U.S. patent application number 17/588796 was filed with the patent office on 2022-07-21 for vertical axis wind turbine.
The applicant listed for this patent is DME Wind Energy Corporation. Invention is credited to Douglas Bachli, Patrick R. Conarro, Sid J. Reyna, Darrin Trussell.
Application Number | 20220228555 17/588796 |
Document ID | / |
Family ID | |
Filed Date | 2022-07-21 |
United States Patent
Application |
20220228555 |
Kind Code |
A1 |
Reyna; Sid J. ; et
al. |
July 21, 2022 |
Vertical axis wind turbine
Abstract
A vertical axis wind turbine (VAWT) with improved and optimized
wind-directing, wind-shaping, and wind-power conversion features is
disclosed. The shapes of these features directly affect the ability
of the VAWT to use the power of moving air, such as wind, to spin a
rotor and create torque on a rotor shaft to generate electricity.
The wind-power-conversion mechanical efficiency of the invention is
significantly improved over previous efforts, to the point that the
invention can convert wind energy into electrical power at a
price-to-performance ratio that competes with or surpasses existing
alternative energy technologies.
Inventors: |
Reyna; Sid J.; (Colorado
Springs, CO) ; Conarro; Patrick R.; (Cascade, CO)
; Bachli; Douglas; (Masonville, CO) ; Trussell;
Darrin; (Masonville, CO) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
DME Wind Energy Corporation |
Fort Collins |
CO |
US |
|
|
Appl. No.: |
17/588796 |
Filed: |
January 31, 2022 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
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16841406 |
Apr 6, 2020 |
11236724 |
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17588796 |
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15193659 |
Jun 27, 2016 |
10612515 |
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16841406 |
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62184742 |
Jun 25, 2015 |
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International
Class: |
F03D 3/04 20060101
F03D003/04; F03D 3/00 20060101 F03D003/00; F03D 15/00 20060101
F03D015/00 |
Claims
1. A vertical axis wind turbine, comprising: at least one rotor
blade adapted to turn a shaft; a rotationally symmetric stator
skirt, wherein at least a portion of a wind-facing surface of the
stator skirt is parabolic, and wherein the stator skirt has a
horizontal cross-section of an ellipse; and at least one stator
fin, each stator fin being attached at a bottom of the stator fin
to the stator skirt and comprising a fin flip, the fin flip being
disposed at an angle of .beta. relative to a longitudinal axis of
the stator fin and adapted to compress wind and direct the wind to
the at least one rotor blade in a predetermined direction, wherein
a height-to-width ratio of the vertical axis wind turbine is
between 0.1 and 3.0.
2. The vertical axis wind turbine of claim 1, wherein the
predetermined direction is counterclockwise.
3. The vertical axis wind turbine of claim 1, wherein the at least
one rotor blade comprises three rotor blades.
4. The vertical axis wind turbine of claim 1, wherein at least one
of a leading vertical face and a trailing vertical face of each
rotor blade is arcuate or parabolic.
5. The vertical axis wind turbine of claim 1, wherein the at least
one stator fin comprises three stator fins.
6. The vertical axis wind turbine of claim 1, wherein the
wind-facing surface of the stator skirt comprises a lower conical
portion and an upper parabolic portion.
7. The vertical axis wind turbine of claim 1, wherein an angle
.alpha. between the wind-facing surface of the stator skirt and a
horizontal axis, as measured by an average or at any point of the
stator skirt, is less than 45.degree. or more than 55.degree..
8. The vertical axis wind turbine of claim 7, wherein angle .alpha.
is between 35.degree. and 40.degree. or between 55.degree. and
65.degree..
9. The vertical axis wind turbine of claim 1, wherein the ellipse
is a circle.
10. A vertical axis wind turbine, comprising: at least one rotor
blade adapted to turn a shaft; a rotationally symmetric stator
skirt, wherein at least a portion of a wind-facing surface of the
stator skirt is parabolic, and wherein the stator skirt has a
horizontal cross-section of an ellipse; a rotationally symmetric
amplifier skirt, wherein at least a portion of a wind-facing
surface of the amplifier skirt is parabolic, and wherein the
amplifier skirt has a horizontal cross-section of an ellipse; and
at least one stator fin, each stator fin being attached at a bottom
of the stator fin to the stator skirt and comprising a fin flip,
the fin flip being disposed at an angle of .beta. relative to a
longitudinal axis of the stator fin and adapted to compress wind
and direct the wind to the at least one rotor blade in a
predetermined direction, wherein a height-to-width ratio of the
vertical axis wind turbine is between 0.1 and 3.0.
11. The vertical axis wind turbine of claim 10, wherein at least
one of a leading vertical face and a trailing vertical face of each
rotor blade is arcuate or parabolic.
12. The vertical axis wind turbine of claim 10, wherein the
wind-facing surface of the amplifier skirt comprises an upper
conical section and a lower parabolic section.
13. The vertical axis wind turbine of claim 10, wherein at least
one of the ellipse of the stator skirt and the ellipse of the
amplifier skirt is a circle.
14. A vertical axis wind turbine, comprising: at least one rotor
blade adapted to turn a shaft; at least one rotor plate attached to
the at least one rotor blade at one or both of a top and a bottom
of the at least one rotor blade; a rotationally symmetric stator
skirt, supporting the at least one rotor plate and comprising N
identical trapezoidal panels, each trapezoidal panel forming an
angle .alpha. with respect to a horizontal axis, the stator skirt
having a horizontal cross-section of a regular polygon having N
sides; at least one stator fin, each stator fin being attached at a
bottom of the stator fin to the stator skirt and comprising a fin
flip, the fin flip being disposed at an angle of .beta. relative to
a longitudinal axis of the stator fin and adapted to compress wind
and direct the wind to the at least one rotor blade in a
predetermined direction; and a top frame, attached to a top of each
stator fin, wherein angle .alpha. is less than 45.degree. or more
than 55.degree..
15. The vertical axis wind turbine of claim 14, wherein the
predetermined direction is counterclockwise.
16. The vertical axis wind turbine of claim 14, wherein the at
least one rotor blade comprises three rotor blades.
17. The vertical axis wind turbine of claim 14, wherein each of a
leading vertical face and a trailing vertical face of each rotor
blade is semielliptical.
18. The vertical axis wind turbine of claim 14, wherein angle
.alpha. is one of (i) more than 12.degree. and less than 45.degree.
and (ii) more than 55.degree. and less than 80.degree..
Description
CROSS-REFERENCE TO RELATED APPLICATIONS
[0001] This application is a continuation of U.S. patent
application Ser. No. 16/841,406, filed 6 Apr. 2020, which is a
continuation-in-part of U.S. patent application Ser. No.
15/193,659, filed 27 Jun. 2016, now U.S. Pat. No. 10,612,515, which
in turn claims the benefit of U.S. Provisional Patent Application
62/184,742, filed 25 Jun. 2015, the entireties of both of which are
incorporated herein by reference.
FIELD OF THE INVENTION
[0002] This disclosure relates to methods, devices, and systems
directed to improving wind directing, shaping, and power
conversion, to create torque on a rotor shaft to generate
electricity.
BACKGROUND OF THE INVENTION
[0003] Although wind power has the potential to provide a large
proportion of the world's electricity needs, the variability in the
velocity of the wind often makes it an unreliable power source. In
particular, this variability makes it difficult to construct
wind-driven power-generating devices that are effective and
efficient under all wind conditions. By way of non-limiting
example, the devices disclosed in U.S. Pat. No. 3,942,909 to
Yengst, U.S. Pat. No. 4,632,637 to Traudt, and U.S. Pat. No.
4,818,181 to Kodric concentrate low and moderate winds to produce
power and are designed to fold or feather in high winds; while
these techniques protect the structural integrity of the device,
they also decrease the device's ability to produce power in high
winds. Conversely, by way of non-limiting example, the device
disclosed in U.S. Pat. No. 5,391,926 to Staley et al. can harness
high winds for power production, but is not capable of generating
adequate torque for continual, reliable power generation in low or
moderate winds.
[0004] One offered solution for the problem of variable wind
velocity has been the vertical axis wind turbine (VAWT). Unlike
horizontal axis (propeller-type) windmills, VAWTs pivot about a
long vertical axis, such that they may face directly into a wind. A
VAWT, therefore, can harness wind energy from large columns of air,
making them practical for power generation in low and moderate
winds. When combined with features that allow a wind-driven power
generator to operate robustly in high winds, a VAWT can be used to
generate power in a wide range of wind conditions. By way of
non-limiting example, one such device is disclosed in U.S. Pat. No.
6,538,340 to Elder. However, given their relative complexity
compared to horizontal axis windmills, VAWTs continue to suffer
from lower cost efficiency than other alternative energy
technologies.
[0005] There is a long-felt need for VAWT devices with improved
cost efficiency, which preferably would provide continual, reliable
power generation in all wind conditions at costs comparable to
other alternative energy generation methods, devices, and
systems.
