U.S. patent application number 11/771035 was filed with the patent office on 2007-10-25 for variable area pump discharge system.
Invention is credited to Brian J. O'Connor.
Application Number | 20070249243 11/771035 |
Document ID | / |
Family ID | 37083702 |
Filed Date | 2007-10-25 |
United States Patent
Application |
20070249243 |
Kind Code |
A1 |
O'Connor; Brian J. |
October 25, 2007 |
VARIABLE AREA PUMP DISCHARGE SYSTEM
Abstract
A highly efficient watercraft propulsion system that operates
continually submerged and relies on a non-circular variable area
pump discharge opening which is configured, positioned and oriented
so as to maximize the hydraulic reaction between the high velocity
water jet stream and the surrounding body of water and is driven by
a positive displacement pump.
Inventors: |
O'Connor; Brian J.;
(Encinitas, CA) |
Correspondence
Address: |
FULWIDER PATTON LLP
200 OCEANGATE, SUITE 1550
LONG BEACH
CA
90802
US
|
Family ID: |
37083702 |
Appl. No.: |
11/771035 |
Filed: |
June 29, 2007 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
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11103318 |
Apr 11, 2005 |
7238067 |
|
|
11771035 |
Jun 29, 2007 |
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Current U.S.
Class: |
440/47 |
Current CPC
Class: |
B63H 11/103 20130101;
B63H 11/06 20130101 |
Class at
Publication: |
440/047 |
International
Class: |
B63H 11/00 20060101
B63H011/00 |
Claims
1. A water jet propulsion device for a watercraft, comprising: a
positive displacement pump for generating a jet of water; a
discharge duct for discharging said jet of water, wherein said duct
defines a discharge opening that is positioned under said
watercraft so as to be fully submerged at all times; and a movable
element disposed within said discharge duct operative to vary the
cross-sectional area of said discharge opening.
2. The water jet propulsion device of claim 1, 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.
3. The water jet propulsion device of claim 2, further comprising a
lip that extends from said discharge duct beyond said discharge
opening so as to define a surface substantially parallel to said
hull along which said discharged jet of water flows.
4. The water jet propulsion device of claim 1, wherein said
discharge opening has a cross section defining a generally
trapezoidal slope wherein top and bottom sides are parallel and
transverse sides may be straight or curved.
5. The water jet propulsion device of claim 1, wherein said movable
element is comprised of two flat, parallel surfaces and two
opposing surfaces that define a wedge having an apex that is
variably extendible from within said discharge duct outwardly
through said discharge opening.
6. The water jet propulsion device of claim 5, wherein said movable
element is moved toward the aft end of the vessel hull by force
generated by a flow of water within said discharge duct impinging
directly on said moveable element.
7. The water jet propulsion device of claim 6, wherein said force
is resisted by a spring which biases said movable element into a
predefined position.
8. The water jet propulsion device of claim 7, wherein said spring
is positioned within said moveable element.
9. The water jet propulsion device of claim 8, wherein said spring
has a non-linear spring rate.
10. The water jet propulsion device of claim 6, wherein said force
is resisted by a hydraulic piston so as to position said movable
element into predefined linear positions.
11. The water jet propulsion device of claim 1, wherein one or more
additional movable elements are disposed within said discharge duct
to vary the cross-sectional area of said discharge opening.
12. (canceled)
13. The water jet propulsion system of claim 1, wherein said
discharge opening is positioned and configured so as to limit
upward and downward diffusion of a discharged water jet stream.
14. (canceled)
15. A water jet propelled watercraft, comprising: a hull for
supporting said watercraft, said hull having an aft end; a positive
displacement pump for generating a water jet; a discharge duct for
directing said water jet rearwardly, said duct having a discharge
opening defining a plane, said plane being disposed below said hull
and forward of its aft end.
16. (canceled)
17. The watercraft of claim 15, wherein said discharge duct
includes moveable control surfaces configured to vary water jet
velocity.
18. The watercraft of claim 17, wherein said moveable surfaces
define a wedge that is moveable into said plane defined by said
discharge opening.
