US 20090211174 A1
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.
1. A tower for supporting heavy loads above a tower Foundation, said tower comprising a plurality of elongated tubular tower sections including at least an outer lower tower section and an inner upper tower section each including a substantially cylindrical peripheral wall, said tower sections being telescopically nestable in a generally vertical position, said outer tower section having a lower end supported from said tower foundation to enable the inner tower section to be extended vertically, said inner tower section supporting said heavy load at an upper end thereof when nested in said outer tower section, a lift mechanism interconnecting said outer and inner tower sections to telescopically extend said inner tower section and lift said heavy load to an extended tower height, and coacting mating wedge surfaces on said outer tower section and said inner tower section to form a rigid wedge joint between a lower end of said inner tower section and an upper end of said outer tower section when said tower sections are vertically extended.
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8. A tower for supporting a heavy load from a tower foundation comprising at least two elongated, telescopically associated tower sections including a lower tower section supported vertically on said tower foundation and an upper tower section telescopically nestable in relation to said lower tower section, a lift mechanism interconnecting said lower tower section and said upper tower section, said lift mechanism including a plurality of generally parallel vertical jackrods and crawler jack assemblies interconnecting said lower tower section and said upper tower section to move said upper tower section vertically to an elevated position in relation to said lower tower section, an upper end portion of said lower tower section and a lower end portion of said upper tower section each including peripheral mating wedge assemblies which are interconnected to retain said upper tower section in said elevated position and in vertical alignment with said lower tower section.
9. A tower for supporting heavy loads above a tower foundation which comprises a plurality of elongated tower sections including at least an outer tower section and an inner tower section nested in a vertical telescoped position with said inner tower section nested within said outer tower section, said outer tower section having a lower end mounted on said tower foundation to enable the nested vertically telescoped tower sections to be extended vertically, said inner tower section supporting said heavy load when nested in said outer tower section, and a lift mechanism interconnecting said outer and inner tower sections to telescopically raise said inner tower section and said heavy load to an extended tower height.
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12. A tower for supporting a heavy load from a tower foundation comprising at least two elongated, telescopically associated tower sections including a lower tower section supported vertically on said tower foundation and an upper tower section telescopically positioned in said lower tower section, a lift mechanism interconnecting said lower tower section and said upper tower section, said lift mechanism including a plurality of generally parallel vertical jackrod and crawler jack assemblies interconnecting said lower tower section and said upper tower section to move said upper tower section vertically to an elevated position in relation to said lower tower section, a lower end portion of said upper tower section including a plurality of peripheral low sway rollers guidingly engaged with a peripheral surface of said lower tower section, said lower tower section including a plurality of upper sway rollers to guide relative vertical movement of said tower sections.
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16. The method of erecting a tall support tower having a plurality of elongated telescopic tower sections above a tower foundation comprising the steps of mounting an outer tower section in vertical position on said foundation, vertically inserting an inner tower section downwardly into said outer tower section, elevating said inner tower section vertically to an expanded tower height, limiting vertical movement of said inner tower section by coacting wedge structures on the upper end of said outer town section and lower end of said inner tower section and extending fastening members through the coacting wedge structures to secure said tower sections in expanded tower height.
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18. A tower for supporting heavy loads above a tower foundation, said tower comprising a plurality of elongated tubular tower sections including at least a lower tower section and an upper tower section each including a substantially cylindrical peripheral wall, said tower sections being telescopically nested and disposed in a generally vertical position, said lower tower section having a lower end supported from said tower foundation to enable said upper tower section to be extended vertically, said upper tower section supporting said heavy load at an upper end thereof when nested in said lower tower section, and a lift mechanism interconnecting said lower and upper tower sections to telescopically extend said upper tower section and lift said heavy load to an extended tower height, coacting structures on a lower end of said upper tower section and an upper end of said lower tower section, said coacting structures being rigidly connected when said upper tower section is vertically extended by fasteners interconnecting said coacting structures.