SUMMARY OF THE INVENTION
[0006] Certain embodiments include a vertical axis wind turbine,
comprising at least one rotor blade, turning a shaft; at least one
rotor plate, attached to the at least one rotor blade at one or
more of a top and a bottom of the at least one rotor blade; a
rotationally symmetric stator skirt, supporting the at least one
rotor plate and comprising N identical trapezoidal panels, each
trapezoidal panel forming an angle .alpha. relative to a horizontal
axis, the stator skirt having a horizontal cross-section of a
regular polygon having N sides; at least one stator fin, each
stator fin being attached at a bottom of the stator fin to the
stator skirt and comprising a fin flip, the fin flip being forming
an angle .beta. relative to a longitudinal axis of the stator fin
and adapted to compress wind and direct the wind to the rotor
blades in a predetermined direction; and a top frame, attached to a
top of each stator fin.
[0007] In some embodiments, the predetermined direction is
clockwise. In other embodiments, the predetermined direction is
counterclockwise.
[0008] In certain embodiments, the at least one rotor blade may
comprise three rotor blades. In some of these embodiments, each of
the three rotor blades is disposed at an angle of 120.degree.
relative each of the other two rotor blades.
[0009] In certain embodiments, each of a leading vertical face and
a trailing vertical face of each rotor blade may be semielliptical.
In some of these embodiments, a distance between the leading
vertical face and the trailing vertical face may be greatest at a
center of each face, such that the horizontal cross-section of the
rotor blade is a crescent. In other embodiments, a distance between
the leading vertical face and the trailing vertical face may be
uniform, such that the horizontal cross-section of the rotor blade
is of constant width.
[0010] In some embodiments, the at least one stator fin may
comprise three stator fins. In other embodiments, the at least one
stator fin may comprise six stator fins.
[0011] In some embodiments, the at least one stator fin may be
disposed in an arrangement that is rotationally symmetric about the
shaft. By way of non-limiting example, the at least one stator fin
may comprise three stator fins spaced 120.degree. apart, or may
comprise six stator fins spaced 60.degree. apart.
[0012] In some embodiments, .beta. may be between about 15.degree.
and about 75.degree., more preferably between about 30.degree. and
about 60.degree., and most preferably about 45.degree..
[0013] In some embodiments, a length of each fin flip may be about
2 inches. In some embodiments, N may be between 3 and 9, more
preferably between 4 and 8, and most preferably 6.
[0014] In some embodiments, .alpha. may be between about 12.degree.
and about 80.degree., more preferably between about 24.degree. and
about 70.degree., and most preferably about 36.degree. or about
60.degree..
[0015] In some embodiments, the rotor blades may be separate
components, each attached to the at least one rotor plate but not
attached to the other rotor blades. In other embodiments, the rotor
blades may be interconnected to form a unitary rotor.
[0016] In some embodiments, the at least one rotor plate may
comprise two or more rotor plates, the two or more rotor plates
being vertically stacked and independently moveable.
[0017] In some embodiments, at least one rotor plate may have at
least one gap or hole to allow vertical air flow.
[0018] In certain embodiments, the vertical axis wind turbine may
further comprise an amplifier skirt, disposed on a top of the
vertical axis wind turbine and attached to the top frame. The
amplifier skirt may be, but need not be, a "mirror image" of the
stator skirt.
[0019] In some embodiments, the at least one rotor blade may have a
diameter greater than a radius of the at least one rotor plate to
which the at least one rotor blade is attached.
[0020] Various embodiments of the present invention are directed to
wind turbine designs that employ both aerodynamic lift and drag
forces, in concert with back pressure relief, in a consolidated
vertical-axis wind turbine apparatus utilizing stator and rotor
blades so as to provide an omni-directional vertical-axis wind
turbine, having an increased capacity to convert wind energy to
electrical energy. The stator blades are designed, adapted and
configured do reduce back pressure, while providing a means for
effectively transferring torque to the rotor blades, which in
certain embodiments, are designed as bidirectional airfoils, and
therefore, are conducive to the laminar conduction of wind through
or around the device. In preferred embodiments, oncoming wind that
is oriented nearly perpendicular to the stator is shaped in a
desired fashion to achieve channeling of the wind into the interior
of the device so as to rotate the rotor by being directed (e.g. via
the flip angle of the end of a stator) so as to achieve desired
overall operating efficiencies and to increase the wind directional
aggregate of the device.
[0021] The shapes of blades employed can vary, but are preferably
selected to be conducive to the laminar flow of wind through the
device, with stator and bade configurations selected to maximize
the induced torque potential and to improve attack angles. The
stator/rotor combination is therefore selected to be effective for
increasing both wind speed and pressure, by means of the
conservation of angular momentum.
[0022] In certain embodiments, the device is devoid of a rounded,
symmetrical base unit (or top unit), with some such designs instead
employing particular linear surfaces in a manner to direct incoming
wind to effectively achieve desired attack angles to the rotor so
as to maximize efficiencies. Certain embodiments include a housing
that includes a top coupled to a bottom via one or more optional
supports, which may include stator elements. The housing may
include surfaces adapted to direct wind from outside the housing to
inside the housing toward the rotor. While the housing may be
surrounded by a net or screen, preferred embodiments eliminate the
same. In other embodiments, a top structure is provided that is
generally symmetrical and the mirror image of the base unit, such
that the same linear surfaces are designed to funnel and direct and
shape the wind into the interior of the device. While the top-most
surface of the top of the device may be curved to direct water or
outside air as desired, in other embodiments the top surface is
relatively flat so as to accommodate the stacking of at least two
units atop each other. In such a manner, a user can decide to stack
units to achieve higher vertical structures, with wind energy
generation possible at each level, thus adding some redundancy to
the overall system, and also providing the ability to slightly
change the internal and working components of the individual units
to adjust for differences in wind conditions. For example,
different sized and shaped rotors or stators can be employed with
two stacked units, thus facilitating some variety of performance
between the two units in any given wind condition experienced. In
some stacked configurations, the air from one unit may be directed
advantageously into the other unit.
[0023] Various embodiments of the present invention include a
plurality of wind turbine diffusers to increase the velocity of the
air entering the turbine's rotor plane, thus increasing the power
output and efficiency by having air being accelerated over the
turbine rotor blades.
[0024] In certain embodiments a static diffuser about a horizontal
axis, but rotatable about the vertical axis, may be employed, and
in still other embodiments, the diffuser further comprises one or
more vent structures located on the exterior surface.
[0025] In aspects of the present disclosure, a vertical axis wind
turbine comprises at least one rotor blade, turning a shaft; a
rotationally symmetric stator skirt, wherein at least a portion of
a wind-facing surface of the stator skirt is parabolic, and wherein
the stator skirt has a horizontal cross-section of an ellipse; and
at least one stator fin, each stator fin being attached at a bottom
of the stator fin to the stator skirt and comprising a fin flip,
the fin flip being disposed at an angle of .beta. relative to a
longitudinal axis of the stator fin and adapted to compress wind
and direct the wind to the rotor blades in a predetermined
direction.
[0026] In embodiments, the predetermined direction may be
counterclockwise.
[0027] In embodiments, the at least one rotor blade may comprise
three rotor blades.
[0028] In embodiments, at least one of a leading vertical face and
a trailing vertical face of each rotor blade may be arcuate or
parabolic.
[0029] In embodiments, the at least one stator fin may comprise
three stator fins.
[0030] In embodiments, the wind-facing surface of the stator skirt
may comprise a lower conical portion and an upper parabolic
portion.
[0031] In embodiments, an angle .alpha. between the wind-facing
surface of the stator skirt and a horizontal axis, as measured by
an average or at any point of the stator skirt, may be less than
about 45.degree. or more than about 55.degree.. The angle .alpha.
may, but need not, be between about 35.degree. and about 40.degree.
or between about 55.degree. and about 65.degree..
[0032] In embodiments, the ellipse may be a circle.
[0033] In embodiments, the vertical axis wind turbine may have a
height-to-width ratio of between about 0.1 and about 3.0.
[0034] In aspects of the present disclosure, a vertical axis wind
turbine comprises at least one rotor blade, turning a shaft; a
rotationally symmetric stator skirt, wherein at least a portion of
a wind-facing surface of the stator skirt is parabolic, and wherein
the stator skirt has a horizontal cross-section of an ellipse; a
rotationally symmetric amplifier skirt, wherein at least a portion
of a wind-facing surface of the amplifier skirt is parabolic, and
wherein the amplifier skirt has a horizontal cross-section of an
ellipse; and at least one stator fin, each stator fin being
attached at a bottom of the stator fin to the stator skirt and
comprising a fin flip, the fin flip being disposed at an angle of
.beta. relative to a longitudinal axis of the stator fin and
adapted to compress wind and direct the wind to the rotor blades in
a predetermined direction.
[0035] In embodiments, at least one of a leading vertical face and
a trailing vertical face of each rotor blade may be arcuate or
parabolic.
