Abstract:
An apparatus for converting the kinetic energy of ocean waves into electricity is disclosed. The apparatus includes a main body member. A generator is located within the main body member. The generator includes a axle having a positive direction and a negative direction. An inner rotor is driven by the axle, wherein the inner rotor is driven only in the negative direction of the axle. An outer rotor surrounds the inner rotor and is also being driven by the axle, wherein the outer rotor is driven only in the positive direction of the driveshaft. A stationary ring is located between the inner rotor and the outer rotor. A drive rod, having a buoy attached to one end, is configured to freely move between an upstroke position and a downstroke position. The drive rod drives the generator as it reciprocates between the upstroke position and the downstroke position.

Description:
CROSS-REFERENCE TO RELATED APPLICATION 
       [0001]    This patent document claims priority to earlier filed U.S. Provisional Patent Application Ser. No. 61/536,642, filed on Sep. 20, 2011, the entire contents of which are incorporated herein by reference. 
     
    
     BACKGROUND 
       [0002]    1. Technical Field 
         [0003]    The present patent document relates generally to an apparatus for converting the energy of wave motion on the surface of a body of water to electricity. 
         [0004]    2. Background of the Related Art 
         [0005]    Generating electricity via ocean waves is a renewable energy source that has yet to be fully realized. Because ocean wave energy represents an unlimited, clean, renewable energy source, harnessing it is highly desirable to power our modern society. 
         [0006]    Prior ocean wave energy converters, such as Ames, U.S. Pat. Nos. 4,232,230; 4,672,222; and 7,352,073 (incorporated herein by reference), although revolutionary in concept and design, suffer from several limitations. The &#39;073 patent, in particular, includes a generator that rotates with magnets and coils, but problems with the arrangement include (1) a requirement for commutation brushes that become worn or compromised in the marine environment and (2) difficulty in adjusting coil properties due to their motion. 
         [0007]    Also because wave energy converters are generally deployed in the ocean, they must be securely anchored lest they become navigation hazards or get damaged. However, traditional mooring methods involve setting multiple lines or fixed columns to the sea floor. This method is very costly, difficult and dangerous as it involves expensive equipment and possibly diving to depths of the ocean with all the known hazards thereof. 
         [0008]    Therefore, there is a perceived need in the industry for an improved generator that lacks commutation brushes and an ability to adjust load properties during use. Furthermore is desirable to have a less costly method of anchoring the energy converters to the sea floor that minimizes the time that divers and submersibles must be used. 
       SUMMARY 
       [0009]    The present invention solves the problems of the prior art by providing an improved generator that includes counter-rotating magnet rings of weight and size efficiently correlating to ratio between upstroke buoyancy force and downstroke gravity force. Furthermore, the coils are fixed thereby eliminating brushes, and allowing easier incorporation of shields and/or weather-proof housing. Additionally, switch components are more readily affixed to stationary coils, than moving coils, so that some coils may be taken out of circuit. The coils are further configured to be isolated from the circuit sot that the load on the buoy may be adjusted, resulting in near fully submerged buoy that more precisely follows complex waves while also providing maximal buoyancy force for power take-off. Finally, the counter-rotating magnet rotors add velocities together to increase polarity switch rate affecting coils. 
         [0010]    In addition, the mooring system includes a plurality of mooring lines conjoined to terminals, at various intervals of lower depth, thereby resulting in fewer anchor points than if lines were not conjoined. Mooring line terminals may simply comprise knotting of the disparate lines but such assembly does not obviate forces that may limit mooring line flexibility when exposed to tensile forces. In a preferred embodiment, the mooring lines are conjoined, at successively lower levels, to terminate at singular anchor points. Because the number of lines decreases at each depth level, the time needed for divers and submersibles for repair, maintenance and installation is significantly reduced compared to traditional multi-line mooring techniques. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0011]    These and other features, aspects, and advantages of the present invention will become better understood with reference to the following description, appended claims, and accompanying drawings where: 
           [0012]      FIG. 1  is a perspective view of a preferred embodiment of the ocean wave energy converter of the present invention; 
           [0013]      FIG. 2  is a partial cross-section view of  FIG. 2 ; 
           [0014]      FIG. 3  is a top cross-section view of the gearbox and generator; 
           [0015]      FIG. 4  is a side cross-section view of the generator; 
           [0016]      FIG. 5  is a exploded view of a buoy showing how the upper and lower shells stack together and the superstructure is assembled; and 
           [0017]      FIG. 6  is a method of mooring the ocean wave energy converters of the present invention to the sea floor. 
