Lattice-skin hybrid tower

Abstract

A tower having internal legs and an external skin providing a hybrid of lattice type towers and tubular type towers. The internal legs and the external skin share tower loading in a manner that optimizes the structural design of the tower, thereby providing benefits of both lattice and tubular type towers. A unique pin connection between tower sections is used to transmit loads smoothly and aid in section alignment. Tower sections are constructed from radial segments which may be nested for shipping such that transportation logistical barriers can be overcome for very large or tall wind turbine towers. The tower sections are then assembled on site using a specialized section assembly system which holds segments from both ends while consecutive segments are added to form a complete cylindrical or tapered section. The section assembly system includes a pair of frames that support the tower segments and align them properly during assembly. The section assembly system may be used to assemble a tower section in either a horizontal or a vertical orientation.

1 . A wind turbine tower comprising: 
 a tower section having a longitudinal axis comprising a plurality of leg structures spaced around a periphery of said tower section and substantially aligned with said longitudinal axis; and    a skin attached to said leg structures wherein loads applied to said tower are shared by said leg structures and said skin.    
   
   
       2 . The wind turbine tower of  claim 1  wherein said leg structures and said skin are fabricated out of steel and wherein said skin is welded to said legs.  
   
   
       3 . The wind turbine tower of  claim 1  wherein said skin is fabricated out of press broken sheet steel.  
   
   
       4 . The wind turbine tower of  claim 1  wherein said tower section is divided into at least two segments along seams that are substantially aligned with said longitudinal axis.  
   
   
       5 . The wind turbine tower of  claim 4  wherein said segments are attached to each other by a plurality of bolts along said seams.  
   
   
       6 . The wind turbine tower of  claim 4  wherein said tower comprises at least two said tower sections and wherein at least one said tower segment is divided into at least two segments.  
   
   
       7 . The wind turbine tower of  claim 1  wherein said tower comprises at least two said tower sections.  
   
   
       8 . The wind turbine tower of  claim 7  wherein said at least two said tower sections fasten to each other with a plurality of mating tapered pin and cavity connectors.  
   
   
       9 . The wind turbine tower of  claim 8  wherein one mating tapered pin and cavity connector is located at the end of each leg structure.  
   
   
       10 . The wind turbine tower of  claim 9  wherein said mating tapered pin and cavity connectors comprise: 
 a tapered pin attached to a first tower section with a transverse hole provided in said pin;    a body attached to a second tower section with a tapered cavity for receiving said tapered pin with a transverse hole provided in said body; and    a bolt inserted through the transverse holes in said pin and said body to fasten said pin and said body together.    
   
   
       11 . A device for attaching two sections of a wind turbine tower comprising: 
 a tapered pin attached to a first tower section with a transverse hole provided in said pin;    a body attached to a second tower section with a tapered cavity for receiving said tapered pin with a transverse hole provided in said body; and    a bolt inserted through the transverse holes in said pin and said body to fasten said pin and said body together.    
   
   
       12 . The device of  claim 11  wherein said tapered pin is seated in firm contact with said tapered cavity when said bolt is inserted through said transverse holes.  
   
   
       13 . The device of  claim 12  wherein compressive forces are transmitted between said two sections of a wind turbine tower by said tapered pin pressing against said tapered cavity.  
   
   
       14 . The device of  claim 13  wherein tension forces are transmitted between said two sections of a wind turbine tower through shear stress in said bolt.  
   
   
       15 . A method of assembling a wind turbine tower comprising the steps of: 
 providing a tower section that is divided into a plurality of radial segments;    providing a frame that is capable of supporting said radial tower segments;    attaching said radial tower segments to said frame; and    fastening said radial tower segments to each other.    
   
   
       16 . The method of  claim 15  wherein the step of providing a frame that is capable of supporting radial tower segments comprises the provision of two frame structures for supporting both ends of said radial tower segments.  
   
   
       17 . The method of  claim 16  further comprising the steps of: 
 providing a mechanism for adjusting the positions said frame structures; and    adjusting said two frame structures relative to each other to align adjacent tower radial tower segments relative to each other during assembly.    
   
   
       18 . The method of  claim 15  further comprising the steps of: 
 providing a mechanism for rotating said frame about a longitudinal axis;    attaching said radial tower segments to said frame one at a time; and    rotating said frame about said longitudinal axis after attaching each said radial tower segment.    
   
   
       19 . The method of  claim 18  wherein each of said radial tower segments has a predetermined radial circumference and said frame is rotated by an angle substantially equal to the radial circumference of each said radial tower segment after attaching each said radial tower segment.  
   
   
       20 . The method of  claim 15  wherein said step of providing a frame that is capable of supporting said radial tower segments further comprises providing said frame in a horizontal orientation.  
   
   
       21 . The method of  claim 15  wherein said step of providing a frame that is capable of supporting said radial tower segments further comprises providing said frame in a vertical orientation.  
   
   
       22 . The method of  claim 15  further comprising the step of: 
 removing said tower section from said frame.    
   
   
       23 . An assembly device for a wind turbine tower wherein said tower comprises a plurality of radial segments, said assembly device comprising: 
 a first frame for supporting a first end of each said radial segment of said tower;    a second frame for supporting a second end of said radial segment of said tower; and    a mechanism for adjusting said first frame relative to said second frame whereby said radial segments may be properly aligned during assembly.    
   
