WO2002038953A2

WO2002038953A2 - Wind tower with ladders and platforms

Info

Publication number: WO2002038953A2
Application number: PCT/US2001/042932
Authority: WO
Inventors: Leonard P. Maliszewski; Patrick C. Lashley
Original assignee: Beaird Industries, Inc.
Priority date: 2000-11-09
Filing date: 2001-11-09
Publication date: 2002-05-16
Also published as: WO2002038953A3; AU2002225600A1

Abstract

A ladder assembly (27) for a tower (10) for a wind power generation.

Description

WIND TOWER WITH LADDERS AND PLATFORMS

RELATED APPLICATION INFORMATION

This application claims the benefit of priority of U.S. patent application Serial No. 09/716,123, filed in the United States Patent & Trademark Office on November 9, 2000.

FIELD OF THE INVENTION

The present invention relates to ladders and platforms used on the interior of wind power generation towers. The ladders and platforms for use with the wind tower comprise a unique construction for use with a unique wind tower which is made from a plurality of welded rings formed into a first, bottom section, having two ends, one end with a first transition ring secured to it, and the other end having a T-shaped flange secured to it. A second, upper section made from a second plurality of rings is secured to the transition ring. The transition ring can be conical or cylindrical in shape. Into the bottom section, an access door can be mounted which is preferably a water-resistant or water tight door. A platform may be installed either on the interior of the bottom section or between the bottom section and the upper section. A first L-shaped flange can be welded to the first transition ring. The upper section can have a second L-shaped flange welded on one end of the section and a conical transition ring welded to the other end. A third L-shaped flange can be welded to the end of the conical transition ring opposite the side welded to the rings of the upper section. A platform is welded to the uppermost portion of the upper section to support the wind generator.

The ladder of this invention has hollow rungs made of polymer. The ladder is installed in the interior of each cylindrical section of the wind tower prior to arriving in the field. This ladder is designed for a wind power tower made from a number of sections.

BACKGROUND OF THE INVENTION A great deal of interest is presently being shown in the development of alternative energy sources. One type of energy in which people are showing interest in is that from the wind. New and more efficient wind turbine generators are being developed, but these need to be placed on towers, which are easy and economical to erect. Conventional towers require people to climb to the top of the towers through the interior of the towers. A need has existed for ladders and platforms in wind towers which are safe for people to use without safety equipment and easy to install.

Towers for wind generators have been described in recent patents such as U.S. Patent No. 4,935,639 for a revolving power tower, or US Patent 4,272,929 for a wind tower. None of the references teach the use of a ladder in combination with a unique wind tower which is pre- elded at the factory, then shipped to a site with minimal assembly needed in the field.

BRIEF DESCRIPTION OF THE DRAWINGS

Figure 1 is a side view of an erected tower embodying the invention with a wind turbine placed on it.

Figure 2 is a front view of an erected wind tower with a wind turbine placed on the upper section. Figure 3 shows the T-shaped flange which secures to the lowest part of a bottom section of a tower to a foundation.

Figure 4 shows the bottom section of a typical 50 meter, two section wind tower.

Figure 5 shows the upper section of a typical 50 meter, two section wind tower.

Figure 6 is a cross sectional view of a first L-shaped flange which secures to the upper section to the bottom section.

Figure 7 is a detailed view of the second L-shaped flange, which secures to the bottom section to the upper section.

Figure 8 is a cross sectional view of the third L-shaped flange, which secures to the upper part of the wind turbine generator. Figure 9 is a view of an assembled 50-meter tower.

Figure 10 is an exaggerated detailed view of the bottom section of one embodiment of the wind tower.

Figure 11 is a detailed view of a ladder attached to a platform.

Figure 12 is a view of a ladder mounted in a tower. Figure 12A is a view of a alternate ladder mounted in a tower.

Figure 13 is a perspective view of the ladder bolted to the tower.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

The present invention relates to a wind tower construction and a method of building a wind tower which utilizes a stringent and detailed certifying body that specializes in towers and wind turbines, particularly wind towers.

