Abstract:
Apparatus for generating electrical energy in a fluid environment, the apparatus including a wing member for disposition in the fluid and pivotally movable about an axis in response to flow of the fluid thereabout, connector rods each pivotally mounted at a first end thereof on the wing on opposite sides of the axis, a crank member attached to a second end of each of the connector rods and rotatable about a pivot axis by movement of the attached connector rod, a housing supporting the wing member, a gear system disposed in the housing, an axle interconnecting each of the crank members and the gear system, and an electrical generator disposed in the housing and driven by the gear system.

Description:
STATEMENT OF GOVERNMENT INTEREST 
     The invention described herein may be manufactured and used by or for the Government of the United States of America for governmental purposes without the payment of any royalties thereon or therefor. 
     CROSS REFERENCE TO OTHER PATENT APPLICATIONS 
     Not applicable. 
     BACKGROUND OF THE INVENTION 
     (1) Field of the Invention 
     The invention relates to the generation of electrical energy, and is directed more particularly to an apparatus and method for generating electric energy in a fluid environment, such as in shore and harbor areas, rivers, ocean bays and inlets, and ocean off-shore. 
     (2) Description of the Prior Art 
     Undersea communications networks and sensors deployed by the United States Navy require a source of electrical power. Typically, such power is provided by shore or ship based generators and/or batteries housed in network nodes and in sensors. 
     There is a need for the generation of the electrical power needs of underwater sensors, instruments, and communications nodes locally. Local electrical power is needed to support sensor functions, recharge power supplies of garaged unmanned underwater vehicles, acoustic communication links, and for deploying and retrieving sea-surface buoys which, in turn, establish satellite communication links, and to provide local computer power for data fusion and other system functions. 
     SUMMARY OF THE INVENTION 
     An object of the invention is, therefore, to provide an apparatus for generating electric energy in an under-sea environment, the apparatus requiring no outside source of fuel or power. 
     A further object of the invention is to provide a method for generating electric energy in an under-water environment by means of a self-powered apparatus. 
     With the above and other objects in view, as will hereinafter appear, a feature of the invention is the provision of an apparatus for generating electrical energy in a fluid environment. The apparatus includes a wing member for disposition in the fluid and pivotally movable about an axis in response to flow of the fluid thereabout. Connecting rods are each pivotally mounted at a first end thereof on the wing on opposite sides of the axis, a crank member is attached to a second end of each of the connector rods and is rotatable about a crank member pivot axis by movement of the attached connector rod. A housing supports the wing member, a gear system disposed in the housing, and an axle interconnects each of the crank members and the gear system. An electrical generator is disposed in the housing and driven by the gear system. 
     In accordance with a further feature of the invention, there is provided an apparatus for generating electrical energy in a fluid environment. The apparatus includes a wing member for disposition in the fluid and having a hydrodynamic axis about which the wing member is movable in pivotal fashion in response to flow of the fluid thereabout, two connector rods, each pivotally mounted at a first end thereof on the wing at respective points removed in opposite directions from the hydrodynamic axis, a first crank member to which a second end of a first of the connector rods is pivotally fixed at a selected distance from a pivot axis of the first crank member, a second crank member to which a second end of a second of the connector rods is pivotally fixed at the selected distance from a pivot axis of the second crank member, a housing for supporting the wing member, and a gear system disposed in the housing. Each of the crank members is fixed to an axle extending into the housing and connected to the gear system, and an electrical generator is disposed in the housing and driven by the gear system to produce electrical energy. Movement of the wing about the hydrodynamic axis thereof causes movement of the connector rods which causes movement of the crank members fixed upon the axles, the gear system being actuated by the rotation of the axles to drive the electrical generator. 