[0036] In embodiments, the wind-facing surface of the amplifier
skirt may comprise an upper conical section and a lower parabolic
section.
[0037] In embodiments, at least one of the ellipse of the stator
skirt and the ellipse of the amplifier skirt may be a circle.
[0038] In embodiments, the vertical axis wind turbine may have a
height-to-width ratio of between about 0.1 and about 3.0.
[0039] In aspects of the present disclosure, a vertical axis wind
turbine comprises at least one rotor blade turning a shaft; at
least one rotor plate attached to the at least one rotor blade at
one or both of a top and a bottom of the at least one rotor blade;
a rotationally symmetric stator skirt, supporting the at least one
rotor plate and comprising N identical trapezoidal panels, each
trapezoidal panel forming an angle .alpha. with respect to a
horizontal axis, the stator skirt having a horizontal cross-section
of a regular polygon having N sides; at least one stator fin, each
stator fin being attached at a bottom of the stator fin to the
stator skirt and comprising a fin flip, the fin flip being disposed
at an angle of .beta. relative to a longitudinal axis of the stator
fin and adapted to compress wind and direct the wind to the rotor
blades in a predetermined direction; and a top frame, attached to a
top of each stator fin, wherein .alpha. is less than about
45.degree. or more than about 55.degree..
[0040] In embodiments, the predetermined direction may be
counterclockwise.
[0041] In embodiments, the at least one rotor blade may comprise
three rotor blades.
[0042] In embodiments, each of a leading vertical face and a
trailing vertical face of each rotor blade may be
semielliptical.
[0043] In embodiments, the at least one stator fin may comprise
three stator fins.
[0044] The present invention generally comprises a wind turbine
that permits a large fraction of the energy of incident wind to be
converted to useful work. The unique construction of the wind
turbine thus yields a more efficient wind turbine that is adaptable
to many uses, including not only energy generation form wind, but
from water in tidal applications.
[0045] While specific embodiments and applications of the present
invention have been illustrated and described, it is to be
understood that the invention is not limited to the precise
configuration and components disclosed herein. Various
modifications, changes, and variations which will be apparent to
those skilled in the art may be made in the arrangement, operation,
and details of the methods and systems of the present invention
disclosed herein without departing from the spirit and scope of the
invention. It is important, therefore, that the claims be regarded
as including any such equivalent construction insofar as they do
not depart from the spirit and scope of the present invention.
[0046] The advantages of the present invention will be apparent
from the disclosure contained herein.
[0047] For purposes of further disclosure and to comply with
applicable written description and enablement requirements, the
following references generally relate to methods, devices, and
systems directed to improving wind directing, shaping, and power
conversion, to create torque on a rotor shaft to generate
electricity, and related methods, devices, and systems, and are
hereby incorporated by reference in their entireties:
[0048] U.S. Pat. No. 3,942,909, entitled "Vertical axis fluid
driven rotor," issued 9 Mar. 1976 to Yengst ("Yengst"). Yengst
describes a vertical axis rotor comprising curved vanes overlapping
in their diameters and attached to a shaft, a pair of spaced-apart
end plates adapted to hold and permit rotation of the shaft to
which the vanes are attached, and means for weighting an edge of
the vanes comprising a plurality of tubes, each tube being
positioned along the outer edge of each vane and connected to a
source of liquid so that as the shaft and vanes rotate, fluid rises
in the tubes.
[0049] U.S. Pat. No. 4,632,637, entitled "Wind turbine," issued 30
Dec. 1986 to Traudt ("Traudt"). Traudt describes a wind turbine
device having a main rotatable driven shaft, a plurality of
elongated blades operatively mounted on the main shaft for unitary
rotation with the main shaft, the blade extending substantially
radially away from the main shaft and adapted to fold downwind
under naturally occurring forces and simultaneously feather in
direct response to the folding movement, and means associated with
the blades for increasing the rate of fold relative to the rate of
feather as the speed of rotation increases.
[0050] U.S. Pat. No. 4,818,181, entitled "Wind turbine," issued 4
Apr. 1989 to Kodric ("Kodric"). Kodric describes a wind turbine
comprising a housing pivotally positioned atop a support structure;
a hub rotatably positioned at one end of the housing; at least two
arm members, attached to and radiating outwardly from the hub and
being spaced equally from one another, each having an identical
structure comprising an inner arm portion and an outer arm portion
at an angle of from 75.degree. to 105.degree. to the inner portion,
the arm members being oriented in the same substantially vertical
plane; a vane pivotally attached to each outer arm portion; means
for biasing the pitch angle of each vane about its outer arm
portion to catch the wind and thereby impart rotation to the hub;
and means for orienting the housing so that the vanes may catch the
wind.
[0051] U.S. Pat. No. 5,391,926, entitled "Wind turbine particularly
suited for high-wind conditions," issued 21 Feb. 1995 to Staley et
al. ("Staley"). Staley describes double-curved, stationary stators
for more effectively directing currents into a rotor assembly to
impart a higher rotational velocity and greater torque upon the
turbine shaft. In addition, the stationary stators provide a
structural integrity necessary for operation during high-wind
conditions. This aspect also prevents the disruption of rotation by
shielding the rotors from winds counter-directional to their
rotation which may occur as the wind shifts.
[0052] U.S. Pat. No. 6,172,429, entitled "Hybrid energy recovery
system," issued 9 Jan. 2001 to Russell ("Russell"). Russell
describes double speed Savonius rotor electrical generating
apparatuses, each of which includes two Savonius type rotors
mounted adjacent to one another for rotation about a common axis
with the blades of the rotor units being arranged so that the rotor
units rotate in opposite directions relative to one another under
the influence of a given wind or flow of water.
[0053] U.S. Pat. No. 6,538,340, entitled "Wind turbine system,"
issued 25 Mar. 2003 to Elder ("Elder"). Elder describes an improved
lightweight vertically rotating wind turbine having enhanced
conversion of wind kinetic energy into usable energy, comprising a
wind-collecting base with a bottom surface defining an area and a
top surface defining an area, wherein the area of the bottom
surface is larger than the area of the top surface, the top surface
comprises an energy-transfer element, and the wind-collecting base
comprises an upward tapered base having an angle to smoothly direct
wind currents; a vertically rotating shaft with a top end and a
bottom end, wherein the bottom end is mechanically connected to the
energy-transfer element; an energy-utilizing device responsive to
the shaft through the energy-transfer element of the top surface of
the base; a top plate attached in the vicinity of the top end of
the vertically rotating shaft; a bottom plate that defines a
diameter and is attached to the vertically rotating shaft at a
location above the top surface of the base; a plurality of
vertically oriented torque generating elements having outer edges
and inner edges which are located circumferentially around the
vertically rotating shaft between the top plate and the bottom
plate and are attached to the round top plate and the round bottom
plate at their ends to form a cage assembly; a plurality of
vertically oriented flat wind directing elements arranged
circumferentially around the cage assembly and adjacent to the
outer edges of the vertically oriented flat torque generating
elements; an open cover comprising concentric braces comprising two
side bearings; and a top shield having a central pivoting point and
an outer terminus above the side bearings of the open cover,
wherein the wind turbine elements are constructed from lightweight
materials which allow the enhanced conversion of wind kinetic
energy into mechanical energy by the wind turbine.
[0054] U.S. Pat. No. 6,638,005, entitled "Coaxial wind turbine
apparatus having a closeable air inlet opening," issued 28 Oct.
2003 to Holter et al. ("Holter"). Holter describes a coaxial wind
turbine apparatus including a pair of rearward-mounted,
spring-loaded fins to orient the air inlet opening to face the
direction of the oncoming wind and close a damper panel or shutter
array at the air inlet opening during very high wind
conditions.
[0055] U.S. Pat. No. 6,740,989, entitled "Vertical axis wind
turbine," issued 25 May 2004 to Rowe ("Rowe"). Rowe describes a
vertical axis wind turbine comprising a turbine rotor with rotor
blades disposed for rotation about a substantially vertical axis;
and a plurality of vertically extending stator vanes
circumferentially spaced apart about the rotor in an annular array,
each vane having a radially inward facing surface, a radially
outward facing surface, and a flange on an outer edge of each
vane.
[0056] U.S. Pat. No. 6,984,899, entitled "Wind dam electric
generator and method," issued 10 Jan. 2006 to Rice ("Rice"). Rice
describes a wind generator for generating electricity in response
to wind flow, comprising a windmill comprising a shaft; a plurality
of blades secured to the shaft; at least two moveable air foils
which form an adjustable size opening for directing a selectable
amount of wind flow into the plurality of blades; a base supporting
the at least two air foils, the base being rotatably mounted for
orienting the at least two air foils into the wind flow; a ring
gear mechanically affixed to the shaft; and a plurality of
generators arranged for mechanical interconnection with the ring
gear.
