Abstract:
The ocean wave energy converter uniquely includes a generator with a rotating inner rotor surrounded by a counter-rotating outer rotor for generating electricity. A reciprocating drive rod drives the inner rotor on the downstroke of the drive rod and the outer rotor on the upstroke of the drive rod through a gear driven driveshaft with clutches. A buoy is attached to end of the drive rod whereby the undulation of the ocean waves relative to the buoy reciprocates the drive rod between the upstroke and the downstroke positions.

Description:
CROSS-REFERENCE TO RELATED APPLICATION 
     This application claims priority to earlier filed U.S. Provisional Patent Application Ser. No. 60/583,374 filed Jun. 28, 2004, the contents of which are incorporated herein by reference. 
    
    
     BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
     The present invention generally relates to an apparatus for converting the energy of wave motion on the surface of a body of water to electricity. The assembly is designed as an ocean wave energy converter module that can be interconnected to other modules to form an ocean wave energy web. 
     2. Background of the Related Art 
     Ames, U.S. Pat. No. 4,232,230 describes an ocean wave energy converter module having several linear reciprocating electric generators, which are assembled in a generally pyramidal or conical form. Their movable armature members are connected to floats (buoys) above the apex which are adapted to follow displacements of the water surface. The lower ends of their stator members are connected at separated points to a damper plate below the surface. A submerged buoyancy chamber is provided above the damper plate to maintain the assembly in proper relationship to the mean surface. Although this design had the advantage of a minimal number of moving parts, it suffered from several disadvantages. Namely, the use of many permanent magnets made the design costly. Moreover, not all the permanent magnets were being used to their optimal capacity resulting in its inefficient use. Therefore, there was a need for an ocean wave energy converter that was less costly to produce and had higher power production efficiency. 
     Ames, U.S. Pat. No. 4,672,22, describes a self-stabilized and expandable system of independent ocean wave energy converter modules and was designed to overcome some limitations of the earlier &#39;230 patent. In particular, the system included replacement of the permanent magnets in the stator members with a reciprocating drive rod that powered a flywheel and attached generator. Provision was also made for use of two generators, the first being scaled for power production on the upstroke of the drive rod and the second scaled for power production on the downstroke of the drive rod. The goal of the &#39;222 patent was to optimize power production on the upstroke of the drive rod where the energy of the wave is concentrated, rather than follow other attempts to create energy converters that attempted to maximize power production on both the peak and the troth of the wave. A design that attempts to maximize both peak and troth power generation suffers from the inherent disadvantage that the ocean wave energy converter risks falling out of synchronization with the period of the oncoming waves and therefore becoming stalled. But even the &#39;222 patent design suffered several undesirable limitations. In particular, the design required the use of two generators. Therefore there is a need for an improved ocean wave energy converter that utilizes a single variable generator to maximize upstroke power generation without risk of stalling of the generator due to synchronization of the drive rod with the period of the waves. 
     SUMMARY OF THE INVENTION 
     The ocean wave energy converter of the present invention solves the problems of the prior art by providing an ocean wave energy converter that uniquely includes a generator with a rotating inner rotor surrounded by a counter-rotating outer rotor for generating electricity. A reciprocating drive rod drives the inner rotor on the downstroke of the drive rod and the outer rotor on the upstroke of the drive rod through a gear driven driveshaft with clutches. A buoy is attached to end of the drive rod whereby the undulation of the ocean waves relative to the buoy reciprocates the drive rod between the upstroke and the downstroke positions. 
     Accordingly, among the objects of the present invention is the provision for an ocean wave energy converter that maximizes upstroke power generation. 
     Another object of the present invention is the provision for an ocean wave energy converter that includes a single generator for generating electricity that includes counter-rotating rotors to maximize power production. 
     Yet another object of the present invention is the provision for an ocean wave energy converter that includes a ballast control system. 
     Yet another object of the present invention is the provision for an ocean wave energy converter that can operate autonomously. 
     Yet another object of the present invention is the provision for an ocean wave energy converter that can be deployed throughout the world. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       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: 
         FIG. 1  is an elevation view of the preferred embodiment of the present invention; 
         FIG. 2  is a partial cross-section view of  FIG. 1 ; 
         FIG. 3  is a partial side cross-section view of a drive rod of the present invention; 
         FIG. 4  is a close-up plan of the gearbox and generator of the present invention; 
         FIG. 5  is a plan view of the generator and gearbox of the preferred embodiment of the present invention; 
         FIG. 6  is a side cross-section view of the generator of the preferred embodiment of the present invention; 
         FIG. 7  is a side cross-section view of the preferred method of storing the unassembled top shell of the main body member of the preferred embodiment; 
         FIG. 8  is a side cross-section view of the preferred method of storing the unassembled top shell of the main body member of the preferred embodiment; 
         FIG. 9  is a side cross-section view of the preferred method of storing the unassembled upper shell of the buoy of the preferred embodiment; 
         FIG. 10  is a side cross-section view of the preferred method of storing the unassembled lower shell of the buoy of the preferred embodiment; 
         FIG. 11  is a side cross-section view of the chassis of the preferred embodiment of the present invention; 
         FIG. 12  is a plan view of the ocean wave energy web of the preferred embodiment of the present invention; and 
         FIG. 13  is a plan view of the deployment capabilities of the preferred embodiment of the present invention. 
