US20110045718A1

US20110045718A1 - Marine propulsion system and method

Info

Publication number: US20110045718A1
Application number: US12/543,783
Authority: US
Inventors: Donald L. Ekhoff
Original assignee: Individual
Current assignee: Individual
Priority date: 2009-08-19
Filing date: 2009-08-19
Publication date: 2011-02-24

Abstract

A marine propulsion system comprises a propulsion wheel that is rotary driven and that includes an arrangement of water-channeling members located to extend only partially below the water level. As a member is partially submerged, water is collected, compressed, accelerated, and ejected as a water jet. An ejection end of each member may be specifically designed to achieve desired thrust characteristics. The water-channeling members may be non-complex, such as being cup-shaped or spoon-shaped, but may include complex curvatures in order to achieve desired thrust characteristics. A hull may be used to precondition the water level presented to the water-channeling members.

Description

TECHNICAL FIELD

The invention relates generally to powering a marine vessel and more particularly to a rotary drive system for marine propulsion.

BACKGROUND ART

There is a wide variety of known techniques for propelling a marine vessel. Manual techniques include the use of oars, paddles, and poles. Sails also provide propulsion without the need of motors. However, motorized propulsion typically provides greater control and greater speed.
Motorized marine propulsion techniques include the use of paddle wheels, screw propellers, and water jets. Paddle wheels are uncommon, since conventional paddle wheels are bulky and tend to be inefficient. The paddle wheels are basically “pushers” in which flat paddle planks are rotated through water, thereby using the viscous flow resistance of the paddle to propel the marine vessel along the surface of the water. The inefficiency results from the insertion and extraction losses, as well as turbulence losses. In comparison, the screw propeller exhibits turbulence losses, but is somewhat more efficient because the propeller remains submerged. Water jets direct a high speed stream of water from a nozzle. While water jets provide advantages over other techniques, inefficiency results from the high levels of wetted surface and turbulence involved in moving an incompressible fluid through an often complex configuration at high velocity.
While the known techniques operate well for their intended purposes, further advantages are sought. Such advances may be in one or more of a number of areas, such as efficiency, speed, safety, and adaptability.