19. The watercraft of claim 17, wherein said moveable surfaces are
parallel and slide in a substantially horizontal orientation.
20. The watercraft of claim 15, wherein said discharge duct
includes a surface extending rearwardly beyond the pump discharge
plane to limit downward diffusion of a discharge water jet.
21. The watercraft of claim 15, wherein said positive displacement
pump comprises a sliding vane pump.
22. The watercraft of claim 15, wherein said positive displacement
pump comprises a counter-rotating dual rotor lobe pump.
Description
CROSS-REFERENCES TO RELATED APPLICATIONS
[0001] This application is a divisional application of U.S. patent
application Ser. No. 11/103,318, filed Apr. 11, 2005 and claims
priority to same and is hereby incorporated by reference in its
entirety.
FIELD OF THE INVENTION
BACKGROUND OF THE INVENTION
[0002] The present invention generally relates to water jet
propulsion devices and more particularly pertains to devices for
varying the area of an orifice through which a water jet is
discharged.
[0003] 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.
[0004] It has been long 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
[0005] The present invention provides a highly efficient pump
discharge system that controls the dynamics of a submerged water
jet employed to propel a watercraft. More particularly, the system
includes a duct having a discharge opening configuration that is
continuously variable in terms of its cross-sectional area. Said
discharge employs an opening having 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.
[0006] 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.
[0007] 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
flow velocity.
[0008] 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 outward 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.
[0009] While the positioning of the pump discharge opening below
the hull of a watercraft has been found to increase the
effectiveness of the discharging jet of water, it is important that
the discharge housing be shaped so as to minimize the hydrodynamic
impact of its presence in such a critical location. The partially
hemispherical shape of the exterior surface of the discharge duct
serves to minimize the dynamic drag profile that extends beyond the
uniform surface of the hull and a smooth blend of the intersecting
surfaces between the duct and the surrounding hull surface promotes
laminar flow over and around the entire surface to thereby minimize
fluid dynamic drag.
[0010] Finally, in order to maximize the efficiency of the
discharge system of the present invention it is necessary to supply
sufficient volumetric flow and pressure head to the upstream side
of the discharge duct so that the discharge volume flow can
maintain the most efficient velocity ratio between the discharge
jet and the adjacent water body in order to maximize the hydraulic
reaction at the plane of the discharge opening and within the
liquid mixing zone. Because of the aforementioned pressure head
requirement, it is preferred that a positive displacement pump be
relied upon to generate the flow of water. Any of a variety of
positive displacement pumps can be utilized including for example,
configurations employing sliding vanes, intermeshing gears,
gerotors or Moineau-type designs which all have high pump
efficiency over a wide range of rotor speed. The pumps can in turn
be driven by any type of powerplant including for example internal
combustion engines and electric motors.
[0011] 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
[0012] FIG. I is a side view of a flat bottom, non-descript boat
hull showing the general shape and typical location of the
discharge duct of a preferred embodiment of the variable area
discharge system of the present invention extending from bottom
surface of the hull;
[0013] FIG. 2 is the rear view of the preferred embodiment shown in
FIG. 1;
[0014] FIG. 3 is an enlarged side view of the discharge duct shown
in FIG. 1;
[0015] FIG. 4 is an enlarged rear view of the discharge duct shown
in FIG. 2;
[0016] FIG. 5 is a further enlarged cross-sectional view taken
along line 4-4 of FIG. 3 showing the control element in its fully
retracted position;
[0017] FIG. 6 is a cross-sectional view similar to that shown in
FIG. 5 but with the control element in its fully extended
position;
[0018] FIG. 7. is a longitudinal cross-sectional view of the
discharge system of the present invention taken along lines 6-6 of
FIG. 5;
[0019] FIG. 8 represents of a planar cross-sectional view, similar
to the section view along line 4-4 in FIG. 3, of another preferred
embodiment of the discharge system of the present invention
employing a dual rotor lobe pump and dual control members.