       
    
    
     DESCRIPTION OF THE PREFERRED EMBODIMENT 
       [0018]    Referring to  FIGS. 1 and 2 , the ocean wave energy converter assembly of the present invention is shown generally at  10 . As will be more fully described below, the assembly of the present invention includes three tubular framing members  20  positioned in a tetrahedral arrangement that has a main body member  12  connected at the apex of the tetrahedron. Each of the tubular framing members  20  contains a drive rod  22  slidably received therein. Each drive rod  22  is respectively connected to its own buoy  249 . The assembly  10  of the present invention can be scaled appropriately to an optimal size for the known conditions or factors at the desired deployment site, such as average wave height, historical maximum wave height, depth of water, strength of currents, etc. One skilled in the art would appreciate how to select the parts and materials to construct an assembly of the present invention of the desired size. 
         [0019]    The main body member  12  of the assembly  10  includes a top shell  14  and a bottom shell  16 . The top shell  14  and bottom shell  16  are secured together around a chassis to form a water-tight inner cavity to contain the generator  18  and ballast control components. Each shell  14 ,  16  is lined with structural foam or other buoyant material to neutralize the buoyancy of the chassis, strengthen the material forming the shells  14 ,  16 , and insulate the components contained therein. 
         [0020]    Each assembly  10  includes three tubular framing members  20  that are arranged in a cone structure or more specifically as edges of the sides of a tetrahedron. The tubular framing members  20  connect to the main body  12  member, forming the apex of the tetrahedron. The tubular framing members  20  attach to the chassis of the module  10  and may be split into sections above and below the chassis. Each tubular framing member  20  contains a drive rod  22 , which is provided at its upper end with a buoy  24 . The tubular framing members  20  terminate at tube base connectors  26  securing them to frame members  28  which may form an equilateral triangle. A damper plate may be supported between the frame members  28 . Although it is preferred that the arrangement of the tubular framing members  20  is tetrahedral, other geometric-shaped arrangements could be used and would be effective. The base connectors  26  may include optional casters  30  to facilitate transportation, deployment and recovery of the assembly. 
         [0021]    Contained within the terminal end of each tubular framing member  20  is a lower shock absorber  32 . The lower shock absorber  32  receives the downward stroke of its respective drive rod  22 . The lower shock absorber  32  reduces the stress on the assembly  10  and prepares the drive rod  22  for its upward stroke as it upwardly urges the drive rod  22 . At the upper end of each tubular member  20  is an upper shock absorber  34 . The upper shock absorber  34  provides an upper travel limit to the upward stroke of its respective drive rod  22 . The upper shock absorber  34  reduces the stress on the assembly  10 , and prepares the drive rod  22  for its downward stroke as it downwardly urges the drive rod  22 . Both the lower shock absorber  32  and upper shock absorber  34  are preferably non-metallic springs, but metal or other compressible materials could be used as appropriate for the size of the assembly in question. It is important to note that the upper and lower shock absorbers  32 ,  34  will not be engaged regularly. In a typical deployment the module  10  are sized for deployment in an environment with wave size complimentary to the size of the module  10 . The shock absorbers  32 ,  34  provide a mechanism to reduce stress and wear on the module during heavy seas. 
