Abstract:
The described invention involves the windmill generation of electric power, particularly from offshore windmill generators. The invention involves inserting an adapter between the nacelle of the windmill and the tower, which includes either a leveling device or a vibration dampening device, or both.

Description:
CROSS REFERENCE TO RELATED APPLICATIONS 
     This application claims the benefit of U.S. Provisional Application No. 60/569,077, filed May 6, 2004. 
    
    
     FEDERALLY SPONSORED RESEARCH 
     Not applicable. 
     REFERENCE TO MICROFICHE APPENDIX 
     Not applicable. 
     FIELD OF THE INVENTION 
     This invention relates generally to the structure for the generation of electric power using a wind turbine, particularly wind turbines erected in an offshore environment. 
     The quest for alternative energy sources is a global priority. One source of electric power is wind energy. Throughout the world, wind patterns exist. In prior years, small wind generating systems were developed in which high wind velocities were required. Also the elevation of the wind systems was mounted quite low failing to take advantage of wind velocities, which are increased above the surface of the earth. In recent years, more efficient and larger wind machines have been developed. These machines operate efficiently at low wind velocities of 2.5 meters per second. 
     BACKGROUND ART 
     The new wind machines also have been mounted on pedestals, which increase the elevation. This elevation increases the efficiency of the wind machine on an average yearly output. The new generation of wind machines requires very little maintenance, i.e., about 2 times per year. Therefore, the machines can be mounted in remote locations and can operate trouble free for extended periods of time. Due to many political and human nature considerations, many wind machines are now being placed in offshore waters. The distance from the shoreline varies but from the human relations viewpoint, they are usually out of the sight of the land. 
     The generating systems can be sized between 1.5 megawatts and 3.5 megawatt machines with some wind turbines being operated at 250 kw. The generating systems including blades, gearboxes and control systems, have been proven and tested. The required towers to elevate the generator have also been proven and tested. The offshore oil and gas industries have proven throughout the world that offshore structures can be designed and installed to withstand the harshest atmospheric environment. 
     New techniques have been developed in the fabrication and installation of these structures. These techniques are useful in the practice of this invention in order to use the most efficient manner to construct, install and maintain offshore wind machines. It is also important to understand that the total cash flow from the wind power machine has a cap due to the sales price of electrical energy onshore. Consequently, the additional cost of installation in providing the structure is of paramount importance. 
     Offshore structures are designed to accommodate the soil bearing capacity of the sub bottom strata. In some cases, extremely soft bottoms were encountered in delta regions of the world. Also, some sub bottoms are hard rock or coral reef. Therefore, the anchoring system, which is required, varies greatly. Also, if wind machines are placed in hardy conditions, ice conditions are a consideration regarding the structural strength of the structure and materials. Consequently, soil borings are required to assure that the structure will have ample strength to accommodate the weight and overturning moment of the wind machine. 
     Another consideration is wave and wind conditions to which the structure is subjected. Therefore, the anchoring of the windmill structure will be different in different areas of the world. With all the variables and substantially unpredictable environments where the wind power generation is attempted, it is little under that post construction problems appear which affect the efficiencies of operation of the installations. 
     While the offshore support structure can be generally constructed as well known in the offshore oil industry and specifically as described in U.S. Pat. No. 4,260,291, two problems have generally developed in connection with the generation of the electric power at these offshore facilities. One such problem is vibration of the structure caused by the wind itself acting upon the structure and the rotation of the windmill blades to turn the generator to develop the electric power. A number of attempts have been made to combat these vibrations problems as described in U.S. Pat. No. 4,515,525 (minimization of the effects of yaw oscillation in wind turbines), U.S. Pat. No. 6,672,837 (wind turbine with an oscillation dampening means) and U.S. Pat. No. 6,695,588 (dampening of oscillations in wind turbines). U.S. Pat. No. 4,469,956 describes a support structure fitted between the windmill and the tower to reduce the communication of vibration from the blades and rotating turbine to the tower. While a number of attempts have been made to solve the vibration problem, much improvement could still be made. 
     Another problem exists with respect to the offshore windmill electric generators. After a period of time there often is a settling of one or more of the support members affecting the alignment of the structure such that the nacelle and axis of the generator and windmill cease to be level or horizontal. This settling is often exacerbated, if not caused, by the vibration of the tower supporting the windmill. This causes uneven forces to be present during operation creating additional wear and tear and resulting inefficiencies, if not a major reconstruction adjustment of the windmill involved. 