     In accordance with a still further feature of the invention there is provided a method for generating electrical energy in a fluid environment. The method includes the steps of providing an assembly comprising an apparatus for generating electrical energy in a fluid environment. The apparatus includes a wing member for disposition in the fluid and pivotally movable about a hydrodynamic center axis in response to flow of the fluid thereabout, connector rods each pivotally mounted at a first end thereof on the wing on opposite sides of the hydrodynamic center axis, a crank member attached to a second end of each of the connector rods and rotatable about a crank member pivot axis by movement of the attached connecting rod, a housing supporting the wing member, a gear system disposed in the housing, an axle interconnecting each of the crank members and the gear system, an electrical generator disposed in the housing and driven by the gear system, and a shell disposed around the crank member, the housing, and portions of the connector rods and axles. The method includes the further steps of placing the shell in the fluid with the wing held by the first ends of the connecting rods at a disposition in the fluid spaced from the shell, the wing being free to move pivotally about the wing hydrodynamic center axis in response to flow of the fluid, and providing an output line from the generator to a selected electricity consumer. 
     The above and other features of the invention, including various novel details of construction and combinations of parts and method steps, will now be more particularly described with reference to the accompanying drawings and pointed out in the claims. It will be understood that the particular device and method embodying the invention are shown by way of illustration only and not as limitations of the invention. The principles and features of this invention may be employed in various and numerous embodiments without departing from the scope of the invention. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       Reference is made to the accompanying drawings in which is shown an illustrative embodiment of the invention, from which its novel features and advantages will be apparent. 
       In the drawings: 
         FIG. 1  is a perspective view of one form of an apparatus for generating electrical energy in a fluid environment, illustrative of an embodiment of the invention; 
         FIG. 2  is a sectional view taken through a wing portion of the apparatus of  FIG. 1 , in a fore-and-aft direction; 
         FIG. 3A  is a diagrammatic view of the wing portion of  FIG. 2  in combination with connector rods, crank members, and a housing portion of the apparatus of  FIG. 1 , single large dot  44 ,  45  representing both an axle and a pivot axis; 
         FIG. 4  is a diagrammatic illustration of components of  FIG. 3A  in combination with a trailing arm, single large dots  44 ,  45  and  46  conjointly representing an axle, pivot axis and a sealed bearing; 
         FIG. 5  is a diagrammatic illustration of the crank members and the contents of the housing portion of the apparatus of  FIGS. 3A ,  6  and  4 ; and 
         FIG. 6  is similar to  FIG. 3A , but showing an alternative disposition of the elements of the apparatus shown in  FIG. 3A , single large dot  44 ,  45  representing both an axle and a pivot axis. 
     
    
    
     DESCRIPTION OF THE PREFERRED EMBODIMENTS 
     Referring to  FIG. 1 , it will be seen that an illustrative apparatus includes a shell  10  having a generally domed carapace portion  12 , shaped similarly to the carapace of a sea turtle. The shell  10  further includes a plastron, or bottom, portion (not shown), shaped similarly to the plastron of a sea turtle. 
     A wing  20  is mounted at a location spaced from the carapace portion  12  of the shell  10 . The wing  20  is supported by a forwardly disposed pair of connector rods, each rod of the pair being designated herein as  22 ,  22   a . (This compound designation is sometimes employed herein to enable making collective reference to structural elements as well as more specific reference positional species of the structure elements.) Wing  20  is further supported by a rearwardly disposed pair of connector rods, each rod of the pair being designated  22 ,  22   b . Note that only one rod of the pair of rearwardly disposed pair of rods is exposed in  FIG. 1 . These rods  22  are pivotally affixed to the wing and extending from the surface of the wing  20  which faces the shell  10 . The wing is further supported by a trailing arm  24  pivotally fixed to the wing  20  and, at an end remote from the wing, pivotally fixed at a pivot point  28  ( FIG. 4 ) to a post or fin  26  upstanding from the shell and pivotal about point  38  ( FIG. 4 ). 
     As shown in  FIG. 1 , the shell  10  is adapted to rest on a sea bed, or the like. In placement of the apparatus, the apparatus may be released at the water surface and, utilizing the wing  20 , glide through the water until coming to rest on the bed of the body of water. 