     
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT 
     Referring to  FIG. 1 , the ocean wave energy converter (“OWEC”) assembly of the present invention is shown generally at  10 . As will be more fully described below, the OWEC assembly  10  of the present invention includes three tubular members  12  positioned in a tetrahedral arrangement that has a main body member  14  connected at the apex of the tetrahedron. Each of the tubular members  12  contains a drive rod  16  slidably received therein. Each drive rod  16  is respectively connected to its own buoy  18 . The OWEC 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 OWEC assembly  10  of the present invention of the desired size. 
     Referring to  FIGS. 1 and 2 , the main body member  14  of the OWEC assembly  10  includes a top shell  20  and a bottom shell  22 . The top shell  20  and bottom shell  22  are secured together around a chassis  24 , which is best seen in  FIG. 11 , to form a water-tight inner cavity to contain the generator  26  and ballast control components (described below). Prior to deployment of the OWEC assembly  10 , the unassembled shells  20 ,  22  and chassis  24  of the main body member  14  may be stacked together, as shown in  FIGS. 7 and 8 , for ease of storage and transportation to the deployment site. Each shell  20 ,  22  is lined with foam  23  or other buoyant material to neutralize the buoyancy of the chassis  24 , the material forming the shells  20 , 22 , and the components (described below) contained therein. 
     Referring back to  FIG. 2 , each OWEC assembly  10  includes three tubular members  12  that are arranged in a cone structure or more specifically as edges of the sides of a tetrahedron. The tubular members  12  pass through the main body member  14  at the apex of the tetrahedron. Each tubular member  12  contains a drive rod  16 , which is provided at its upper end with a buoy  18 . The tubular members  12  terminate at tube base connectors  28  securing them to an optional flat damper plate  30  which may be in the form of an equilateral triangle. Although it is preferred that the arrangement of the tubular members  12  is tetrahedral, other geometric-shaped arrangements could be used and would be effective. The base connectors  28  may include optional casters  32  to facilitate transportation, deployment and recovery of the OWEC assembly  10 . 
     Contained within the terminal end of each tubular member  12  is a lower shock absorber  34 . The lower shock absorber  34  catches the downward stroke of its respective drive rod  16 . The lower shock absorber  34  reduces the stress on the OWEC assembly  10  and prepares the drive rod  16  for its upward stroke as it upwardly urges the drive rod  16 . At the upper end of each tubular member  12  is an upper shock absorber  36 . The upper shock absorber  36  provides an upper travel limit to the upward stroke of its respective drive rod  16 . The upper shock absorber  36  reduces the stress on the OWEC assembly  10 , and prepares the drive rod  16  for its downward stroke as it downwardly urges the drive rod  16 . Both the lower shock absorber  34  and upper shock absorber  36  are preferably metal springs, but other materials could be used as appropriate for the size of the OWEC assembly  10  in question. 
     Also best seen in  FIG. 2 , the tubular members  12  serve respectively as guides or sleeves for a drive rod  16  contained therein. The drive rods  16  each have a rack  38  secured to the length of the drive rod  16  that passes through a gear box section  40  of the main body member  14 . The rack  38  has teeth thereon  42 , which can best be seen in  FIG. 3 . The teeth  42  on the rack  38  engage and drive a gear  44  in the gear box section  40  (described below). The drive rods  16  also may be partially or wholly filled with foam  46 , or other buoyant material, to neutralize the buoyancy of the drive rod  16 , thereby enhancing the buoyancy of the buoy  18 , as seen in  FIGS. 2 and 4 . Turning back to  FIG. 2 , a secondary shock absorber  48  is attached to the lower end of the drive rod  16 . The secondary shock absorber  48  of the drive rod  16  works in conjunction with the upper shock absorber  36  in the respective tubular member  12  to limit the upward travel of the drive rod  16  and reduce the stress thereon. 
     Referring to  FIGS. 4 and 5 , a close up view of the gear box section  40  and generator  26  of the main body member  12  of the preferred embodiment are shown in detail. As the gear  44  is driven by the drive rod  12 , the gear  44  drives a driveshaft  50  which is rotatably mounted within an axle bracket  52 . The driveshaft  50  extends through a double labyrinth seal  54  and through a generator bracket  56  and into a generator  26 . Although a double labyrinth seal  54  is preferred, other seals could be used. Bearings  58  are included to smooth the rotation action on the driveshaft  50 . Optional bushings  60  may also be included to dampen any vibration generated by the general operation of the OWEC assembly  10 . 
