I. Field of the Invention
The present invention relates generally to elevating support structures or towers. More particularly, the present invention is directed to a partially counter-balanced, multi-stage pivoting support tower assembly for supporting a conventional elevated operating device of interest, such as an electric power generating wind turbine, in which ease of raising the tower and lowering the tower to service the device of interest are advantages.
II. Related Art
Support towers for electric power generating wind turbine devices, radio transmitters, cellular phone relay stations, television antennae equipment and other such elevated devices have been in use for many years. These towers usually are assembled from successive sections raised by derrick cranes or the like and bolted into place by workers who have scaled the assembled portion. The device of interest is normally fixed to a mast attached to the top section of the tower. In order to service or repair a wind turbine or other device carried by the upper-most section of the tower, service personnel must either climb the tower and work on the device in situ or disassemble the device from the tower and lower it to the ground for it to be accessible there.
Tilt-up tower constructions have also been proposed such as in U.S. Pat. No. 4,366,386. However, such towers do not have a multi-step tilt-up system with a leveraged construction which allows easy staged tilting for both placement and maintenance.
Given the above, it therefore would present a great advantage if such a tower could be erected and lowered for service without the need for cranes or workers to climb the tower or relatively high powered winches. The present invention allows these operations to be carried out from the ground and without the need for heavy equipment, only small, low-powered winch devices or the like.
By means of the present invention there is provided a collapsible, tilt-up and pivoting support tower assembly for supporting an elevated device of interest, such as an electric power generating wind turbine, which requires only a small, low-power operating winch to raise and lower the tower providing both ease of raising into place and lowering for disassembly or servicing of associated equipment. The support tower assembly of the invention includes an upper tower section and a tower base section pivotally joined together. In one embodiment, the assembly is based on three-point support in which the tower base section is also pivotally mounted on two legs and has a free leg to provide a third support point. Both the upper tower section and the tower base section are readily raised and lowered using separate cable systems and a mechanized winch. A mounting base system is provided which includes three spaced points of support for receiving the support legs for the base section and includes a pair of spaced pivotal mounts and a fixed leg receiving mount spaced from the pivotal mounts and providing an anchor point for the third leg.
In one illustrative embodiment, the free leg of the pivoting tower base section is a composite strut leg or strut support that includes converging struts. It combines with a pair of base section pivoting support legs having free upper ends and lower ends designed to be received and pivotally attached to a pair of spaced pivotal shaft mounts using openings in the lower ends thereof and pivot pins. An upper tower section is provided which is designed to attach to and pivot about a main pivot shaft connected with the free upper ends of the base section. The upper section support legs are pivotally mounted using bearings so that the upper tower section is able to pivot between an upright raised position and a lowered service or assembly position. The upper tower section includes an extended aspect extending beyond the pivot assembly which compliments the tower base section and provides an extended lever arm for ease of pivoting the upper tower section.
A winching mechanism is provided for selectively pivoting the tower base section and the upper tower section utilizing cables. Pulleys are provided to selectively reduce the cable tension force needed to pivot the upper tower section. Latching systems selectively fix the upper tower section to the tower base section and the free strut leg of the tower base section to the fixed mount to secure the tower in an upright or fully raised position. These may be in the form of removable bolts.
In the fully upright position, the tower of this embodiment assumes a slightly truncated profile on the side described by the pivoting legs. This places the center of balance of the upper tower section slightly beyond the pivot joints and thereby slightly biases the upper section toward pivoting into a lowered position when it is not retained in place. As indicated above, the upper tower section is normally latched in place by being bolted to the tower base section. Cable tension is used to replace the latch bolt when it is desired to lower the upper tower section so that lowering is accomplished by using the winch to play out cable. Thus, the cable system for the upper tower section should be in place when the upper tower section is unlatched.
It should be noted that the number of base points of support or base support configuration may be varied so long as a stable system is provided. A four-leg or four-point support embodiment along with an embodiment with a platform base are also illustrated in the detailed description.
An embodiment having an open-sided pivoting base tower section in combination with a pivoting boom or upper tower section is also described. The upper tower section pivots from the top of the lower tower section on spaced bearing assemblies and is leveraged by a tail section which, when the upper tower section is raised, nests in the open side of the base tower section where the tail is fastened to the lower tower section. The lower tower section may be bolted to a platform. The upper tower section is not truncated and is slightly biased to pivot downward when it is released by mounting the bearing assemblies slightly off center with respect to the upper tower section.
