Vertical axis wind turbine with tensile support structure having rigid or collapsible vanes

Description

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present embodiments are generally directed to a machine for extracting rotational mechanical energy from naturally occurring wind. More particularly, the embodiments include a tensile mounted Savonius-type turbine for transmitting tensile support loads and capturing wind energy.

2. Description of Existing Art

Small or micro wind energy is one of the fastest growing forms of domestic and residential electricity generation and is a great investment for homeowners and small business owners. Small scale wind turbines can be used for anything that requires a small amount of power such as an electric gate, outdoor lights, pumping water, battery charging and the like.

Vertical axis wind turbines (VAWTs) and specifically, Savonius-type VAWTs have existed for many years. FIG. 1 illustrates a basic Savonius arrangement, include wind pattern and resulting rotation. However, practical applications have been limited due to excessive bearing wear if supported from beneath or excessive support structure requirements if supported at each end via rigid mounts. The requirement for rigid mounting and excessive wear increases costs both in terms of time and expense for materials.

Additionally, since Savonius-type turbines generally yield lower power output and thus are generally better suited for residential use, there are safety issues that come into play. A spinning piece of metal is a danger to people, especially children, as well as pets. Further, residential uses can also require a check on both noise and aesthetics as one could likely not erect a noisy, eyesore in their neighborhood.

Further still, given the current mobile, “on-the-go” world in which we live, the ability to generate and access power in various locations to run handheld or other low power devices is desirable. As described above, known VAWTs are stationary in view of the requirement for a rigid mount.

Accordingly, there is a need for a portable, physically robust, adaptable, low power generation VAWT that reduces repairability costs, including time and expense, that is safe, quiet and aesthetically acceptable for residential use.

SUMMARY OF THE INVENTION

A first embodiment is a wind power harvesting system comprising a turbine including: a bottom disk and a top disk; and a first and a second panel of material each attached at a first end thereof to the bottom disk and at a second end thereof to the top disk wherein as a result of the attachments, together the first and second panel of material are capable of forming a Savonius shape, and further wherein the first and second panels of material are collapsible.

A second embodiment is a wind power harvesting system comprising at least two turbines, each including: a bottom disk and a top disk; and a first and a second panel of material each attached at a first end thereof to the bottom disk and at a second end thereof to the top disk wherein as a result of the attachments, together the first and second panel of material are capable of forming a Savonius shape, and further wherein the first and second panels of material are collapsible.

A third embodiment is a method for producing a wind power harvesting system comprising: attaching each of a first and second panel of collapsible material to each of an inner facing side of a bottom disk and top disk, such that each of the first and second panels of material forms a semi-circular shape and a combination of both the first and second panels forms a Savonius configuration; attaching a first tension control component to an outer facing side of the bottom disk and a second tension control component to an outer facing side of the top disk; and attaching a power generating component to at least one of the first tension control component and the second tension control component.

BRIEF DESCRIPTION OF THE FIGURES

The preferred embodiments are illustrated by way of example and are not limited to the following Figures:

FIG. 1 illustrates a basic prior art Savonius arrangement;

FIGS. 2(a) through 2(c) illustrate various view of furled and unfurled turbine in accordance with an embodiment described herein;

FIGS. 3(a) and 3(b) illustrate various views of an inverted turbine in accordance with an embodiment described herein;

FIG. 4 illustrates a multiple turbine configuration in accordance with an embodiment described herein; and

FIGS. 5(a) and 5(b) illustrate furled and unfurled views of the turbine as part of a hoisting system in accordance with an embodiment described herein.

FIGS. 6a and 6b illustrate an exemplary hoisting system for unfurling a turbine described herein.

DETAILED DESCRIPTION

Various embodiments and aspects of the embodiments will be described with reference to details discussed below, and the accompanying drawings will illustrate the various embodiments. The following description and drawings are illustrative of the invention and are not to be construed as limiting the invention. Numerous specific details are described to provide a thorough understanding of various embodiments of the present invention. However, in certain instances, well-known or conventional details are not described in order to provide a concise discussion of embodiments of the present inventions. All terms used herein are intended to have their ordinary meaning in the art unless otherwise provided.