The present invention has been created to build a tower which is tuned to the frequency of the wind turbine generator which is placed on the top of the tower. The novel wind tower is constructed using an optimization program which determines the minimum plate thickness needed and structural components required to preclude vibration and harmonic build up in the tower created by the wind generator, while insuring strength in the tower. The method for building this tower utilizes an optimization program to determine the exact thickness for each individual plate used in the tower construction in order to both achieve minimum steel thickness (thereby reducing materials cost, the cost of transporting the tower, and the cost in man hours to cut the steel or other metal used in the tower), while maintaining structural integrity and overall strength in the tower. Each tower is also designed to various earthquake and wind parameters dictated by specialty certification-governing bodies. For each tower, the novel method of construction includes as a step, an independent review and approval of the engineered characteristics of the tower by a specialty certification-body. In one embodiment, the tower and marine certification body of Germanischer Lloyd can be used. In another embodiment, the certification body, Det Norske Veritas of Denmark, could be used.

Figure 1 shows tower 10 of the invention comprising a plurality of sections. In Figure 1, two sections 12 and 14 are shown. One end of the bottom section 12 is embedded in a cement foundation 18 to anchor and hold- the tower erect, and upper section 14 supports the wind turbine generator 20. The bottom and the upper sections are made from a plurality of rings, preferably cut from steel, aluminum or metal alloy, with each ring having the same diameter. It has been found that all sections should be of a length to allow easy transportation and assembly. Referring now in detail to the Figures, Figure 1 shows one embodiment of the present invention, a fifty-meter tower. The towers of this invention can range in height from 32 to over 80 meters. For a 50-meter wind tower 10, two tubular sections, preferably cylindrical hollow sections are used, specifically, a bottom section 12 and an upper section 14. The bottom section 12 is connected to a T-shaped flange 16, which is bolted to studs embedded in a concrete foundation 18. The concrete foundation 18 may be used with threaded rods or other materials to anchor and hold the resulting wind tower erect against the overturning movement caused by the turbine mounted to the top and when the wind reaches velocities in excess of 100 mph. The wind tower 10 is designed to support a wind turbine generator 20. Any of a variety of generators could be used, pivoting, stationary, low horsepower, and high capacity turbines. The bottom and upper sections are preferably made from steel, such as cold rolled steel, but other suitable metals can be used as well, such as aluminum or metal alloys.

The bottom section 12 and upper section 14 are preferably constructed from a plurality of rings, each ring having the same outer diameter as the others which are used to make a particular section. In Figure 2, the rings of the bottom section 12 include first bottom ring 22 which is welded to second bottom ring 24. Third bottom ring 26 is welded to both second bottom ring 24 and fourth bottom ring 28. The additional rings 30, 32 and 34 are welded together in a like manner. The outer diameter of each ring in the bottom section 12 is identical. The outer diameter of each ring, 38, 40, 42, 44, 46, 48, 50, and 52 in the upper section 14 is identical. However, the outer diameter of the rings of the bottom section 12 differs from the outer diameter of the rings in the upper section 14. The outer diameter of the rings of section 12 can be up to approximately fifty (50%) wider than the outer diameter of the rings of section 14. The diameter of the bottom section 12 could be between about 10 and about 50% larger than the upper section 14. The rings for the bottom section 12 and the upper section 14 shown in both Figures 1 and

2 are pre-welded to each other at the factory site in the most preferred embodiment. It is within the scope of the invention to consider welding the rings to each other at the tower site to form a section. The overall size of the subsequently created sections of welded rings is selected so that the sections can be transported from the factory to the site in an economical manner and with the least amount of road permits. It is contemplated that a tractor-trailer or train could be successfully used as a transport device or even a train to more the sections.

