Patent Application
20210362980
The invention relates to mast climbers.
Mast climbers are devices in which a powered platform ascends a mast. Used in construction, they can deliver materials and workers to particular heights along the exterior of a building more efficiently than static scaffolding.
Existing mast climbers have a number of issues. For one, the mast is usually a form of truss, constructed using steel members welded together. The sheer number of members makes welding a mast together a time-consuming task. The platform itself is usually driven by a relatively complex drive system, powered by hydraulics or a gasoline engine.
One aspect of the invention relates to a mast climber. The mast climber includes a mast and a platform. The mast is comprised of at least two segments, including a bottom segment and one or more body segments. Each segment has a sidewall that is made of sheet metal. Each segment has at least one gear rail assembly. A platform is adapted to be connected to the mast for vertical movement along the mast. The platform is equipped with a drive system that moves the platform up and down the mast using the at least one gear rail assembly.
For example, the sidewall of the mast may be made of two pieces of sheet metal, each bent into an L-shape, and welded at two opposite corners. Each segment also has a top plate and a bottom plate. The top and bottom plates from adjacent segments are bolted together. The sidewalls of each segment may have relatively large open areas to reduce both weight and wind loading. Many of the segments may be made of a lightweight metal, such as aluminum, although in some cases, the bottom segment may be made of a stiffer material, such as steel. The mast may be provided with two gear rail assemblies on opposite corners.
Another aspect of the invention relates to the drive system of a platform in a mast climber. The drive system comprises at least one electric motor with a gear adapted to engage with the at least one gear rail assembly. The drive system also comprises at least one battery. In one embodiment, the drive system may comprise two electric motors, each of which has a gear and each of which engages a separate gear rail on the mast. A second battery may be provided. The drive system may also include a backup power source. The backup power source may be a generator that can charge the batteries and provide emergency power, or it may be a third battery capable of powering one or both of the motors for some period of time.
Other aspects, features, and advantages of the invention will be set forth in the description that follows.
The invention will be described with respect to the following drawing figures, in which like numerals represent like features throughout the description, and in which:
As shown in
Instead, the segments 18, 20 are comprised of pieces of sheet metal. As can be seen in
Each segment may be constructed e.g., by taking a sheet of metal, cutting the open area 26, bending, and welding. Generally speaking, it is advantageous to make each segment as light as possible while retaining the stiffness and stability necessary to extend a reasonable height. For example, in the illustrated embodiment, the mast 12 may reach a height of 70 feet (21 meters) freestanding, and more than 300 feet (91 meters) when tethered to a building. To reduce weight, most of the segments 20 are made of aluminum, which is lighter than steel and other conventional materials. For example ⅜-inch (9.5 mm) sheet 6061 aluminum may be used for most segments 20. Most segments 20 are of an easily-handled height, e.g., 60 inches (1.5 m).
The bottom segment 18 may differ from the other segments 20 in at least some embodiments. Because the bottom of the mast 12 may require additional stiffness in order to ensure stability, the bottom segment 18 may be made of steel, and may be welded directly to the base 16. The bottom segment 18 may also be made somewhat taller than the body segments 20 of the mast, e.g., 84 inches (2.1 m). However, to facilitate mating with other segments 20, the bottom segment 18 may otherwise be made to the same dimensions. For example, each type of segment 18, 20 may have a common side width of 23.3 inches (0.59 m) on each side. Although the use of different materials for the bottom segment 18 is advantageous in terms of weight savings, in some embodiments, the segments 18, 20 may all be made of the same material. That material may be steel, particularly if the mast 12 is to be subjected to particularly extreme loading conditions.
As shown in
Each segment 18, 20 also has a top plate 36 and a bottom plate 38. The top plate 36 and the bottom plate 38 cap each segment 18, 20. As shown, the segments 18, 20 include vertical projections 40 and the top and bottom plates 36, 38 include notches 42 such that the top and bottom plates 36, 38 are aligned correctly on installation. Generally speaking, the shapes of the top and bottom plates 36, 38 match the shapes of the sidewalls of the segments 18, 20: the corners of the top and bottom plates 36, 38 are rounded where the sidewall segments are bent and sharper where the edges are welded. Both of the top and bottom plates 36, 38 have central openings 44, in both cases, squares with rounded corners. The top and bottom plates 36, 38 may be secured by welding or with fasteners.
In the illustrated embodiment, although the segments 18, 20 are mostly symmetrical about several axes, but they are nonetheless given a defined top and bottom. More specifically, the gear rails 32 have cooperating engaging structure that helps gear rail segments from adjacent mast segments 18, 20 to join together. Specifically, one end of each gear rail 32 has a notch 48. The other end of the same gear rail 32 has a corresponding projection 50. Other types of male and female complementary engaging structures may be used.