SUMMARY OF THE INVENTION

A marine propulsion system in accordance with the invention is comprised of a rotary driven propulsion wheel having an arrangement of water-channeling members with cavities that are configured to first concentrate incoming water and then eject the water as an accelerated flow. The mounting and the driving of the propulsion wheel are such that each water-channeling member periodically extends only partially into the water in which the marine vessel resides. As a particular water-channeling member is partially extended into water, a quantity of water is “scooped” within the cavity of the member. Inclined surfaces of the cavity cause the scooped water to be channeled from the submerged portion upwards toward a central region of the cavity. The water continues to follow the contour of the cavity surfaces and is ejected in a rearward direction as an accelerated jet of water.
In one embodiment, the cavity surface of each water-channeling member terminates in a curved end. The design of the curved end determines the direction of the water jet ejected from the member. While geometries of the system components will vary with the needs for a particular application of the invention, it is likely that the ejected water from a curved end will be a water jet with a velocity much greater than the velocity of the water-channeling member. Thus, the curved end is preferably directed such that the jet avoids contact with the other water-channeling members of the propulsion wheel, thereby avoiding efficiency losses.
The water-channeling members may be connected to the propulsion wheel along its exterior surface or may be integrated to the propulsion wheel during manufacture. Rather than having a planar region to contact the water, each water-channeling member may be described as having a cup-shape or a spoon-shape, although more complex shapes have advantages. Regardless of the particular shape of each member, water is gathered under the influences of inertial forces, consolidated into a high speed jet, and then ejected rearward. The jet ejection event is a direct function of the rotational location of the water ingestion. Once the water is ingested, the water follows the contour of the cavity while it consolidates/accelerates into a jet. The direction of this jet from the curved end is a function of the placement of the water intake plus a few degrees of rotation, which is due to the time required for the ingested water to travel through the water-channeling member. At rest, water will rise into the “hole” being formed by the “digging” of consecutive scoops, but as speed increases, water is additionally made available towards the forward edge of the rotating propulsion wheel, due to the advancement of the marine vessel through the body of water.
The curved end of each water-channeling member can be configured to define thrust characteristics. For example, the mounting of the water-channeling members and the geometry of the curved ends may be designed to define a direction of propulsion that is nominally parallel to the water level surrounding the marine vessel. Alternatively, the curved end may have a termination at a downward angle toward the water level, such that a component of lifting force is applied in addition to the lateral, forward propulsion. This lifting force may be used to reduce friction as the marine vessel is moved along the surface of the water. In addition, the water-channeling members may be designed to create a high pressure area that has a tendency to lift the vessel by inciting hydraulic pressures acting directly on the water-channeling members. Other embodiments may have more of a lip which will cup water into the cavity to increase thrust while decreasing lift.
If the water-channeling members are too closely spaced along the propulsion wheel, water projected from one member may strike the reverse side of the subsequent member, regardless of the design of the curved end. If a greater amount of thrust is desired, the water-channeling members may be arranged in multiple axially separated rows, with each row having a number of aligned members. Additionally, the members of adjacent rows may be axially misaligned, such that the members of the adjacent rows are staggered.
The mount which secures the propulsion wheel to the marine vessel may be configured to provide additional advantages. The mount may be enabled to move in a direction perpendicular to the water surface, thereby allowing the propulsion wheel to adapt dynamically. For example, articulating legs may be used in a manner similar to suspension systems for land vessels. Then, the propulsion wheel is free to rise or lower relative to the marine vessel. This permits a smoother passage of the marine vessel than would be achieved if the propulsion wheel were rigidly mounted to the vessel. Using such a “suspension system” or other means of absorbing path disruption in a controlled manner is most important for Ultra high Speed designs that may use the invention.
Amphibious embodiments are contemplated. For example, the water-channeling members may be adapted to allow travel along a beach or along the surface of ice. Alternatively, the propulsion wheel may be connected to rolling elements which are driven by the same rotary drive and which support the vessel upon exiting from the water. This rolling action will also accommodate passage over submerged objects such as ice and will have minimal detrimental effect on wildlife.
This technology is similar to the turbine concept used in generating hydropower. While other differences exist, the most significant difference between the invention and the power-generating systems (for example, the Pelton wheel and the Turgo wheel) is that the propulsion wheel of the invention is powered through water, rather than being powered by water.
Drag can be further reduced by including a hull or similar structure positioned forwardly of the propulsion wheel to precondition the water level. For example, the mounting of the propulsion wheel may include a hull, below which the end regions of water-channeling members periodically extend to contact water. The rotational axis of the propulsion wheel is at a distance from the bottom of the hull to limit emersion of the water-channeling members as described above. Using the hull, the water level surrounding the marine vessel is consistently higher than the “apparent” level of water contacted by the members. This is because the hull “conditions” the surface of the water contacted by the members.
An advantage of the invention is that a greater efficiency is possible, as compared to conventional propeller-drive and jet-drive systems for marine vessels, because cavitation losses and large surface frictional pumping losses are significantly reduced or even eliminated. Another advantage is that maintenance and service requirements are reduced, since under normal circumstances only a small portion of the moving components of the propulsion system extend to the water and the large portion is easily accessible.
The propulsion system functions as a gyro stabilizer for the marine vessel. Where the propulsion wheel spins on a horizontal axis at high speed and with a considerable diameter and mass, the propulsion wheel will resist vessel rotations about its rotational axis and a vertical axis. This is most desirable when the vessel is at speed in rough water. It is further contemplated that this effect may be applied when propulsion of the vessel is not desired. The propulsion wheel can be raised sufficiently to spin freely without contact with water. Sea sickness is a result of the undulating “figure eight” motion that is unfamiliar to land passengers. The invention may be used to reduce vessel motion to a much simpler rocking of the vessel about a port/starboard axis, thereby reducing common side-to-side rocking motion. It is possible to place an additional gyro-wheel within the propulsion wheel, so that this advantage is available irrespective of propulsion speed. In military applications, this effect may be used to stabilize a platform from which munitions are aimed.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a perspective view of one embodiment of a propulsion system in accordance with the invention.

