Abstract:
The present invention is a device for converting rotational energy into useable power by buffering the created rotational energy from the rotational energy used to create the output power. Thus, in one embodiment, a pendulum within a buoy is used to create rotational energy from ocean wave movement and the created rotational energy then drives a hydraulic pump which in turn drives a hydraulic motor to create a second rotational force which is then used to create an electrical output. In this manner, the hydraulic fluid acts as the buffer between the wave-created rotational energy and the rotational energy actually used to create the output electricity.

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
       [0001]    This application is related to commonly owned U.S. patent application Ser. No. 12/777,996, entitled “SYSTEM AND METHOD FOR CONVERTING OCEAN WAVE ENERGY INTO ELECTRICITY”, filed on May 11, 2010, Attorney Docket No. NWPP.P0001US.CP1C1, the disclosure of which is hereby incorporated herein by reference. 
     
    
     TECHNICAL FIELD 
       [0002]    The present disclosure relates to the generation of electric power. More specifically, the present invention relates to a method and apparatus for renewable energy generation using a pressure transfer material as an intermediary clutch between a rotary motion generator and an energy generator operating from generated rotary motion. Even more specifically, this disclosure relates to converting ocean wave energy to electricity and the exploitation thereof. 
       BACKGROUND OF THE INVENTION 
       [0003]    The notion of harnessing the power of ocean waves has held mankind&#39;s attention for quite some time. As such, there have been several inventions directed towards converting the kinetic energy of waves into electrical energy. However, to date, such inventions have been largely ineffective. One such invention, disclosed in U.S. Pat. No. 3,231,749 (the &#39;749 patent), provides a “Wave Power Generator” having a buoy with a centrally mounted vertical shaft and a pendulum fixed to the shaft for causing the shaft to rotate with the circular motion of the pendulum. The &#39;749 patent further includes a weight fixed to the outer end of the pendulum and a generator fixed to the outer side of the weight. 
         [0004]    The &#39;749 patent calls for a generator mechanism to be placed along the peripheral of the pendulum arm and employs an outer planetary gear to generate power. As a practical matter, factors such as manufacturing complexity, mechanical stress, and thermal expansion would render the disclosed invention unreasonably expensive to maintain and inefficient to use. For instance, it is unlikely that the outer planetary gear would be able to maintain a perfectly circular shape, absent expensive bracing. As is known in the art, as the diameter of the outer gear increases, the mass of the structural support required to maintain circularity of the pendulum&#39;s motion under operational stress increases at a ratio greater than one-to-one. In the likely event that the outer planetary gear becomes eccentric, the pendulum mechanism would become bound or jammed, rendering the system less efficient or inoperable. Avoiding the problem of eccentricity would best be negated by placing some sort of spring-loaded device or other suspension mechanism along the pendulum to allow the pendulum to move freely. Such a mechanism also would be unreasonably expensive, complex, and difficult to maintain. Moreover, the pendulum&#39;s operating efficiency would be reduced as the suspension mechanism absorbs a portion of the pendulum&#39;s kinetic energy. 
         [0005]    Put another way, placing the generator mechanism far from the center of rotation also places the torque moment far from the center of rotation. When the torque moment is too far off-center, any eccentricity in the rotating pendulum is amplified. 
         [0006]    The &#39;749 patent is inadequate for other reasons as well. For instance, the disclosed invention does not address how torque exerted on the buoy by the pendulum is handled. Without an effective “anti-torque” mechanism, the mechanical resistance of the generator will cause the buoy to rotate with the pendulum as it swings within the buoy. Because the generator is mounted to the buoy itself, the generator will see no rotation at its own frame of reference. This results in the buoy simply rotating in the ocean, and thus completely ineffective for producing energy. 
         [0007]    U.S. Pat. No. 7,453,165 entitled “METHOD AND APPARATUS FOR CONVERTING OCEAN WAVE ENERGY INTO ELECTRICITY”; U.S. Pat. No. 7,737,569 entitled “SYSTEM AND METHOD FOR CONVERTING OCEAN WAVE ENERGY INTO ELECTRICITY”; U.S. patent application Ser. No. 12/777,996 entitled “SYSTEM AND METHOD FOR CONVERTING OCEAN WAVE ENERGY INTO ELECTRICITY”; U.S. Pat. No. 7,629,704 entitled “METHOD AND APPARATUS FOR CONVERTING OCEAN WAVE ENERGY INTO ELECTRICITY; and U.S. patent application Ser. No. 12/607,878; hereby incorporated by reference, show various systems for using wave energy for the generation and distribution of electrical energy. While each of these is valuable and operated well, a problem still remains in that any renewable energy source, whether it be ocean waves, wind, or any other mechanism that creates rotary motion, inherently varies in pressure, temperature and/or force (speed). Thus, the output is subject to large variations over time. Normally, however, when it is desired to produce, for example, electricity, it is most efficient to do so with a constant source of rotational energy. Rotational forces created by waves, or by air flow, typically are not constant, thereby causing inefficiencies and other problems with power generation. 
