U.S. patent application number 12/461718 was filed with the patent office on 2010-06-10 for decorative wind turbine having flame-like appearance.
This patent application is currently assigned to Natural Power Concepts, Inc.. Invention is credited to John Pitre.
Application Number | 20100140950 12/461718 |
Document ID | / |
Family ID | 41707601 |
Filed Date | 2010-06-10 |
United States Patent
Application |
20100140950 |
Kind Code |
A1 |
Pitre; John |
June 10, 2010 |
Decorative wind turbine having flame-like appearance
Abstract
A wind turbine has a visual envelope suggestive of a flame. The
turbine has a rotor adapted to rotate about an axis of rotation
that is perpendicular to a direction of a prevailing wind. The
visual envelope is curvilinear, generally wider toward the root
end, and narrower near the tip. A power take off device converts
rotation of the rotor into a useful and preferably transmissible
form of energy.
Inventors: |
Pitre; John; (Honolulu,
HI) |
Correspondence
Address: |
STEPTOE & JOHNSON LLP
1330 CONNECTICUT AVENUE, N.W.
WASHINGTON
DC
20036
US
|
Assignee: |
Natural Power Concepts,
Inc.
Honolulu
HI
|
Family ID: |
41707601 |
Appl. No.: |
12/461718 |
Filed: |
August 21, 2009 |
Related U.S. Patent Documents
|
|
|
|
|
|
Application
Number |
Filing Date |
Patent Number |
|
|
61189950 |
Aug 22, 2008 |
|
|
|
Current U.S.
Class: |
290/55 ;
416/146R; 416/223R |
Current CPC
Class: |
Y02E 10/74 20130101;
Y02B 10/30 20130101; Y02E 10/72 20130101; F05B 2220/25 20130101;
F05B 2250/25 20130101; F03D 3/061 20130101 |
Class at
Publication: |
290/55 ;
416/223.R; 416/146.R |
International
Class: |
F03D 9/00 20060101
F03D009/00; F03D 3/06 20060101 F03D003/06; F03D 11/00 20060101
F03D011/00 |
Claims
1. A wind turbine comprising: a rotor adapted to rotate about an
axis of rotation that is perpendicular to a direction of a
prevailing wind, said rotor having blades characterized by having:
(a) a root end, (b) a tip end remote from the root end along the
axis of rotation, and (c) a curvilinear radial envelope that is
generally wider toward the root end and narrower near the tip; and
a fixed supporting structure.
2. A wind turbine as in claim 1 wherein the minimum envelope width
is less than about fifty percent (50%) the maximum envelope
width.
3. A wind turbine as in claim 1 wherein the minimum envelope width
is less than about twenty five percent (25%) the maximum envelope
tip.
4. A wind turbine as in claim 1 wherein the minimum envelope radius
is less than about ten percent (10%) the maximum envelope
radius.
5. A wind turbine as in claim 1 where the rotor comprises a
plurality of blades oriented axially along the axis of rotation,
each blade having a root end proximate to the rotor root end and a
tip end proximate to the rotor tip end, each blade having a leading
edge position at the tip end that is advanced circumferentially
around the axis of rotation relative to the leading edge position
at the root end.
6. A wind turbine as in claim 5 wherein a blade leading edge
position at the tip end is advanced at least about sixty degrees
(60 deg.) around the axis of rotation relative to the leading edge
position at the root end.
7. A wind turbine as in claim 5 wherein a blade leading edge
position at the tip end is advanced at least about ninety degrees
(90 deg.) around the axis of rotation relative to the leading edge
position at the root end.
8. A wind turbine as in claim 1 wherein the rotor is without a
central axel along the axis of rotation.
9. A wind turbine as in claim 1 further including a housing at the
root end enclosing an electric generator.
10. A wind turbine as in claim 1 wherein the rotor further includes
a housing at the root end enclosing an electric generator.
11. A wind turbine as in claim 9 wherein the housing couples to the
rotor of an electric generator.
12. A wind turbine as in claim 9 wherein the housing couples to the
stator of an electric generator
13. A wind turbine as in claim 9 wherein the housing includes a
first part coupled to rotate with the blades and a second part
coupled to remain non-rotational.
14. A wind turbine as in claim 1 further including a power take off
device.
15. A wind turbine as in claim 1 further including at least one
photovoltaic cell.
16. A wind turbine as in claim 1 further including an attachment
fixture for mounting to a post.