[0057] U.S. Pat. No. 7,329,965, entitled "Aerodynamic-hybrid
vertical-axis wind turbine," issued 12 Feb. 2008 to Roberts et al.
("Roberts"). Roberts describes a vertical axis wind turbine which
includes a rotor airfoil and stator blade combination. The rotor
airfoils have a horizontal cross-section with a crescent shape
including a convex leading side and a concave trailing side with a
thicker middle section that tapers to narrower sections at ends.
The stator blades have a horizontal cross-section with a planar
side and a convex side. Rotor airfoil and stator blade combinations
are secured between upper and lower annular sails.
[0058] U.S. Pat. No. 7,347,660, entitled "Cross-flow wind turbine,"
issued 25 Mar. 2008 to Taylor et al. ("Taylor"). Taylor describes
cross-wind turbines wherein an airfoil stator causes wind to
accelerate along its surface and creates a low pressure area on the
leading face of the rotor blade during the power stroke. A blocking
stator blocks wind from impeding the movement of the rotor blades
during the return cycle and directs wind onto the trailing face of
the rotor blades during the power cycle. A large pressure
differential is created between the leading face of the rotor blade
and the trailing face of the rotor blade during the power cycle
which creates a large amount of force that rotates the rotor blade
about the central shaft.
[0059] U.S. Pat. No. 7,573,148, entitled "Boundary layer wind
turbine," issued 11 Aug. 2009 to Nica ("Nica"). Nica describes a
wind turbine comprising a stator assembly having a plurality of
stator blades for tangentially redirecting wind into an enclosure
formed by the stator blades; and a rotor assembly positioned within
the enclosure formed by the stator blades, the rotor assembly
having a plurality of stacked disks connected to a shaft means, the
stacked disks being closely spaced from each other so as to create,
in use, a boundary layer effect on surfaces of the disks that
contributes in rotating the disks, each disk having a plurality of
rotor blades disposed on an outer circumference thereof, each disk
defining at least one opening thereon for redirecting the wind
axially through each of the disks; whereby, in use, the stator
blades redirect the wind tangentially to the rotor assembly and
entirely within the enclosure formed by the stator blades before
the wind is redirected axially through each of the disks.
[0060] PCT Application Publication No. 2010/003955, entitled "Wind
turbine apparatus," published 3 Feb. 2011 to Blafield et al.
("Blafield"). Blafield describes a wind turbine apparatus
comprising a generator and a substantially vertical shaft, the
shaft being directly mounted to the generator for rotating the
generator. At least one lightweight vane member is also provided.
The at least one vane member is attached to the shaft to provide a
twisted self starting rotor unit. An electronic control apparatus
is provided for controlling the speed of rotation of the
generator.
[0061] U.S. Patent Application Publication No. 2012/0099994,
entitled "Vertical-axis wind rotor," published 26 Apr. 2012 to
Eguizabal ("Eguizabal"). Eguizabal describes a wind rotor with a
vertical shaft, of the type which incorporates a pair of supports
suitably fixed at the ends of the shaft thereof, which supports
form the support means for a plurality of blades aligned
circumferentially about the shaft, comprising two types of blades
with an identical or similar main aerodynamic profile, vertically
projected with advanced rotational displacement and twisted and
with a shortened chord in the opposite direction, one blade
configured for drag and another blade configured for lift, the
chords of the blades being oriented at an angle, radially,
uniformly, concentrically, and vertically at the base of the rotor,
with the leading edge outward, alternately and equidistantly
arranged at the lower base thereof.
[0062] U.S. Pat. No. 8,232,664, entitled "Vertical axis wind
turbine," issued 31 Jul. 2012 to Stroup et al. ("Stroup"). Stroup
describes a vertical axis wind turbine for generating electricity
comprising a tower base; a tower frame attached to the base; a
vertically extending wind turbine mounted in the tower frame and
having a central shaft and a plurality of wind blades attached
thereto, the shaft being attached to an electric generator for
producing electricity therefrom upon rotation of the shaft; a
plurality of diverter doors, each diverter door being movably
connected to the tower frame adjacent the wind turbine, the
plurality of diverter doors being movable to seal the wind turbine
in a housing formed by the plurality of diverter doors when winds
exceed a predetermined velocity; and a plurality of electric
motors, one of the electric motors being coupled to each of the
diverter doors to variably position the coupled diverter door
relative to each other diverter door for controlling air flow to
the turbine, whereby a vertical standing wind turbine generates a
controlled electrical output while controlling air flow to the wind
turbine and being protected against storms by the individual
movement of each of a plurality of diverter doors.
[0063] U.S. Pat. No. 8,354,756, entitled "Vertical axis turbine to
generate wind power," issued 15 Jan. 2013 to Ellis ("Ellis"). Ellis
describes an apparatus, comprising an axle extending along a center
axis, and a plurality of cup shaped blades coupled to the axle
around the center axis, each blade comprising a concave face having
a parabolic concavity along a plane parallel to the center axis,
the parabolic concavity having a first focus and a first vertex;
and a convex tail having an exterior surface that is parabolic
along the plane parallel to the center axis, the exterior surface
having a second focus coincident the first focus in the plane and a
second vertex in the plane, wherein a distance between the first
focus and the first vertex is less than a distance between the
second focus and the second vertex.
[0064] U.S. Patent Application Publication No. 2013/0287570,
entitled "Self-starting Savonius wind turbine," published 31 Oct.
2013 to Gdovic ("Gdovic"). Gdovic describes a self-starting
Savonius wind turbine including a frame, a rotor assembly that is
rotatable about a central axis of rotation, and an energy utilizing
device operably connected to the rotor assembly. The rotor assembly
has at least two rotors, each rotor having at least two rotor
blades. Rotation of the rotor assembly is initiated by wind coming
from any direction blowing on any one of the plurality of blades.
The rotors are configured in a stacked orientation with the blades
fixed at a rotated angular position relative to one another to
start rotation of the rotor assembly in variable wind
conditions.
[0065] U.S. Patent Application Publication No. 2014/0044535,
entitled "Wind turbines augmented with rotating diffusers,"
published 13 Feb. 2014 to Wood ("Wood I"). Wood I describes a
diffuser-augmented wind turbine including a first diffuser ring
arranged to form a turbine rotor cowling, the diffuser being fixed
to and rotatable with the turbine rotor about the horizontal axis
of the wind turbine. The first diffuser ring may have one or more
dynamic, aero-elastic, vortex entrainment devices attached to a
trailing edge of the diffuser. The first diffuser ring may include
one or more slot gaps arranged within its body, each slot gap
creating a channel between the interior and exterior surfaces of
the first diffuser ring.
[0066] U.S. Patent Application Publication No. 2014/0227092,
entitled "Diffuser augmented wind turbines," published 14 Aug. 2014
to Wood ("Wood II"). Wood II describes a wind turbine diffuser with
an expanded outlet area in which the diffuser outlet area is
greater than its cross sectional area. The diffuser may be formed
of one or more diffuser rings, at least one of which may form a
turbine cowling. Each diffuser ring may have an inlet area that is
smaller than the outlet area of the directly upstream ring. The
portion of an upstream ring outlet which is not occluded by the
downstream ring may form a diffuser outlet such that the total
outlet area of the diffuser is larger than the cross-sectional
area.
[0067] U.S. Pat. No. 8,829,704, entitled "Wind turbine generator
and motor," issued 9 Sep. 2014 to Grigg ("Grigg"). Grigg describes
a parallel and vertical axis turbine including a plurality of wing
assemblies having vertical pivot shafts extending between two
vertically spaced end assemblies that are joined to a central
driveshaft assembly. The wing assemblies are rotatable about their
respective pivot axes from a drive position in which they extend
radially outwardly from the central axis and transverse to incident
fluid flow to maximally capture fluid flow and rotate the turbine,
to a glide position in which the wings extend tangentially to the
direction of rotation and parallel to incident fluid flow to
minimize drag.
[0068] U.S. Patent Application Publication No. 2014/0356180,
entitled "Wind turbine for facilitating laminar flow," published 4
Dec. 2014 to Oelofse ("Oelofse"). Oelofse describes a
circular-oriented laminar flow facilitating turbine, comprising at
least leading and trailing circumferentially distributed foils,
which rotate about an axis and are sized and spaced to facilitate a
laminar flow between the foils, the foils having leading edges at
distances R1 and R2, respectively, from the axis, the foils having
chords C1 and C2, respectively, and the foils being spaced apart by
a distance S, wherein R2 is within 10% of R1 and C2 is within 10%
of C1, R1:C1 is between 2.9 and 3.5 inclusive, C1:S is at least 3:1
inclusive, and the leading foil has a high pressure portion and a
low pressure portion, wherein at least 90% of the high pressure
portion is curved in a manner that facilitates the laminar
flow.
[0069] U.S. Patent Application Publication No. 2015/0063978,
entitled "Wind turbine," published 5 Mar. 2015 to Poole ("Poole").
