a watercraft to achieve enhanced efficiency.
[0003] A variety of jet pump configurations have previously been
used to propel watercraft. Most such configurations comprise
kinetic pumps of one form or another that serve to accelerate water
to a high velocity in order to achieve the desired propulsive
force. The losses associated with the high velocities, the
non-aligned flow and the turbulent flow inherent in the operation
of many such pump configurations limits the efficiency that is
ultimately attainable. Nonetheless, kinetic pumps, or dynamic pumps
as they may also be referred to, are the most commonly used type of
pump for marine propulsion applications and typically rely on an
impeller to push water through a duct. Positive displacement pumps
on the other hand are capable of generating high hydrostatic
pressures at essentially zero velocity and could conceivably be
able to provide substantial gains in terms of efficiency. However,
the positive displacement pump configurations that have been
proposed for the propulsion of watercraft and the adaptations of
such pumps to watercraft that have been proposed have failed to
cause the use of positive displacement pumps to gain wide
acceptance for such purpose.
[0004] It is well known that the velocity with which a water jet is
discharged from a watercraft relative to the velocity of the
watercraft has a direct effect on the efficiency of such a system.
Propulsion efficiency, whether measured with respect to fuel
consumption or vessel speed, is a function of both water jet
discharge velocity and volumetric flow. While the water jet
discharge velocity can of course be controlled by pump's volumetric
output, the jet velocity can also be controlled by varying the
cross-sectional area of the orifice through which the water is
discharged. Accordingly an increase in the cross sectional area of
the discharge orifice for a given pump output reduces the water
discharge velocity while a decrease of the cross-sectional area
serves to increase said velocity.
[0005] It has long been recognized that the ability to vary
discharge orifice area can significantly enhance propulsion
efficiency over a wide range of operating conditions and thereby
reduce fuel consumption. A large variety of configurations that are
either cylindrical, conical, hemispherical or combination of same
have been suggested for a discharge orifice that is variable in
terms of both area and flow path shape along with various
mechanisms to control the water discharge velocity as a function of
any of various parameters. Even greater efficiency would
nonetheless be desirable.
SUMMARY OF THE INVENTION
[0006] The present invention provides a highly efficient water jet
propulsion system for a watercraft by relying on a non-pulsating
positive displacement pump to move water through a duct. Moreover,
the pump is preferably arranged so as to be fully submerged at all
times. It is further preferred to arrange its inlet opening such
that water is forced directly into the pump by the movement of the
watercraft through the water. It is additionally preferred to
combine the pump with a submerged variable area discharge opening
so as to allow for the velocity of the discharge jet to be
optimized relative to the velocity of the surrounding water.
Finally, it is preferred to package the entire propulsion system so
as to be attachable to the bottom of a hull or other fully
submerged surface of a watercraft.
[0007] A positive displacement pump displaces a preselected volume
of water from the input side of the pump to the output side of the
pump with each pump cycle or rotation and substantially precludes
any return of water from its output side to its input side even
when operating at low velocities and/or under high head pressures.
Positive displacement pumps add both potential energy as well as
kinetic energy to a continually displaced volume of water and the
displaced volume per cycle or rotation is independent of cycle or
rotation rate. As such, positive displacement pumps are readily
distinguishable from kinetic or dynamic pumps that rely on for
example impellers or paddle wheels to move water. A positive
displacement pump is capable of generating substantial hydrostatic
pressures at very low jet velocities. Non-pulsating configurations
generate a constant flow throughout each cycle or rotation. This
delivery characteristic has unexpectedly been found to further
enhance efficiency in propelling a watercraft. The net result is an
increase in performance potential, a reduction in fuel consumption
and a commensurate reduction in emissions.
[0008] The preferred pump configuration is a counter-rotating rotor
pump which may also be referred to as a counter-rotating lobe pump
or external gear pump. Additionally it is preferred that the
rotors' lobes follow a helical path along the rotors' rotational
axes with a sufficient amount of twist to ensure that there is a
continual discharge of fluid as the rotors are rotated. An example
of such a pump is described in U.S. Pat. No. 3,164,099 to Hitosi
Iyoi which is incorporated herein by reference in its entirety.