FIG. 2 is a perspective view of the system of FIG. 1 within a hull.

FIG. 3 is a schematic view of the invention in an operational mode.

FIG. 4 is an end view of the propulsion system of FIG. 1 as used within a tunnel hull.

FIG. 5 is a perspective view of an alternative embodiment of a water-channeling member.

FIG. 6 is another embodiment of a water-channeling member in accordance with the invention.

DETAILED DESCRIPTION

With reference to FIG. 1, a propulsion system 10 in accordance with one embodiment of the invention includes two rows of water-channeling members 12 and 14 connected to a propulsion wheel 30. The water-channeling members 12 are in a row that is axially separate from the water-channeling members 14 of the other row. The members 12 and 14 are “water-channeling,” since they are configured to collect water and channel the collected water so as to provide a thrust having desired characteristics. In FIG. 1, the members have a cup-shape, but other configurations are within the scope of the invention, including spoon-shaped members and those with a more complex geometry (for example, those which will be described with reference to FIGS. 5 and 6).
The mounting of the water-channeling members 12 and 14 to the propulsion wheel 30 may be accomplished using techniques known in the art. In FIG. 1, each member is connected to a plate 18 which is mounted to the propulsion wheel by fastening hardware, such as screws or bolts. Alternatively, the water-channeling members may be integrally formed with the propulsion wheel during a manufacturing process. The structure of the illustrated propulsion wheel is similar to that of a wheel of a land vessel.
In a typical embodiment, a motorized rotary drive is coupled to operate the propulsion wheel 30. However, the propulsion system may be manually driven, such as by coupling the propulsion wheel to rotate as a person operates hand or foot pedals. Thus, the rotary drive may include a motor engine or may be an assembly similar to that of a bicycle.
In the embodiment of FIG. 1, the propulsion wheel 30 is connected to a rotating central assembly 32 by three spokes 34. A belt 33 or chain couples the central assembly 32 to a drive gear 35. A representation of a motor 50 is included for reasons of explanation, but the rotary drive motor may vary significantly for alternative packaging requirements. Mounting plates 44 may be used to attach a pair of side walls 36 and 38 to a pivot plate 46 that attaches to a stationary portion 42. A restriction pin 48 may be included to set a limit as to the lower range of motion of the pivot plate. While not shown, a second restriction pin may be used to similarly limit the upper range of motion.
The side walls 36 and 38 are on opposite sides of the propulsion wheel 30 to combine with a shroud 40 to cover the water-channeling members 12 and 14, other than at a lower end of the propulsion system. In the illustration of FIG. 1, the nearer side wall 36 is shown in phantom, so as to allow the internal components to be viewed.
In operation, only the lowermost portion of the propulsion system 10 should reside below the system's “apparent water level.” Referring to FIGS. 1 and 2, this apparent water level is below the level of the water in which the marine vessel resides. A hull 37 may be used to condition the water level so as to define the apparent water level when the vessel is at speed. Only the bottom 39 of the hull is illustrated in FIG. 1, so that it may be seen that the shroud 40 has a termination 52 that is generally along the same horizontal plane with the hull bottom. This allows water to enter the region that is between the two sidewalls 36 and 38 and below the hull.
FIG. 3 represents the operation of the propulsion system 10, but only one row of water-channeling members 12 is shown. Briefly stated, each water-channeling member 12 is rotated into the surface of the water, thereby collecting and accelerating the water in conformance with the face of the member. Each water-channeling member is contoured to include side features which constrain and direct the water towards the centerline of the water-channeling member, thereby placing compressive forces into the water stream. These compressive forces act to accelerate the flow of said water stream, causing the rearward ejected water stream to provide useful forward thrust (Arrow 54 represents the forward direction). The water-channeling member may be limited to an emersion of only one-third of its length. That is, for purposes of propulsion, the member is only one-third engaged. Water is gathered under the influences of inertial forces, is consolidated into a high speed jet 78, and is ejected rearward. The jet ejection event is a direct function of the