[0020] FIG. 9 is an enlarged view of encircled region 9 shown in
FIG. 8 illustrating a single control member in the fully extended
position where the axial translation aft is determined by the
position of the internal hydraulic piston; and
DETAILED DESCRIPTION OF THE INVENTION
[0021] The pump discharge system of the present invention provides
for the enhanced efficiency of a water jet such as is used for the
propulsion of a watercraft. The figures generally illustrate
preferred embodiments of the discharge system in terms of its
configuration, the mechanism for varying the cross-sectional area
of the discharge opening and its positioning with respect to the
watercraft.
[0022] FIG. 1 is a side view of a watercraft 12 showing the hull
bottom that has been fitted with the discharge system of the
present invention. The discharge housing 14 is positioned under the
hull so as to ensure that the discharge opening 16 remains
submerged at all times during all modes of operation. Its
submersion 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 18 of
the hull. The leading surface of the discharge housing is a
generally spherical contour 15 that is blended with a smooth radius
17 along its transition into the hull.
[0023] FIG. 2 is a rear end view of a watercraft that has been
fitted with the discharge system of the present invention. The
discharge housing 14 is shown centered on the bottom surface 22 of
the hull with the continuation of the generally spherical frontal
contour 15 extending along the bottom surface of the housing 14.
The control element 24 and the discharge opening 16 are also
clearly illustrated.
[0024] FIG. 3 is an enlarge side view of the discharge housing 14
extending from the bottom of the hull 22. Its leading surface 15 is
blended into the surrounding hull with a blend radius 17 while its
aft end in the region of the discharge opening 16 defines a
substantially vertical cut through the contoured end. A movable
control element 24 with which the cross-sectional area of the
discharge opening 16 is alterable is seen protruding from the
discharge opening. Additionally visible is a bottom lip 26 that
extends beyond the discharge opening from the bottom surface of the
discharge housing.
[0025] FIG. 4 is an enlarged rear view of the discharge housing 14
extending from the bottom of the hull 22. Clearly visible is the
movable control element 24 that is centrally positioned within the
non-circular discharge opening 16 and the parallel upper and lower
control surfaces, 39 and 41 respectively, on which the control
element slides.
[0026] FIG. 5 is a further enlarged cross-sectional view taken
along lines 4-4 of FIG. 3. The movable control member 24 is
centrally disposed within the discharge housing 14 and includes a
forward section 28 that defines a smoothly curved surface that
serves to split and divert the flow of water around the control
member. The aft section 30 of the control member generally defines
a wedge shape in cross-section. The control member is shown in its
fully retracted position wherein only a small portion of the
wedge-shaped end extends outwardly beyond the discharge opening 16.
In such position, the control member blocks off the least amount of
the total cross-sectional area of the discharge opening to thereby
maximize the amount of cross sectional area through which the flow
of water is discharged.
[0027] Additionally shown in FIG. 5 is a guiding member 32 and a
guide pin 34 which is accommodated in respective slots 36, 38
formed in the control member. Such elements serve to constrain the
movement of the control member so as to be moveable only along the
longitudinal axis of the control member 24 and additionally serve
to limit the maximal amount of extension as well as retraction.
Additionally, these elements can be relied upon to support the
bottom surface of the discharge duct 14 as well as the bottom lip
26 and prevent deformation of the respective components when
subjected to high pressure differentials between the internal
region of the discharge housing and surrounding water body. The
particular embodiment shown in these drawings relies on a
compression spring 40 to bias the control member into its fully
retracted position. The spring rate of the spring is selected so as
to allow the control member to extend rearwardly at a linear rate
as the water flow from the pump increases, corresponding to a
predictable linear position resulting in the desired discharge flow
area. A variable rate spring may also be used to provide alternate
positioning of the control member at comparable pump flowrates.