[0009] The efficiency provided by the positive displacement pump is
further enhanced with its combination with a discharge opening that
is continuously variable in terms of its cross-sectional area. Such
discharge configuration employs an opening having a cross-sectional
shape that is substantially trapezoidal. The sides of the discharge
opening transverse to the parallel sides are straight or curved and
may be substantially parallel so as to define a rectangle.
Additionally, the discharge duct is positioned on the submerged
portion of the watercraft hull so that the pump discharge flow is
ejected into the surrounding water thereby creating a direct
hydraulic coupling to thereby enhance thrust efficiency.
[0010] It is additionally preferred that the inlet be arranged so
as to cause water to be forced into the pump as the watercraft
moves through water. This inlet ram feature has the benefit of
increasing the static pressure head on the suction side of the pump
thereby reducing the possibility of rotor cavitation at high pump
speeds and therefore allows the pump to operate at higher speeds
than have heretofore been possible. Efficiency is further enhanced
by arranging the inlet, pump and outlet along a straight line. This
not only ensures that the entire propulsion system is fully
submerged at all times to preclude any loss of prime but further
eliminates any inefficiencies that could otherwise be introduced if
the flow of water into, through and out of the pump were forced to
change direction.
[0011] On vessels that generally have a flat bottom, the discharge
opening of the duct may generally define a horizontally oriented
tapered trapezoidal duct. On large vessels, several ducts may be
installed at various orientations on the submerged portion of the
curved hull. A contoured or generally wedge-shaped control element
is movably disposed within the duct such that its narrow end is
variably extendible out through the exit of the discharge opening.
The control element thereby serves to block off a central portion
of the discharge opening to reduce the total cross-sectional area
that remains open to the flow of water there through. Its wedge
shape serves to block off a progressively larger portion of the
discharge opening's cross-sectional area as the control element is
caused to translate out through the discharge opening which in turn
results in an increase in the water jet velocity. Conversely,
retraction of the control element serves to increase
cross-sectional area to thereby reduce water jet velocity.
[0012] The linear position of the wedge-shaped control element may
be translated by any number of actuation means including, but not
limited to, mechanical, hydraulic, or servo electronic systems or
combinations thereof. A variety of different control means may also
be relied upon to govern the position to which the control element
is actually shifted including, but not limited to, manual
selection, direct action of pump output or more sophisticated
systems such as for example a microprocessor that considers a
plurality of parameters and calculates an optimum setting. A
preferred embodiment simply relies on the action of a spring to
bias the control member into its retracted position. As the force
of the flow of water impinging on the frontal surfaces of the
control element is increased by an increase in the volumetric pump
output, the bias of the spring is overcome to cause the control
element, which is constrained vertically between the upper and
lower, parallel surfaces of the discharge duct, to shift linearly
towards the discharge opening thereby causing a further increase in
flow velocity.
[0013] The location and orientation of the discharge opening serves
to further enhance the propulsion efficiency of the water jet
discharge system of the present invention. Accordingly, the
discharge opening is positioned so as to remain submerged at all
times to create a direct hydraulic reaction between the discharge
jet and the surrounding body of water. By positioning the discharge
opening so as to extend from the bottom of the hull at a location
substantially forward of the trailing edge of the hull, the section
of hull aft of the discharge opening in the plane of the upper
surface of the duct prevents the upward diffusion of the jet.
Additionally, an extension of the duct's bottom surface aft of the
discharge opening limits the amount of downward diffusion of the
jet in the plane of the lower surface of the duct. By constraining
the discharged jet between the hull and the duct extension aft of
the discharge opening, a greater portion of the discharge flow is
constrained so as to remain substantially parallel to the direction
of desired thrust i.e. in-line with the direction of travel. The
result is an increase in axial thrust, or vessel driving force,
than if the pump discharge is allowed to diffuse freely.
[0014] The pump, inlet opening and discharge opening are preferably
disposed within a housing that is attachable to the bottom of the
hull of a watercraft. A transfer box extending upwardly and through
the hull is relied upon to transfer rotation from a prime mover to
the pump. It is important that the shape of the submerged portion
of the pump housing is streamlined in such a way so as to minimize
the hydrodynamic impact of its presence in such a critical
location.