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22. A tower for supporting heavy loads above a tower foundation, said tower comprising a plurality of elongated tubular tower sections including at least a lower tower section and an upper tower section each including a perimeter structure, said tower sections being telescopically nested and disposed in a generally vertical position, said lower tower section having a lower end supported from said tower foundation to enable said upper tower section to be extended vertically, said upper tower section supporting said heavy load at an upper end thereof when said tower sections are nested and a lift mechanism interconnecting said lower and said upper tower sections to telescopically extend said upper tower section and lift said heavy load to an extended tower height, coacting connecting structures on a lower end of said upper tower section and an upper end of said lower tower section, said connecting structure being matingly and rigidly engaged when said tower sections are vertically extended, and fasteners interconnecting said connecting-structures when said tower sections are extended to tower height.
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.
1. Field of the Invention
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.
2. Description of the Prior Art
Wind-powered windmills and turbines have been in use for many years for producing power for many purposes. Wind power to drive wind turbine generators to generate electrical energy have been used as an alternative energy source for many years, and the development of such uses of wind power is ongoing as exemplified by the following U.S. Pat. Nos.:
Initial development of wind turbine generators to produce electrical energy involved relatively small turbines and generators having a capacity of approximately 50 to 65 kilowatts, which were supported by small towers of approximately 50 to 75 feet in height. Towers of this height were typically fabricated from steel truss members of rectangular plan configuration and of lightweight construction. The lightweight construction enabled the towers to be initially positioned generally horizontally with the lower end pivotally connected to a foundation and the wind turbine and generator mounted at the upper end. The tower was then tilted upwardly to a vertical position by a cable and winch assembly or other power source to pivot the tower to a vertical position on the foundation from the generally horizontal position. This tilting of the tower provided a relatively inexpensive installation that could be quickly and efficiently completed in a short time and required the use of only small and highly mobile erection equipment. 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. This was resolved by bolting multiple steel adapter structures to the anchor bolts with the flat upper surface of each adapter receiving one of the feet on the tower. The tower feet were then bolted to the top of the adapters through matching bolt holes in the feet and top surface of the adapter.
More recent wind power generation included the development of larger and more efficient and cost-effective turbines capable of driving larger generators, having capacities up to approximately 750 kilowatts. The larger turbines and higher capacity generators required that taller support towers be provided in order to maximize the use of winds existing at higher elevations which have higher average speeds and smoother air flow characteristics than winds closer to the ground. In order to erect the larger towers to support the wind turbine generators at the higher elevations needed to maximize power production, heavy lift cranes with a lift capacity of up to 230 tons are used. The taller towers, either steel truss or tubular cross-sectional configuration are erected in sections by the crane and assembled in the vertical position. Each section of the tower is rigidly affixed to the adjacent tower sections by means of bolted connections. In the case of tubular cross-section towers the bolted connections are created through use of matching inwardly oriented flanges at each joint which contained matching bolt holes to receive the bolts. The wind turbine generators are then mounted on top of the vertically oriented tower. This procedure is effective for towers up to approximately 180 feet in height with turbine and generator assemblies weighing up to approximately 60,000 pounds.
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. An extra-heavy lift crane work site requires extensive preparation of road bases with minimal tolerance for allowable slope of the road or for side to side pitch and crane working pads which require the use of heavy temporary matting beneath the cranes. 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.
Heavy lift cranes are typically near their maximum safe working ranges when erecting wind turbine generators of 600-750 kilowatt capacity on towers as high as 200 feet. This condition makes it necessary to suspend erection work during winds in excess of 20 to 25 miles-per-hour in order to avoid excessive wind loads on the long crane booms and on the structure being lifted that exceed the safe working loads of the crane. 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. Such generators will require towers as tall as 350 feet in height with turbine generator combinations weighing in excess of 150,000 pounds. 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.
In order to overcome the constraints described above in connection with tall towers for large and heavy wind turbine generators, the present invention provides a tall tower capable of supporting a heavy wind turbine generator that starts out as multiple independent tubular tower sections which are telescopically nested inside each other while in a generally vertical position at the job site. The number of tower sections is dependent on the desired tower height and configuration and may require two, three or four, or even more, tower sections. The telescopically nested vertical sections are appropriately interconnected so as to be internally spaced one from another while oriented in a generally vertical nested position at the job site prior to vertical extension. The outermost vertical tower section has a lower end rigidly connected to a tower supporting foundation by the use of appropriate anchor bolts. One or more inner tower sections are then lifted and placed vertically in nested relation inside the outermost tower section. The wind turbine generator is then mounted on the top end of the innermost tower section.