17. A wind turbine as in claim 1 further including a fineal
coupling the blades at the tip ends.
18. A wind turbine as in claim 1 wherein: (a) the rotor has an
envelope with a maximum width and height; and (b) the cross
sectional area of the envelope is less than the area of a rectangle
having the maximum height and width.
Description
CROSS-REFERENCE TO RELATED APPLICATIONS
[0001] This application claims priority to U.S. Provisional Patent
Application 61/189,950 entitled, "Fine Arts Innovations," and filed
Aug. 22, 2008.
STATEMENT REGARDING FEDERALLY SPONSORED RESEARCH OR DEVELOPMENT
[0002] None.
NAMES OF THE PARTIES TO A JOINT RESEARCH AGREEMENT
[0003] None.
BACKGROUND
[0004] According to the U.S. Department of Energy, modern,
wind-driven electricity generators were born in the late 1970's.
See "20% Wind Energy by 2030," U.S. Department of Energy, July
2008. Until the early 1970s, wind energy filled a small niche
market supplying mechanical power for grinding grain and pumping
water, as well as electricity for rural battery charging. With the
exception of battery chargers and rare experiments with larger
electricity-producing machines, the windmills of 1850 and even 1950
differed very little from the primitive devices from which they
were derived. As of July 2008, wind energy provides approximately
1% of total U.S. electricity generation.
[0005] As illustrated in FIG. 1, most modern wind turbines
typically have 3-bladed rotors 10 with diameters of 10-80 meters
mounted atop 60-80 meter towers 12. The average turbine installed
in the United States in 2006 can produce approximately 1.6
megawatts of electrical power. Turbine power output is controlled
by rotating the blades 10 around their long axis to change the
angle of attack (pitch) with respect to the relative wind as the
blades spin around the rotor hub 11. The turbine is pointed into
the wind by rotating the nacelle 13 around the tower (yaw).
Turbines are typically installed in arrays (farms) of 30-150
machines. A pitch controller (for blade pitch) regulates the power
output and rotor speed to prevent overloading the structural
components. Generally, a turbine will start producing power in
winds of about 5.36 meters/second (12 miles per hour) and reach
maximum power output at about 12.52-13.41 meters/second (28-30
miles per hour). The turbine will pitch or feather the blades to
stop power production and rotation at about 22.35 meters/second (50
miles per hour).
[0006] In the 1980s, an approach of using low-cost parts from other
industries produced machinery that usually worked, but was heavy,
high-maintenance, and grid-unfriendly. Small-diameter machines were
deployed in the California wind corridors, mostly in densely packed
arrays that were not aesthetically pleasing in such a rural
setting. These densely packed arrays also often blocked the wind
from neighboring turbines, producing a great deal of turbulence for
the downwind machines. Little was known about structural loads
caused by turbulence, which led to the frequent and early failure
of critical parts. Reliability and availability suffered as a
result.
[0007] A dominant factor driving development of wind turbine
technology is a desire for increased power production. Where wind
turbines are intended to reduce carbon emissions that would
otherwise occur from the burning of fossil fuel, high power output
means a greater reduction in carbon emissions. Increasing power
production typically reduces cost of generation of electricity by
allowing fixed costs to be spread over a larger amount of variable
power production.
[0008] One factor affecting the power output from a wind turbine is
rotor size. In a typical, 3-bladed, horizontal axis wind turbine,
the amount of energy available to be captured depends on the sweep
area of the rotor blades. The greater the sweep area, the greater
the potential amount of energy in the wind that could be captured.
As of August 2009, rotor blades may exceed 100 meters in
length.
[0009] Another factor affecting the power output from a wind
turbine is efficiency, that is, the percentage of available power
in a given cross section of wind that the turbine actually
captures. It is generally believed that horizontal axis wind
turbines that have their axis of rotation parallel to the direction
of the prevailing wind have better efficiency than transverse-axis
wind turbines. So-called "horizontal axis" wind turbines have
rotors with an axis of rotation that is horizontal (i.e., parallel
to the earth's surface) and typically parallel to the direction of
the prevailing wind. So-called "vertical axis" wind turbines
typically have rotors with an axis of rotation that is vertical
(i.e., at right angles to the earth's surface) and typically
perpendicular to the direction of the prevailing wind. Wind
turbines that have rotors with an axis of rotation perpendicular to
the direction of the prevailing wind are often called "transverse
axis" wind turbines, regardless of the orientation of their axis of
rotation.
