Patent Application
20130121832
This invention concerns a wind driven turbine for the generation of electricity that includes a turbine wheel rotatably mounted on a laterally extending central axis, with an electrical generator in driven relationship with the turbine wheel.
Windmills have been used for many generations for the purpose of pumping water from the ground and for generating electricity. The basic advantage of the windmill is that it uses the power of the wind to move the blades. This rotary movement is converted into various useful purposes. For example, wind turbines including turbine blades mounted on towers have been placed in areas where steady winds are prevalent and the rotary movements of the wind driven turbine blades are used to generate electricity.
In order to take maximum advantage of the wind energy, the blades of the conventional wind turbines are very large and must be made of expensive rigid material, with no extra support at the outer tips of the blades. The conventional wind turbine blades rotate at a high rate of revolutions and must withstand both the centrifugal forces generated by the fast revolution of the blades and the cantilever bending forces applied to the blades by the wind. Since the outer portions of the blades move at a very high velocity and are engaged by strong winds, the larger the blades the stronger they must be and the more expensive they become. Thus, there is a practical limit as to the length and width of the turbine blades.
Another wind turbine concept is disclosed in U.S. Patent Publications 2010/0266407 A1 and 2010/0264663 A1. These wind turbines have a turbine wheel that includes an elongated central axle structure and an outer concentric circular rail, and support cables extend radially form the ends of the axle structure and converge inwardly toward connection with the outer concentric rail, similar to the conventional bicycle wheel. In this way, the outer concentric circular rail is firmly yet rotatably supported in its concentric relationship with the central axle structure. Turbine blades extend radially between and are supported at their ends by the central axle structure and the outer concentric circular rail. With this construction the turbine blades are not self-supportive at their outer ends, but are supported at their ends by the central axle structure and the outer concentric circular rail.
The outer concentric circular rim supports the outer portions of the turbine blades so that the force of the wind applied to the blades may be absorbed to a major extent by the outer rim so there is little if any cantilever force applied to the blades. This allows the blades of the wind turbine to be formed of lighter weight material, material that is not required to bear as much stress in comparison to the typical free bladed turbine. This also allows the use of turbine blades that may be much longer than the blades of conventional prior art wind turbines.
An electrical generator may be mounted to the turbine wheel, such as to the outer concentric circular rail to generate electricity in response to the atmospheric wind engaging the blades and rotating the turbine wheel.
In addition to the above noted recent developments, it would be desirable to increase the effective forces of the atmospheric winds against the turbine blades of a wind turbine, particularly in slow wind conditions. For example, the prior art teaches the use of a shroud mounted about the turbine blades of a wind turbine that develops a zone of high velocity wind at the blades of the wind turbine to form a greater air pressure differential across the blades of the wind turbine. See U.S. Patent Publications 2020/0308595 A1, 2011/0085901 A1, and U.S. Pat. No. 6,849,965 B2. However, the shrouds add to the weight of the overall structures and it appears that the turbine blades are of conventional short and heavy cantilever designs and do not have the blade length for higher performance.
Thus, it would be desirable to produce and use a wind turbine that has light weight long turbine blades and includes a means for inducing a zone of low pressure air at or behind the turbine blades for increasing the pressure differential across the blades, thereby enabling the wind turbine to be more efficient, particularly during low wind conditions.
Briefly described, this disclosure sets forth the features of a wind turbine that is powered by atmospheric wind and which can be used to create rotary energy that is transformed into an end product, such as to drive an electrical generator, to run a grist mill, or to pump water. The end use may vary in accordance with need, but a practical end use for the wind turbine is to create electricity by driving a generator.
A turbine wheel is mounted on a mast or other turbine wheel support for generating power by rotating in response to oncoming atmospheric wind. The turbine wheel includes a central axle structure for mounting on the turbine wheel support, a perimeter rim extends coaxially about the central axle structure and rotates about the central axle structure. An airfoil is mounted to the perimeter rim and is rotatable with the perimeter rim about the central axle structure.
A plurality of turbine blades are mounted in the turbine wheel and each blade includes an inner end supported by the central axle structure and an outer end supported by the perimeter rim.
