Abstract:
A method and apparatus for constructing a tower, where the apparatus may include a structure including a foundation including a plurality of hydraulic cylinders; a truss tower located on the foundation and configured to support a tower built on the foundation; and a controller configured to control extension and retraction of the hydraulic cylinders.

Description:
FIELD OF THE INVENTION 
     The present subject matter relates generally to tower structures, and more specifically to methods and apparatus for assembling tower structures. 
     BACKGROUND OF THE INVENTION 
     Construction of towers for support of various items has been practiced for many years. Various towers of various materials, including wooden, steel, and, more recently, concrete, have been provided to support, for example, electrical transmission lines. In a like manner, wind driven apparatus including windmills and wind-driven power generators in various forms and designed for many purposes (including for example pumping of water from wells as well as, more recently, generation of electrical power) have also been developed. 
     Such towers are generally constructed of multiple pieces that are assembled at the location of the tower. The pieces are usually hoisted in place by a crane. Cranes can be very expensive to maintain and operate, and a substantial hourly cost is incurred for every hour the crane is on site. 
     For example, a large construction crane may require  16  truckloads to transport all of the component parts, substantial labor to assemble and inspect, and then substantial labor to disassemble. Accordingly, a method and apparatus for constructing a tower that minimizes or eliminates the need for a crane is desired. 
     SUMMARY OF THE INVENTION 
     The present invention broadly comprises a method and apparatus for constructing a tower. In one embodiment, the apparatus may include a structure including a foundation including a plurality of hydraulic cylinders; a truss tower located on the foundation and configured to support a tower built on the foundation; and a controller configured to control extension and retraction of the hydraulic cylinders. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       A full and enabling disclosure of the present subject matter, including the best mode thereof, directed to one of ordinary skill in the art, is set forth in the specification, which makes reference to the appended figures, in which: 
         FIG. 1  illustrates a perspective view of an embodiment of the present invention; 
         FIG. 2  is a top view of the foundation of the embodiment shown in  FIG. 1 ; 
         FIG. 3  illustrates a top view of the tower and a schematic of the cylinder control system; 
         FIG. 4  is a side view of all of the cylinders extended before the insertion of a new level; 
         FIG. 5  is a side view showing half of the cylinders retracted and half extended; 
         FIG. 6  is a side view of the first block that is fully inserted and the hydraulic cylinders below are extended to contact the block; 
         FIG. 7  is a side view of the insertion of the second block; 
         FIG. 8  is a side view of the completion of a level; and 
         FIG. 9  is a top view of an embodiment of the restraining truss shown in  FIG. 1 . 
     
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
     Reference is presently made in detail to exemplary embodiments of the present subject matter, one or more examples of which are illustrated in or represented by the drawings. Each example is provided by way of explanation of the present subject matter, not limitation of the present subject matter. In fact, it will be apparent to those skilled in the art that various modifications and variations can be made in the present subject matter without departing from the scope or spirit of the present subject matter. For instance, features illustrated or described as part of one embodiment can be used with another embodiment to yield a still further embodiment. Thus, it is intended that the present subject matter covers such modifications and variations as come within the scope of the disclosure and equivalents thereof. 
       FIG. 1  shows a perspective view of an exemplary embodiment of an apparatus  10  for constructing a tower  80  in accordance with the present invention. Tower  80  supports wind turbine  82 , but towers made according to the present invention may support other equipment, power lines, or other objects. Any such towers may be constructed according to the present invention. 
     Apparatus  10  includes a foundation  20  and a truss tower  40  located on the foundation  20 . Foundation  20  includes a plurality of hydraulic cylinders  22 , shown in  FIGS. 3-8 . Truss tower includes vertical legs  42 , upper restraining truss  44 , and lower restraining truss  46 . As shown in  FIG. 2 , the base  42 A of each vertical leg  42  of the truss tower  40  rests on foundation  20 . 
       FIG. 1  shows a truss tower including two restraining trusses, but more than two can be included and are within the scope of the present invention. The restraining trusses  44  and  46  provide horizontal force to support the tower  80  during construction of the tower. In particular, the restraining trusses  44  and  46  counteract uneven forces on the tower  80  during the method of construction described hereafter. 