[0015] These and other advantages of the present invention will
become apparent from the following detailed description of
preferred embodiments which, taken in conjunction with drawings,
illustrate by way of example the principles of the invention.
BRIEF DESCRIPTION OF THE DRAWINGS
[0016] FIG. 1 is a side view of a watercraft fitted with the
propulsion system of the present invention;
[0017] FIG. 2 is a front view of the watercraft shown in FIG.
1;
[0018] FIG. 3 is a rear view of the watercraft shown in FIG. 1;
[0019] FIG. 4 is a perspective view of the submerged portion of the
housing that contains the propulsion system of the present
invention;
[0020] FIG. 5 is a sectioned perspective view taken along lines V-V
of FIG. 1;
[0021] FIG. 5a is a perspective view of the helical rotors shown in
FIG. 5;
[0022] FIG. 6 is a cross-sectional view of an alternative
embodiment of discharge opening configuration of the propulsion
system of the present invention shown in its full retracted
state;
[0023] FIG. 7 is a cross-sectional view of the discharge opening
configuration shown in FIG. 6 in its fully protracted state;
[0024] FIG. 8 is a cross-sectional view of an alternative
embodiment of the propulsion system of the present invention;
[0025] FIG. 9 is a perspective view of a preferred embodiment of
the propulsion system of the present invention; and
[0026] FIG. 10 is a cross-sectional view of the propulsion system
shown in FIG. 9.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS
[0027] The water jet propulsion system of the present invention
provides for enhanced efficiency in the propulsion of a watercraft.
The figures generally illustrate preferred embodiments of the
propulsion system in terms of its pump configuration, its
adaptation to and orientation relative to a hull, a mechanism for
varying the cross-sectional area of the discharge opening and the
packaging of its various components.
[0028] FIG. 1 is a side view of a watercraft 12 showing the
propulsion system 14 of the present invention fitted to the bottom
of its hull 16. The system includes a housing 18 that contains a
pump (not visible) and has an inlet opening 20 at its forward end
and a discharge opening 22 at its aft end. The housing is
positioned under the hull so as to ensure that the inlet opening,
pump and discharge opening remain fully submerged at all times
during all modes of operation. The submersion of the outlet opening
even under maximum acceleration from low speeds or at maximum
velocity ensures that the hydraulic reaction between the liquid jet
stream and the adjacent, relatively static body of water can be
maximized at all times. As can be seen in the FIG. 1, the discharge
opening is positioned well forward of the aft edge 24 of the
hull.
[0029] FIG. 2 is a front view of the watercraft 12 showing the
propulsion system 14 extending below the hull 16. The inlet opening
20 is shown centered in the forward end of the housing 18. FIG. 3
is a rear view of the watercraft 12 showing the propulsion system
14 extending below the hull 16. The outlet opening 22 is shown
centered in the aft end of the housing 18. FIG. 4 is a perspective
view of the submerged portion of the housing 18 that contains the
propulsion system 14 disposed on the bottom of the hull 16.
[0030] FIG. 5 is a perspective view of a cross-section of the
propulsion system 14 taken along lines V-V of FIG. 1. Visible in
this view is jet pump 26 that is substantially centrally located
within housing 18. The preferred pump configuration that is shown
is a counter-rotating helical rotor pump. In the preferred
embodiment shown, each rotor 28, 30 includes three lobes 32,
wherein the rotors are positioned such that the lobes from each
rotor sealingly intermesh with one another at the center and
sealingly engage the seal regions 34 that are formed in each side
of the housing. Rotation of the rotors causes a fluid to be
positively displaced from one end of the pump to the opposite end
of the pump while backflow is precluded. Rotation in the direction
indicated by the arrows will cause fluid to be forced from the
inlet end 20 to the outlet end 22. Only one particular such pump
configuration is shown while different numbers of lobes and lobe
profiles can be used. In the preferred embodiment, the lobes 32 and
hence the recess 36 there between describe a helical shape relative
to the axis of rotation 38 of each rotor as is most visible in FIG.
5a. The number of lobes and recesses will determine the angle that
is described by the seal regions 34. Additionally shown in FIG. 5
are gussets 42, 44 that are position within both the inlet end 20
as well as the outlet end 24 of the housing 18. The gussets serve
not only to align the flow to and from the pump but also serve as
structural members to reinforce the housing.
