Telescopic support tower

Abstract

A support tower for heavy loads or large structures such as a wind turbine generators, constructed of a plurality of telescopic tower sections with the outer lower tower section having a lower end supported from a foundation and at least one or more inner upper tower sections telescoped in an initial vertical nested relation within the outer lower tower section. The heavy load is mounted on an upper end of the inner upper tower section while in the initial vertical nested relation. The inner upper tower section or sections are then lifted upwardly to an extended tower height by lift mechanisms and the tower sections are secured in vertically extended position by inter-engaging wedge joint structure with bolt fasteners extending through mating wedge surfaces to retain the telescopic tower sections vertically extended and position the heavy load in a vertically elevated position.

Description

CROSS REFERENCE TO RELATED APPLICATION: [0001] This application is a continuation-in-part of pending U.S. patent application Ser. No. 09 / 729,250, filed Dec. 5, 2000, entitled “Tilt-Up and Telescopic Support Tower for Large Structures”, the disclosure of which is incorporated by reference as if fully set forth herein.BACKGROUND OF THE INVENTION [0002] 1. Field of the Invention [0003] The present invention generally relates to tall support towers for large structures, such as wind turbine generators, microwave antennas or the like, and, more specifically, to tall support towers which are constructed of multiple telescopic sections that telescopically extend vertically to the tower's full height and / or to tall support towers which are telescopically and vertically nested at the site of installation in a generally vertical position, and then extended upwardly to a final extended position to form a support tower. [0004] 2. Description of the Prior Art [0005] Wind-powered windmills and tu...

AI Technical Summary

Benefits of technology

[0014] The inner tower section or sections and the wind turbine generator are then telescopically extended vertically to a final elevated position to a final elevated position or the maximum vertical height of the tower. As the tower sections are extended to full height, segmental wedge sections mounted around the outside wall of the lower end of an inner upper section matingly engage circular wedge surfaces on the inside wall at the upper end of the lower outer tower section. The tower sections are then fastened together by securing the mated wedge components using radial bolts to form a rigid wedge joint structure. By using a telescoping tower assembly, the necessity for having extra-heavy lift cranes at the job site can be eliminated. Additionally, the towers can be telescopically lowered for maintenance access purposes, eliminating the need for extra-heavy lift cranes during maintenance activities.

[0017] The lifting mechanisms further include a guide system to guide the tower sections as they telescope vertically with respect to each other. The guide system includes upper and lower sway rollers interacting between adjacent tower sections in a manner to engage the rollers with internal and external surfaces of the tower sections as the sections are being extended. This engagement of the rollers prevents relative lateral movement between tower sections so that adjacent tower sections are kept vertical and in-line and resisting the force of side winds while telescoping upward. The guide system also prevents the tower sections from coming into contact with each other, which could cause damage to hardware installed on the inner surfaces of each tower section, as well as guiding the tower sections during assembly and retraction.

[0022] A further object of the present invention is to provide a support tower in accordance with the preceding objects in which the erection process can be safely and quickly performed by a small crew of personnel while maintaining complete stability of the tower sections during erection, with the elevating process being reversible in the event it is necessary to lower the load supported at the upper end of the tower for maintenance or replacement purposes.

[0023] Yet another object of the present invention is to provide a telescoping support tower for heavy wind turbines in which the telescoping tower sections are provided with guiding mechanisms to maintain the sections in alignment during lifting and lowering and to prevent sway that may be caused by high winds acting on the nacelle and turbine blades.

[0024] Still a further object of the present invention is to provide a support tower for supporting heavy structures at a high elevation in accordance with the preceding objects in which the cost of erection is minimized by utilizing equipment that can be easily transported to and from the site of erection, requiring the use of a minimum number of personnel during the erection procedure, enabling the erection process to be completed in a safe and efficient manner in adverse weather and lighting conditions and enabling heavy structures to be mounted on the tower when the tower sections are in vertical nested position and then extending the nested telescopic tower sections along with the heavy load to the full vertical height of the tower.

[0025] Yet another object of this invention to be specifically enumerated herein is to provide a telescopic tower for wind turbines and other structures in accordance with the preceding objects and which will conform to conventional forms of manufacture, be of simple construction and easy to use so as to provide a support tower that will be economically feasible, long lasting and relatively trouble free in operation.

Problems solved by technology

A problem existed, however, in that as the tower was tilted into vertical position, the feet of the tower conflicted with anchor bolts that protruded from the foundation which would prevent the tower from setting flat on the foundation.

However, as the tower height increased along with the generating capacity and the weight of the wind turbine generator, the costs of installation increased materially.

The transportation costs to move a heavy lift crane to a site of installation and then remove it from the site of installation, as well as the rental cost for a heavy lift crane, can be extremely high.

A typical heavy lift crane with a lifting capacity of approximately 230 tons is barely capable of installing a 750 kilowatt wind turbine generator on a tower that is about 200 feet tall.

Extra-heavy lift cranes with even higher costs are required for taller towers or heavier generators.

Use of the extra-heavy lift cranes increases costs dramatically due to the very high rental and transportation costs of these larger units.

Additional costs include the requirement for multiple large trucks and trailers for moving the extra-heavy lift crane to and from the job site, increased risk of serious accidents while traveling during movement of the crane to and from the job site, as well as at the job site, and increased wear and tear on public highways and plant site roads.

The massive size of extra-heavy lift cranes and their limited mobility require that work sites be well prepared to assure stability during the erection process.

Also, once on a job site, the cranes need to be moved frequently from one wind turbine foundation to another which further adds to high maintenance costs on the cranes and roads and expensive time-consuming moving procedures.

This is especially problematic at preferred and available job sites which are usually near the top of hills, ridges or mountains which require erection equipment to be highly mobile in order to minimize erection time and cost.

Use of the extra-heavy lift cranes means that many of the best sites cannot be used due to the excessive cost of road and pad construction needed for the larger cranes.

In job sites where such towers are erected, it is not unusual for erection work to be delayed for several days during a windy season and work is frequently delayed due to inclement weather such as rain, ice accumulation or snow.

Other constraints associated with heavy and extra-heavy lift crane use include requirements for good visibility so that the operator can see hand signals given by a load master, limited availability of extra-heavy lift cranes during periods of high construction activity, limited availability of extra-heavy lift cranes capable of erecting wind turbine generators having a capacity greater than 750 kilowatts and the time and large number of equipment components necessary to move larger capacity lift cranes to and from the site of tower erection.

The cost and availability of extra-heavy lift cranes has become a serious limiting factor to further economic development of wind energy especially in view of the ongoing development of wind turbine generators having a capacity of up to approximately 2,500 kilowatts.

Accordingly, the use of increasingly heavier wind turbine generators mounted on even taller towers has reached a point where the cost of construction has become a significant constraint to further development.

Likewise, the limited availability of extra-heavy lift cranes capable of erecting such taller towers and installing heavier wind turbine generators at the upper end thereof have introduced additional serious constraints on the development of wind-powered electrical energy generation.

While the above-identified patents and prior developments in the construction of supporting towers for wind-powered energy include towers which are pivotally supported for tilt-up erection, sectional tower constructions and telescopic tower constructions, the prior art does not disclose a tower assembly incorporating features which can be constructed to a height and weight capacity necessary to support the larger wind turbine generators without the use of extra-heavy lift cranes.

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