       FIG. 9  shows a close up top view of a restraining truss, such as upper restraining truss  44 . Each restraining truss includes force bearing devices  48  to transfer force from the truss tower  40  to the tower  80 . Further, the force bearing devices  48  allow tower  80  to move past vertically as additional levels are added to tower  80  from below. In the embodiment shown in  FIG. 9 , the force bearing device includes rollers  49  to exert horizontal force on tower  80  while still allowing tower  80  to move vertically. However, other devices known in the art may be used in this manner. Further, the force bearing devices may include hydraulic cylinders  50  to tighten the force bearing device up to the wall of tower  80 . The embodiment shown in  FIG. 9  includes a hydraulic cylinder  50  for each force bearing device  48 . However, fewer may be used as long as the restraining truss can be sufficiently tightened around tower  80 . 
     In the embodiment shown in  FIGS. 1-9 , tower  80  has an octagonal cross-section. However, other cross-section shapes are possible, such as square or circular cross-sections. All of these modifications are within the scope of the invention. 
     Tower  80  as shown in  FIG. 1  includes a wind turbine  82  located on top of levels  84 . In one embodiment, levels  84  are first constructed with a crane, the truss tower  40  is constructed around the levels  84 , and then the crane lifts the wind turbine  82  to the top of levels  84 . The following procedure is then used to add additional levels to the tower using hydraulic cylinders  22 . However, if a heavy object like a wind turbine is not going to be located at the top of the tower, then the truss tower  40  can be constructed over foundation  20  and all levels can be constructed using the hydraulic cylinders  22 . This would allow the elimination of the need for a crane, as the addition of levels using the hydraulic cylinders  22  only needs a forklift, as discussed hereafter. 
     In an embodiment for a tower  80  with a wind turbine  82 , 10 2 m levels  82  may be constructed using a crane, and a height of wind turbine  82  may be 50 m. Thus, each leg  42  would be 20 m tall, upper restraining truss  44  would be at 20 m in height while lower restraining truss  46  may be at approximately 8 m from the bottom of truss legs  42 . Truss legs  42  may be square of 12 inches on a side, and may be 22 feet apart from each other. 
     In the embodiment shown in  FIG. 1 , foundation  20  is constructed, and hydraulic cylinders  22  and block supports  24  are installed in the foundation  20 . Hydraulic cylinders  22  are arranged in pairs, with a block support  24  extending between each pair of cylinders. A plurality of levels  84  are constructed using a crane, the truss tower  40  is constructed around levels  82  and on foundation  20 , and the wind turbine  82  is added to the top of levels  84 . Additional levels are then added using hydraulic cylinders  22  and block supports  24  as shown in  FIGS. 4-8 . In the embodiment shown in  FIGS. 1-9 , hydraulic cylinders  22  and block supports  24  are then removed from foundation  20  after the desired number of additional levels are added. 
     In the embodiment shown in  FIGS. 1-9 , there are  24  hydraulic cylinders  22 . In one embodiment, cylinders  22  are sized to lift a concrete tower with a final weight of 1800 tons. However, towers of any dimensions and material may be constructed using this method and apparatus. The size and number of cylinders may vary depending on the dimensions of the tower and the building material. All of these modifications are within the scope of the present invention. 
     In this regard, in the embodiment shown in  FIGS. 1-9 , each level  84  and  86  is slightly wider than the level above, as shown in  FIG. 3 . When the final level is added, the bottom of this final level will line up with the top of foundation  20 . 
     The first step of the process is shown in  FIG. 4 , in which all of hydraulic cylinders  22  are extended to push up tower  80  by the height of one level. In the embodiment shown in  FIGS. 1-9 , all of the levels  84  and  86  have approximately a same height. However, different heights could be used as long as the extension height of hydraulic cylinders  22  is greater than the tallest level. At this step, the tower must slide past the force bearing devices  48  on the restraining trusses, as noted above. 
     As shown in  FIG. 5 , one half of hydraulic cylinders  22  are then retracted to allow block  86 A of new level  86  to be inserted. As noted above, in the embodiment shown in  FIGS. 1-9 , new level  86  is made of two equal sized blocks  86 A and  86 B. However, embodiments where three or more blocks are used and/or each block is more or less than half of each level are possible and are within the scope of the present invention. 