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.
In order to telescopically extend the tower sections nested in their starting vertical position with the outermost section rigidly bolted to the foundation, lifting mechanisms in the tower are activated to extend the nested tower sections. Upper and lower sway roller assemblies are provided on the tower sections to guide the tower sections during relative vertical movement. The upper sway roller assemblies are removed after the tower sections have been vertically extended and bolted. In one embodiment, the lifting mechanism between the outermost tower section and the adjacent or second tower section nested inside the outermost section is a jacking mechanism, and the lifting mechanism between the second tower section and additional tower sections, such as a third and perhaps fourth tower section, is a cable and pulley mechanism. The cable and pulley mechanism interconnects each of the innermost upper tower sections preferably in a manner such that all of the innermost upper nested tower sections automatically extend when the jacking mechanism extends the second tower section from its nested relationship within the outer lowermost tower section.
Alternatively, additional jacking mechanisms in lieu of the cable and pulley mechanisms may be positioned internally of the second tower section to engage and lift the lower end of the third tower section, and similarly for additional tower sections, if used. The multiple jacking mechanisms can be operated simultaneously or independently through the use of manual controls or a computerized control system, giving full control of the telescoping operation.
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.
The jacking mechanism is positioned internally of the outermost lower tower section and can include crawler jacks positioned on vertical, parallel jackrods extending between the upper and lower ends of the outermost lower tower section. The crawler jacks are positioned below the second tower section and engage the lower end of the second tower section to lift it upward, or lower it downward. Preferably, conventional hydraulic jacks are used.
It is therefore an object of the present invention to provide a support tower for a wind turbine generator in which the tower includes a plurality of telescopically associated tower sections that are initially assembled in vertically nested relationship while being supported on a tower foundation with the outer lowermost tower section rigidly connected to the supporting foundation. A wind turbine generator is mounted on the upper end of the innermost upper tower section. The nested tower sections are then telescopically extended vertically to elevate the inner tower sections and the wind turbine generator to a fully extended position.
Another object of the present invention is to provide a support tower including a plurality of nested telescoped tower sections of decreasing cross-sectional area from a lower tower section to an upper tower section. The tower sections are initially nested in a vertical position with the outermost section securely anchored to the foundation and the one or more inner tower sections supported on the top of its next outermost tower section. The tower load, such as a wind turbine generator or the like, is mounted on the upper end of the uppermost tower section after which the tower sections are extended to their full vertical height to position the tower load in an elevated position.
Still another object of the present invention is to provide a telescoping support tower in which adjacent tower sections in the fully extended position have a rigid and fixed wedge joint between the lower end of the inner upper section and the upper end of the lower outer section which extends around the circumference of the joined sections.
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.
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.
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.
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.
These together with other objects and advantages that will become subsequently apparent reside in the details of construction and operation as more fully hereinafter described and claimed, reference being had to the accompanying drawings forming a part hereof, wherein like numerals refer to like parts throughout.
Although a preferred embodiment and alternative lift mechanisms for vertically extending the tower are disclosed and explained in detail, it is to be understood that the embodiment and alternatives are given by way of illustration only. It is not intended that the invention be limited in its scope to the details or sequence of construction and arrangement of components set forth in the following description or illustrated in the drawings. Also, in describing the preferred embodiment specific terminology will be utilized for the sake of clarity. It is to be understood that each specific term includes all technical equivalents that operate in a similar manner to accomplish a similar purpose.