       BRIEF SUMMARY OF THE INVENTION 
       [0008]    The present invention is a device for converting rotational energy into useable power by buffering the created rotational energy from the rotational energy used to create the output power. Thus, in one embodiment, a pendulum within a buoy is used to create rotational energy from ocean wave movement and the created rotational energy then drives a hydraulic pump which in turn drives a hydraulic motor to create a second rotational force which is then used to create an electrical output. In this manner, the hydraulic fluid acts as the buffer between the wave-created rotational energy and the rotational energy actually used to create the output electricity. 
         [0009]    In one embodiment, at least one accumulator is used to equalize the hydraulic pressure between the pendulum controlled rotating shaft and the induction generator used to create the output energy. 
         [0010]    In one embodiment, parasitic hydraulic fluid is used to control the system in order to conserve power. The parasitic energy is derived from excess pressures created by the wave motion and stored in the accumulator at times when the pendulum is turning with more force than is necessary to generate output power. 
         [0011]    In one alternate embodiment, a plurality of primary buoys are used, each with a pendulum, a hydraulic motor, and an internal generator. One or more generation buoys are combined in one or more electrical transformers on a barge or on-shore. 
         [0012]    The foregoing has outlined rather broadly the features and technical advantages of the present invention in order that the detailed description of the invention that follows may be better understood. Additional features and advantages of the invention will be described hereinafter which form the subject of the claims of the invention. It should be appreciated by those skilled in the art that the conception and specific embodiment disclosed may be readily utilized as a basis for modifying or designing other structures for carrying out the same purposes of the present invention. It should also be realized by those skilled in the art that such equivalent constructions do not depart from the spirit and scope of the invention as set forth in the appended claims. The novel features which are believed to be characteristic of the invention, both as to its organization and method of operation, together with further objects and advantages will be better understood from the following description when considered in connection with the accompanying figures. It is to be expressly understood, however, that each of the figures is provided for the purpose of illustration and description only and is not intended as a definition of the limits of the present invention. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0013]    For a more complete understanding of the present invention, reference is now made to the following descriptions taken in conjunction with the accompanying drawing, in which: 
           [0014]      FIG. 1  depicts one embodiment of a buoy in accordance with the present invention; 
           [0015]      FIG. 2A  depicts an embodiment of a schematic showing a hydraulic clutch and control circuit; 
           [0016]      FIG. 2B  is a legend for use with  FIG. 2A ; and 
           [0017]      FIG. 3  depicts an embodiment of a buoy network for generating electricity. 
       
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
       [0018]      FIG. 1  depicts one embodiment  10  of a system in accordance with the present invention. Note that the control circuitry, as well as the generator, can be within a buoy housing for use in liquid wave induced motion or within a windmill housing for use with air induced motion. In practice, some or all of these devices can be mounted external to the housing. As will be seen, the actual power generation is physically decoupled from the primary rotation source and connected thereto by hydraulic lines. Thus, if desired, power distribution can be achieved at a location separate from the location of primary rotation. In some situations, this separate location can be above or below the buoy and, in other situations, the generation can be achieved remote from the buoy where the primary rotation is created, perhaps in a separate buoy or housing. 
         [0019]    For purposes of discussion herein it will be assumed that both primary rotation and power generation, as well as control therefore, are all within single housing  10 . Pendulum  12 , which can, if desired, be made adjustable, rotates vertically-oriented shaft  14  within housing  10 , as the housing tilts and bounces under the influence of wave motion. This rotation, created by wave motion and captured by the pendulum rotating within the buoy, provides the kinetic energy for creating a primary source of rotation. In the embodiment shown, the rotation is from wave action of water. The rotation can be caused by any source, such as air movement or perhaps even piezoelectric contractions and/or movement. As shown, the wave action is unpredictable and non-uniform, and can be zero at times. Also, the direction of shaft rotation is at times clockwise and at other times it is counter-clockwise. 