     As shown in  FIG. 2 , the wing  20  is provided with a forward pivot axis  30  extending wing-tip to wing-tip proximate the forward edge  32  of the wing. Disposed aft of the forward pivot axis  30  by about one-fourth of the fore-and-aft dimension of the wing is a hydrodynamic-center axis  34  of the wing, extending parallel to the forward pivot axis  30 . A forward end of the trailing arm  24  ( FIGS. 1 and 4 ) is pivotally connected to the wing at the center of the hydrodynamic axis, i.e. the center of the tip-to-tip wing length. Disposed aft of the hydrodynamic axis  34  by about one-fourth of the fore-and-aft dimension of the wing is an after pivot axis  36 , extending parallel to the forward pivot axis  30  and hydrodynamic axis  34 . The pivot axis  36  is, therefore, at about the fore-and-aft mid-point of the wing. 
     Referring to  FIGS. 3A and 4 , it will be seen that the connector rods  22  are pivotally connected to crank members  40 , illustrated in  FIGS. 3A-6  as crank wheels. The crank wheels are of equal diameter and the connector rods  22  are attached to the crank wheels at respective points on the wheels disposed equal distance from the centers of the wheels. 
     Alternatively, the crank members  40  may be crank rods  40   a , shown in phantom in  FIG. 3A . The crank rods  40   a  are of equal length. The connector rods  22  are attached to the crank rods  40   a  at respective points of the crank rods  40   a  disposed at equal distances from the pivot axes  45  of the crank rods  40   a . (Note that in  FIGS. 5 ,  3 A and  6  axle element  44 , pivot axis  45 , and sealed bearing  46  may be represented by a single large dot.) 
     Referring now to FIGS.  1  and  3 A- 6 , a water-tight housing  42  is mounted within the shell  10  ( FIG. 4 ). The crank members  40  are each mounted on an end of an axle  44 . The axles  44  are mounted in water-tight bearings  46  ( FIG. 5 ) and extend into the interior of the housing  42 . The axles  44  are each connected to a reduction gear  48 . (Note that in  FIG. 4  axel  44 , pivot axis  45 , and sealed bearings  46  are represented by a single large dot.) 
     In the embodiment shown in the drawings, four of the connector rods  22  are connected to the wing  20 , two  22   a  at the forward pivot axis  30  and two  22   b  at the after pivot axis  36 . The connector rods  22  are each connected to a crank member  40  which, in turn, is mounted on an axle  44  extending through a sealed bearing  46  and into the housing  42 . 
     The two starboard connector rods  22  are each connected to a starboard crank member  40   a  ( FIG. 5 ), the two starboard crank members being mounted on the starboard side of the housing  42 . Similarly, the two port connector rods  22  are each connected to a port crank member  40   b , the two port crank members  40   b  being mounted on the port side of the housing  42 . 
     The forwardmost pair of crank members  40  are each mounted on a forwardmost axle  44   a  and the after pair of crank members are each mounted on an after axle  44   b . The forwardmost axle  44   a  is further affixed to a forwardmost reduction gear  48   a , while the after axle  44   b  is affixed to an after reduction gear  48   b . The reduction gears  48   a ,  48   b  are each engaged with an idler gear  50 . Fixed in the hub of the idler gear is an axle  52  having a flywheel  54  fixed thereon and extending into an electrical generator  56 . 
     The apparatus is intended to supply power to a consumer outside of the apparatus. Output line  58  is provided for connection to such consumer, which as noted hereinabove, can be a sensor, a communication device, an underwater vehicle, and the like. 
     While it is expected that the apparatus will, in most instances, be deployed to rest on a seabed, or the like, it is contemplated that the apparatus will be used on the hulls of water-borne vessels such as barges, and the like. In such instances, the apparatus will be fixed to the hull of the vessel with the wing  20  extending downwardly, or outwardly, from the hull of the vessel, as depicted in  FIG. 6 . 
