Self-deploying tethered ballast system for a wave energy converter

Abstract

The present disclosure proposes a unique self-deploying ballast system (18) for a small wave energy converter that will fit within the cylindrical housing (12) of a common Class A- Type sonobuoy (10) creating an integrated system that can be deployed in a conventional manner by aircraft. The present design replaces established "bucket and flaps" designs for a folding umbrella-like design, which utilizes arms (24, 26) which fold out twice to provide maximum possible surface area while still being able to be compactly folded up in order to fit seamlessly into the bottom end of a conventional sonobuoy housing (12).

Description

[0001] TITLE

[0002] SELF-DEPLOYING TETHERED BALLAST SYSTEM FOR A WAVE ENERGYCONVERTER

[0003] BACKGROUND OF THE DISCLOSURE

[0004] (1) Field of the Invention: The instant invention generally relates to wave energy converter systems, and more particularly to a tethered ballast system for a wave energy converter.

[0005] (2) Description of Related Art: Sonobuoys are commonly used in open ocean deployments for oceanographic and environmental data collection (temperature, etc.), surveillance, SOS transmitters, etc. Their deployment duration is currently limited by power constraints, i.e. battery life. The only possible way to increase deployment duration is to provide the buoys with an energy generation system to recharge the batteries. Wave energy conversion is the most likely source.

[0006] There are several general approaches to wave energy conversion. However, open ocean wave energy converters are typically designed as point absorbing systems. Point absorbers are buoys that move up and down on the water surface. There are several methods of converting the up and down motion of the point absorber to electricity, but all point absorbers work by exploiting the motion of the wave relative to a fixed, or minimally moving, reference frame. In open waters, a point absorber must operate by exploiting the relative motion between the ocean surface and the relatively calm deeper water. Motion associated with a wave decreases exponentially away from the surface, with a layer of no motion generally reached at a depth equal to approximately one half the horizontal wavelength.

[0007] Current large format point absorber wave energy converters use a tethered, ballast system(heavy steel bucket and flaps) to stabilize the wave energy converter beneath the waves while the buoy bobs up and down in relative motion to the waves. The main issue with this design is that the components for the bucket and flap system are big and heavy, and expensive to build and deploy. Specialized heavy equipment is required for deployment and their deployment is anything but rapid. The design seriously limits where and how such systems can be deployed and operate and they are certainly not suitable for smaller sonobuoy deployments which are preferably dropped by aircraft.

[0008] Known prior art includes US Patent No. 9,581,128 Systems and Methods for WaveEnergy Conversion, US Patent No. 11,156,200 Tethered Ballast Systems for Point Absorbing Wave Energy Converters and US Patent No. 11,920,551 Wave-Powered Electricity Generation Device.

[0009] SUMMARY OF THE DISCLOSURE

[0010] Smaller scale wave energy converter (WEC) devices that are currently under development may be fit within the cylindrical housing profile of a common Class A-Type sonobuoy. Such WEC devices may also be utilized for life rafts or other ocean vessels requiring a power source. What is lacking in the art is a smaller, lightweight ballast system to stabilize an integrated sonobuoy / WEC in the water.

[0011] The present disclosure proposes a unique self-deploying ballast system for a smaller wave energy converter that will also fit within the cylindrical housing of a common Class A- Type sonobuoy creating an integrated system that can be deployed in a conventional manner by aircraft.

[0012] Generally speaking, the ballast system is responsible for creating the upward drag needed for the point absorber type system to function. The present system opposes the motion of the sonobuoy through the inertial force it provides by creating a significant upward drag in the water, mimicking the addition of a substantial mass below the waves. The relative motion of the sonobuoy can then be captured by the WEC power train to generate electrical energy that can be used to power the equipment on the sonobuoy, (ocean surveying equipment, SOS transmitters, etc.). The ballast system is designed to generate maximal drag on the upstroke, while creating minimal drag on the downstroke. This system is self-deployable and capable of producing a maximum added mass (drag) with the given space and weight constraints. The lightweight design of these smaller sonobuoy systems can rapidly be deployed from aircraft to operate at any arbitrary point in the ocean.