In the drawings wherein like reference characters denote like parts throughout the same:
a is a perspective schematic elevational view of one embodiment of a truss-type support tower assembly constructed in accordance with the invention shown in a fully deployed or elevated position;
b is a side elevational view of the embodiment of
c is an enlarged fragmentary schematic detail of pivot mount for a support leg of a support tower assembly;
d is an enlarged fragmentary schematic detail of a pivot assembly between an upper tower section and tower base section;
a is an enlarged schematic representations of a winch/pulley system as in
b is an enlarged schematic representation of a winch/pulley system for operating the pivot functions of the upper tower section as in
a-8f are schematic views that depict the stages of deployment or erection of a support tower of another embodiment of the invention which does not use a truss-type construction;
The detailed description is directed to one or more embodiments of the inventive concepts of the present invention and this material is presented as being representative of these concepts but is not intended to be interpreted as limiting with respect to any aspect of the invention. In view of the above, the embodiments of the drawings will be described. One embodiment is illustrated in
a and 1b illustrate in schematic form perspective and side elevational views of an embodiment of a collapsible, tilt-up support tower assembly shown in the fully deployed or elevated position. The support tower assembly, generally denoted by the reference character 10, includes a lower tower section or tower base section 12 and an upper tower section 14. The upper tower section 14 carries a vertically disposed mast 16 supported from and secured to a support member or tower tube 18. Tower tube 18 and mounting post or mast 16 or other such devices are designed to carry an elevated operating device of interest such as a wind turbine power generating device, radio transmitter, cellular phone relay station, television antennae, or other elevated equipment.
The tower base section 12 includes a pair of spaced pivotally mounted diverging support legs 20 and 22 forming two points of support. A pair of strut members 23 and 24 are connected from the upper portions of the pair of spaced diverging pivotally mounted legs 20 and 22 and converge to form a third point of support at 25. As will be described, the tower base section support legs 20 and 22, together with third point of support 25, provide an anchored, stable three-point support for the tower base section of the fully deployed tower. As best seen in the plan view of
The upper tower section 14 is designed to compliment and interlock with tower base section 12 and is mounted to pivot about a pivot shaft 44 on pivot bearing 46 and 48, which are preferable conventional split pillow block assemblies bolted together, as shown in the enlarged fragmentary view of
The upper tower section is provided with an extended aspect which includes extended fixed leg 50 and lower converging strut members 52 and 54. Strut members 52 and 54 connect to pivot shaft 44, which is, in turn, disposed to rotate inside of the bearings 46 and 48, and converge with extended leg 50 into a mounting assembly 56 which may be a pair of spaced flange plate members which includes provision to be selectively bolted (i.e., removably fixed) to the tower base section at 57. The pivoting function is accomplished with the assistance of a cable and a pulley system as will be described. A rather small mechanized winch 58 is used to raise both the tower base section 12 and the upper tower section 14. A fixed pulley is shown at 60.
The upper tower section 14 further includes a pair of converging/diverging upper leg members 62 and 64 which match and commonly connect to and pivot shaft 44 with the struts 52 and 54 at the lower ends thereof inside of the aforementioned bearings 46 and 48. The upper portions of leg members 62 and 64 converge with leg 50 to support tower tube 18 at the upper ends thereof. Lateral bracing as at 66 and X-bracing as at 67, if desired, are used to strengthen the tower structure as needed in both the base section 12 and upper tower section 14.
It will be appreciated that the pivoting complimentary sectional construction of the tilt-up support tower assembly of the invention enables greatly facilitated vertical assembly of the structure and lowering for servicing of associated elevated operating devices mounted on the top of the support tower assembly mast. In this manner, the entire tower support structure and any electric wiring cable can be assembled on the ground prior to being raised into position in sections. Generally, the operating device (not shown) will be mounted on the tower mast 16 and necessary electrical or other connections made when the upper tower section is partially raised as depicted in
The tower erecting or raising assembly steps are illustrated in
In accordance with the tower design of the invention, the raising of the support tower assembly structure is a two-step process devised to reduce both the stress on the tower structure itself and the force required to operate associated raising and control cables. As shown in
The raising process for the support tower assembly begins with the assembled structure in its fully lowered position with the pivoting legs 20 and 22 attached to the base. The bolt or the fastening device at 57 that connects the upper tower section 14 with the tower base section 12 is removed to allow the two sections to pivot independently and freely relative to each other about shaft 44. A base cable 70 is attached to be operated by winch 58 under pulley 60 and at an attachment point 72 on the base section 12 as depicted in
As depicted in
Thus, an important aspect of the present invention involves the leveraged pivot mounting and design of the upper tower section using pivot shaft 44 between sections 12 and 14 which combines with the tilt-up base to allow a rather easy two-step, tilt-up erection process. In this manner, a rather large support tower assembly can be raised and lowered for service or moving by using only a small power winch and pulley system and without the need for a crane or other piece of heavy equipment on site.
As can be seen best in
Another embodiment of a support tower in accordance with the invention is depicted in
a depicts the tower 200 in a fully lowered or initial assembly position. The base tower section is connected to a foundation at one or more base pivot connections as at 230 using pivot lugs and shafts in the manner of earlier described embodiments. The base tower section is also provided with a folding (hinged) or removable leverage strut 232 to provide additional leverage to aid in the pivoting operation making it an easy low-power lift. A lifting cable 234 is connected between the free or top end of the base tower section at 236 and a winch or other force applying device at 238, and using the leverage strut connected at 240.
b represents an initial phase of erecting the base which is continued in
As seen in
The tower is shown fully deployed with cables attached in
This invention has been described herein in considerable detail in order to comply with the patent statutes and to provide those skilled in the art with the information needed to apply the novel principles and to construct and use embodiments of the example as required. However, it is to be understood that the invention can be carried out by specifically different devices and that various modifications can be accomplished without departing from the scope of the invention itself.