     In use, the apparatus is typically placed upon a seabed or released at or near the water surface and allowed to glide to the seabed. The apparatus will typically align itself such that the wing forward edge  32  is normal to the fluid flow direction. The fluid flow exerts on the wing  20  a lifting force, which is normal to the direction of fluid flow, a drag force which is exerted on the wing  20  in the direction of fluid flow, and a pitching moment, which acts at the hydrodynamic axis  34  of the wing  20  and tends to increase the angle of incidence of the wing  20 . The pitching moment is independent of the lifting force. 
     The connector rods  22  allow the wing  20  to move in a vertical swimming motion induced by the lift force, while the trailing arm  24  steadies the wing  20  against horizontal motion that would otherwise be induced by the drag force. 
     The pivot points of the connector rods  22  on the wing  20  are symmetrically located forward and aft of the wing hydrodynamic axis  34 . The trailing arm pivot point is located on the hydrodynamic axis  34 . The after end of the trailing arm  24  is pivotally connected to the fin  26 . The wing supporting connector rods  22  drive a transmission system  44 ,  48 ,  50 ,  52 ,  54  to cause the electrical generator  56  to rotate in response to the wing  20  swimming motion. 
     The wing  20  is free to pivot about the connector rods  22  and the trailing rigid arm  24 , such that the angle of the wing  20  relative to the direction of fluid flow may oscillate in a smooth symmetrical fashion between a peak upward angle of attack that results in an upward-directed flow-induced force on the wing  20 , a neutral high position that results in no flow-induced force on the wing  20 , a peak downward angle of attack that results in a downward-directed flow-induced force on the wing  20 , and a neutral low position that results in no flow-induced force on the wing  20 . As the oscillation continues, the force caused by the fluid flow varies in a nearly sinusoidal manner between a peak upward force and a peak downward force. The symmetry of the structure insures that the magnitude of the peak upward force is substantially equal to the magnitude of the peak downward force. The magnitude of the total flow-induced force depends upon the fluid flow velocity, the area of the wing  20 , and the angle of attack of the wing  20  relative to the direction of fluid flow. 
     An alternative system (not shown) includes a plurality of wings, each connected to another by a plurality of connector rods and each held in fore-and-aft place by a pivoting rigid trailing arm, so that all wings are free to move in parallel with each other, and flow-induced forces on the wings result in appropriate forces on the crank members. The flow-induced total force is proportional to the total area of the plurality of wings. 
     The above-described apparatus is adapted for use in seawater where corrosion and organic growth are major concerns. The apparatus permits most of the mechanical parts to be disposed out of the water environment. Six pivot points are located in the water, four to support the wing  20  by means of the connector rods  22  and two to allow the rigid trailing arm  24 , which holds the wing  20  against the force of the water current, to move through a small angle to follow the up and down motion of the wing  20 . If desired, these six pivot points can be sealed (not shown) and permanently lubricated for close to friction-free operation. 
     The wing  20  may also be used for lift for navigating the apparatus from one site to another. After reaching an operational site, the wing  20  is used to generate electrical power from local tidal currents. 
     Using the above-described apparatus, the invention provides a method for converting the undulating motion of a wing suspended in a moving fluid into circular motion of a flywheel which is used to drive an electrical generator. The undulating motion is similar to the action of a whale or other sea creature with a horizontal tail fin. 
     It will be understood that many additional changes in the details, materials, steps and arrangement of parts, which have been herein described and illustrated in order to explain the nature of the invention, may be made by those skilled in the art within the principles and scope of the invention as expressed in the appended claims. For example, while the apparatus is immediately intended for use of the type set forth hereinabove, it is recognized that the apparatus described herein can be upscaled to provide power similar to current off-shore wind mills, but with no danger to birds, which is a problem with off-shore “wind farms”.