         [0020]    Rotating shaft  14  then causes shaft  14 ′ of hydraulic pump  15  to rotate, either directly, or geared (not shown). The rotation of pump  15 , in turn, causes hydraulic pressure within lines  18 . This hydraulic pressure, as will be discussed in more detail, drives hydraulic motor  16  via control device  17 . Control device  17  is, in one embodiment, a hydraulic control device, such as the SPDB Series from Hagglunds which serves to maintain a relatively constant rotation of shaft  160 , thereby maintaining generator  24  at a constant rpm. This regulation is, for example, controlled by swash plate  161 . Motor  16 , in one embodiment, is designed for use when shaft  14  rotates, for example, between 3 and 40 rpm. In this situation, when rotation exceeds 40 rpm, a valve (not shown in  FIG. 1 ) opens and accumulator  22  absorbs the excess hydraulic pressure, thereby regulating the flow rate to motor  16 . When the rpm from shaft  14  ( 14 ′) falls below 3 rpm (or any other set number) pressure is released from accumulator  22 . In this manner, the hydraulic fluid pressure and flow rate are regulated to accommodate the uncertain and changing environmental conditions of the wave (or air) input power source. The rotation caused by hydraulic motor  16  on shaft  201  then drives electrical power generator  24  to achieve a power output which can be used, perhaps in combination with other similar buoy devices, to deliver electrical power into a network for distribution into a power grid. Note that it is expected that shaft  201  turns in one direction (either clockwise or counter-clockwise) but not both directions. 
         [0021]    In one alternate embodiment, several buoys can be used to generate electrical power which is transferred to a single central location and transferred to the utility. 
         [0022]    In some situations it may be possible to combine the generated hydraulic pressure from many such buoys at a single location and use the accumulated pressure to drive a larger hydraulic motor, thereby generating a large amount of electricity from a single location, driven by hydraulic pressure from several locations. 
         [0023]      FIG. 2A  depicts an embodiment of a schematic, such as schematic  20 , showing a hydraulic clutch and control circuit in accordance with one aspect of the invention.  FIG. 2B  shows a legend for use with  FIG. 2A . As discussed above, hydraulic pump  15  is driven by pendulum  13 , which causes the shaft of the pump to rotate either in the clockwise direction or counter-clockwise direction. Hydraulic pump  15  is, in one embodiment, a hydraulic motor, such as motor CB Series from Hagglunds. In this embodiment, the motor is being used in reverse such that instead of hydraulic fluid being pumped into the motor to make the shaft rotate, the shaft is being rotated by the pendulum and the hydraulic fluid is being pumped out. Depending upon rotation direction, the hydraulic fluid is either being pumped out of outlet A (assume counter-clockwise rotation) or outlet B (assume clockwise direction). Note that when hydraulic flow direction is out of outlet A then the fluid is replaced by fluid going into outlet B. This direction control is established by unload valve  210  which is responsive to rotation direction to open either its right or left side. Rotation direction can be determined, for example, by sensing devices  202  and  203 . 
         [0024]    Assuming counter-clockwise direction of pump  15 , then hydraulic fluid under pressure exits pump  15  via outlet A and is blocked from path  240  by unload valve  210  being closed in this direction (because of the pump rotation direction). Path  241  is also blocked because of check valve  231 , leaving only paths  242  and  243 . Path  242  leads to high pressure accumulator  22 . Path  243  leads to control accumulator  23 . Accumulator  23  provides a source of pressure and a mass balance for the hydraulic control circuit. Note that the lines marked with Xs are the control lines for the system. 
         [0025]    Assuming clockwise direction of pump  15 , then hydraulic fluid under pressure exits pump  15  via outlet B and is blocked from path  245  by unload valve  210  being closed in this direction (because of the pump rotation direction). Path  244  is also blocked because of check valve  232 , leaving only path  246  which leads to high pressure accumulator  22 . Path  243  leads to control accumulator  23 . Note that the lines marked with Xs are the control lines for the system. 
         [0026]    High pressure accumulator  22  is also filled by path  247  from reservoir accumulator  21  via check valve  234 . Accumulator  21  provides a source of new fluid to the operating system and is refilled by hydraulic fluid flowing via path  248  out of hydraulic motor  16 . 
         [0027]    Hydraulic motor  16 , which is used to drive induction generator  24 , typically would be driven in a single direction and under hydraulic fluid from accumulator  22  via path  249  and pressure control valve  217  and flow control valve  218 . Hydraulic motor  16  is, in one embodiment, a hydraulic motor, such as motor SP Series from Hagglunds. It is important that the output rotation of motor  16  be relatively constant, and valves  217  and  218  serve this function. Thus, the output shaft rotation speed of motor  16  has been decoupled from the rotation direction and rotation velocity of buoy shaft  14 . 
