Wind Turbine Tower

Abstract

A wind tower erected on a foundation in which individual levels are formed by connecting a plurality of cast concrete panels along their vertical joints. Additional levels are installed on each prior level and secured with an all-thread post tensioning system and couplers.

Description

CROSS-REFERENCE TO RELATED APPLICATIONS

None.

STATEMENT REGARDING FEDERALLY SPONSORED RESEARCH OR DEVELOPMENT

Not Applicable.

BACKGROUND OF THE INVENTION

Wind towers have progressively grown higher and higher in order to reach wind that is more consistent. One hundred meter towers fulfill the height requirement but are so massive that construction is quite expensive and requires components that cannot be readily trucked to the site without difficulty. This invention relates to a wind turbine tower and more particularly to a wind turbine tower that may be assembled from a plurality of prestressed, precast concrete cast panels.

The art described in this section is not intended to constitute an admission that any patent, publication or other information referred to herein is “prior art” with respect to this invention, unless specifically designated as such. In addition, this section should not be construed to mean that a search has been made or that no other pertinent information as defined in 37 C.F.R. §1.56(a) exists.

BRIEF SUMMARY OF THE INVENTION

The invention provides a wind tower that may be erected on a foundation using a plurality of panels that are separately cast and brought on site for erection. Wind towers are often built to 100 meters or more in height. This means that the base of wind towers can be massive and may exceed the normal carrying limits for flatbed trucks. While it is possible to have over-size loads, often such loads must be re-routed past lower bridges, power lines and similar barriers. The invention builds wind towers of whatever height is required by forming multiple levels, with each level being made from a plurality of panels. Each panel has corbel sides that is enlarged and forms the vertical joint with adjacent panels. An all-thread post tensioning system is in each panel running vertically with couplers connecting each panel at their horizontal joints. Each corbel has ties through the corbels for strengthening and a sleeve in the corbels accepts a wire strand that may be routed through each corbel to link all panels together around the inner periphery. Ferrules inserted into the panel and bolted to the concrete are also used to make the connections between adjacent panels in each level.

Additional levels are added on top of each assembled level of panels with the all-thread post tensioning system and couplers. Near the top of each level a “wagon wheel” is formed during construction with bolts to each panel that attach “spokes” consisting of beams that extend toward the tower center such that one beam for each panel is directed toward the center of the tower.

BRIEF DESCRIPTION OF THE DRAWINGS

A detailed description of the invention is hereafter described with specific reference being made to the drawings in which:

FIG. 1 is a front elevational view of the subject of the invention shown with subterranean foundation portion below grade;

FIG. 2 is a bottom plan view with shallow depth of field of the assembled first level thereof;

FIG. 3 is a top plan view of the top level of the assembly of FIG. 1 with shallow depth of field;

FIG. 4 is an elevational view of one of the plurality of panels of the first level;

FIG. 5 is a top plan view thereof;

FIG. 6 is a bottom plan view thereof;

FIG. 7 is an enlarged view of the top plan view of FIG. 5 showing greater detail thereof;

FIG. 8 is an enlarged bottom plan view of the bottom plan view of FIG. 6 showing greater detail thereof;

FIG. 9 is a perspective view of the subject of FIG. 6 with a fragmentary part of the second level and shown from below, outside and to the left thereof;

FIG. 10 is a sectional detail taken along line 10-10 in FIG. 21 and slightly enlarged;

FIG. 11 is an enlarged section taken from area encircled by rectangular enclosure 12 in FIG. 2;

FIG. 12 is a fragmentary sectional elevation taken along line 12-12 in FIG. 11;

FIG. 13 is a top plan view of the subject of FIG. 3 and enlarged to show greater detail;

FIG. 14 is an enlarged fragmentary detail taken from the rectangular enclosure 15 in FIG. 13;

FIG. 15 is an enlarged sectional elevation taken along line 15-15 in FIG. 9;

FIG. 16 is an elevational detail taken from the area encircled by the rectangular enclosure 16 in FIG. 1;

FIG. 17 is an enlarged sectional detail with shallow depth of field taken along line 17-17 in FIG. 16;

FIG. 18 is a fragmentary elevational detail taken along 18-18 in FIG. 2;

FIG. 19 is a fragmentary elevational detail view taken from area enclosed by 19 in FIG. 18;

FIG. 20 is a fragmentary elevational detail view taken from area enclosed by 20 in FIG. 18;

FIG. 21 is a fragmentary top plan view taken along line 21-21 in FIG. 19;

FIG. 22 is a fragmentary top plan sectional detail taken along line 22-22 in FIG. 19; and

FIG. 23 is a fragmentary top plan section taken along line 23-23 in FIG. 20.

DETAILED DESCRIPTION OF THE INVENTION

A wind tower 10 is erected on a foundation 12 using multiple levels 14, with each level 14 having a plurality, shown as fourteen, of panels 16 that are separately cast and brought on site for erection. The foundation 12 is typically of concrete, and previous foundations have been huge, often six to twelve feet thick and up to sixty feet square or in diameter. Existing foundations may be used with this invention. As shown in FIGS. 1 and 17, the first level 14 of concrete panels 16 must be secured to the foundation 12. As shown, one suitable method is to use an anchor bolt system such as from Williams Form Engineering Corporation which employs long threaded anchor bolts 20 embedded in the concrete foundation 12. Any suitable anchor method may be used to anchor the first level of panels 16 to a foundation 12.