     Block  86 A is inserted by the use of a forklift. Block  86 A is then connected to the level above. Block  86 A may be adhered to the block above, or may have grooves or projections that mate with the block above, or both. During this time, uneven forces are placed on the existing tower  80 . Accordingly, restraining trusses  44  and  46  exert horizontal forces on the tower  80  to prevent tower  80  from tipping over due to these uneven forces. 
     At this point, the other half of the hydraulic cylinders  22  are retracted, as shown in  FIG. 6 . This allows block  86 B to be inserted using a forklift, as shown in  FIG. 7 . Block  86 B is then connected to the level above in a similar manner as block  86 A, as shown in  FIG. 8 . This should end the uneven forces on the tower, and reduce the load on the truss tower  40 . 
     Finally, the new level  86  is pushed up the height of a level by extending all of the hydraulic cylinders  22 , as shown in  FIG. 4 . Half of the hydraulic cylinders are then retracted to allow the next level to be added, as described above. However, in the embodiment shown in  FIGS. 1-9 , the seams between the two blocks are alternated from level to level. That is, the seam between two blocks is only located on a particular face for every other level, as shown in  FIG. 1 . Thus, for example, a first level  86  is constructed by lowering a front half of hydraulic cylinders  22 , adding block  86 A to the front opening, lowering the back half of hydraulic cylinders  22 , and then adding back block  86 B. The following level would be constructed by lowering either the right (or left) half of hydraulic cylinders  22 , adding block  86 A to the right (or left) opening, lowering the left (or right) half of hydraulic cylinders  22 , adding block  86 B to the left (or right) opening. This is accomplished using the control computer  60  shown in  FIG. 3 . 
     Control computer  60  receives position and pressure readings from each of the cylinders  22  through lines  60 A ( FIG. 3  does not show all of lines  60 A). Control computer  60  then sends signals to control pressurized fluid to each cylinder  22  through line  60 C to pressure manifold  62 . Based on the signals from the control computer  60 , pressure manifold  62  supplies pressurized fluid to each cylinder  22  through a respective valve  62 A. (Not all of valves  62 A are shown in  FIG. 3 .) Control computer  60  also controls a return valve on each cylinder  22  through line  60 B. (Not all of lines  60 B are shown in  FIG. 3 .) When the return valve is opened by control computer  60 , fluid runs through a respective return line  66 A to fluid reservoir  66 . (Only one of the  24  return lines  66 A is shown in  FIG. 3 ). Fluid from fluid reservoir  66  is pressurized by electrical or diesel pump  64  before it is supplied to the pressure manifold  62 . 
     Control computer  60  has several programs to control multiple sets of the cylinders  22 . As discussed above, in the embodiment shown in  FIGS. 4-8 , half of cylinders  22  are controlled to extend and retract together, and the halves are alternated for each level between (1) right and left half and (2) front and back half. Thus, control computer  60  at has programs to extend and retract (1) the right half of cylinders  22 , (2) the left half of cylinders  22 , (3) the front half of cylinders  22 , and (4) the back half of cylinders  22 . Additional commands such as all extend and all retract can also be programmed into control computer  60 . Further, if each level includes more than 2 blocks, additional commands will be needed to control smaller subsets of cylinders  22 . 
     Accordingly, a tower  80  may be constructed with less use of a crane, or without the use of a crane at all. As a forklift is much cheaper to operate than a crane, a substantial cost savings may be gained by using the present method and apparatus for constructing a tower. 
     The present written description uses examples to disclose the present subject matter, including the best mode, and also to enable any person skilled in the art to practice the present subject matter, including making and using any devices or systems and performing any incorporated and/or associated methods. While the present subject matter has been described in detail with respect to specific embodiments thereof, it will be appreciated that those skilled in the art, upon attaining an understanding of the foregoing may readily produce alterations to, variations of, and equivalents to such embodiments. Accordingly, the scope of the present disclosure is by way of example rather than by way of limitation, and the subject disclosure does not preclude inclusion of such modifications, variations and/or additions to the present subject matter as would be readily apparent to one of ordinary skill in the art.