[0028] FIG. 6 illustrates the control member 24 in its fully
extended position in reaction to the force exerted on the leading
surfaces of the forward section of the control member by the flow
of water generated by a pump (not shown) upstream of the discharge
duct 14. The stationary guiding member 32 and guide pin 34 serve to
prevent lateral deflection of the control member and upon contact
with the proximal ends of the respective slots 36, 38, limit its
movement rearwardly. The guide pin 34 also prevents downward
deformation or deflection of the bottom lip 26 potentially caused
by the pressure exerted thereon by the discharging jet.
[0029] FIG. 7 is a cross-sectional view taken along lines 6-6 of
FIG. 5. The illustration clearly shows the positioning of the
discharge opening 16 and a portion of the discharge duct 14 below
the hull 22 of a watercraft. Flow is generated by a pump that is
not shown that may be positioned at relatively remote forward
location with respect to the discharge duct. Additionally visible
in this Figure is the interconnection between parallel surfaces 39
at the top of the duct and 41 at the bottom of the duct and guide
pin 34. The guide pin as well as the stationary guiding element 32
serve to stabilize the bottom surface 41 of the duct and the bottom
lip 26 preventing possible deformation caused by hydraulic forces.
Deflection and/or deformation of the bottom surface 41 of the duct
could impair the smooth actuation of the control element 24 as well
as allow the flow of water between the control element 24 and
either the top 39 or the bottom surface 41 of the duct.
Additionally, deflection of the bottom lip 26 would compromise its
ability to prevent downward diffusion of the discharged water
jet.
[0030] FIG. 8 illustrates a preferred embodiment of the present
invention wherein a positive displacement pump and more
specifically, a dual rotor multiple lobe positive displacement pump
42 is relied upon to generate a flow of water past the control
element 24 which is illustrated in the fully retracted position and
through discharge opening 16. The individual rotors are arranged so
as to rotate about parallel axes that can be vertical as shown or
tilted with respect to the horizontal plane. The rotors may be
driven by a single powerplant or by multiple power plants. A dual
lobe pump configuration is preferred because the rotor lobes while
acting to positively displace the water, never actually touch the
housing surface thus eliminating wear and it is fully reversible
allowing reverse thrust. Forward vessel thrust is provided by the
counter-rotation of the rotors 42 whose rotational direction is
indicated by the superimposed rotation arrows drawing water into
the upstream side of the pump passing through a structural grille
44, and is accelerated within the transport pocket 48 and
thereafter forced toward the control member 24 within the discharge
housing 14. Axial force from the impact of the moving water on the
frontal surface of the control member 24 causes the body of the
member to move aft. This embodiment of the invention uses a
hydraulic piston 34 to position the control member 24 variably from
its fully retracted to its fully extended position shown in FIG. 9
depending on the volume of hydraulic fluid supplied via the feed
port 33 to the piston chamber 35. The piston is contained in the
guide element 32 that extends from the upper to lower surface 46 of
the discharge housing. Structural support for the housing bottom
surface 46 and the lip extension 26 is supplied by the guide
element 32 and the center guide vane 45. While The pumps may driven
by any type of powerplant including for example the ubiquitous
internal combustion engine or by an electric motor.
[0031] FIG. 9 is an enlarged view of encircled area 9 of FIG. 8
illustrating a single control element 24 in the fully extended
position. While the force to move the control member aft is
supplied by the impact of the pump flow on the forward surface 28
of the control element, its precise axial location is fixed by the
axial location of the piston 34 that is contained within the guide
element 32 wherein passage 33 allows hydraulic flow to and from
chamber 35 to establish the axial location of the control element
24.
[0032] In operation, reliance on a positive displacement pump in
conjunction with a fully submerged-discharge-opening having a
variable cross-sectional area combine to yield 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 16 allowing the hydraulic reaction to be
maximized. Finally, the use of a positive displacement pump allows
sufficient pressures to be generated and maintained so that the
desired jet velocities can be attained to create the most effective
hydraulic reaction between the liquid discharge and the surrounding
body of water. An overall performance increase can therefore be
realized to the extent that thrust produced by the water jet over
the full operating range of the pump output can be maximized.
Accordingly, 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.
[0033] 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.
* * * * *