         [0022]    The tubular framing members  20  serve respectively as guides or sleeves for a drive rod  22  contained therein. The drive rods  22  each have a rack  36  secured to the length of the drive rod  22  that passes through a gear box section of the main body member  12 . The rack  36  has teeth thereon, which engage and drive a gear  38  in the gear box section (described below). The drive rods  22  also may be partially or wholly filled with foam, or other buoyant material, to neutralize the buoyancy of the drive rod  22 , thereby enhancing the buoyancy of the buoy  24 . A secondary shock absorber  40  is attached to the lower end of the drive rod  22 . The secondary shock absorber  40  of the drive rod  22  works in conjunction with the upper shock absorber  34  in the respective tubular framing member  20  to limit the upward travel of the drive rod  22  and reduce the stress thereon. 
         [0023]    Referring to  FIGS. 3 and 4 , a close up view of the gear box section and generator  18  of the main body member  12  of the preferred embodiment are shown in detail. As the gear  38  is driven by the drive rod  22 , the gear  38  drives an axle  42  which is rotatably mounted within an axle brackets  44 . The axle  42  extends through a double labyrinth seal  46  and through a bushing  48  and into a generator  18 . The opposite end of the axle  42  is supported by a bushing  48  and axle bracket  44 . Although a double labyrinth seal is preferred, other seals could be used. Bearings may be included to smooth the rotation action on the axle  42 . Optional bushings may also be included to dampen any vibration generated by the general operation of the assembly. 
         [0024]    The generator  18  includes an inner rotor  50 , a counter-rotating outer rotor  52 , and a stationary ring  54  positioned between then inner and outer rotors  50 ,  52 . The inner rotor  50  is preferably constructed of a circular array of sixteen permanent magnets  56 , although other numbers of magnets could be used. The outer rotor  52  is preferably constructed of a circular array of eighteen permanent magnets  58 , although other numbers of magnets could be used. A number of T-shaped brackets  60  may be used to arrange the magnets concentrically about each rotor  50 ,  52 . The inner rotor  50  and outer rotor  52  may also be formed from electromagnets as well, thereby making the generator  18  an alternator instead. The stationary ring  54  is constructed of one or more coils  62 , preferably seventeen although sixteen or eighteen could be used, of a number of loops of wire having an input lead and an output lead. The stationary ring  54  is fixed in position within the generator  18  and does not rotate. Shielding  65  may be provided between each coil  64 . 
         [0025]    A first pair of clutches  66  connects the inner rotor  50  to the axle  42  and allows the axle  42  to turn the inner rotor  50  in one direction only. A second pair of clutches  68  connects the outer rotor  52  to the axle  42  and allows the outer rotor  52  to only turn in the opposite direction of the inner rotor  50 . Rotational movement of the inner rotor  50  relative to stationary ring  18  induces electricity in the coils  62  and through leads  63 . Inducing electricity in a coil through use of a magnet is well-known in the art and does not need to be described in detail herein. The leads are connected to a cord  70  which carries the generated electricity to other modules or shore as described below. 
         [0026]    In an alternative embodiment, the inner rotor and outer rotor of the generator are constructed of one or more coils of a number of loops of wire and the stationary ring is constructed of a circular array of permanent magnets. Thus, being the opposite of the preferred embodiment. If electromagnets are used in place of permanent magnets, load balancing may be accomplished by selectively energizing coils as is known in the art with alternators. 
         [0027]    The inner cavity of the main body member  12  also includes an active ballast control system that includes a proportional controller  72 , a pump  74 , and three bladders  76  that are secured to the chassis. The proportional controller  72  measures the attitude and depth to the assembly  10  relative to mean sea level and generates control inputs to the pump  74  to keep the assembly at an optimum depth in the water. The pump  74  fills or evacuates the bladders  76  according to the inputs received from the proportional controller  72 . The bladders  76  are fashioned of a non-porous flexible material that is easily deformed. The pump  74  is connected by wires to the cord  70  and are powered from excess electrical power generated by the generators  18 , but also could be easily supplemented from driveshaft motions or other optional sources such as an additional battery (not shown). 