rotational location of the water ingestion. Once the water is ingested, it follows the contour of the cavity in the face of the member while it consolidates/accelerates into the jet. The direction of this jet from the curved end of the member is a function of the placement of the water intake plus a few degrees of rotation, which is due to the time required for the ingested water to travel through the water-channeling member. Each member 12 takes a “bite” of the water as the member scoops into the water. The successive bites (or scoops) are represented by different crosshatchings of the “bites,” which match the different hatchings of the water-channeling members. At rest, water will rise into the “hole” being formed by the “digging” of consecutive scoops, but as speed increases, water is additionally made available towards the forward edge of the rotating propulsion wheel, due to the advancement of the marine vessel through the body of water.
As the propulsion system 10 drives the marine vessel forward, the hull 39 functions to condition the water for smooth successive “bites” by the rotating water-bearing members 12. The efficiency of the system is increased if the propulsion wheel 30 and the members 12 are enclosed within the fairing (the side walls 36 and 38 and the shroud 40 that is shown in FIGS. 1 and 2). One reason is that the members 12 should not be overfilled. A general rule of thumb is that a member should take a “bite” which is approximately one third of its total capacity to hold water. “Overfilling” may result in performance that is typical of a conventional paddle wheel, wherein the only reaction is from pushing on the water, rather than a combination of pushing on the water and “jetting” the channeled water. The hull is designed to reduce the likelihood that overfilling will occur. Moreover, by enclosing the rotating components, aerodynamic drag is reduced. The top of the propulsion wheel is moving at approximately twice the speed of the marine vessel and the added impulse speed of the members 12 would create considerable drag if the components were exposed. In addition to reducing drag, the fairing reduces noise, reduces spray, and increases safety.
An advantage of the invention is that the propulsion system induces little turbulence. Water is directed in a laminar flow. Additionally, the “wetted area” is very small, since only one face of a water-channeling member receives water and since only a portion of the member is immersed. This provides a control over surface friction losses. By contrast, a conventional propeller blade is fully immersed and subject to high surface frictional losses when translating through the water.
FIG. 4 is an end view of a tunnel hull 82 as used with a Jet Ski. A seat portion 84 is attached atop the hull portion. Because of the design of the tunnel hull, the water level 86 of the marine vessel is well above the water level 88 presented to the water-channeling members 12 and 14. As water flows relative to the vessel, each water-channeling member scoops a “bite” of water, compresses the water toward the central region of the cavity of the rearward face, and ejects the accelerated water rearward.
The tunnel hull of FIG. 4 provides advantages with respect to safety and to protection of the system. As can be seen, the marine vessel can pass over a person without a high risk of the rotating members 12 and 14 injuring the person. Similarly, if the hull passes over a log or other object, the members 12 and 14 are not likely to be damaged.
FIG. 5 illustrates an alternative configuration for the water-channeling members. In this embodiment, each member 62 comprises a pair of fingers 64 and 66. When the member is connected to a propulsion wheel and is allowed to extend into water such that only the ends of the fingers are submerged, water will be received and channeled upwardly. A curved end 68 has a configuration that will at least partially determine the thrust characteristics of the individual member. The overall configuration of the member determines the increase in velocity of water, while the configuration of the curved end will play a role in the direction of applied force. The angle at which the individual member is mounted to the propulsion wheel will determine the “attack angle” of the fingers 64 and 66 and will determine an angle at which water is projected from the curved end 68.
FIG. 6 is another embodiment of a water-channeling member. In this embodiment, the member 70 has a blunted water pick up end 72. A greater volume of water is able to be collected. However, as with the other embodiments, there is a region in which the ingested water will accelerate, so that water is increased in velocity and is projected from a curved end 74 having a configuration designed to achieve desired thrust characteristics.