Poole describes a vertical axis wind turbine system that converts
wind energy into electrical or mechanical energy, comprising at
least one turbine rotor with a plurality of blades for receiving
head-on wind generated airflow, at least some of the blades moving
in a downstream wind direction and some of the blades moving in a
return upwind direction as the rotor rotates; a rotor support
structure mountable to a base or support for holding the at least
one rotor in the wind generated airflow; and wind shield means
mountable upwind of at least a portion of the rotor to protect the
return blades from head-on wind airflow.
[0070] U.S. Patent Application Publication No. 2015/0086366,
entitled "Wind turbine blade and blade hub," published 26 Mar. 2015
to Barnes et al. ("Barnes"). Barnes describes a Darrieus-type
vertical axis wind turbine comprising a vertical tower supported
for rotation, and one or more blades each connected to the tower
causing rotation in response to wind energy therewith, wherein each
blade has an upper root end connected to the top of the tower by a
separable blade hub and a lower root end connected to the bottom of
the tower by a separable blade hub.
[0071] U.S. Patent Application Publication No. 2015/0152840,
entitled "Dual-turbine wind power station placed on a vertical
axis," published 4 Jun. 2015 to Varga et al. ("Varga"). Varga
describes a dual-turbine wind power station arranged on a vertical
axis, comprising a machine housing constructed over a solid base;
an internal rotor comprising one or more blades; an internal shaft
having a lower set of bearings at a point on its lower end and an
upper set of bearings at a point on its upper end, both of which
provide for rotational motion of the shaft about the vertical axis
of the internal shaft, the lower end of which is connected to a
first electric energy-producing electrical machine either directly,
or with the aid of a first transmission device; an external rotor
which rotates in a direction opposite to that of the internal rotor
comprising one or more blades, an external shaft which rotates
about the vertical axis it shares with the internal rotor, the
external shaft having a lower set of bearings at a point on its
lower end and an upper set of bearings at a point on its upper end,
both of which provide for rotational motion of the shaft about the
vertical axis of the external shaft, wherein the lower shaft end of
the internal rotor is placed into the lower shaft end of the
external rotor and the lower end of the external shaft is connected
to a second electric energy-producing electrical machine either
directly, or via a second transmission device; and an oval support
structure comprising a grid-like shell that surrounds the internal
rotor and external rotor.
[0072] As may be understood by those of ordinary skill in the art,
certain components or features of the foregoing references may be
incorporated and used in embodiments of the present disclosure. By
way of non-limiting example, particular shapes or arrangements of
blades, materials used to construct devices, or device sizes as
disclosed in the prior art may be incorporated into embodiments of
the present disclosure, and such uses are within the scope of this
disclosure.
[0073] In various embodiments of the present invention, the blade
design has both drag and lift characteristics. In some embodiments,
an open rotor design allows for the lift feature to be taken
advantage of. Specifically, an open rotor design permits air to
flow over the blades to fully develop the lift and does not limit
the flow to adjoining blades.
[0074] In various embodiments of the present invention, the stator
skirt design amplifies and accelerates the wind speed into the
rotor. This is important because the power output of a wind turbine
scales with the cube of the wind speed, e.g. a twofold increase in
the wind speed results in an eightfold increase in available power.
The VAWTs of the present invention can rotate even at very low wind
speeds as a result of the wind speed amplification provided by the
stator skirt.
[0075] In various embodiments of the present invention, stator fins
direct the wind in the direction of blade rotation and have a major
impact on the overall torque efficiency.
[0076] In various embodiments of the present invention, an open
frame design allows the entire rotor-stator system to receive wind
energy from any direction. Wind varies greatly in direction and
velocity on a continuous basis, and also exhibits rolling and
swirling vortices. The VAWTs of the present invention can respond
instantaneously to any change in wind direction or velocity.
[0077] As used herein, "at least one," "one or more," and "and/or"
are open-ended expressions that are both conjunctive and
disjunctive in operation. For example, each of the expressions "at
least one of A, B, and C," "at least one of A, B, or C," "one or
more of A, B, and C," "one or more of A, B, or C," and "A, B,
and/or C" means A alone, B alone, C alone, A and B together, A and
C together, B and C together, or A, B, and C together.
[0078] It is to be noted that the term "a" or "an" entity refers to
one or more of that entity. As such, the terms "a" (or "an"), "one
or more," and "at least one" can be used interchangeably herein. It
is also to be noted that the terms "comprising," "including," and
"having" can be used interchangeably.
[0079] The embodiments and configurations described herein are
neither complete nor exhaustive. As will be appreciated, other
embodiments of the invention are possible utilizing, alone or in
combination, one or more of the features set forth above or
described in detail below.
BRIEF DESCRIPTION OF THE DRAWINGS
[0080] FIGS. 1A and 1B are perspective and top cross-sectional
views, respectively, of a basic vertical axis wind turbine
according to embodiments of the present disclosure;
[0081] FIG. 2 is a top cross-sectional view of a vertical axis wind
turbine having blades of constant cross-sectional width, according
to embodiments of the present disclosure;
[0082] FIG. 3 is a top cross-sectional view of a vertical axis wind
turbine having six stator fins, according to embodiments of the
present disclosure;
[0083] FIG. 4 is a top cross-sectional view of a vertical axis wind
turbine having a stator skirt angle of 60.degree., according to
embodiments of the present disclosure;
[0084] FIG. 5 is a top cross-sectional view of a vertical axis wind
turbine having a unitary rotor, according to embodiments of the
present disclosure;
[0085] FIG. 6 is a top cross-sectional view of a vertical axis wind
turbine having solid rotor plates devoid of holes or gaps,
according to embodiments of the present disclosure;
[0086] FIG. 7 is an isometric view of a vertical axis wind turbine
having an amplifier skirt, according to embodiments of the present
disclosure;
[0087] FIG. 8 is a top cross-sectional view of a vertical axis wind
turbine having rotor blades with diameters larger than a radius of
a rotor plate, according to embodiments of the present
disclosure;
[0088] FIGS. 9A and 9B are top cross-sectional and isometric views,
respectively, of a vertical axis wind turbine having an amplifier
skirt and enlarged stator fins, according to embodiments of the
present disclosure;
[0089] FIGS. 10A, 10B, and 10C are isometric, front, and top
cross-sectional views, respectively, of a vertical axis wind
turbine having parabolic stator and amplifier skirts, according to
embodiments of the present disclosure;
[0090] FIGS. 11A and 11B are each computer-generated views of air
flow through the vertical axis wind turbine illustrated in FIGS. 1A
and 1B;
[0091] FIGS. 12A, 12B, and 12C are each computer-generated views of
air flow through the vertical axis wind turbine illustrated in FIG.
7;
[0092] FIGS. 13A, 13B, and 13C are each computer-generated views of
air flow through the vertical axis wind turbine illustrated in
FIGS. 9A and 9B; and
[0093] FIG. 14 is a bar graph showing the mechanical efficiency of
vertical axis wind turbines according to various embodiments of the
present disclosure.
DETAILED DESCRIPTION OF THE INVENTION
[0094] Referring now to FIG. 1A, a basic vertical axis wind turbine
is illustrated. As illustrated in FIG. 1A, vertical axis wind
turbines according to the present disclosure comprise five parts: a
stator skirt 110, at least one stator fin 120, at least one rotor
plate 130, at least one rotor blade 140, and a top frame 150.
Additional parts may be, but need not be, present to fall within
the scope of the present disclosure. The rotor blades 140 turn a
shaft and are attached to the rotor plates 130 at the top, the
bottom, or both of the rotor blades 140. The stator skirt 110
supports the rotor plates 130 and, as illustrated in FIG. 1A, is
rotationally symmetric and comprises trapezoidal panels, with each
trapezoidal panel forming an angle with respect to a horizontal
axis. Thus, the stator skirt 110 has a horizontal cross-section of
a regular polygon with a number of sides equal to the number of
trapezoidal panels. The stator fins 120 are attached at their
bottoms to the stator skirt 110. Each stator fin 120 comprises a
fin flip, which is disposed at an angle to the longitudinal axis of
the stator fin 120 and is adapted to compress wind and direct the
wind to the rotor blades 140 in a predetermined direction. The top
frame 150 is attached to the tops of the stator fins 120 and is
provided to maintain rigidity and structural integrity of the
stator fins 120 and the vertical axis wind turbine as a whole.
[0095] Referring now to FIG. 1B, various design features of the
vertical axis wind turbine are illustrated. In this embodiment,
three semielliptical crescent-shaped rotor blades 140 are provided,
each forming an angle of 120.degree. relative to each of the other
rotor blades 140; those of ordinary skill in the art will
understand that other numbers, arrangements, and shapes of rotor
blades 140 may be suitable for particular applications. In this
embodiment, three stator fins 120 spaced 120.degree. apart are
provided; those of ordinary skill in the art will understand that
other numbers and arrangements of stator fins 120 may be suitable
for particular applications. In this embodiment, each fin flip
forms an angle of 45.degree. relative to the longitudinal axis of
the stator fin 120 and is two inches in length; those of ordinary
skill in the art will understand that other angles and lengths of
fin flips may be suitable for particular applications. In this
embodiment, the stator skirt 110 comprises six trapezoidal panels
and thus has a horizontal cross-section of a regular hexagon, with
each trapezoidal panel forming an angle of 36.degree. relative to a
horizontal axis; those of ordinary skill in the art will understand
that other numbers and angles of trapezoidal panels, and thus other
shapes of stator skirt 110, may be suitable for particular
applications. Referring now to FIG. 2, another embodiment of a
vertical axis wind turbine is illustrated.