     SUMMARY OF THE INVENTION 
     This invention involves solving the problem of vibration and the leveling of the nacelle and generating unit by inserting an adapter between the tower and the nacelle which includes the structure for either or both solutions. This adapter includes the separation from direct contact of the nacelle with the tower and provides an adjustable device for leveling the apparatus for generating the electricity. The vibration dampening is accomplished by a plurality of radially spaced separators contacting the tower structure through shock absorbing thrust washer material placed in an annular space created between a support tube attached to the tower structure and a support shaft attached to the structure carrying the nacelle. 
     The leveling is accomplished by a plurality of radially disposed support blocks for a leveling base plate carrying the nacelle which are adjustable in height by moving support blocks along an inclined plane using a jack screw which is accessible from the interior of the tower during periods of maintenance. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       Appended hereto are drawings to aid those skilled in the art in the practice of the invention described herein: 
         FIG. 1  is a view of an electric generating windmill tower installation in schematic form. 
         FIG. 2  shows the assembled apparatus, in section, of this invention which includes both the leveling device and the vibration dampening device. 
         FIG. 2   a  is a plan view showing the orientation of the adjusting elements in the leveling device. 
         FIG. 2   b  is a plan view end section showing the orientation of the elements of the vibration dampening device. 
         FIG. 3   a  is an elevation view end section of one element of the leveling device. 
         FIG. 3   b  is a plan view of one element of the leveling device. 
         FIG. 4  is an elevation end section of one element of the vibration dampening embodiment of this invention. 
     
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
     The installation costs must also be controlled to allow economic benefit to this operation. Therefore, in considering transportation, lifting, assembly, weather conditions, and other factors a lift boat unit appears to be the most economical method by which the installation of the windmill assembly can be accomplished. Lift boats have been used in offshore oil production for years and can operate in water depths of six feet through 200 feet and are also used to erect windmill structure. The lift boat has three or four legs for stability on which the structure is lifted out of the water to the height desired adjacent to the windmill structure for stability purposes. The lift boat would carry the parts the structure to the site and use rotating cranes of about 150-ton capacity to assemble the structure. 
     In order to facilitate the assembly of the tower assembly and nacelle generating pod, a work platform is required. A work platform is mounted to cantilever beams which can be extended from the bow of the liftboat to the work area on the structure being erected. The platform also includes a hinged section which allows the work platform to be spaced about the diameter of the tower assembly. Personnel and equipment can be transferred to the work area via a walkway which is also mounted to the cantilever beams. Once the platform has completed its duties, it can be retracted onto the liftboat deck for transit purposes. 
     The wind machines themselves have three major components. First a variable pitch, usually three-bladed fan. The second is a generation system with a gearbox and mounting means usually housed in a nacelle. The support tower, which elevates the hub height approximately 260 feet from the base, sometimes up to about 380 feet, is the third component. The structure is mounted on a base appropriate for the environment in which it is to operate. 
     The electric generating windmill of the present invention is situated on a tower as generally shown in  FIG. 1 . This tower is supported by a base  10  here shown with a plurality of piles  10   a  driven into the ocean bottom with a jacket  10   b  prepared to receive the tower  12  shown in  FIG. 1  as having two sections  12   a  and  12   b . It is understood that any suitable base construction may be used in the practice of this invention. The Tower  12  is normally sectioned in order to provide for ease of transportation and erection at the site. Of course, more sections could be used than the two as shown. On the tower  12  is a nacelle  14  which houses the generator unit (not shown) and other operative parts known in the art for the overall success of the operation, including a rotatable horizontal shaft generator attached at one end to a plurality of blades  16  oriented to cause the shaft to rotate in response to wind action to generate electric power. The adapter  20  of this invention includes at least one of a vibration dampening device or a leveling table located between the tower  12  and the nacelle  14 . While the adapter  20  is shown with the leveling element on top, which is preferred, they may be changed through a simple adjustment of the parts. Greater detail of a combination vibration dampening and leveling device built into a single adapter is shown at  FIGS. 2 ,  2   a  and  2   b  and is a preferred embodiment of this invention. The adapter  20  is constructed of an outer shell  22  which is attached to the tower  12  in an appropriate manner, usually by being welded to the tower  12 . Of course, one skilled in the art would understand that it could be attached using bolts and flanges. It also includes radially disposed support tubes  24  around the adapter and attached, usually welded, to a base plate  26  as shown in  FIGS. 2 and 2   b.    