The steps in assembling and extending the tower 10 include first the mounting of the lowermost and outermost tower section 12 onto a foundation 20. After the tower section 12 has been lifted by a suitable crane and positioned on the foundation 20, flange 22 on the lower end of tower section 12 is secured with anchor bolts 24 to fixedly and rigidly support the tower section 12 on the foundation 20. The second tower section 14 is then lifted to a position above and in alignment with the foundation-secured tower section 12 and lowered vertically into the lowermost tower section 12 for a major portion of its length, as illustrated in
After the three tower sections have been nested, the turbine generator 18 is lifted by a crane and supported on the upper end of the uppermost and third tower section 16 as illustrated in
It is noted that while three tower sections 12, 14, and 16 have been illustrated, the number of tower sections may be varied from as few as two to as many as five or more. The total number of tower sections used is determined by the total height of the tower. As illustrated in
The weight of the tower sections vary with the largest, outer tower section 12 weighing up to approximately 80,000 pounds and the combined nacelle, generator 18 hub and blade assembly forming the turbine generator weighing up to approximately 140,000 pounds. The weight characteristics of the tower sections and the turbine generator varies considerably but the necessity of lifting the tower sections for sequential vertical telescopic nesting as illustrated in
As illustrated in
The annular wedge surfaces 32 and 34 coact and engage with vertically spaced arcuate segmented wedge members 38 and 40 which are mounted around the exterior surface of a lower end portion of an upper tower section 14. The wedge members 38 and 40 include upwardly and inwardly inclined wedge surfaces 42 and 43, respectively, which mate with and rigidly engage the wedge surfaces 32 and 34 on the inside wall of the cylindrical upper end section 28 of the tower section 12. As illustrated in
The wedge members 38 and 40 include bolt holes 44 which are aligned with bolt holes 48 in the lower end of the tower section 14. The upper cylindrical end section 28 has corresponding holes 46. When the wedge members 38 and 40 are mated with wedge surfaces 32 and 34 during the vertical extension of the tower section 14 in relation to the tower section 12, bolt holes 46 and 44, 48 become aligned. Radial bolts 52 can then be extended therethrough, preferably from the interior of the tower section 14 and retaining nuts 54 threaded onto the outer end of the bolts 52 thereby to rigidly and fixedly form a wedge joint, generally designated by reference numeral 41, between the lower end of upper tower section 14 and the upper end of lower tower section 12. Wedge joint 41 retains the tower section 14 in its extended and elevated relation to the outermost and lowest tower section 12.
The above-described wedge joint anchoring connection between the tower sections as they are extended from their initial vertically nested relationship to their extended telescopic relationship provides a rigid connection between a lower end of an upper tower section and an upper end of a lower tower section. At the same time, this anchoring connection can be undone to enable upper tower sections to be lowered down into the lower tower sections if it becomes necessary to lower the turbine generator for repair or replacement. The lift mechanism that is used for elevating the upper tower sections is also used to lower the upper tower sections back to the initial nested position illustrated in
In order to maintain alignment of the bolt holes in the mated wedge surfaces 32, 34, 42 and 43, the horizontal radial bolt joint requires alignment of the sections when extending the sections from their nested position to their extended position. This alignment is necessary in order to assure that the bolt holes 46 at the top of a lower outer tower section align with the bolt holes 44 and 48 near the bottom of the next upper tower section. The alignment structure is illustrated in
Support blocks 64 are welded to the exterior of the tower section 14 in peripherally spaced and aligned relation to the alignment block 60. Each support block 64 includes a horizontal bottom surface 66 that is parallel to the bottom surface 61 of the alignment block 60. Thus, when lowered into position, the bottom surfaces 61 and 66 support the section 14 when nested in tower section 12 by engaging the upper end or top edge 129 of cylindrical upper end section 28 of the tower section 12.