[0096] This embodiment is similar to the embodiment illustrated in
FIG. 1B, except that the rotor blades 140 have constant
cross-sectional width, as opposed to the crescent-shaped blades 140
of FIG. 1B.
[0097] Referring now to FIG. 3, another embodiment of a vertical
axis wind turbine is illustrated. This embodiment is similar to the
embodiment illustrated in FIG. 1B, except that the turbine is
provided with six stator fins 120, as opposed to the three stator
fins 120 of FIG. 1B.
[0098] Referring now to FIG. 4, another embodiment of a vertical
axis wind turbine is illustrated. This embodiment is similar to the
embodiment illustrated in FIG. 1B, except that the trapezoidal
panels of the stator skirt 110 form an angle of 60.degree. relative
to a horizontal axis, as opposed to the 36.degree. angle of FIG.
1B.
[0099] Referring now to FIG. 5, another embodiment of a vertical
axis wind turbine is illustrated. This embodiment is similar to the
embodiment illustrated in FIG. 1B, except that the rotor blades 140
are interconnected to form a unitary rotor, as opposed to FIG. 1B,
in which each rotor blade 140 is a separate component, attached to
at least one rotor plate 130 but not to the other rotor blades
140.
[0100] Referring now to FIG. 6, another embodiment of a vertical
axis wind turbine is illustrated. This embodiment is similar to the
embodiment illustrated in FIG. 1B, except that the rotor plates 130
are solid and devoid of holes or gaps, as opposed to FIG. 1B, in
which holes are present in the rotor plates 130.
[0101] Referring now to FIG. 7, another embodiment of a vertical
axis wind turbine is illustrated. This embodiment is similar to the
embodiment illustrated in FIG. 1B, except that the turbine is
provided with an amplifier skirt 160, disposed on top of the
vertical axis wind turbine and attached to the top frame 150. As
illustrated in FIG. 7, the amplifier skirt 160 may be, but need not
be, a "mirror image" of the stator skirt 110. The amplifier skirt
160 captures and amplifies the wind and directs it into the
uppermost of two sets of vertically stacked rotor blades 140.
[0102] Referring now to FIG. 8, another embodiment of a vertical
axis wind turbine is illustrated. This embodiment is similar to the
embodiment illustrated in FIG. 1B, except that the rotor blades 140
have a diameter that is larger than a radius of the rotor plate
130, as opposed to the blades 140 of smaller diameter in FIG. 1B.
Thus, in the embodiment illustrated in FIG. 8, the rotor blades 140
"overlap" near the shaft.
[0103] Referring now to FIG. 9A, another embodiment of a vertical
axis wind turbine is illustrated. In this embodiment, the vertical
axis wind turbine is provided with substantially enlarged stator
fins 120 and fin flips, each stator fin 120 now having a
longitudinal axis that runs most of the way from an outer edge of
the rotor plate 130 to an outer edge of the stator skirt 110. The
enlarged stator fins 120 and fin flips funnel and direct a
significantly increased volume of incoming wind into the rotor
blades 140 as compared to smaller stator fins 120, for example as
illustrated in FIG. 1B.
[0104] Referring now to FIG. 9B, an isometric view of the
embodiment of FIG. 9A is illustrated. The embodiment also comprises
an amplifier skirt 160 similar to that illustrated in FIG. 7,
disposed on top of the vertical axis wind turbine and attached to
the top frame 150. As illustrated in FIG. 9B, the amplifier skirt
160 may be, but need not be, a "mirror image" of the stator skirt
110. The amplifier skirt 160 captures and amplifies the wind and
directs it into the rotor blades 140.
[0105] The angle .alpha. between a horizontal axis and the surface
of the stator skirt 110 and/or amplifier skirt 160 may be selected
to provide a desired wind shaping profile. By way of first
non-limiting example, the angle .alpha. may be less than about
90.degree., less than about 85.degree., less than about 80.degree.,
less than about 75.degree., less than about 70.degree., less than
about 65.degree., less than about 60.degree., less than about
55.degree., less than about 50.degree., less than about 45.degree.,
less than about 40.degree., less than about 35.degree., less than
about 30.degree., less than about 25.degree., less than about
20.degree., less than about 15.degree., less than about 10.degree.,
or less than about 5.degree., or alternatively less than about any
whole number of degrees between about 1 and about 90. By way of
second non-limiting example, the angle .alpha. may be more than
about 0.degree., more than about 5.degree., more than about
10.degree., more than about 15.degree., more than about 20.degree.,
more than about 25.degree., more than about 30.degree., more than
about 35.degree., more than about 40.degree., more than about
45.degree., more than about 50.degree., more than about 55.degree.,
more than about 60.degree., more than about 65.degree., more than
about 70.degree., more than about 75.degree., more than about
80.degree., or more than about 85.degree., or alternatively more
than about any whole number of degrees between about 0 and about
89. It is to be expressly understood that the angle .alpha. of the
stator skirt 110 and the angle .alpha. of the amplifier skirt 160
may be the same or different.
[0106] Referring now to FIGS. 10A and 10B, another embodiment of a
vertical axis wind turbine is illustrated. As illustrated in FIGS.
10A and 10B, vertical axis wind turbines according to the present
disclosure comprise at least three parts: a stator skirt 210, at
least one stator fin 220, and at least one rotor blade 240.
Additional parts, such as a rotor plate (not illustrated), may be,
but need not be, present to fall within the scope of the present
disclosure. The rotor blades 240 turn a shaft, and may in some
embodiments be attached to rotor plates (if present) at the top,
the bottom, or both of the rotor blades 240. The stator skirt 210,
as illustrated in FIGS. 10A and 10B, is rotationally symmetric and
comprises a paraboloid, typically an elliptical paraboloid, such
that at least a portion of a wind-facing surface of the stator
skirt 210 has a generally parabolic shape. The stator skirt 210
also comprises a substantially planar base for stability when
placed on the ground or another horizontal support. In some
embodiments, as illustrated in FIGS. 10A and 10B, the surface of
the stator skirt 210 may comprise two portions: an approximately
conical lower portion (i.e. where the slope of the surface relative
to a horizontal axis is approximately constant) and an
approximately parabolic upper portion (i.e. where the slope of the
surface relative to a horizontal axis generally decreases with
increasing vertical distance from the substantially planar base,
and may, but need not, be approximately zero at an apex or vertex
of the stator skirt 210). Importantly, the stator skirt 210
typically has a horizontal cross-section not of a polygon but
rather of an ellipse, and in many embodiments a circle. The stator
fins 220 are attached at their bottoms to the stator skirt 210.
Each stator fin 220 comprises a fin flip, which is disposed at an
angle to the longitudinal axis of the stator fin 220 and is adapted
to compress wind and direct the wind to the rotor blades 240 in a
predetermined direction. In some embodiments, a top frame (not
illustrated) may be provided, and may be attached to the tops of
the stator fins 220 to maintain rigidity and structural integrity
of the stator fins 220 and the vertical axis wind turbine as a
whole.
[0107] As illustrated in FIGS. 10A and 10B, the vertical axis wind
turbine also comprises an amplifier skirt 260, disposed on top of
the vertical axis wind turbine and attached to the tops of stator
fins 220 (or, in some embodiments, a top frame to which the stator
fins 220 may in turn be attached). The amplifier skirt 260 captures
and amplifies the wind and directs it into the rotor blades
240.
[0108] As further illustrated in FIGS. 10A and 10B, the amplifier
skirt 260 may be, but need not, be, a "mirror image" of the stator
skirt 210. The amplifier skirt 260 generally, like the stator skirt
210, is rotationally symmetric and comprises a paraboloid,
typically an elliptical paraboloid, in which at least a portion of
a wind-facing surface of the amplifier skirt 260 has a generally
parabolic shape, extending downwardly from a top portion to form an
angle with respect to a horizontal axis. In some embodiments, as
illustrated in FIGS. 10A and 10B, the surface of the amplifier
skirt 260 may comprise at least two portions: an approximately
conical upper portion (i.e. where the slope of the surface relative
to a horizontal axis is approximately constant) and an
approximately parabolic lower portion (i.e. where the slope of the
surface relative to a horizontal axis generally decreases with
increasing vertical distance from the approximately conical
portion, and may, but need not, be approximately zero at an apex or
vertex of the amplifier skirt 260). Unlike the stator skirt 210,
whose base must generally be substantially planar for stability,
the amplifier skirt 260 may additionally have a curved, arcuate, or
parabolic top portion, as illustrated in FIGS. 10A and 10B;
however, in some applications (e.g. where it is intended to
vertically stack multiple vertical axis wind turbines, one atop
another), it may be desirable for the amplifier skirt 260 to have a
substantially planar top portion.