For larger towers, such as those 60 to 80 meters in height, a bottom section 12, and upper section 14 and middle section (not shown) are needed. In towers over 80 meters in height, four sections are contemplated, namely a bottom section 12, an upper section 14, and two additional sections. The additional sections can be bolted together with flanges. One or more novel conical transition rings can be used with these additional sections. If additional conical transition rings are used, then the additional conical transition rings are preferably welded onto the additional sections at the factory. If additional flanges are used on the additional rings, it is preferred that they be L- shaped flanges. In the preferred embodiment, a door 21 is placed in the bottom section 14, to permit access to the interior of the tower for painting, bolt tightening or wind turbine maintenance purposes. Preferably, the door is a water-resistant door, such as a door with an encapsulated gasket which can be locked.

Figure 3 shows a welded T-shaped flange 16 of which stub 17 forms a part, located at the lower end of bottom section 12. Stub 17 aids in the alignment and welding of T-shaped flange 16 to ring 22. Bolt holes on inside and outside bolt circles in T-shaped flange 16 allows wind tower 10 to be secured to the anchor bolting of cement foundation 18.

Figure 4 shows the bottom section 12 having the plurality of welded rings 22 to 36 having identical outer diameters and a first conical transition ring 56. A first L-shaped flange 52 is welded to the conical transition ring 56.

Figure 5 shows the upper section 14 made from a plurality of welded rings 38 to 50 having identical outer diameters. A second L-shaped flange 60 is welded to the bottom ring 38 of the upper section 14. On the top portion of upper section 14, a second conical transition ring 58 is welded to cylindrical ring 50.

Both conical transition rings 56 and 58 and rings 36 and 50, which are attached below conical transition rings 56 and 58 respectively, preferably are reinforced by having thicker plates than the plate thickness used in the adjacent rings 34 and 48, respectively, in the sections 12 and 14. In addition, L-shaped flanges 52 and 62, disposed on one side of the conical transition rings, provide additional support for the stress load transfer from the wind turbine down the tower walls.

The first transition ring 56 and conical transition ring 58 are hollow segments. The first transition ring 56 has a slightly larger diameter than the conical transition ring 58. These rings are initially cut from flat plate in a shape which is designed for the particular wind tower height selected. The cut plate is then rolled, and the ends are welded together, typically using submerged arc welding. The reinforcing of the conical transition rings can be accomplished by welding a second plate to the interior of the ring.

For a 50-meter tower, a preferred embodiment uses a bottom section having an outer diameter of 118 inches, and an upper section having an outer diameter of 90 and 15/16^th inches. A third L-shaped flange 62 is fitted to the top portion of the second conical transition ring

56. A detail of the first L-shaped flange is shown in Figure 6 and a detail of the second L-shaped flange is shown in Figure 7. The third L-shaped flange is shown in Figure 8. Each L-shaped flange has a sloping side 66 to compensate for warpage during welding.

In Figure 6, the L-shaped flange has a flange stub 54 and a sloped side 66. The conical transition ring 56 is welded to the stub 64.The sloped side 66 is used so that when the stub 54 is welded, the flange aligns flush its mating flange. The stub ends facilitate welding the flanges quickly to the ring.

In Figure 7, the second L-shaped flange 60 is shown with a flange stub 68 and a sloped side 66, the flange stub 68 being welded to the bottom ring 38 of the top section 12. In Figure 8, the third L-shaped flange 62 is shown with a flange stub 70 and a sloped side

66, the flange stub 70 being welded to the top conical transition ring 58.

On the interior of the tower is welded a ladder assembly 27 having parallel legs and rungs disposed between the legs and affixed thereto, as shown in Figure 9. The ladder is preferably made from of a polymer, PNC, fiberglass, plastic coated metal, laminate structure or combinations of those materials. The ladder assembly 27 is installed to be spaced from the interior walls of the tower using supporting brackets, which enable maintenance people to use the interior of the tower and repair the wind turbine without the need for any additional safety equipment, such as a safety harness. The ladder assembly 27 is constructed in such a manner that the back of a maintenance person is in close contact with the interior wall of the tower. Preferably, the ladder assembly is constructed no more than thirty inches away from the tower wall. In this construction, climbing occurs more safely than when the ladder is constructed at other positions. The ladder may extend from the bottom section 12 through to the top of the upper section 14 in a vertically straight configuration. In an alternate embodiment, the ladder assembly 27a may be in the form of a vertically spiral configuration, as shown in Figure 12a.