     In each support tube  24  is a support shaft  28  positioned coaxially with it forming an annular space between the support tube  24  and the support shaft  28 . The support shaft  28  is fixed to the lower base plate  30  of the leveling table of this invention. The lower base plate  30  and the support shaft  28  are secured to the adapter  20  through the shell  22  by a reduced diameter shaft  63  through a thrust washer  32  held in place by a pre-tensioning nut  34  on a threaded extension  64 . The periphery of the lower base plate  30  is penetrated by a plurality of tapped holes  36  to receive lock bolts  38  to secure the upper leveling based plate  40  which is drilled and tapped with bolt holes  41  to carry the attachment of the nacelle  14 . The nacelle  14  may be attached directly to the adapter  20  of this invention or may be attached with some intermediate structure. The lower base plate  30  carries a plurality of radially oriented leveling elements  42  as shown in  FIG. 2   a . In an embodiment of this invention where only the vibration dampening device is included in the adapter  20 , the nacelle  14  would be attached directly to the lower base plate  30 . 
     The detail of the leveling elements  42  is shown in  FIGS. 3   a  and  3   b  which includes an adjusting bolt  44  which, when rotated, turns a jack screw  46  which is journaled at both ends through bearings  40  and  50 . The bearings  48  and  50  are carried by lips  49  and  51  which are part of, or attached to, lower base plate  30 . Rotation of the jack screw  46  by turning the adjusting nut  44  moves a support block  52  along an inclined plane  54  which, as the block  52 , moves, will correspondingly raise or lower the upper leveling base plate  40  to accomplish the leveling of the nacelle  14 . Once leveled, the support block  52  can be secured in place by tightening down on the adjusting lock nut  56 . The inclined plane  54  and lips  49  and  51  are shown in  FIG. 3B  as a part of lower base plate  30 . It is understood that the inclined plane  54  and lips  49  and  51  may be part of a separate piece attached to the lower base plate  30 . Using the leveling device of this invention allows the wind generator to be easily leveled from the inside of the tower  12 , even while the generator is operating. 
       FIG. 4  shows the detail of the vibration dampening device constructed of the support tube  24  and the support shaft  28  and the attachment of the support tube  24  to the base plate  26  and the attachment of the support shaft  28  to the lower leveling base plate  30 . The annular space between the support tube  24  and support shaft  28  is occupied by a means  60  for isolating the vibration of the support shaft  28  from the support tube  24  and from the tower  12  and the base  10 . The isolating means  60  is compressed toward the base plate  26  by a shoulder  62  on the support shaft  28  depending upon the anticipated forces on the windmill. There a small diameter shaft  63  at the end of support shaft  28  extends through the base plate  26  and a thrust washer  32  through a threaded reduced diameter shaft  64  about which the pre-tensioning nut  34  is secured. The smaller diameter shaft  63  creates an annular space  66  in the base plate  26  and therefore does not have hard, direct communication with the tower  12  at any point. 
     There are many means for separating or isolating metal parts that are satisfactory for use in the practice of this invention such as, for example, fabric washer material, vulcanized rubber shock absorber material, friction springs or deformable shock absorbing units from Ringfeder Corporation (Westwood, N.J.). The preferred material for the isolation means are the Ringfeder friction springs. Other materials which may be satisfactory in some situations are coil springs or bellville springs. Regardless of the means used, one skilled in the art would be able to size and tension the isolation device to serve the windmill structure involved. 
     In the construction of the wind generator, usual procedures are followed, preferably utilizing a jack-up barge to accomplish the erection and the adapter  20  is lifted into place after the lower leveling base plate  30  is in position and pre-tensioned by tightening the pre-tensioning nut  34  on the threaded reduced diameter extension  64  of the support shaft  28 . 
     When both devices are present in the adapter, the two elements of this invention, the vibration dampener and leveler compliment each other. The leveling device reduces the vibration created by the absence of a level nacelle carrying the generating unit and the vibration dampening structure of this invention prevents or materially reduces the communication of vibration from the power generating apparatus through the tower and thus reduce the stresses placed upon the support for the structure allowing it to remain more level. 
     This invention, having been described above and shown in accompanying drawings, will lead those skilled in the art to many alternatives and variations without departing from the scope of the claims which follow and are intended to be a part of this invention.