[0109] Referring now to FIG. 10C, various design features of the
vertical axis wind turbine are illustrated. In this embodiment,
three arcuate rotor blades 240 are provided, each forming an angle
of about 120.degree. relative to each of the other rotor blades
240; those of ordinary skill in the art will understand that other
numbers, arrangements, and shapes of rotor blades 240 may be
suitable for particular applications. In this embodiment, three
stator fins 220 spaced about 120.degree. apart are provided; those
of ordinary skill in the art will understand that other numbers and
arrangements of stator fins 220 may be suitable for particular
applications. In this embodiment, each fin flip 225 forms an angle
of about 45.degree. relative to the longitudinal axis of the stator
fin 220; those of ordinary skill in the art will understand that
other angles and lengths of fin flips may be suitable for
particular applications. In this embodiment, the stator skirt 210
comprises a circular paraboloid, i.e. has a circular horizontal
cross-section; those of ordinary skill in the art will understand
that other shapes, most typically elliptical shapes, of the
horizontal cross-section of the stator skirt 210 may be suitable
for particular applications.
[0110] The angle .alpha. between a horizontal axis and the surface
of the stator skirt 210 and/or amplifier skirt 260, as measured by
an average or at any point of the stator skirt 210 and/or the top
of the amplifier skirt 260, may be selected to provide a desired
wind shaping profile. By way of first non-limiting example, the
angle .alpha. may be less than about 90.degree., less than about
85.degree., less than about 80.degree., less than about 75.degree.,
less than about 70.degree., less than about 65.degree., less than
about 60.degree., less than about 55.degree., less than about
50.degree., less than about 45.degree., less than about 40.degree.,
less than about 35.degree., less than about 30.degree., less than
about 25.degree., less than about 20.degree., less than about
15.degree., less than about 10.degree., or less than about
5.degree., or alternatively less than about any whole number of
degrees between about 1 and about 90. By way of second non-limiting
example, the angle .alpha. may be more than about 0.degree., more
than about 5.degree., more than about 10.degree., more than about
15.degree., more than about 20.degree., more than about 25.degree.,
more than about 30.degree., more than about 35.degree., more than
about 40.degree., more than about 45.degree., more than about
50.degree., more than about 55.degree., more than about 60.degree.,
more than about 65.degree., more than about 70.degree., more than
about 75.degree., more than about 80.degree., or more than about
85.degree., or alternatively more than about any whole number of
degrees between about 0 and about 89. As described above, the shape
of the surface of the stator skirt 210 and/or amplifier skirt 260
may be entirely parabolic (i.e. the angle .alpha. decreases
continuously from the base of the stator skirt 210 and/or top of
the amplifier skirt 260, e.g. to about zero at an apex or vertex of
the stator skirt 210 and/or amplifier skirt 260), or may comprise
both a parabolic portion and a conical portion (i.e. the angle
.alpha. is substantially constant). It is to be expressly
understood that the angle .alpha. of the stator skirt 210 and the
angle .alpha. of the amplifier skirt 260 may be the same or
different.
[0111] One advantage of the present invention lies in its
usefulness to shape the arcuate rotor blades 240 to correspond to,
interface with, and/or match the shape of the stator skirt 210
and/or amplifier skirt 260 to provide a desired airflow pattern. By
way of first non-limiting example, a center or terminal point of
one or more rotor blades 240, when the rotor blade 240 is in a
selected rotational position, may coincide with a center of
curvature of the stator skirt 210 and/or amplifier skirt 260 or a
portion thereof. By way of second non-limiting example, a radius of
curvature of one or more rotor blades 240 may be the same as, or
have a selected ratio to, a radius of curvature of the stator skirt
210 and/or amplifier skirt 260 or a portion thereof.
[0112] In some embodiments, vertical axis wind turbines of the
present invention may include rotor blades 240 that are modular,
i.e. that can be individually repaired or replaced without
disassembly or modification of other rotor blades 240 or any other
part of the vertical axis wind turbine. Particularly, in the
practice of the present invention, it may be possible to add,
remove, or replace one or more rotor blades 240 without disturbing
the other rotor blades 240, thus reducing downtime of the turbine
as a whole, and potentially even allowing the turbine to operate
with less than a full complement of rotor blades 240 while one or
more of the blades are replaced, repaired, and/or refurbished. The
modularity of rotor blades 240 may also make assembly less
time-consuming and challenging, and/or may allow for the ability to
adapt the turbine to a particular environment of use or modify the
wind turbine after initial installation.
[0113] Another advantage of the present invention is that, unlike
many vertical axis wind turbines of the prior art, a ratio of the
turbine's height to its diameter or width may be kept relatively
low. A low height-to-width ratio provides several advantages,
including but not limited to improved performance and improved
ability to stack turbines atop each other. By way of non-limiting
example, height-to-width ratios of turbines of the present
invention may be less than about 3.0, less than about 2.9, less
than about 2.8, less than about 2.7, less than about 2.6, less than
about 2.5, less than about 2.4, less than about 2.3, less than
about 2.2, less than about 2.1, less than about 2.0, less than
about 1.9, less than about 1.8, less than about 1.7, less than
about 1.6, less than about 1.5, less than about 1.4, less than
about 1.3, less than about 1.2, less than about 1.1, less than
about 1.0, less than about 0.9, less than about 0.8, less than
about 0.7, less than about 0.6, less than about 0.5, less than
about 0.4, less than about 0.3, less than about 0.2, or less than
about 0.1, or alternatively may fall within a range of at least
about any tenth of a whole number between about 0.1 and about 3.0
and no more than about any other tenth of a whole number between
about 0.1 and about 3.0.
[0114] Another advantage of the present invention is that, unlike
many vertical axis wind turbines of the prior art, the embodiment
illustrated in FIGS. 10A through 10C presents no corners or sharp
edges in the path of oncoming wind. Instead, all wind-facing
surfaces of the turbine of FIGS. 10A through 10C are arcuate,
parabolic, or otherwise free of sharp angles. This feature of the
present invention may provide several important benefits. By way of
first non-limiting example, corners or sharp edges in the path of
air into the turbine may impede the flow of air to the rotor blades
240, create discontinuities or other undesirable effects in the
pattern of air flow, or otherwise diminish the effectiveness of the
turbine in efficiently capturing wind energy; by providing
wind-facing surfaces free of sharp angles, the embodiment
illustrated in FIGS. 10A through 10C may thus have an improved
airflow pattern and/or improved efficiency. By way of second
non-limiting example, stresses or other forces exerted on the
turbine by incoming air may be exacerbated by and/or focused upon
corners or sharp edges, thus making the turbine more susceptible to
mechanical damage or failure at or near such corners or sharp
edges; by providing wind-facing surfaces free of sharp angles, the
embodiment illustrated in FIGS. 10A through 10C may thus have
improved structural integrity and/or an extended useful life.
[0115] Another advantage of the present invention is that, due to
the improved mechanical resilience and structural integrity of the
vertical axis wind turbine and its components, lighter materials,
i.e. materials having a lower density and/or a higher
strength-to-weight ratio, may be used to construct any one or more
of the stator skirt 110/210, the stator fins 120/220, the rotor
plate 130, the rotor blades 140/240, the top frame 150, the
amplifier skirt 160/260, and/or any other parts or components of
the vertical axis wind turbine. By way of non-limiting example, any
one or more of these and/or other components may comprise a
material selected from the group consisting of fiberglass,
lightweight wood (e.g. balsa wood), aluminum, and a solid foam.
[0116] Referring now to FIGS. 11A and 11B, air flow through the
embodiment of FIGS. 1A and 1B is illustrated.
[0117] Referring now to FIGS. 12A, 12B, and 12C, air flow through
the embodiment of FIG. 7 is illustrated.
[0118] Referring now to FIGS. 13A, 13B, and 13C, air flow through
the embodiment of FIGS. 9A and 9B is illustrated.
[0119] Referring now to FIG. 14, the mechanical efficiency of
various embodiments is illustrated. Specifically, the bar labeled
R34 refers to the embodiment illustrated in FIG. 2; the bar labeled
R33 refers to the embodiment illustrated in FIGS. 1A and 1B; the
bar labeled R36 refers to the embodiment illustrated in FIG. 3; the
bar labeled R38 refers to the embodiment illustrated in FIG. 5; the
bar labeled R39 refers to the embodiment illustrated in FIG. 6; the
bar labeled R42 refers to the embodiment illustrated in FIG. 8; the
bar labeled R40 refers to the embodiment illustrated in FIG. 7; and
the bar labeled R50 refers to the embodiment illustrated in FIGS.