         [0028]    Control accumulator  23 , has various controls, including pressure transmitter  250 , to control system operation in a variety of ways. For example, depending upon pressure control valve  215 , control hydraulic fluid can be sent to switch  218  to adjust or turn off valve  218  which, in turn, controls the operation of motor  16 . Overflow from accumulator  23  can be sent to accumulator  21  via pressure control valve  216 . Note that one function accumulator  23  fulfills is to use the pressures created by the wave action for control purposes instead of requiring external power, or battery and instead of using generated output power. This parasitic power then is essentially “free” because it uses excess energy that otherwise would be wasted. 
         [0029]    Accumulator  21  fills the system, when necessary, by sending hydraulic fluid to pump  15  via lines  244  and  241  via check valves  232  and  231 , respectively. 
         [0030]    Operating temperatures and pressures are important and the system monitors the temperatures, for example, from accumulator  22  senders (transmitters)  204  and  205 , and accumulator  21  temperature sender  206  and, if necessary, cools the system using, for example, sea water. Various switches, such as switches  214 ,  212 ,  218  and  219  can be manually or hydraulically controlled to bypass or turn on or off various control portions of the system as required. 
         [0031]    While any number of output rotational velocities can be used for induction generator  24 , a preferred range for use in a buoy system is between 3 rpm and 40 rpm. Of course, the system can be set to work with any desired range of primary rotational velocities. Also, the system pressure accumulators and/or the pendulum-shaft structure should be sized and/or adjusted to take into account the expected rotational average velocities t a particular location. Since wave action varies from place to place and from time to time adjustments can be made on a periodic basis to maintain the rotational velocity within the limits of the system so that power output remains constant and relatively uninterrupted. 
         [0032]    System pressure should be maintained at any of a number of settings depending on the current operating conditions. A preferred operation set point for the high pressure system would be, for example, 3500 psig. This set point, which could allow for a temporary condition of increased pressure (say 4500 psig), resulting from higher than average mechanical speed (rpm) input, will allow for the temporarily increase in operating electrical generation until the transient condition resolves back to the set point, which in our example is 3500 psig. Similarly during periods of low mechanical speed input, the system pressure is reset to a lower developed pressure, say 2500 psig, until conditions resolve back to the set level of 3500 psig level. The feed forward input from relative positions of the buoy shell versus current pendulum position will predict changes in the pendulum speed input in order that system components can be positioned to support contained operation. In one embodiment, both hydraulic fluid pressure as well as flow rate, are monitored and/or controlled as necessary. 
         [0033]      FIG. 3  depicts an embodiment of a buoy network, such as network  30 , for generating electricity from a plurality of buoys  10 - 1  to  10 - 4 . The buoys would be interconnected to distribution point  31  by cables  32 - 1  to  32 - 4  (or hydraulic lines in systems where hydraulic fluid is accumulated over a plurality of buoys). While only four such buoys are shown, any number or configuration can be used. Also, as discussed above, one of these buoys, or connection point  31 , can be used for the actual power generation at the voltage required, while the other buoys, called primary buoys, could be used to create power, perhaps at lower levels for use in power generation. In some embodiments, hydraulic lines would interconnect the buoys. Output  33  would be electric power, or, in some embodiments, hydraulic fluid, to a distribution grid. Note that when primary buoys are used (buoys without electric power generation capability) the hydraulic (or other power transfer substance) can be transmitted to a power buoy, to a fixed station in the water, to an anchored vessel, or even to a land-based power generation station. Also, note that such a system could be used for creating temporary power for docked or anchored vessels. The power can be delivered to the vessels either in the form of electricity or, for example, in the form of hydraulic fluid for turning a hydraulic generator. 
         [0034]    Although the present invention and its advantages have been described in detail, it should be understood that various changes, substitutions and alterations can be made herein without departing from the spirit and scope of the invention as defined by the appended claims. Moreover, the scope of the present application is not intended to be limited to the particular embodiments of the process, machine, manufacture, composition of matter, means, methods and steps described in the specification. As one of ordinary skill in the art will readily appreciate from the disclosure of the present invention, processes, machines, manufacture, compositions of matter, means, methods, or steps, presently existing or later to be developed that perform substantially the same function or achieve substantially the same result as the corresponding embodiments described herein may be utilized according to the present invention. Accordingly, the appended claims are intended to include within their scope such processes, machines, manufacture, compositions of matter, means, methods, or steps.