         [0028]    Pressure sensors may also be included in the inner cavity of the main body member  12  and in the buoys  24  and may be used to send control data to the pump  74  and bladders  76  for adjusting the assembly attitude. It may be desirable to have assemblies  10  raised or lowered, in relation to waves, for maintaining optimal buoy stroke (too high or low results in reduced buoy action). The sensor data form the inner cavity data integrates with the buoy pressure data. Buoy input to controls may be from pressure sensors located at buoy&#39;s lower shell. These sensors provide data to a control matrix of an array of assemblies. That is, individual buoy movements contribute to mapping entire wave fields engaging an array. “Downwave” modules use data for predicting wave action, interference, cancellation that are likely to engage them and optimally pre-adjust the generator “just-in-time”. The result at most times enables near fully submerged, wave-following buoys (most buoyancy force and driveshaft travel length responding to subject wave). 
         [0029]    Housed in the inner cavity of the main body  12 , a control system may incorporate sensor networks including pressure sensors in the buoy  24 . Due to independent buoy  24  motions, an associated sensor would require wireless data transmission to buoyancy chamber controls and such radio transmission has possibly deleterious effect to marine bio-forms. Improved sensing means are contained in the inner cavity, only, within and between which inner cavity walls and structural foam is provided signal attenuating liner thereby reducing or eliminating external signal transmission. 
         [0030]    Sensing means comprise non-contacting proximity sensor, associated with the axle  42 , which counts revolution quantity, velocity, and direction relative to start position. Axle  42  and sensor zero stage may be neutrally located near mid-point, between a buoy and drive rod  22  fully extended and retracted positions, and thus deviations from zero stage indicate buoy  24  and drive rod  22  position. A number of such sensors, associated with respective buoys of a plurality of assemblies, form composite data of the positions of all buoys  24  of an array and, thus, a wave by wave profile of the ambient seascape. Sequential updates provide predictors for assessment of wave field motions, for example, by combining disparate geographic data points that may indicate the eventual creation or dissipation of interference wave amplitudes at specific positions in the future. Such data is incorporated in the control system to precisely adjust generator properties just-in-advance of incoming waves. A desirable feature is expressed when a buoy  24  follows a wave surface, while remaining near full submergence, utilizing maximal buoyancy force and axle  42  travel length to power electrical generators  18 . 
         [0031]    Buoy wave-following capability is affected by generator  18  loads expressed through the rack and pinion motion converter. Large loads may induce back-forces into the system that stall, or even stop, buoy motion. While this condition is desirable in module servicing or certain stages of power extraction, for example, to hold down buoy in submerged position for eventual release in approaching wave crests or to hold up buoy in overly energetic wave conditions, also desirable is to control such features. For such purpose, generator coil segments are separable, by switches, from the coils in the stationary ring thereby enabling individual segments to be taken out of loop and diverting the electromotive force affecting the assembly. In effect, the variably exerted generator loads may incorporate with buoy sensing means to thereby form precise control topology for improving the operation and electrical output of a module array. 
         [0032]    At times a module  10  may raise or lower to disadvantageous position due to environmental influences such as wave activity or changes of water temperature. At such instance is desirable for the module  10  to reposition at attitudes promoting optimal buoy  24  and drive rod  22  operation. For the purpose, buoyancy chamber pressure sensor indicates its position relative to the hydroface. When a module  10  sinks or floats out of range of optimal operational positions, pumps  74  are activated to introduce seawater to or expel seawater from bladders  76  thereby adjusting buoyancy of the chamber. 
         [0033]    Referring to  FIGS. 1 ,  2  and  5 , each buoy  24  includes an upper shell  80  and a lower shell  82 . The upper shell  80  and the lower shell  82  are secured together with rivets  84 , or other suitable fasteners, around a superstructure  86  to form a water-tight chamber, thereby making the buoy  24  highly buoyant. The upper shell  80  optionally includes an eyebolt  88  to assist in assembling, deployment and recovery of the assembled buoys  24 . The superstructure  86  includes a radial cuff  90  that primarily supports and strengthens the upper and lower shells  80 ,  82 . Internal braces  92  are secured within the chamber of the upper and lower shells  80 ,  82  to give the buoy  24  added strength and rigidity. The internal braces  92  are attached the drive rod  22  and radial cuff  90 . Each shell  80 ,  82  is lined with foam or other buoyant material to neutralize the buoyancy of material forming the shells  80 ,  82  and the internal braces  92  container therein, thereby enhancing the buoyancy effect of the empty chamber. 