[0013] A typical sonobuoy is about 5 inches in diameter and 3 feet long. The above-noted smaller wave energy converters are designed to fit within the upper portion of the cylindrical housing of the sonobuoy along with sonobuoy sensors, electronics, transmitter and power systems.

[0014] The present design replaces the established “bucket and flaps” design for a folding umbrella-like design, which utilizes arms which fold out twice to provide maximum possible surface area while still being able to be compactly folded up in order to fit seamlessly into the bottom end of a conventional sonobuoy housing.

[0015] An exemplary ballast system in accordance with the present disclosure fits within the lower portion of the sonobuoy and expands the ballast arrangement well beyond the diameter of the sonobuoy to be capable of providing the added mass (drag) requirements. As noted above, the design resembles an upside-down umbrella which expands upon deployment.

[0016] The design fully utilizes the reduced size allocations to produce the highest added mass(drag) possible with the smallest displacement relative to the sonobuoy. This is achieved through twice collapsible spring-loaded support members that arc released by a fully mechanical key mechanism that is tension driven. Through the use of this key release, the design is able to remain hydrodynamic until it reaches its operating depth, where it fully expands and locks into place for a rapid deployment.

[0017] While embodiments of the invention have been described as having the features recited, it is understood that various combinations of such features are also encompassed by particular embodiments of the invention and that the scope of the invention is limited by the claims and not the description.

[0018] BRIEF DESCRIPTION OF THE DRAWING FIGURES

[0019] While the specification concludes with claims particularly pointing out and distinctly claiming particular embodiments of the instant invention, various embodiments of the invention can be more readily understood and appreciated from the following descriptions of various embodiments of the invention when read in conjunction with the accompanying drawings in which:

[0020] Fig. 1 is a perspective view of an exemplary embodiment of a sonobuoy including the tethered ballast system accordance with the teachings of the present disclosure;

[0021] Fig. 2 is perspective view of the exemplary sonobuoy with the tethered ballast canopy fully deployed;

[0022] Fig. 3 is another perspective view of the exemplary sonobuoy with the tethered ballast canopy fully deployed;

[0023] Fig. 4 is a bottom view of the canopy illustrating a vent flap in the center of the canopy;

[0024] Figs. 5A-5D are illustrations of the operating movement of the tethered umbrella canopy through a wave motion;

[0025] Fig. 6 is an upper perspective view of the ballast system with the canopy removed to view the hinge and arm components;

[0026] Fig. 7 is a lower perspective view of the ballast system with the canopy removed to view the hinge and arm components;

[0027] Fig. 8 is a top view thereof;

[0028] Fig. 9 is a bottom view thereof;

[0029] Fig. 10 is a side view thereof;

[0030] Fig. 11 is another perspective view illustrating separation of the swivel / release key from the arm assembly to allow deployment;

[0031] Fig. 12 is another perspective view with two of the arm assemblies removed to illustrate the inner central rod, upper and lower hinge mounts, connecting arms and extension springs;

[0032] Fig. 13 is another view illustrating connections of the central suspension line and canopy suspension lines;

[0033] Fig. 14 is a side view of the arms and suspension lines thereof in the fully deployed position; and

[0034] Fig. 15 is an enlarged perspective view of the lower fixed hinge mount and arms, showing the extension springs.

[0035] DETAILED DESCRIPTION OF THE EXEMPLARY EMBODIMENTS

[0036] Certain exemplary embodiments will now be described to provide an overall understanding of the principles of the structure, function, manufacture, and use of the device and methods disclosed herein. One or more examples of these embodiments are illustrated in the accompanying drawings. Those skilled in the art will understand that the devices and methods specifically described herein and illustrated in the accompanying drawings are nonlimiting exemplary embodiments and that the scope of the present invention is defined solely by the claims. The features illustrated or described in connection with one exemplary embodiment may be combined with the features of other embodiments. Such modifications and variations are intended to be included within the scope of the present disclosure. Further,in the present disclosure, like-numbered components of the embodiments generally have similar features, and thus within a particular embodiment each feature of each like-numbered component is not necessarily fully elaborated upon. Additionally, to the extent that linear or circular dimensions are used in the description of the disclosed systems, devices, and methods, such dimensions are not intended to limit the types of shapes that can be used in conjunction with such systems, devices, and methods. A person skilled in the art will recognize that an equivalent to such linear and circular dimensions can easily be determined for any geometric shape. Further, to the extent that directional terms like top, bottom, up, or down are used, they are not intended to limit the systems, devices, and methods disclosed herein. A person skilled in the art will recognize that these terms are merely relative to the system and device being discussed and are not universal.