SUMMARY
[0010] An object of the invention is to provide a wind turbine for
deployment in high-visibility areas. Other objects of the invention
include: [0011] 1. providing a transverse axis wind turbine; and
[0012] 2. providing a wind turbine with integrated photovoltaic
cells.
[0013] These and other objectives are achieved by providing a
transverse axis wind turbine with a visual envelope suggestive of a
flame. Blades of the wind turbine preferably have a curvilinear
envelope that tapers near a tip end and wrap around the axis of
rotation. The cross section of such a wind turbine typically would
be smaller than that of a wind turbine with a rectangular cross
section having the same maximum width and height. A preferred wind
turbine includes an electric generator and may optionally include
photovoltaic cells that store energy in a battery, capacitor, or
other storage device. A preferred wind turbine also includes a
connection for transmitting electrical power.
BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWING
[0014] Reference will be made to the following drawings, which
illustrate preferred embodiments of the invention as contemplated
by the inventor(s).
[0015] FIG. 1 illustrates a prior art wind turbine.
[0016] FIG. 2 is a side view of a decorative wind turbine.
[0017] FIG. 3 is a top view of the wind turbine if FIG. 2.
[0018] FIG. 4 is a cut-away side view of the wind turbine if FIG. 2
illustrating a location of an electrical generator.
[0019] FIG. 5 is a side view of a blade for a decorative wind
turbine.
[0020] FIG. 6 is a perspective view of a decorative wind turbine
with a mount bearing photovoltaic cells.
DETAILED DESCRIPTION OF THE INVENTION
[0021] FIG. 2 is a side view of an exemplary, decorative wind
turbine. Visually, a preferred turbine has an overall appearance
suggestive of a candle or other flame. This can be accomplished by
providing a vertical axis rotor with a bottom end (along the axis
of rotation) having a generally wider visual cross section, a top
end having a generally narrower visual cross section, and a
curvilinear envelope. The widest visual cross section may be in the
middle. For purposes of description, an exemplary turbine will be
described as having a base end and a tip end with an implication
that the turbine frequently will be oriented with the tip end up
and the bottom end down to be suggestive of the way a candle or
other flame often has a wider base, an even wider center, and a
narrower tip than the both. This orientation is not required. The
visual cross section may broadest in the middle, but preferably
tapers to a relatively narrow tip.
[0022] Structurally, an exemplary turbine includes a rotating part
(rotor) and a fixed part. The rotating part includes blades 20a,
20b, 20c, 20d and, optionally, a rotating housing 22. The blades
20a, 20b, 20c, 20d preferably attach at their root (base) ends to a
rotational housing 22. The blades 20a, 20b, 20c, 20d may connect
together at their tip ends through a cap or fineal 27. (The term
"fineal" is used here to mean any structure--preferably but not
necessarily decorative--used to join tips of blades. A fineal may
alternately be a plate or other shape.) FIG. 2 illustrates a
turbine with four blades, but differing numbers of blades may be
used. The fixed part of the turbine usually will include a base 24
and, optionally a fixed housing. The base 24 may include a central
post 25 and a disc-shaped horizontal plate 26, though other
supporting arrangements may be used.
[0023] Aerodynamically, the blades 20a, 20b, 20c, 20d are adapted
to rotate about a central axis that extends from the cap or fineal
27 to a centroid of the housing 22. The blades 20a, 20b, 20c, 20d
and cap or fineal 27 preferably provide sufficient structural
strength that no central axel is required. Frequently, the axis of
rotation will be perpendicular to the ground, and blades will be
adapted to rotate in the presence of a wind traveling in a
direction parallel to the ground, making it a so-called transverse
axis wind turbine. In a preferred embodiment, the blades 20a, 20b,
20c, 20d, housing 22, and cap or fineal 27 are joined together and
rotate as a single unit. Alternately, the blades may couple to a
non-rotating housing or other structure through a bearing.