The segments 18, 20 themselves are secured by bolts inserted through sets of openings 52 in the top and bottom plates 36, 38. The sidewalls of the segments 18, 20 also have sets of openings 54 that may be used to secure structure connectors to connect the mast 12 to external structures. In the illustrated embodiment, these openings 54 are on two opposite sidewalls; the other two sidewalls have no such structures.
In some embodiments, the segments of the mast may be internally braced, e.g., with a rod that traverses from a lower corner to an upper corner on the opposite side of the segment. For example, a reinforcing rod may run between the two opposite corners to which gear rail assemblies 28 are not attached. However, in the illustrated embodiment of the mast 12, the segments 18, 20 are without internal bracing, and the present inventors have found that, for most loading conditions, such bracing is unnecessary.
As shown in
The central area 58 of the base 16 has an additional stand or foot 74 that is connected to the central area 58 itself. The additional foot 74 adds stability on center. In some embodiments, the additional foot 74 may also be connected to the interior of the bottom segment 20.
The platform 14 has the form of a box truss, wider than the base 16, but having about the same depth as the base 16. As will be described below, the central portion of the platform 14, proximate to the mast 12, is used to house the drive systems and other moving components of the platform 14; the sides of the platform 14, which are shown as open trusses in the view of
Notably, the cradle 86 does not completely encircle the mast 12. As shown in
The drive system of the platform 14 is also shown, at least in part, in
Each of the motors 92 in this embodiment is a 25HP electric motor. The transmissions 94 reduce the 1750 rpm natural speed of these motors 92 to an operating range. In the illustrated embodiment, a variable frequency drive (VFD) further reduces the motor speed controllably to a range that may be as low as 60 rpm. Altogether, the VFD is capable of driving the motors 92 at a range of speeds, ranging from a slow speed of a few feet per minute to speeds like 300 ft/min, which are more commonly seen in elevators. The VFD, whose components may be housed in the enclosure 84 on the platform 14, also serves to coordinate the movements of the two motors 92.
The advantage of having electric motors 92 and batteries 100 is that the energy to power the motors 92 may be supplied from any number of sources. For example, in some scenarios, solar panels may be installed as decking on the platform 14 to charge the batteries 100 continuously while the mast climber 10 is in operation. In the illustrated embodiment, a generator 104 is installed in its own compartment 106. The compartment 106 in which the generator 104 is installed is essentially in the center of the platform 14, again just adjacent to the mast 12, which is beneficial for the weight distribution and balance of the platform 14.
The generator 104 provides a means of charging the batteries 100, and can also be used for emergency power, should both batteries 100 fail. In the illustrated embodiment, the generator 104 is a 25 kW generator, fueled by gasoline, diesel, or a similar such fuel.
In embodiments of the invention, having a generator 104 onboard is not critical. In some embodiments, a generator may be located off the platform and connected to the batteries 100 via cabling. In other embodiments, the batteries 100 may have sufficient energy to handle typical daily movement, and a generator may be located on the ground to recharge the batteries 100 when the mast climber 10 is not in use.
When considering whether to include a generator 104, one may wish to consider the typical failure and safety scenarios. In the case of a failure or safety issue, most likely, the platform 14 need only deliver its occupants to the next floor down, from which the occupants can evacuate. Thus, in many emergencies, the platform 14 may only need to move a few feet, e.g., 10-20 feet, to accomplish that function. Given that, the capability to fully recharge both batteries 100 may not be necessary. Instead, for example, a third battery may be installed in the central compartment 106 instead of a generator. That third battery may have sufficient capacity, e.g., to power one of the motors 92 for 30 minutes, sufficient time to bring the platform 14 to ground level to evacuate its occupants.
There are other ways in which power may be supplied to the batteries 100. For example, a motor whose output shaft is turned by an outside force becomes an electrical generator and generates power. Thus, when the platform descends, the forced movement of the gears 98 against the gear rails 32 may generate power which can be routed back to the batteries 100. This “backpressure” on the motors 92 may be used in conjunction with other power sources, like solar power, to charge the batteries 100.
As those of skill in the art may note, the availability of power is only one potential safety consideration. Like many systems for which safety is a consideration, the mast climber 10 is preferably overengineered, at least in aspects that relate to safety. For example, the motors 92 may be selected such that only one is sufficient to move the platform 14 or to hold it in place against gravity. Along the same lines, depending on the amount of weight the platform 14 is intended to carry, a single motor 92 and a single gear rail assembly 28 may be sufficient.
While the invention has been described with respect to certain embodiments, the description is intended to be exemplary, rather than limiting. Modifications and changes may be made within the scope of the invention, which is defined by the appended claims.
This application claims priority to, and the benefit of, U.S. Provisional Patent Application No. 63/028,223, filed May 21, 2020.
| Number | Date | Country | |
|---|---|---|---|
| 63028223 | May 2020 | US |