9A and 9B. The bar labeled R45 refers to an embodiment not
specifically illustrated in the Drawings but within the scope of
this disclosure. These efficiency values were calculated based on
computational fluid dynamics (CFD) analyses which simulated wind
flow and wind loading on the various features of the several
embodiments. As FIG. 14 illustrates, the embodiment illustrated in
FIG. 7 and the embodiment illustrated in FIGS. 9A and 9B are most
efficient. One of ordinary skill in the art, however, will
recognize that various other embodiments and features of
embodiments may be suitable for particular applications.
[0120] Vertical axis wind turbines have been proposed to address
the problem in wind direction. In vertical axis wind turbines a
rotor assembly rotates typically on bearing assemblies affixed to a
rotor shaft and supported by a base. See, e.g., U.S. Pat. Nos.
1,697,574 and 1,766,765 to Savonius and U.S. Pat. No. 1,835,018 to
Darrieus. Prior art designs, however, suffer from poor efficiency
and starting problems, have vertical rotors that do not rotate fast
enough, have insufficient rotor tip velocities, and complex and
expensive rotor blade designs. Conventional vertical wind turbines,
despite being capable of operating from wind coming from any
direction, have not been as widely used in generation of energy as
have horizontal turbines, due to one or more of the above
referenced problems. The present invention, however, addresses such
deficiencies and thus provides a superior device and method for
generating electrical energy.
[0121] Certain embodiments of the present invention include a wind
turbine apparatus comprising a generator, a substantially vertical
shaft, the shaft being adapted to be directly mounted to the
generator for rotating the generator, a plurality of shaped blades
associated with the shaft, and in some embodiments, an electronic
control apparatus for controlling the speed of rotation of the
generator by controlling loading of the generator. In certain
embodiments, a permanent magnet synchronous generator is employed
where at least one permanent magnet comprises at least one rare
earth metal. In other embodiments, at least one of the stators,
blades, and base and top wind deflector panels (e.g. when a
hexagonal construct is used) are adjustable in terms of one of:
size, length, extension (such as by having telescoping elements
adjustable in view of wind conditions), angle, shape, ribbing,
canting, and temperature (e.g. so as to melt ice or snow thereon).
In various embodiments, a control apparatus or controller for
controlling operation of at least one vertical wind turbine (and in
certain embodiments, two or more stacked turbines) includes a
processor to optimize rotation based on wind speed and power
output, tip speed, and/or positioning of the rotor and the stator
of the generator such that a predetermined relation between the
wind speed and tip speed and/or power output is maintained.
[0122] The controller may, additionally or alternatively, control
other aspects or parameters of the vertical axis wind turbine or
systems comprising vertical axis wind turbines. By way of first
non-limiting example, the controller may be operable to control
mechanical parameters of the generator; particularly, where the
generator is an alternator (i.e. a generator producing alternating
current), the controller may be operable to control the number of
poles, rotational speed, and/or frequency of the alternator. By way
of second non-limiting example, the controller may be operable to
control the output voltage of the electrical generator, e.g. by
reconfiguring a voltage regulator. By way of third non-limiting
example, the vertical axis wind turbine (or system comprising a
vertical axis wind turbine) may comprise, in addition to the
controller, a mechanical and/or electronic braking mechanism for
either the rotor blades 140/240, the generator shaft, or both, and
the controller may be operable to apply the braking mechanism to
slow the rotation of the rotor blades 140/240, the generator shaft,
or both when the rotational speed exceeds a predetermined
value.
[0123] Various embodiments are adapted to be ground secured units,
while other embodiments provide wind turbine devices adapted for
positioning on a roof, pole, scaffold or on a mast, and preferably
include a telecommunications or other remote control
functionalities such that remote control of the units can be
achieved to maximize efficiencies and power output. Still other
embodiments provide for protective shields to be put in place,
preferably via remote control, such that the units are protected
from certain environmental conditions when desired, such as in
extremely high winds, storms, etc. The units can be made from any
suitable material, but in certain embodiments, they comprise a
majority of plastic or composite portions to reduce weight, to
facilitate manufacture and to promote use when weight
characteristics are paramount. Thus many embodiments include those
made form from at least one of plastic material, composite
material, laminate material, fiberglass and aluminum.
[0124] The power generation system may comprise a local grid, means
for converting from AC to DC voltage between the at least one wind
turbine apparatus and the local grid, a local energy storage
connected to the local grid, at least one further local energy
production apparatus, and a connection to another grid. Directing
the output of such units to a storage facility or to charge
batteries is also contemplated.
[0125] Similarly, the provision of photovoltaic panels as part of
the wind turbine constructs is rendered possible due to the
expansive panels of the base and top portions (in certain
embodiments), including the uppermost portion of the units that
will be exposed to sunlight, thus facilitating energizing of the
units with the assistance of solar powered systems. By way of first
non-limiting example, a photovoltaic panel may be placed on a
suitable portion of the surface of the amplifier skirt 160/260. By
way of second non-limiting example, the amplifier skirt 160/260 may
itself be a photovoltaic panel, i.e. may perform the dual function
of shaping incoming wind into the rotor blades 140/240 while
simultaneously producing solar energy. In certain embodiments in
which vertical axis wind turbines of the invention include, or are
integrated with, photovoltaic systems, a controller may be operable
to synchronize alternating current waveforms of the wind-generated
current and the solar-generated current, and may in embodiments be
enabled to synchronize the total electrical output of the vertical
axis wind turbine system with an electrical grid or network to
which the vertical axis wind turbine system is interconnected.
[0126] Embodiments of vertical axis wind turbines according to the
present invention may comprise, or be configured to work with, a
gearbox, which converts the rotation of the rotor blades 140/240
into a rotation (usually at a faster rotational speed) of an
electrical generator to produce electricity. However, in many
embodiments, it is possible and may be desirable for a
"direct-drive" system to be provided, in which the shaft turned by
the rotor blades 140/240 is directly interconnected to an
electrical generator, without an intermediate gearbox, such that
the generator spins at the same speed as rotor blades 140/240;
typically (but not always), the slower rotational speed of the
generator is compensated for by increasing the diameter of the
generator's rotor to allow for the inclusion of more magnets to
create the required frequency and power. Such "direct-drive"
vertical axis wind turbines may be preferred over generation
systems comprising a gearbox for various reasons, including, by way
of non-limiting example, increased efficiency, reduced noise,
longer lifetime, higher torque at low rotational speeds, faster and
more precise positioning, drive stiffness, and avoidance of certain
mechanical issues to which gearboxes may be particularly
susceptible (e.g. accumulated fatigue torque loading, reliability
issues, maintenance costs, etc.). Thus, it is to be expressly
understood that the scope of the present invention includes both
vertical axis wind turbine systems comprising (or adapted to
interface with) a generator system comprising a gearbox, and
vertical axis wind turbine systems comprising (or adapted to
interface with) a direct-drive generator system (e.g. a permanent
magnet synchronous generator). These and other embodiments may also
provide vertical axis wind turbine systems according to the present
invention having fewer moving parts than those of the prior art,
further reducing maintenance needs and costs and improving the
useful life of the turbine system.
[0127] The invention illustratively disclosed herein suitably may
be practiced in the absence of any element which is not
specifically disclosed herein. It is apparent to those skilled in
the art, however, that many changes, variations, modifications,
other uses, and applications of the invention are possible, and
also changes, variations, modifications, other uses, and
applications which do not depart from the spirit and scope of the
invention are deemed to be covered by the invention, which is
limited only by the claims which follow.
[0128] The foregoing discussion of the invention has been presented
for purposes of illustration and description. The foregoing is not
intended to limit the invention to the form or forms disclosed
herein. In the foregoing Detailed Description of Certain
Embodiments of the Invention, for example, various features of the
invention are grouped together in one or more embodiments for the
purpose of streamlining the disclosure. The features of the
embodiments of the invention may be combined in alternate
embodiments other than those discussed above. This method of
disclosure is not to be interpreted as reflecting an intention that
the claimed invention requires more features than are expressly
recited in each claim. Rather, as the following claims reflect,
inventive aspects lie in less than all features of a single
foregoing disclosed embodiment. Thus, the following claims are
hereby incorporated into this Detailed Description of Certain
Embodiments of the Invention, with each claim standing on its own
as a separate preferred embodiment of the invention.
[0129] Moreover, though the description of the invention has
included description of one or more embodiments and certain
variations and modifications, other variations, combinations, and
modifications are within the scope of the invention, e.g. as may be
within the skill and knowledge of those in the art, after
understanding the present disclosure. It is intended to obtain
rights which include alternative embodiments to the extent
permitted, including alternate, interchangeable, and/or equivalent
structures, functions, ranges, or steps to those claimed, whether
or not such alternate, interchangeable, and/or equivalent
structures, functions, ranges, or steps are disclosed herein, and
without intending to publicly dedicate any patentable subject
matter.
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