Referring to FIGS. 2a through 2c, a tensile mounted, collapsible structure 10 is shown wherein the semi-circular or hemispherical buckets or vanes 15 (hereafter “vanes”) are formed of a collapsible material such as a fabric (e.g., sailcloth) and transmit the tensile support loads through the structure as well as capturing wind energy. The vanes 15 are attached to top 20 and bottom 25 disks, made of suitable rigid material e.g., plywood, fiberglass, aluminum, reinforced foam, corrugated plastic or composites, etc. A rotating bearing 30, either in plane or above the top disk 20, with clevis or eye hook attachment (not shown) is attached to the upper tensile support structure 35, which may be cable, rope, or the like. The vanes 15 are connected to the inner-facing surfaces 20a, 25a (only outer-facing surface 20b is shown for the top disk and only inner facing surface 25a) of the top and bottom disks 20, 25 at connection points (shown as dashed lines C in FIG. 2(a)) by suitable means including glue, staples, stitching or the like. The semi-circular deployed shape of the vanes is determined by the placement of connection points C, as appropriate for a “Savonius” configuration. A preferred aspect ratio, height of vane to diameter of semi-circle formed by vane, of 6 to 8, optimizes performance. The configuration of the vanes is not limited as described, but could include multiple panels in various arrangements.

Any moving material, including wind, carries kinetic energy and momentum. The basic laws of kinematics allow an easy analysis of a first approximation of performance. Essentially, any wind-power mechanism captures energy by slowing down the speed of the wind involved.

The function of a wind turbine is to transform the wind's kinetic energy into electricity. Accordingly, we begin with the calculation of kinetic energy or E_k, where:
E_k=½MV²

And substitute the mass of the air cylinder (ρAV=M) to arrive at
E_k=½ρAV³

A Savonius vertical-axis wind turbine is a slow rotating, high torque machine that uses predominantly drag (minimal lift possible) to convert the power of the wind into torque on a rotating shaft. The rotation cannot be faster than the approaching wind speed. Because of the “C” curvature, the scoops experience less drag when moving against the wind than when moving with the wind. This differential drag causes the Savonius turbine to spin. Because it spins on a vertical axis, there is no need to have a directional device to keep the unit aligned in the path of the wind like other models. It can catch the wind in any direction and react immediately to changes in wind direction. This type of turbine is considered a “drag style” turbine from an aerodynamic point of view.

The vanes 15 can be made of fabric (e.g., nylon) or any other suitable material (e.g., woven hemp or bamboo) for collapsible version, or suitable rigid material (e.g., fiberglass, aluminum, etc.) for a non-collapsible version. If made from fabric, the vanes are constructed as flat rectangles and attached to the upper and lower disks at appropriate connection points C in order to achieve the desired scoop shape.

The vanes 15 are held to their shape by the tensile forces acting on the entire system, as well as the impinging wind force on the concave (wind-facing) side of each vane, and the cross-flow air pressure acting against the concave side of the back-winded vane. FIG. 1 illustrates wind flow and resulting direction of rotation.

The bottom disk 25 is suitably connected for translating extracted mechanical energy via first a rope, cable or other flexible means 40 which is connected to the center of bottom disk 25 which then connects to rotating shaft 43 which is part of the electrical generator, alternator, or other rotating mechanical working device 45. The rotating shaft 43 may be formed of steel, aluminum, etc. For generator 45, with improvements in non-cogging generator technology, the wind power collected by smaller-scale vertical-axis wind turbines can be more efficiently and effectively captured and utilized. For example, referring generally to the technology described in pending U.S. patent application Ser. No. 12/778,586 entitled “RADIAL FLUX PERMANENT MAGNET ALTERNATOR WITH DIELECTRIC STATOR BLOCK” the substance of which is incorporated herein by reference in its entirety, one skilled in the art can readily devise a suitable generator for capturing the wind power collected by smaller-scale vertical-axis wind turbines described herein.

In operation, the tensile loads on the system are transmitted from the upper support 35, through the rotating thrust bearing 30, to the top disk 20, through the vanes 15, through the bottom disk 25, through a connector 40 to the rotating shaft 43 of the generator or alternator 45. Thus, each component must be capable of withstanding the maximum design loads as a function of static tension and dynamic tension (caused by wind loading). The more the wind increases, the higher the tensile loads on the turbine.

The embodiments described herein do not require the shaft to pass through the vanes which leaves the air space around the vanes unblocked, thus maximizing power coefficient.