Returning to Figure 1, it is preferred that a T-shaped concrete foundation 18 be poured into a hole dug in the ground. Other foundation configurations may be possible so long as the combined natural frequency of the wind turbine generator 20, wind turbine tower 10, and concrete foundation 18 meet acceptable frequency criteria. Rebar is included to strengthen the cement surrounding the tower. Studs (not shown) can extend from the concrete pad 18 to which the metal T-shaped flange 16 which is welded to the bottom section 12, can be attached. The studs can be attached to the flange with bolts or other conventional means. The concrete foundation 18 not only gives additional stability to the tower, but also assists in dampening the natural frequency vibrations caused by the wind to the tower.

At the top of the tower 10, there is provided a platform 25 from which a wind turbine generator 20 is installed on L-shaped flange 62 of the top section 14. Pivot pins and conventional mounting means are used to allow the installed wind generator 20 to face the wind direction. Additionally, a middle platform can be installed at a midpoint or other point in the tower from which maintenance work can be done. The ladder assembly can rise vertically through the platform to facilitate maintenance activity on the interior of the tower.

Figure 10 shows one embodiment for the bottom section 12 of the wind tower 10. In this embodiment, the base may have a floor that can be slanted at an angle of from about 2 to about 10 degrees from the base's horizontal plane. The tower of this invention can be assembled in such a manner to allow only a minimum personnel to erect the tower with no specialized welding required. The first step in such a procedure is to excavate a foundation site. It is assumed that the soil around the hole is compact, undisturbed soil, although an engineer prior to construction should generally verify soil conditions. In compact, undisturbed soil it is found that the best shape of the hole would be relatively narrow and deep, allowing the amount of cement used to be kept to a minimum.

In the hole, a concrete foundation 18 is created. Studs are cast into the foundation. The bottom section 12 is placed over the studs and the T-shaped flange 16 of the bottom section 12 is bolted to the studs. The T-shaped flange 16 is welded to one end of bottom section 12. The flanges can be welded to the bottom section at the factory in the most preferred embodiment. In addition, at the factory, the transition ring 56 can be welded to the top of the bottom section 12, on the end opposite the T-shaped flange 16. Also at the factory, a first L-shaped flange 52 can be welded to the first conical transition ring 56, on the end opposite the T-shaped flange of the bottom section 12. Once the bottom section 12 is in place, the upper section 14 is raised until it reaches the top of the first transition ring 56. The upper section 14 consists of a second L-shaped flange 60 welded to the bottom portion of the upper section 14 at the factory in the preferred embodiment. The second L-shaped flange 60 is then bolted to the first L-shaped flange 52 in the field. No field welding is necessary to secure the bottom section 12 to the upper section 14. At the factory, a second conical transition ring 58 is welded to the edge of the upper section 14 which is opposite the edge of the second L-shaped flange 60. The second conical transition ring 58 has welded to it, on the side opposite the second L-shaped flange 60 of the upper section 14, a third L-shaped flange 62. To this third L-shaped flange 62 is bolted the housing 20.

Figure 9 shows the interior of the wind tower 10, where one or more platforms 25 and 29 optionally can be secured. One platform 25 is contemplated for the top of the tower. The platforms

25 and 29 preferably are bolted to studs welded to the interior of the tower. The welding preferably occurs at the factory prior to shipping of the sections to the field. In the most preferred embodiment, the tower is shipped with the ladder assembly and the platforms already installed, so that there is minimal field assembly work needed. To reduce the possibility for destruction of the wind turbine generator, the tower supporting the generator must be sufficiently strong to withstand winds in excess of 100 miles per hour. Some designs may require towers capable of enduring winds of 160 mph.

Towers of this design can be easily modified after the initial machine is placed on the tower. If, for example, the user of the tower wishes to support a heavier load or perhaps a different machine requiring a.different connection, all that need be done is to reverse the steps of assembly, unbolting and lowering the machine and unbolting and lowering the various sections starting at the top until the section which is desired to be replaced is removed. For a different type of machine, all that may be required is removing the uppermost section and replacing it with a similar section having a different means for attaching the new machine to the tower. For a heavier machine, replacement may require changing the structure of the sections to strengthen them.