Referring again to FIG. 3, the water-channeling members 12 can be shaped and oriented to produce desirable characteristics. Nominally, the reaction jet 78 may be directed fully rearward for a maximum thrust. However, aiming the jet downwardly will produce lift, which may be used to provide levitation of the marine vessel so as to reduce friction.
As previously noted, the propulsion system 10 may be connected to the marine vessel using a suspension system similar in affect to suspension systems of land vessels. In combination with providing levitation, the result is that a smoother and more efficient ride is possible. In the interest of further improving upon efficiency and performance, the hull is utilized. Conceptually, the moving components operate by transforming a section of scooped water into a much smaller cross section or “jet” of high speed water. The ratio may be roughly 3:1, but other ratios are considered. When a water-channeling member contacts water at its tip, the velocity of “x” of the water is ejected at “3x”. This results in a reaction thrust being applied to the propulsion wheel 30 and, therefore, the hull. Any viscous flow losses at the face of the water-channeling member are exhibited on the propulsion wheel and consequently the hull. The only undesirable losses acting on the system are aerodynamic losses on the propulsion wheel at the top side of its rotary motion. For this reason, it is enclosed within the shroud.
The propulsion system may be adapted for use with amphibious vessels. The rotary drive that powers the rotation of the propulsion wheel 30 may also power rowing elements that are linked through or separately from the propulsion wheel. For example, the rolling element may be a broad rim that is allowed to travel on a beach when the marine vessel exits the water.
While the increased efficiency of the propulsion system relative to conventional systems provides advantages in high speed applications, recreational applications are also considered. For example, the rotary drive for powering the propulsion wheel 30 may be manual, such as the use of a peddling system similar to a bicycle.
There are a number of different possible lifting forces. As speed increases, there is a significant lifting force developed as water flows upwardly and encounters the compound curved end that forms the exit jet 78. This forces the water-channeling member 12 both forward and upward. The upward force helps support the weight of the marine vessel. If the members 12 are properly angled and sufficient speed is generated, there may be conditions in which the vessel is fully supported, eliminating contact with the water and therefore eliminating drag which would otherwise result from viscous shear of the hull against the surface of the water. At this point, aerodynamic drag and gravitation would be in equilibrium with the forces generated by the propulsion system, and normal aquatic speed restrictions would be substantially reduced.
In some applications, the fairing or hull for the propulsion system is the marine vessel itself, as is the case in the embodiment of FIG. 4. However, in other applications, the hull can provide floatation as well as desired stationary stability. It is possible to connect the propulsion system in a hollow watertight hull that is attached to the marine vessel using a suspension system that enables movement relative to the marine vessel. That is, the hull is able to adjust with waves and other changes in the water level of the main body of water. For example, where two propulsion systems are used to power a boat, two hulls may be connected to the boat in an “outrigger” manner. In many applications of the invention, the suspension should be at the very front of the marine vessel, so as to help support the bow from dipping into the water trough, only to nose into the next wave crest. If propulsion pads are used to follow these undulations while tractoring up and down the wave faces, a much more consistent motive force can be obtained.
From the foregoing, it is apparent that the invention operates on inertial mechanisms in which water is in contact with a “cupped” member only on its compression side. The system “slings” water at accelerated speeds as an efficient reaction jet mechanism with minimal lossy contact with the water being ejected. Convention paddle boats work primarily on viscous drag principles, while propellers work on lifting body (wing) principles. Water jets work primarily on pumping/ejection principles. The present invention controls losses associated with all of these mechanisms, such as tip vortexes, cavitation, turbulent flow, and compressibility/flow issues.