A plurality of cables extend between the central axle structure and the perimeter rim and support the perimeter rim from the central axle structure such that said perimeter rim is rotatable about said central axle structure.
The air foil is shaped to redirect the atmospheric wind in an outwardly directed approximately conical shape extending downstream from the central axle structure for forming a reduced atmospheric air pressure downstream of the airfoil for enhancing the movement of atmospheric air through the plurality of turbine blades.
The perimeter rim may extend radially outwardly from the air foil, and an electrical generator may be positioned at the perimeter rim for converting the rotatory movements of the perimeter rim into electricity.
The central axle structure of the turbine wheel supports the turbine wheel on a horizontal axis and the turbine wheel is movable on the turbine wheel support about a vertical axis to face the changing directions of oncoming wind.
The airfoil may be connected to the perimeter rim and move in unison with the perimeter rim. The air foil may be formed of a series of air foil segments extending about the perimeter rim.
Other objects, features and advantages of this invention may be understood upon reviewing the accompanying drawings when taken in conjunction with the following specification and claims.
Referring now in more detail to the drawings in which like numerals indicate like parts throughout the several views,
The turbine wheel includes a central axle structure 16 that is supported by the mast 12, with the central axle structure being horizontally oriented and rotatable about a horizontal axis 18.
Turbine wheel 14 includes a circular turbine blade support ring 19 extending concentrically about and rotatable about said central axle structure. The circular turbine blade support ring 19 includes perimeter rim 20 that extends coaxially about the central axle structure 16 and that is rotatable about the central axle structure 16, and circular airfoil 22 mounted inwardly of perimeter rim 20 and also extending circumferentially about said central axle structure. A plurality of turbine blades 24 extend radially from the central axle structure 16 to the circular turbine blade support ring 19. The turbine blades 24 are supported at their inner ends by the central axle structure 16 and at their outer ends by the circular turbine blade support ring 19.
While only three turbine blades 24 are illustrated in
As shown in
Airfoil 22 is a part of turbine blade support ring 19 and is a circular structure that is also coaxial with respect to the central axle structure 16. Airfoil 22 is joined to the perimeter rim 20 and to the turbine cables 26. Accordingly, airfoil 22 rotates in unison with turbine wheel 14 about central axle structure 16, as will be described in more detail hereinafter.
The atmospheric wind 36 moves toward the front edge of the turbine blades 24 and travels across the lift surface 32 and stable surface 34 as shown by the dash lines of
The longitudinal axis 30 of the air foil 22 is oriented at an angle of attack 39 with respect to the direction of the on-coming atmospheric wind 36. The angle of attack 39 typically will be approximately 20° from the direction of the oncoming atmospheric wind 36.
It can be seen from the trailing wind direction illustrated at 38 that a substantial redirection of the atmospheric wind takes place as the wind travels across the airfoil 22. This redirection of the atmospheric air induces a reduced air pressure at and behind the perimeter rim 20. The reduced air pressure at and behind the turbine wheel tends to increase the velocity of the oncoming atmospheric air.
As shown in
As the turbine wheel rotates the turbine blades 24, the turbine wheel develops centrifugal forces, but the circular shape of the turbine blade support ring 19, including its perimeter ring 20 and air foil 22, bear most of the centrifugal forces instead of the turbine blades. This allows the use of increased dimensions and weights of the turbine blades. The centrifugal force tends to increase the stability of the overall turbine wheel and also increase the effective strength that supports the turbine blades, adding to the possible dimensions and weights of the turbine blades in high atmospheric wind conditions.
As shown in
As shown in
The air foil 22 may be hollow with spars and other conventional interior structural means, as is conventional in the art.
The turbine blades may be made of fiberglass, polyvinylchloride, woven fabric or other materials suitable for the predicted atmospheric conditions, and that hold their shapes over an extended time use.
The cables 26 may be made of various metal materials or non-metal materials. The expression “cables” is to include other structures, preferably of light weight material, that function in tension to hold the turbine blade support ring in place, such as rods or spokes under tension.
It will be understood by those skilled in the art that while the foregoing description sets forth in detail preferred embodiments of the present invention, and modifications, additions, and changes might be made thereto without departing from the spirit and scope of the invention, as set forth in the following claims.