The first level of panels 16 are arranged on the foundation 12 to affix to anchor bolts 20 in the foundation. Each panel 16, as shown in FIGS. 4-10, is a cast concrete panel that may include steel reinforcing 18 and through which an all-thread post tensioning system 22 attached to anchor bolts 20 is attached. As shown in FIGS. 4-6, the panels 16 vary in width since each upper level is smaller in diameter in the wind tower.

Each panel 16 has a corbel side end 26 that is enlarged and forms the vertical joint between adjacent panels 16. An all-thread post tensioning system 22 is in each panel 16 running vertically with couplers 24 connecting each panel 16 at their horizontal joints. The post tensioning system 22 as shown is available, for example, from Williams Form Engineering Corp. and consists of an all-thread bar, couplers, local zone reinforcing, washers and nuts. The post tensioning system 22 may be threaded through the length of the panels 16 via channels 34 formed in the concrete, with or without metal or plastic corrugated ducts in the concrete of the panels 16. The connection between horizontally adjacent panels 16 is shown in FIGS. 2, 4-10, 21-23. The corbels 26 allow thinner flanges and better edge to edge alignment. Each corbel 26 may include strengthening via reinforcing cabling 30 around vertical reinforcing rods 32.

During assembly of the first level 14, several panels 16 are erected and temporarily braced while being aligned and secured to the anchor bolts 20. The first level panels may be quite large, typically eight feet wide at the base and up to fifty-six feet in height which is readily accommodated by trucks. With an eight foot width, a typical 100 meter tower's first level can be 35 feet in diameter. The upper ends of the panels 16 are preferably attached to a wagon wheel system 40 in which a plurality of rods or beams 42 are attached at one end 44 to each panel 16 and radiate inwardly like spokes of a wheel where they are secured together. As shown in FIGS. 11 and 12, the spokes or beams 42 may be structural beams such as I-beams in shape of simply steel members and are affixed to a central hub 46. The wagon wheel system 40 ensures that each level is secure adjacent its top and properly aligned prior to further attachments.

As shown in FIGS. 13 and 14, the beam ends 44 may be bolted via bolts 48 to the inner surfaces of each panel 16. Additionally, FIGS. 18 and 19 shows that additional attachments may be made between panels 16 at each corbel 26 with bent plates 50 and bolts 52. Finally, once the level is thus positioned, one or more post-tensioning rings 58 may be positioned in corbel channels 60 as best shown in FIGS. 20-23 and may be tensioned to provide increased strength for each level. The ring 58 may be a wire strand or other material for post tensioning around the inner periphery of the assembled panels 16 in a level 14.

Each additional level 14 could be constructed as above; however, ideally each succeeding level would be built at ground level as per the first level other than attaching it to a foundation. An on-site crane can then lift the next level up and place it on top of the previous level. Each level is attached to the other levels by the all-thread post tensioning system 22 such that the upper levels are always locked to the lower levels. FIGS. 7-9 and 21 shows that each horizontal edge of the panels 16 may include one or more mating alignment dimples 70 and protrusions 72. When so included, a level being placed on top of a previously assembled level may be positioned exactly where it is intended by aligning the dimples 70 with the protrusions 72.

Construction of the wind tower 10 continues with the addition of each new level. Typically, as many as seven levels may form a wind tower. At the final, top level, a bolt pattern may be included for attachment to the nacelle and mate with its bolting pattern.

The construction of the wind tower 10 has many advantages. The individual panels 16, while large at the lowest level are readily transported on truck beds since their width is easily handled by trucks. With a decreasing radius as the tower gains height, each succeeding level has smaller, lighter panels meaning that each new level is smaller and lighter than the last which eases construction. The wagon wheel system 40 means that after each level has been added the wind tower 10 is stable and construction could stop for weather, strikes or other delays unlike conventional wind towers which may not be structurally sound until completely assembled.

The wagon wheel system 40 may be temporary and could be removed after the next level is added, may be partially removed to allow room for ladders and power cables or may be permanent. The top level wagon wheel 40 may likewise be kept or partially or completely removed after the nacelle is attached.

The trapezoidal shaped panels 16 are generally trapezoidal in shape and preferably are flat or substantially flat which makes them easier to fabricate and to transport. Although they could be curved to simulate a round wind tower, each succeeding level will be more complex in the required curves so a flat panel is preferred.

While post tensioning is preferred, the height of the wind tower could dictate changes in the post tensioning which may be done as described or using any of the present systems for post tensioning including those that use grout in the holes bearing the cables.

The construction and tower as described herein also has the benefit that a single panel could be replaced as needed in the unlikely event of damage during construction from a crane, for example. The concrete construction provides a wind tower with very low deflection compared to steel. The thermal mass of concrete towers is also better for heat than steel towers and avoids convection of heat to the nacelle as is found in steel towers.