In addition, in order to prevent relative rotation of the tower sections 12 and 14 during vertical movement of the upper tower section 14, a vertically extending guide bar 68 is welded to the inside of the lower tower section 12; the guide bar 68 extends substantially throughout the length of the tower section 12. A roller bracket 70 is mounted on the exterior of the upper tower section 14 and supports a pair of rollers 72 that engage opposed surfaces of the guide bar 68 as illustrated in
The guide bar 68 is accurately positioned relative to the joint bolt holes 46 and 44, 48 in the mating wedge structures 38 and 40 so as to control the rotational position of the upper tower section 14 when being telescoped upwardly in tower section 12 and maintain alignment of the bolt hole 46 with the bolt holes 44 and 48. As illustrated in
Vertical movement of the telescopic tower sections, such as tower section 14, is also guided by upper sets of sway roller assemblies, generally designated by reference numeral 80, mounted in spaced relation around the upper end section 28 of the tower section 12 (and tower section 14 in the case of a three section tower). Preferably, twelve sets of sway roller assemblies 80 are removably mounted on the upper end of lower tower section 12. The roller assemblies 80 act against the outside surface of the tower section 14 while section 14 is being nested downwardly into tower section 12 and then subsequently telescoped upwardly. In addition, lower sway control roller assemblies, generally designated by reference numeral 82, are mounted at the bottom of tower section 14 (and tower section 16 in a three tower section arrangement) which act against the inside of the shell of the lower tower section 12 to provide guidance and sway prevention control while tower section 14 is being telescoped. As illustrated in
The roller assembly 82 is initially installed on the mounting bracket 85 with only one bolt 94 while the tower section 14 is still on the ground and easily accessible. The clevis frame 84 thus hangs vertically on the one bolt 94 while the section 14 is being nested to avoid interference with the inside diameter of the wedge surfaces 32 and 34 on the cylindrical upper end section 28 at the top of the lower section 12. After nesting of the tower sections and before telescoping the nested tower sections upwardly, the clevis frame 84 is rotated on the single mounting bolt 94 to a generally horizontal position with the assistance of lever arm 96, and the other two bolts 94 are inserted and tightened. After completion of the upward telescopic movement of tower section 14 and the wedge members 38 and 40 are bolted in place with bolts 52 after mating of the wedge surfaces 32,34 and 42,43, the lower sway control roller assemblies 82 mounted on the second skirt ring 86 on tower section 14 are lowered by retracting the hydraulic jacks 100 to the bottom of tower section 12 for removal.
The upper sway control roller assemblies 80 are mounted at the top of tower section 12, and tower section 14 if a third tower section 16 is used, while the tower sections are still on the ground and easily accessible. Each upper sway control roller assembly 80 includes a roller assembly 81 and a roller assembly bracket 106, preferably in the form of a rectangular tube. The bracket 106 extends vertically approximately three feet above the top of the cylindrical upper end 28 of the lower tower section 12 and down to a pad 107 that contacts the outer surface of the conic transition member 26. The roller assembly 81 at the top of the tubular bracket 106 is positioned with clearance to the outside of the tower section 14 that is being telescoped down into tower section 12. The roller assembly 81 is pivotally mounted on bracket 106 by a shaft 83 to allow the roller assembly to swivel which permits the roller assembly 81 to swivel 30° outwardly when the sections 12 and 14 are being vertically nested. The multiple roller assemblies 80 thus form a tapered lead-in when swiveled 30° as shown in
As illustrated in
The wedge joint 41 described previously functions to provide a very strong joint when an upper section 14 is telescoped upwardly within a lower section 12 and the internal wedge surfaces 32 and 34 on the lower section 12 mate with and lockingly engage the external wedge segments 38 and 40 on the upper tower section 14. The joint is completed when the bolts 52 and nuts 54 rigidly secure the cylindrical wedge mating surfaces to one another. The mating engagement of the internal and external wedge surfaces forms a very strong joint when the surfaces are engaged by upward movement of an upper tower section to a position to enable securing bolts 52 to be inserted through the wedge structures to form the wedge joint and rigidly secure the tower sections in their extended position.
When lowering an upper tower section into a lower tower section, it is necessary that wedge members 38 and 40 be removed from the upper tower section in order for the upper tower section to move downwardly through the cylindrical upper end section 28 of the lower tower section. After the upper tower section has been lowered into the lower tower section, the wedges 38 and 40 are applied to the recesses 50 in the lower exterior surface of the upper tower section, such as tower section 14. This assembly is preferably obtained by having the wedge members 38 and 40 made of an arcuate sectional or segmented construction which can be bolted to or otherwise detachably secured in recesses 50 on the external surface of the lower end portion of the upper tower section. When the upper tower section is lowered into the lower tower section, the external diameter of the lower end of the upper tower section, without the wedge members 38 and 40 thereon can be moved downwardly into the lower tower section. After the upper tower section is moved downwardly into the lower tower section, the segmental wedge members 38 and 40 are attached to the exterior surface of the lower end of the upper tower section by bolts or the like with access to the lower end of the upper tower section being provided by a large access opening 13 at the lower end of the lower tower section 12. If it becomes necessary to move an upper tower section completely out of a lower tower section, such as when disassembling the tower, access may be had to the lower end of the upper tower section through the access opening 13 when the upper tower section is lowered thereby enabling removal of the segmental wedge members 38 and 40 so that the upper tower section can be lifted vertically upwardly out of the lower tower section.