The invention contemplates using cylindrical sections. For a specific example, it is contemplated that for a 50-meter tower the bottom section could have seven (7) rings, preferably each of the exact same outer diameter and the upper section would have eight (8) rings, with each ring having the same exact outer diameter. The conical transition rings for the 50-meter tower could have a slope of up to about 15 degrees.

The tower may include one coat of 20-year life paint to prevent corrosion. The tower may have optional equipment, such as two grounding lugs attached to the upper section for grounding of lightening. In addition, a control box for the wind generator turbine would be located on the interior of the tower, supporting the power and signal cables from the turbine.

As an example, an 80-meter tower may consist of four sections with three conical transition rings. In the bottom section, six (6) rings could be used, six (6) rings could be in the second section, six (6) rings could be in the third section and six (6) rings could be in the upper section. The diameter of the bottom section may be equal to the second section, which could be 5%> larger than the third section, which could be equal to the upper section. Platforms could be preinstalled in the tower at the top of each section. A marine door would be installed in the bottom section. A ladder would rise from the ground level in the bottom section to the upper section on the interior of the tower. A detail of the ladder is shown in Figure 11. Ladder legs 100 and 102 are shown bolted to a platform 116. Rungs 104 are disposed between legs 100 and 102, which may be parallel plates or parallel metal plates. The legs 100 and 102 are bolted to L-shaped platform flanges 106 and 108 respectively using standard rivets or bolts 110, 112, 114 and one other bolt not shown. The platform 116 has extensions 118 and 120 which support the platform where the ladder passes through the platform. The platform is bolted to studs in the tower walls which support the platform.

Figure 12 shows a tower 10 having an interior wall 11 with a ladder assembly 27 mounted to the interior wall of the tower. Legs 100 and 102 are shown secured by brackets 122 to bracket 144 to the interior wall 11. Platform 116 is shown mounted in the center of the tower and platform 144 is shown mounted to the top of the tower. Figure 13 is a view from the bottom of the tower of the ladder. The ladder legs 100 and 102 extend up the tower. To the legs are bolted a plurality ofbrackets including brackets 146, 148, 150, 152, 154, 158 and 160. These "J-shaped" brackets are bolted to a plurality of studs, including studs 162, 164 and 166.

Claims

1. A ladder for a wind tower wherein the wind tower comprises: an interior wall; a T-shaped flange; a bottom section having a first end and a second end, said first end being welded to said T-shaped flange, and wherein said first end with said T-shaped flange is anchored to a cement foundation; a first conical transition ring having a first edge and a second edge, said first edge welded to said second end, and said second edge welded to a first L-shaped flange; an upper section comprising a first upper end and a second upper end; a second L-shaped flange welded to said first upper end, and a second conical transition ring having a first conical edge and a second conical edge, said first conical edge welded to said second upper end and said second conical edge welded a third L-shaped flange, wherein said ladder comprises: a pair of parallel legs; a plurality of rungs disposed between said parallel legs, and a plurality of support brackets, said plurality of brackets securing said ladder to said interior wall in such a manner that said ladder is no more than thirty (30) inches from said interior wall.

2. The ladder for a wind tower of claim 1, wherein said ladder is composed of a material selected from a group consisting of polymer, PNC, fiberglass, plastic coated metal, laminated metal and combinations thereof.

3. The ladder for a wind tower of claim 1 , wherein said plurality of support brackets are in the form of J-shaped brackets.

4. The ladder for a wind tower of claim 1 , wherein at least one platform is mounted within said wind tower.

5. The ladder of claim 1 , wherein said ladder is bolted to said at least one platform mounted within said wind tower.

6. The ladder of claim 1 , further consisting of a coat of paint.

7. The ladder of claim 1, wherein said ladder rises vertically from said bottom section to said upper section.

8. The ladder of claim 1, wherein said ladder wraps around said interior wall of said wind tower in a spiral configuration.