   
       24 . The assembly device of  claim 23  further comprising a measuring device that measures the alignment of said radial tower segments and wherein said mechanism for adjusting said frame makes adjustments based on said measured alignment of said radial tower segments.  
   
   
       25 . The assembly device of  claim 23  wherein said assembly device orients said radial tower segments in a substantially horizontal orientation during assembly.  
   
   
       26 . The assembly device of  claim 23  wherein said assembly device orients said radial tower segments in a substantially vertical orientation during assembly.  
   
   
       27 . The assembly device of  claim 23  wherein said first frame and said second frame are adjustable to accommodate tower sections of varying size and geometry.  
   
   
       28 . A method of assembling a wind turbine tower comprising the steps of: 
 providing a tower section that is divided into a plurality of radial segments;    supporting each of said tower segments substantially horizontally;    aligning said tower segments relative to each other; and    fastening said radial tower segments to each other.    
   
   
       29 . The method of  claim 28  further comprising the step of: 
 providing a frame to support said tower segments during assembly.    
   
   
       30 . A method of assembling a wind turbine tower comprising the steps of: 
 providing a tower section that is divided into a plurality of radial segments;    supporting each of said tower segments substantially vertically;    aligning said tower segments relative to each other; and    fastening said radial tower segments to each other.    
   
   
       31 . The method of  claim 30  further comprising the step of: 
 providing a frame to support said tower segments during assembly.    
   
   
       32 . An assembly device for a wind turbine tower wherein said tower comprises a plurality of radial segments, said assembly device comprising: 
 a frame for supporting said radial segments in a substantially horizontal orientation; and    a mechanism for adjusting the alignment of said radial segments relative to each other during assembly.    
   
   
       33 . An assembly device for a wind turbine tower wherein said tower comprises a plurality of radial segments, said assembly device comprising: 
 a frame for supporting said radial segments in a substantially vertical orientation; and    a mechanism for adjusting the alignment of said radial segments relative to each other during assembly.    
   
   
       34 . A wind turbine tower comprising: 
 a plurality of load bearing leg structures; and    a skin attached to said leg structures to provide cladding for said tower.    
   
   
       35 . The wind turbine tower of  claim 34  wherein said skin eliminates potential perching locations for birds on said tower.  
   
   
       36 . The wind turbine tower of  claim 34  wherein said leg structures are substantially aligned with a longitudinal axis of said tower and wherein said skin bears a substantial portion of torsional loads applied to said tower.  
   
   
       37 . The wind turbine tower of  claim 34  wherein a first set of said leg structures are substantially aligned with a longitudinal axis of said tower to bear bending loads applied to said tower and wherein a second set of said leg structures are attached to said first set of leg structures in a diagonal orientation to bear torsional loads applied to said tower.  
   
   
       38 . The wind turbine tower of  claim 34  wherein said leg structures define a first load path and wherein said skin defines a second load path in parallel with said first load path and wherein bending loads applied to said tower are shared between said first load path and said second load path.  
   
   
       39 . The wind turbine tower of  claim 38  wherein a majority of bending loads are borne by said first load path.  
   
   
       40 . The wind turbine tower of  claim 34  wherein said leg structures define a first load path and wherein said skin defines a second load path in parallel with said first load path and wherein torsional loads applied to said tower are shared between said first load path and said second load path.  
   
   
       41 . The wind turbine tower of  claim 40  wherein a majority of torsional loads are borne by said second load path.  
   
   
       42 . The wind turbine tower of  claim 34  wherein said leg structures define a first load path and wherein said skin defines a second load path in parallel with said first load path and wherein both bending and torsional loads applied to said tower are shared between said first load path and said second load path.  
   
   
       43 . The wind turbine tower of  claim 42  wherein wherein a majority of bending loads are borne by said first load path and wherein a majority of torsional loads are borne by said second load path.  
   
   
       44 . The wind turbine tower of  claim 34  wherein said load bearing legs bear substantially all of the loads applied to said tower and wherein said skin does not bear a significant portion of the loads applied to said tower.  
   
   
       45 . The wind turbine tower of  claim 34  wherein said skin is formed of press-broken sheet steel.  
   
   
       46 . A frame for supporting a wind turbine tower section during assembly wherein said tower section comprises a plurality of radial segments, said frame comprising: 
 a pair of frame structures disposed opposite each other to support opposite ends of said tower section wherein each of said frame structures comprises attachment points for attaching each said tower segment; and    a mechanism for adjusting said frame structures relative to each other whereby said tower segments can be aligned during assembly of said tower section.    
   
   
       47 . The frame of  claim 46  wherein said mechanism for adjusting said frame structures comprises a mechanism for translating at least one of said frame structures in three orthogonal directions.  
   
   
       48 . The frame structure of  claim 47  wherein said mechanism for adjusting said frame structures further comprises a mechanism for rotating said frame structures about a longitudinal axis.  
   
   
       49 . The frame structure of  claim 46  wherein said frame structures are disposed to maintain said tower section in a substantially horizontal orientation during assembly thereof.  
   
   
       50 . The frame structure of  claim 46  wherein said frame structures are disposed to maintain said tower section in a substantially vertical orientation during assembly thereof.  
   
   
       51 . The frame structure of  claim 46  wherein said frame structure is adjustable to accommodate tower sections of various sizes and geometries.