At each joint between levels or between corbels a compressible sealant may be included (not shown) to avoid the need to caulk any joints.

While this invention may be embodied in many different forms, there are shown in the drawings and described in detail herein specific preferred embodiments of the invention. The present disclosure is an exemplification of the principles of the invention and is not intended to limit the invention to the particular embodiments illustrated.

This completes the description of the preferred and alternate embodiments of the invention. Those skilled in the art may recognize other equivalents to the specific embodiment described herein which equivalents are intended to be encompassed by the claims attached hereto.

Claims

1. A wind turbine tower comprising:

a) a concrete foundation;

b) a first level of a plurality of cast, flat or substantially flat concrete panels, said concrete panels each having an enlarged corbel side along a vertical edge to which an adjacent concrete panel is secured, said corbel sides including a sleeve to accept a wire strand to link all panels in said first level around an inner periphery of said first level defined by the plurality of concrete panels;

c) a second level of a plurality of cast, flat or substantially flat concrete panels, each said concrete panel including enlarged corbel sides as in said first level and linked together in said second level as in the first level, said second level being positioned on top of said first level;

d) further levels of a plurality of cast concrete panels, each arranged on top of a lower level until the desired height has been achieved; and

e) each level of cast concrete panels including an all-thread post tensioning system and couplers to connect first to the foundation via anchor bolts and then to each level such that each level is securely secured to adjacent levels.

2. A method for fabricating a wind tower comprising the steps of:

(a) building a tower foundation including anchor points for a wind tower;

(b) forming a first tower level from a plurality of cast, flat or substantially flat concrete panels, said concrete panels each having an enlarged corbel side along a vertical edge to which an adjacent concrete panel is secured, said corbel sides including a sleeve to accept a wire strand to link all panels in said first level around an inner periphery of said first level defined by the plurality of concrete panels, linking said concrete panels together through said sleeves with wire strand;

(c) connecting said first tower level to said foundation anchor points and to an all-thread post tensioning system within each panel running vertically in each panel; and

(d) forming additional tower levels on top of a lower tower level using a plurality of said concrete panels with each said panel connected to an adjacent concrete panel in each tower level with wire strand through sleeves in corbel sides of each panel, each succeeding level being connected to a preceding level and any upper level by the all-thread post tensioning systems in each concrete panel running vertically.

3. The method of claim 2 further including the step of further providing connections between adjacent concrete panels in each level via plates in each panel and bolts.

4. The method of claim 2 further including the step of forming a wheel adjacent the top of at least one level via a plurality of spokes connected to each panel in said level and extending inwardly toward a center of the levels and interconnecting the spokes at or near said center.

5. The method of claim 2 wherein each tower level above the first level is constructed on site and lifted on top of the tower.

6. The method of claim 2 wherein each level includes a plurality of dimples and/or protrusions on the bottom and top of said panels as locating lugs to mate with another level.

7. A concrete panel for use in constructing wind towers comprising a generally trapezoidal panel having a wider bottom than a top, a pair of vertical sides with an enlarged corbel along each side, said panel defining an inner and outer face, said corbels being reinforced with reinforcing rod and cables, said concrete panel further including a plurality of openings extending from the bottom through said top to accommodate a post tensioning system.

8. The concrete panel of claim 7 wherein said corbels include a sleeve along the inner face such that a cable may be passed from one corbel to the other for interconnections to another similar panel.

9. A wind turbine tower comprising:

a) a concrete foundation;

b) a first level of a plurality of cast, flat or substantially flat concrete panels, said concrete panels each having an enlarged corbel side along a vertical edge to which an adjacent concrete panel is secured, said corbel sides being linked to each adjacent panel mechanically in said first level around an inner periphery of said first level defined by the plurality of concrete panels;

c) a second level of a plurality of cast, flat or substantially flat concrete panels, each said concrete panel including enlarged corbel sides as in said first level and linked together in said second level as in the first level, said second level being positioned on top of said first level;

d) further levels of a plurality of cast concrete panels, each arranged on top of a lower level until the desired height has been achieved; and

e) each level of cast concrete panels including an all-thread post tensioning system and couplers to connect first to the foundation via anchor bolts and then to each level such that each level is securely secured to adjacent levels.

10. The wind turbine tower of claim 9 wherein each level of said tower includes post tensioning rings securing each of the corbel sides to one another.

11. The wind turbine tower of claim 9 further including a wheel formed adjacent the top of each level by connecting each panel of said level to a spoke which in turn is connected to a central hub.

12. The wind turbine tower of claim 9 wherein said panels include a plurality of dimples and/or protrusions on the bottom and top of said panels as locating lugs to mate with another level.

13. The wind turbine tower of claim 9 further including metal plates between each mating corbel which are bolted to each corbel to thereby join each panel to the adjacent panel.

14. The wind tower of claim 9 further including a sleeve through said corbel sides such that a cable may be passed from one corbel to an adjacent corbel for interconnecting adjacent panels.

15. The wind tower of claim 14 wherein a post tensioning system is run through each corbel side sleeve and tensioned to interconnect all panels within a level.