         [0034]    One end of the drive rod  22  is passed through an aperture  94  on the lower  82  shell and secured to the upper shell  80 . Optional bracing elements  96  are secured to around the drive rod  22  and to the lower shell  82  to reduce the strain on the lower shell  82  and drive rod  22  from the force of the waves impacting the buoy  24 . Prior to deployment of the assembly, the unassembled shells  80 ,  82  of the buoys  24  may be stacked together for ease of storage and transportation to the deployment site. 
         [0035]    The buoy  24  upper and lower shells  80 ,  82  have a conical shape with a circular cross-section and, together, they form a tetras. This tetras shape has been found to be optimal to smooth fluid flow about the buoy  24  in order to maximize stroke power, yet minimize rotational torque on the generator  18  assembly, thereby increasing the lifespan of the mechanical components. 
         [0036]    In operation, the assembly  10  floats in a body of water with the buoys  24  partially submerged at the surface, and the remaining part of the assembly  10  submerged in the water. As each wave passes, the buoys  24  are raised and lowered moving the drive rods  22  in the tubular framing members  20 . The motion of a drive rod  22  drives the counter-rotating portions of the generator  18 . Each buoy/drive rod combination drives its own generator  18 . The sum-total electrical output of an array of modules  10  may be transported to shore by an umbilical cord  70  or used to power an accessory module for desalination or hydrogen production operations. Each assembly  10  forms a module that can be interconnected to other modules to form an ocean wave energy web or matrix to mass produce electricity. The ocean wave energy web is capable of being deployed throughout the bodies of water of the world. 
         [0037]    Referring now to  FIG. 6 , arrays  100  generally form neutrally buoyant, horizontal planes near below the hydroface  101 . Typically of breadth spanning multiple wavelengths, in most instances some array  100  portions are influenced by downward gravity forces from wave troughs while other portions are influenced by upward buoyancy force from buoys  24  and buoyancy chambers. Buoy drive shafts  22  freely travel, with only contacting tube bearings, and forces exerted on the truss tend to cancel out thereby having negligible effect on truss attitude. At times, however, large waves exert correspondingly higher forces, above operational range, causing extension of buoy drive shafts  22  to positions in contact with shock absorption means contained in tubular framing members  20 . 
         [0038]    At such instant buoys  24  and module  10  lower portions become more dependent systems than in normal operating conditions. These vertical forces, while efficiently distributed in the truss matrix, tend to be greatly dissipated in the water column by optional damper plate horizontally disposed between lower module framing members  28 . 
         [0039]    The self-stabilizing feature thus requires only light bottom, slack mooring. Examination of module array  100  mooring determined that relatively few mooring attachment points are required to be distributed among a module array  100  for keeping a module array  100  on station. Portions of the mooring lines  102 , when conjoined and extended from terminals  104  at some depth below hydroface  101 , perform efficiently in similar manner to laid rope for coalescing mooring stresses and inherently increasing tensile strength. 
         [0040]    In large module arrays  100 , deployed in deeper water, a plurality of such mooring lines  102  may in similar fashion be conjoined to terminals  104 , at various intervals of lower depth, thereby resulting in fewer anchor points  106  to the seafloor  108  than if lines  102  were not conjoined. Mooring line terminals  104  may simply comprise knotting of the disparate lines  102  but such assembly does not obviate forces that may limit mooring line  102  flexibility when exposed to tensile forces. An improved mooring junction comprises box, with top and bottom opening, supporting spring-loaded reels. Lines  102  are wrapped on reels to some extent providing sufficient pay-out or take-up for maintaining sufficient tension that reduces line  102  sagging and shock loads exerted on truss modules  10 . 
         [0041]    It would be appreciated by those skilled in the art that various changes and modifications can be made to the illustrated embodiments without departing from the spirit of the present invention. All such modifications and changes are intended to be within the scope of the present invention.