     As seen in  FIGS. 5 and 6 , the generator  26  includes an inner rotor  62  and a counter-rotating outer rotor  64 . The inner rotor  62  is preferably constructed of a circular array of permanent magnets. The outer rotor  64  is constructed of one or more coils of a number of loops of wire having an input lead  66  and an output lead  68 . A first pair of clutches  70  connects the inner rotor  62  to the driveshaft  50  and allows the driveshaft  50  to turn in one direction only. A second pair of clutches  72  connects the outer rotor  64  to the driveshaft  50  and allows the outer rotor  64  to only turn in the opposite direction of the inner rotor  62 . Rotational movement of the inner rotor  62  relative to the outer rotor  64  induces electricity in the coil of the outer rotor  64  and through the leads  66 ,  68 . 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  66 ,  68  are connected to the umbilical chord  74  which carries the generated electricity to other modules or shore as described below. 
     In an alternative embodiment, the inner rotor  62  of the generator  26  is constructed of one or more coils of a number of loops of wire and the outer rotor  64  is constructed of a circular array of permanent magnets. Thus, being the opposite of the preferred embodiment. 
     In yet a third embodiment (not shown), a stationary coil is secured adjacent to the outer rotor  64  of the generator  26 . 
     Referring back to  FIG. 2 , the inner cavity of the main body member  14  also includes an active ballast control system that includes a water level sensor  76 , a pump  78 , and three bladders  80  that are secured to the chassis  24 . The water level sensor  76  measures the attitude and depth to the OWEC assembly  10  relative to mean sea level and generates control inputs to the pump  78  to keep the OWEC assembly  10  at an optimum depth in the water. The pump  78  fills or evacuates the bladders  80  according to the inputs received from the water level sensor  76 . The bladders  80  are fashioned of a non-porous flexible material that is easily deformed. The pump  78  and water level sensor  76  are connected by wires  82  to the umbilical chord  74  and are powered from excess electrical power generated by the generators  26 , but also could be easily supplemented from other optional power sources such as an additional battery, windmill, or a solar panel (not shown). 
     Referring back now to  FIGS. 1 and 2 , each buoy  18  includes an upper shell  84  and a lower shell  86 . The upper shell  84  and the lower shell  86  are secured together with rivets  88 , or other suitable fasteners, to form a water-tight chamber  90 , thereby making the buoy  18  highly buoyant. The upper shell optionally includes an eyebolt  92  to assist in assembling, deployment and recovery of the assembled buoys  18 . Internal braces  94  are secured within the chamber of the upper and lower shells  84 ,  86  to give the buoy  18  added strength and rigidity. Each shell  84 ,  86  is lined with foam  96  or other buoyant material to neutralize the buoyancy of material forming the shells  84 ,  86  and the internal braces  94  container therein, thereby enhancing the buoyancy effect of the empty chamber  90 . One end of the drive rod  16  is passed through an aperture  83 , best seen in  FIG. 10 , on the lower shell  86  and secured to the upper shell  84 . Optional bracing elements  98  are secured to around the drive rod  94  and to the lower shell  86  to reduce the strain on the lower shell  86  and drive rod  16  from the force of the waves impacting the buoy  18 . Prior to deployment of the OWEC assembly  10 , the unassembled shells  84 ,  86  of the buoys  18  may be stacked together, as shown in  FIGS. 9 and 10 , for ease of storage and transportation to the deployment site. 
     In operation, the OWEC assembly  10  floats in a body of water with the buoys partially submerged at the surface, and the remaining part of the OWEC assembly  10  submerged in the water. As each wave passes, the buoys  18  are raised and lowered moving the drive rods  16  in the tubular members  12 . The motion of a drive rod  16  drives the counter-rotating portions of the generator  26 . Each buoy/drive rod combination  18 / 16  drives its own generator  26 . The sum-total electrical output of an array of modules may be transported to shore by an umbilical cord  74  or used to power an accessory module for desalination or hydrogen production operations. Each OWEC assembly  10  forms a module  100  that can be interconnected to other modules to form an ocean wave energy web  102  to mass produce electricity, an example of which is shown in  FIG. 11 . The ocean wave energy web is capable of being deployed throughout the bodies of water of the world, as seen in  FIG. 12 . 
     The OWEC assembly  10  of the present invention provides several improvements over the ocean wave energy converters described in the prior art. For example, a counter-rotating generator  26 , which converts more wave energy to electricity, from both the upwards and downward movement of the shaft is used. Also, bellow sleeves, which previously were used to seal the upper end of each tubular member  12 , have been eliminated. Also, the tube base connectors  28  are made by extractive end cuts with through holes having common axes perpendicular to the major axes of the tubular members  12 . 
     Therefore, it can be seen that the present invention provides a unique solution to the problem of generating reusable energy from ocean waves that is a significant improvement over the prior art and has substantial commercial merit. 
     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 except as limited by the scope of the appended claims.