Deployment or unfurling of the collapsible structure is performed by pulling the top and bottom disks 20, 25, which are connected by/to the vanes 15, in opposite directions (usually vertically) by the tensile support members 30, 40, stretching the vanes into shape. Referring to FIG. 2c, by way of particular example, in the furled position, the bottom disk 25 rests on the generator 45, with the slack lower support rope (not shown) attaching the two therebetween, with the collapsed vanes 15, top disk 20, connecting lines (not shown), thrust bearing 30, slack upper support (not shown) further resting thereon. When collapsed, the turbine may be stored in a soft or hard shell container, improving portability. Alternatively, or in addition thereto, fasteners, such as straps formed of Velcro or having snaps or the like, could be used to maintain the collapsed state of the turbine by attaching the top and bottom disks at the edges.

Referring to FIGS. 3a and 3b, in an alternative configuration, the entire assembly described with respect to FIGS. 2a through 2c can be set up to operate inverted, i.e. with the generator 45 at the top of the system and the turbine(s) suspended beneath. A freely suspended embodiment can be built in the inverted mode, with the generator fixed at the top, connected to the turbine, and a heavy weight 33 affixed to or incorporated into the bottom disk. In this embodiment, the device would “swing” to some extent in stronger winds. Alternatively, the system could be anchored at the bottom and not free swinging.

In an alternative configuration, FIGS. 4a and 4b illustrate a particular example wherein the tensile support members 30, 40 could be attached to the top and bottom disks 20, 25 by rope, cable, and other means 44 at eye hooks 42 or other connection means located at connection points 41. The configuration resembles macrame lines. This particular macrame configuration could be on both ends or just a single end of the turbine.

Referring to FIGS. 5a and 5b, yet another embodiment utilizes multiple turbines stacked in a single tensile configuration, wherein only the top/bottom unit requires a rotating bearing. The individual turbines 48a-c are attached to each other using any known securing means including but not limited to glue, clips, nails, screws or the like and could even share a common disk at the point of connection (see FIG. 5a). This enables the torque from several turbines to be combined for output to a single generator. Alternatively, the turbines could be connected, but separated by some amount by flexible means such as rope, cable, etc. at the point of connection (see FIG. 5b). As with the single turbine configurations described above, this configuration can be inverted.

Furling of the system is accomplished by relaxing the tension on the top support and allowing the disks to collapse together, forming a cookie-like configuration with the collapsed fabric vanes sandwiched between the two disks. Furling can be accomplished in a matter of seconds, and used as a means of securing the turbine when not needed, for portability or stowing, or in the event of strong winds.

Similarly, another means of reducing or stopping power output on the device entails the use of “snuffer sock,” which can be pulled over the deployed device, thereby cutting down or off the wind flow to the vanes. A snuffer may be used in combination with deployment and furling, to prevent rotation until completely deployed and to stop rotation prior to furling. The snuffer sock material may be fabric or any other suitable material.

FIGS. 6a and 6b illustrate just one example of a hoisting system for unfurling the turbine. Two crossing masts 50(a) and 50(b) with a line 55 between them that is connected to the turbine, comes up in accordance with the directional arrows indicated through manual or mechanized means and the line 55 pulls the turbine to the unfurled position as indicated in FIG. 6b.

Generally, the portable embodiments described herein offer an improved power source for generating power in the range of 1 Watt up to multiple Kilowatts and offers at least the following advantages over existing vertical axis wind turbines: reduced cost due to need for fewer bearings and use of fabric vanes and resulting decrease in maintenance time and materials, e.g., replacement of bearings; elimination of destructive torque loads on support mounts; portability, e.g., collapsible assembly to greater than 10:1 ratio and fabric vanes are lighter in weight; on-demand furling in case of excessive wind speeds; safety concerns reduced or eliminated with replacement of sharp edge injuries, relative to rigid vanes; turbine can be hoisted into working position from any available structure of opportunity that is taller than the height of the turbine (e.g., mast, flagpole, trees (from or between), buildings, etc.). One skilled in the art can, without undue experimentation, optimize the size, dimensions and materials using the description set forth herein in order to achieve various outputs. The trade-offs between size, mounting, materials and power generation are well within the scope of this description and would be appreciated by one skilled in the art.

The applications for the portable vertical turbine system described herein are unlimited. For example, the systems described herein are ideal for use on boats and beaches, including beach houses. The power generated could be stored or used to as needed to power various electronic devices or recharge batteries.