[0037] The following detailed description presents the currently contemplated modes of carrying out the invention. The description is not to be taken in a limiting sense, but is made merely for the purpose of illustrating the general principles of the invention.

[0038] As used herein, the singular forms “a,” “an,” and “the” include the plural reference unless the context clearly dictates otherwise.

[0039] Except where otherwise indicated, all numbers expressing quantities of elements, and so forth used in the specification and claims are to be understood as being modified in all instances by the term “about.” The term “about” is understood in light of the technology embodied herein.

[0040] For the purposes of describing and defining the present teachings, it is noted that the term “substantially” may be utilized herein to represent the inherent degree of uncertainty that may be attributed to any quantitative comparison, value, measurement, or other representation. The term “substantially” may also utilized herein to represent the degree by which a quantitative representation may vary from a stated reference without resulting in a change in the basic function of the subject matter at issue.

[0041] Referring to Figs. 1-4, an exemplary embodiment of a sonobouy including the subject self-deploying, tethered ballast system is illustrated and generally indicated at 10. Notwithstanding the illustration of an exemplary sonobuoy 10, its should be understood that the present WEC and tethered ballast system may be utilized for other ocean vessels orequipment requiring a power source, and in particular may be highly useful with emergency life raft apparatus to supply energy for emergency beacons or lighting.

[0042] The sonobouy 10 generally has an outer cylindrical housing 12 in which monitoring, surveillance or other electronics 14 may be housed, along with a wave energy converter 16, and the subject ballast system 18. A typical sonobuoy housing 12 may be about 5 inches in diameter and about 3 feet long. However, the subject invention should not be limited by any particular dimensional or geometric aspects recited herein.

[0043] An exemplary ballast system 18 in accordance with the present disclosure fits within the lower portion of the sonobuoy 10 and expands the ballast arrangement well beyond the diameter of the sonobuoy to be capable of providing the added mass (drag) requirements. As noted above, the design resembles an upside-down umbrella which expands upon deployment.

[0044] The design fully utilizes the reduced size allocations to produce the highest added mass (drag) possible with the smallest displacement relative to the sonobuoy. This is achieved through twice collapsible spring-loaded support members that arc released by a fully mechanical key mechanism that is tension driven. Through the use of this key release, the design is able to remain hydrodynamic until it reaches its operating depth, where it fully expands and locks into place for a rapid deployment.

[0045] Generally speaking, the ballast system 18 is responsible for creating the upward drag needed for the point absorber type system to function. The present system opposes the motion of the sonobuoy 10 through the inertial force it provides by creating a significant upward drag in the water, mimicking the addition of a substantial mass below the waves. The relative motion of the sonobuoy can then be captured by the WEC power train to generate electrical energy that can be used to power the equipment on the sonobuoy, (ocean surveying equipment, SOS transmitters, etc.). The ballast system 18 is designed to generate maximal drag on the upstroke, while creating minimal drag on the downstroke. This system is self-deployable and capable of producing a maximum added mass (drag) with the given space and weight constraints. Figs. 5A-5D illustrate conceptual operation of the tethered umbrella ballast wherein after deployment (Fig. 5A), the umbrella system cyclically opens and closes with the rise and fall of the waves, i.e. when descending (Figs. 5B and 5D), the umbrella would close, providing minimal drag and when ascending (Fig. 5C), the umbrella opens providing maximal drag resistance and a pulling energy to be captured by the wave energy converter.

[0046] Referring now to Figs. 6-15, an exemplary construction of the ballast system 18 is illustrated and described. The ballast system 18 comprises a central rod 20 having an upper end and a lower end and further having a fixed hinge mount 22 at a lower end thereof.