Claims

What is claimed is:

1. A propulsion system for a marine vessel comprising:

a rotary drive assembly for applying drive power;

a propulsion wheel coupled to said rotary drive assembly such that operation of said rotary drive assembly causes rotation of said propulsion wheel;

a plurality of water-channeling members connected to said propulsion wheel to extend outwardly from said propulsion wheel, each said water-channeling member having a cavity configured such that incoming water is concentrated and accelerated, each said water-channeling member further having an ejection end having a geometry for ejection of said water from said cavity of said water-channeling member; and

a mount configured to secure said propulsion wheel to said marine vessel such that during said rotation of said propulsion wheel each said water-channeling member is positioned to periodically extend only partially into water in which said marine vessel resides and such that a quantity of said water is received within each said water-channeling member upon partial extension into said water.

2. The propulsion system of claim 1 wherein said cavity of each said water-channeling member is defined by inwardly sloping surfaces, such that said incoming water is concentrated and accelerated toward a centerline of said cavity, said ejection end being located and oriented to continue laminar flow of said water for said ejection.

3. The propulsion system of claim 1 wherein each said water-channeling member has one of a cup-shape or a spoon-shape.

4. The propulsion system of claim 1 further comprising a hull, said mount positioning said propulsion wheel such that said water-channeling members only partially below a bottom of said hull during said rotation of said propulsion wheel, said hull being configured to define a selected water level with respect to operation of said propulsion wheel.

5. The propulsion system of claim 4 wherein said propulsion wheel has a rotational axis positioned relative to said bottom of said hull such that said ejection ends of said water-channeling members remain above said bottom of said hull during said rotation of said propulsion wheel.

6. The propulsion system of claim 4 wherein said hull is attached to said marine vessel by a suspension that enables movement of said hull relative to said marine vessel in response to waves and other changes in levels of water in which said marine vessel resides.

7. The propulsion system of claim 1 wherein said ejection end of each said water-channeling member has a configuration to define a direction of an ejected water jet as said propulsion wheel is rotated.

8. The propulsion system of claim 7 wherein said configuration of said ejection end includes a termination that is angled downwardly.

9. The propulsion system of claim 1 wherein said propulsion wheel has a rotational axis, said rotary drive assembly being connected to drive said propulsion wheel about said rotational axis, said water-channeling members being arranged in at least two axially separate rows, each said row having a plurality of aligned said water-channeling members.

10. The propulsion system of claim 9 wherein said water-channeling members of adjacent said rows are axially misaligned, such that said water-channeling members are staggered.

11. The propulsion system of claim 1 wherein each said water-channeling member has a plurality of fingers position to scoop said water during said rotation of said propulsion wheel.

12. A propulsion method for a marine vessel comprising:

providing a propulsion wheel having a plurality of water-channeling members connected to said propulsion wheel to extend outwardly therefrom, each said water-channeling member having a cavity to receive, concentrate and direct water;

connecting said propulsion wheel to a marine vessel such that said water-channeling members are positioned to periodically extend only partially into water when said propulsion wheel is rotated, including orienting said water-channeling members such that said cavities acquire a quantity of said water when partially extended into said water; and

driving said propulsion wheel so as to rotate in a manner to power said marine vessel, said connecting of said propulsion wheel including directing each said water-channeling member such that said water is collected and concentrated in conformance with a contour of said cavity and is ejected from said water-channeling member following acceleration of said water.

13. The propulsion method of claim 12 further comprising controlling a level of water presented to said water-channeling members, such that said level remains substantially constant regardless of changes in conditions of water in which said marine vessel resides.

14. The propulsion method of claim 13 wherein controlling said level of water includes connecting said propulsion wheel within a hull such that said water-channeling members are able to extend only partially below a bottom of said hull.

15. The propulsion system of claim 14 further comprising attaching said hull to said marine vessel using a suspension system, including enabling said hull to respond to waves independently of said marine vessel.

16. The propulsion method of claim 12 wherein connecting said water-channeling members includes establishing an angle of said water-channeling members to provide a lifting force to said marine vessel during driving of said propulsion wheel, said lifting force being variable with changes in rotational speed of said propulsion member.

17. The propulsion method of claim 12 wherein connecting said water-channeling members includes providing at least two rows that are offset axially.

18. The propulsion method of claim 17 wherein connecting said water-channeling members further includes providing staggering for adjacent said rows, such that said water-channeling members in said adjacent rows are axially misaligned.

19. The propulsion method of claim 12 wherein providing said propulsion wheel includes defining said water-channeling members to have one of a spoon-shape or a cup-shape.