[0031] While the embodiment illustrated in FIG. 5 has a discharge
opening with a fixed cross-sectional area, further efficiencies are
gained with the fitment of a mechanism for varying the
cross-sectional area of the discharge opening such as is shown in
FIGS. 6 and 7. A moveable control element 46 is positioned in the
discharge opening 22 and is shaped such that a shift in its
longitudinal position will cause the discharge area 48 to change.
Full retraction of the control member, as is shown in FIG. 6, will
serve to maximize the cross-sectional area and thereby minimize the
velocity of the flow of water while full protrusion, as is shown in
FIG. 7, will minimize the cross-sectional area and thereby maximize
the velocity of the flow of water. Any of a variety of control
member configurations can be employed as can any of various
mechanisms to alter the position of the control member so as to
achieve a desirable ratio of the jet velocity relative to the
surrounding water velocity. FIG. 8 illustrates an alternative
preferred embodiment wherein five lobe helical rotors 28a, 30a
force the flow of water past two control elements 46a, 46b.
Additionally visible is a bottom lip 50a that extends beyond the
discharge opening from the bottom surface of the housing to limit
downward diffusion of the water jet.
[0032] FIG. 9 is a perspective view of the propulsion system 14 of
the present invention. A transfer box 52 extends from the top of
the housing 18 for transferring rotation from a prime mover (not
shown) via flange 54 to the pump rotors that are disposed within
the housing. Both the inlet opening 20 as well as the discharge
opening 22 are visible. A flange 56 extends about the periphery of
the housing to facilitate its attachment to the bottom of a hull.
Any of a variety of prime movers can be relied upon to power the
propulsion system including, but not limited to internal combustion
engines, electric motors, hydraulic motors, vertical axis wind
turbines and even human power.
[0033] FIG. 10 is a cross-sectional view of the embodiment shown in
FIG. 9. In this particular embodiment, a flow 58 of water into the
inlet opening 20, past rotor 30 and out through discharge opening
22 can describe a substantially horizontal path. The decrease in
the height of the outlet conduit and the commensurate decrease in
cross-sectional area serves to accelerate the jet before being
discharged. In the particular embodiment that is illustrated, a
gear set 60, 61 serves to transfer rotation from flange 54 to the
rotors.
[0034] In operation, reliance on a non-pulsating positive
displacement pump in water jet propulsion systems yields
substantial gains in efficiency over previously used devices. More
specifically, a counter-rotating helical rotor pump is able to
provide an aligned continuous flow at the most efficient velocity
without turbulence. The non-pulsating flow characteristic
eliminates the thrust disruptions inherent in pulsating
configurations and the inefficiencies resulting therefrom. Such
pump in conjunction with a fully submerged discharge opening having
a variable cross-sectional area yields extremely high propulsion
efficiency over the entire range of pumping capacity. Adjustment of
the cross-sectional area of the discharge opening allows the
discharge jet velocity to be set to propel a vessel at its best
fuel efficiency or, if desired, to provide maximum driving force
over a wide range of vessel operating parameters such as weight,
displacement and weather conditions. The submerged variable area
discharge opening in combination with the installation location on
the hull and a bottom lip serve to limit diffusion of the water jet
thereby minimizing the dynamic mixing losses aft of the discharge
plane allowing the hydraulic reaction to be maximized. It is
contemplated that the propulsion system of the present invention
can be sized and adapted to most any watercraft from motorized
surfboards and kayaks, to sport and pleasure boats to freighters
and tankers. In each such application, overall energy consumption
can be significantly reduced as the water discharge velocity
leaving the housing can be optimized at any given vessel speed to
yield the highest possible propulsion efficiency using the least
amount of fuel. Unlike water jet propulsion systems that discharge
above the waterline of a vessel, there is no need for complicated
diversion systems that direct the flow of water forward to provide
reverse thrust. A simple reversing of the rotor rotation provides
reverse thrust by causing the water to flow from the submerged
discharge end out the submerged inlet.
[0035] While particular forms of the invention have been described
and illustrated, it will also be apparent to those skilled in the
art that various modifications can be made without departing from
the spirit and scope of the invention. Accordingly, it is not
intended that the invention be limited except by the appended
claims.
* * * * *