[0047] A plurality of inner support arms 24 are each hinged at a lower end thereof to the fixed hinge mount 22 and are equally spaced around the peripheral edges of the fixed hinge mount. In the present embodiment, there are four spaced arms 24 hinged about a generally square fixed hinge mount 22.

[0048] A plurality of outer support arms 26 are hinged at a proximal end thereof to respective upper ends of the inner support arms 24.

[0049] A central collar 28 is slidably received for axial movement around the central rod 20 wherein the central collar 28 is able to slide upwardly and downwardly relative to the lower fixed hinge mount 22.

[0050] A plurality of connecting arms 30 are respectively hinged at the inner ends thereof to and equally spaced around a periphery of the central collar 28, and respectively hinged at the outer ends thereof to the inner arms 24 at a point between the lower and upper ends thereof.

[0051] A plurality of extension springs 32 are captured between the upper surface of the fixed hinge mount 22 and the bottom surface of the central collar 28 in a normally retracted unbiased condition. In this manner, the springs 32 act to normally bias the inner and outer support arms 24,26 to a retracted position. In the present embodiment, there are 4 separate extension springs 32 captured between the fixed hinge mount 22 and the central collar 28. A single spring 32 is illustrated in Fig. 12 for clarity of the connection points, while additional symmetrically spaced springs 32 may be seen in the enlarged view in Fig. 15.

[0052] Turning briefly back to Figs. 1-4, a drag canopy 34 is secured to the outer surfaces of the inner and outer support arms 24, 26 with retention plates 36 bolted to the respective outer surfaces of the inner and outer support arms 24, 26. In some embodiments, the canopy 34 may be a rubber material which is capable of long-term deployment in a submerged salt water environment. The drag canopy 34 may include at least one vent opening in the drag canopy. Preferably, the opening is formed by a separate canopy cap section 38 secured over an opening in the center of the drag canopy 34, adjacent to the fixed hinge body 22. The vent opening allows a controlled flow of water though the center of the canopy 34 to control drag and reducestresses on the support arms 24, 26. The vent operates similar to the relief vents on conventional umbrella configurations.

[0053] In order to retain the support arms 24, 26 in a folded (retracted) condition within the cylindrical housing body 12 of the sonobouy 10, the system includes a separable swivel key 40 which has locking keys 42 or studs extending from a bottom surface thereof. The locking keys 42 align with and are inserted into respective key openings or slots 44 in the end surfaces of the upper ends of the inner support arms 24 (see Figs. 6 and 10). The keys 42 hold the arms 24, 26 in a folded inward configuration prior to deployment.

[0054] A central suspension line 46 has a lower end connected to an eye bolt on the top of the central rod 20 and an upper end connected to another eye bolt on the bottom of the release key 40. In the illustrated embodiments, the suspension line 46 is a length of cord or wire tied off between the opposing eye bolts on the rod 20 and release key 42 (See Fig. 2, 3, 13 and 14).

[0055] A plurality of canopy suspension lines 48 are connected at inner ends thereof to and are equally spaced around a periphery of the swivel key 42 and respectively connected at their outer ends to the terminal ends of the outer support arms 26 (see also Figs. 2, 3, 13 and 14).

[0056] A main tether line 50 connects is connected to an eye bolt on the top of the swivel key 42 and to the sonobuoy housing 12 (and / or to a tensioned reel on the WEC 14) to connect the two systems together (Figs. 2, 3, 13 and 14).

[0057] The present ballast system 18 along with the smaller wave energy converter 14 is thus, as a whole, able to provide reliable energy generation to extend the length of oceanographic monitoring and / or naval surveillance missions as they would be able to recharge the scouting device’s batteries during the mission rather than having to take it out of the water, recharge, and then redeploy.

[0058] While embodiments of the invention have been described as having the features recited, it is understood that various combinations of such features are also encompassed by particular embodiments of the invention and that the scope of the invention is limited by the claims and not the description.