After the segmental wedge members 38 and 40 have been applied to the lower end of an upper tower section, the upper tower section can be moved upwardly to engage the wedge members 38 and 40 with the wedge surfaces 32 and 34. The dimensional configuration of the inclined wedging surfaces is such that the bolt holes in the upper tower section in wedges 38 and 40 and the bolt holes in the cylindrical upper end portion 28 of the lower tower section will be at the same elevation. The guide 68 and rollers 72 prevent relative rotation of the tower sections thereby aligning the bolt holes to enable bolts 52 to be inserted through the inclined mating surfaces to rigidly secure the wedge joint.
To provide access to the interior of the upper tower section after it has been elevated to its final position, an internal ladder structure (not shown) is provided in the tower sections in the same manner as disclosed in the cross-referenced co-pending application Ser. No. 09/729,250 (hereinafter the “referenced '250 application”). The guide bar 68 and associated rollers 72 maintain alignment of the bolt holes in the lower and upper tower sections, in the wedge members 38 and 40, and in the cylindrical upper end section 28 of the lower tower section.
The tower sections 14 and 16 can be extended and retracted by conventional hydraulic jacks 100 on jackrods 103. The jackrods 103 have their upper ends extending through flange 29 at the lower end of the transition area 26 adjacent gussets 27 for attachment on the flange 29. Conventional hydraulic jacks useful for the present invention are available from Scanada Lifting Systems, Inc. of Bow, N.H. Depending on the size and weight of the tower section, four to eight such hydraulic jacks should be used to lift and lower each section, and preferably five or six. Alternatively, crawler jacks may be used, or a cable rigging assembly may be used to lift upper section 16, in a three or more section tower, all in the manner disclosed in the referenced '250 application. However, the cable rigging arrangement for the instant invention utilizes rope constructed of composite fibers in lieu of steel cables or wire rope. The composite fiber rope is lighter in weight for the rated strength and diameter and has greater flexibility and durability as compared to a steel wire rope. Composite fiber rope useful in the present invention is available from Puget Sound Rope Co. of Anacorta, Wash., or the Cortland Rope Co. of Cortland, N.Y.
As illustrated in
The access opening 13 also provides access to the hydraulic jacks 100 and the jackrods 103. The jacks and jackrods enable the lower sway roller assemblies 82, once separated from the lower end of the upper tower section to be lowered by the jacks after the wedge joint has been completed for removal of the lower sway rollers. Thus, by removal of the upper roller assemblies 80 and the lower roller assemblies 82, the interior and exterior of the tower sections are substantially devoid of external and internal projections.
When it becomes necessary to perform maintenance or replacement of components that can not be accomplished by accessing the interior of the extended tower through the internal ladder (not shown), the tower can be lowered by reversing the extension procedure. By sequential attachment of the lower roller assemblies 82 and the upper roller assemblies 80 to each tower section as the tower sections are lowered enables stable retraction of the tower sections. With the tower sections extended, the lower sway rollers 82 may be attached to the bottom of the upper tower section 14 and the upper roller assemblies 80 may be attached to the exterior of the upper end portion of the lower tower section 12. The upper tower section 14 then may be lowered after the bolts 52 holding the wedge joint connection are removed. Thus, the tower can be returned to the position illustrated in
The foregoing is considered as illustrative only of the principles of the invention. Further, since numerous modifications and changes will readily occur to those skilled in the art, it is not desired to limit the invention to the exact construction and operation shown and described, and, accordingly, all suitable modifications and equivalents may be resorted to, falling within the scope of the invention.