Claims

What is claimed is:

1. A tethered ballast system for a wave energy converter comprising: a central rod having an upper end and a lower end; a fixed hinge mount at a lower end thereof; a plurality of inner support arms each hinged at a lower end thereof to and equally spaced around a periphery of the fixed hinge mount; a plurality of outer support arms hinged at a proximal end thereof to respective upper ends of the inner support arms; a central collar slidably received for axial movement on the central rod; a plurality of connecting arms respectively hinged at inner ends thereof to and equally spaced around a periphery of the central collar, and respectively hinged at outer ends thereof to said inner arms at a point between the lower and upper ends thereof; at least one retraction spring captured between the fixed hinge mount and the central collar in a normally retracted condition to normally bias said inner and outer support arms to a retracted position; a drag canopy secured to said inner and outer support arms; a swivel key; a central suspension line having a lower end connected to said central rod and an upper end connected to said release key; and a plurality of canopy suspension lines connected at an inner end thereof to and equally spaced around a periphery of the swivel key and connected at an outer end thereof respectively to terminal ends of said outer support arms.

2. The tethered ballast system of claim 1 wherein the swivel key comprises a release key having key formations which interact with mating key formations on said support arms to maintain the support arms in a retracted position until disengaged.

3. The tethered ballast system of claim 1 further comprising at least one vent opening in the drag canopy.

4. A sonobuoy apparatus comprising: a cylindrical housing; a wave energy converter disposed within a portion of the housing; and a tethered ballast system disposed within a lower portion of the housing, the tethered ballast system comprising: a central rod having an upper end and a lower end; a fixed hinge mount at a lower end thereof; a plurality of inner support arms each hinged at a lower end thereof to and equally spaced around a periphery of the fixed hinge mount; a plurality of outer support arms hinged at a proximal end thereof to respective upper ends of the inner support arms; a central collar slidably received for axial movement on the central rod; a plurality of connecting arms respectively hinged at inner ends thereof to and equally spaced around a periphery of the central collar, and respectively hinged at outer ends thereof to said inner arms at a point between the lower and upper ends thereof; at least one retraction spring captured between the fixed hinge mount and the central collar in a normally retracted condition to normally bias said inner and outer support arms to a retracted position; a drag canopy secured to said inner and outer support arms; a swivel key; a central suspension line having a lower end connected to said central rod and an upper end connected to said release key; and a plurality of canopy suspension lines connected at an inner end thereof to and equally spaced around a periphery of the swivel key and connected at an outer end thereof respectively to terminal ends of said outer support arms; wherein the central suspension line is connected to the WEC for generating electrical power.

5. The sonobuoy apparatus of claim 4 wherein the swivel key comprises a release key having key formations which interact with mating key formations on said support arms to maintain the support arms in a retracted position until disengaged.

6. The sonobuoy apparatus of claim 5 further comprising at least one vent opening in the drag canopy.

7. A tethered ballast system for an ocean vessel comprising: a central rod having an upper end and a lower end; a fixed hinge mount at a lower end thereof; a plurality of inner support arms each hinged at a lower end thereof to and equally spaced around a periphery of the fixed hinge mount; a plurality of outer support arms hinged at a proximal end thereof to respective upper ends of the inner support arms; a central collar slidably received for axial movement on the central rod; a plurality of connecting arms respectively hinged at inner ends thereof to and equally spaced around a periphery of the central collar, and respectively hinged at outer ends thereof to said inner arms at a point between the lower and upper ends thereof; at least one retraction spring captured between the fixed hinge mount and the central collar in a normally retracted condition to normally bias said inner and outer support arms to a retracted position; a drag canopy secured to said inner and outer support aims; a swivel key; a central suspension line having a lower end connected to said central rod and an upper end connected to said release key; and a plurality of canopy suspension lines connected at an inner end thereof to and equally spaced around a periphery of the swivel key and connected at an outer end thereof respectively to terminal ends of said outer support arms.

8. The tethered ballast system of claim 7 wherein the swivel key comprises a release key having key formations which interact with mating key formations on said support arms to maintain the support arms in a retracted position until disengaged.

9. The tethered ballast system of claim 7 further comprising at least one vent opening in the drag canopy.

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