[0024] When viewed from the side as in FIG. 2, the blades 20a, 20b,
20c, 20d have a visual envelope that is not rectangular. The
envelope can be thought of as the outline of the silhouette, the
shadow the blades would cast on a wall, or in mathematical terms,
as an outline of a projection of the blades onto a plane parallel
to the axis of rotation. In the example of FIG. 2, the envelope is
curvilinear, which here means that at least a portion of the
envelope is curved rather than a straight line. The envelope has a
height denoted in FIG. 2 as line segment H-H. The envelope has
maximum width at points denoted in FIG. 2 as arrows MW. The area of
the envelope is less than the area of a rectangle of the same
height and maximum width. The curvilinear envelope reduces the
cross section of wind that engages the turbine blades, which in
turn reduces the total amount of power that potentially could be
captured when compared to a turbine with a rectangular envelope of
equal height and maximum width. The minimum width of the envelope
at the tip may be less than 50%, 25%, or even 10% of the maximum
width depending: on the number of blades; the overall height,
width, and other dimensions of the turbine; and other factors.
[0025] FIG. 3 is a top view of the wind turbine of FIG. 2 showing a
view of blades 20a, 20b, 20c, 20d, housing 22, base plate 26, and
cap or fineal 27. FIG. 3 designates two points 28, 29 along the
leading edge of one of the blades 20a. The leading edge of the
blade 20a attaches at its tip to the cap or fineal 27 at a first
point 28. The leading edge of the blade 20a attaches at its base to
the housing 22 at a second point 29. In FIG. 3 it can be seen that
the point of attachment to the cap or fineal 27 is advanced
approximately 90 degrees around the central axis of rotation. The
degree of advancement may be 45 degrees, 90 degrees, or more than
180 degrees depending on the number of blades, the overall turbine
geometry, and other factors. The degree of advancement may mean
that different portions of the blade engage with the wind at
different times to cause a torque to rotate the rotor. This has an
effect of smoothing out the torque over time when compared to
transverse axis turbines with straight blades. In such
straight-bladed turbines, torque impulses are more discrete as an
individual blade moves into and out of its orientation of maximum
torque.
[0026] The term "leading edge" here is used here only as a
convenient point of description to refer to the point of
attachment. It is the side of the blade facing into the direction
of the prevailing wind when on the downwind part of its rotational
cycle. When the blade is on the downwind part of its rotational
cycle, the "leading edge" would be facing opposite the direction of
the blade's travel. The term is not intended to require the blade
to operate at any particular velocity relative to the prevailing
wind. Where the point of attachment of the tip is greater than 180
degrees, one portion of the blade may be on an upwind leg while
another portion of the leg may be on the downwind leg of rotation.
The leading edge may be identified by choosing any portion of the
blade while on the downwind leg.
[0027] As can be seen in FIG. 2, the advancement of the point of
contact at the blade tips contributes to a visual appearance
suggesting a flame. FIGS. 1 and 2 also illustrate that the blades
20a, 20b, 20c, 20d become narrower toward the tip, which further
contributes to the visual appearance of a flame.
[0028] FIG. 4 is a cut-away side view of the wind turbine of FIG. 2
illustrating a location of an electrical generator 30. The
generator 30 preferably has a rotor coupled through a flange 31 to
the rotational housing 22 or other rotational structure that in
turn couples to the blades 20a, 20b, 20c, and 20d. The generator 30
preferable has a stator coupled through a casing mount 32 to the
central post 25 or other non-rotating structure. The housing 22 is
clear to rotate with the blades 20a, 20b, 20c, 20d without
interference from the casing mount 32 or other fixed structure. The
generator 30 preferably has bearings sufficient to support the
axial (weight) load and lateral (side) stresses of the blades 20a,
20b, 20c, 20d and other rotational components. The housing 22
preferably is weatherproofed to shield the rotor and other
electrical components, such as electrical storage device, fuses,
wiring, connectors, etc., from rain and other elements.
[0029] FIG. 5 is a side view of a blade 40 for a decorative wind
turbine. The blade has a root end 41 and a tip end 42. The blade
also has a leading edge 43 and a trailing edge 44. The blade chord
(cross section taken in a direction from the leading edge to the
trailing edge) is wider at the root end 41 than at the tip end 42.
When viewed in a static position as in FIG. 5, it can be seen that
blade has a twist along its length from the base end 41 to the tip
end 42. The orientation of a blade chord at the tip end 42 is
advanced around the axis of rotation relative to the orientation of
a chord at the base end 41.
[0030] FIG. 6 is a perspective view of an alternate, decorative
wind turbine integrated with photovoltaic cells 53. Here, the
photovoltaic cells 53 attach to a top surface of a base plate 54.
The base plate 54 couples to a mount 55, which may be a hollow
cylinder adapted to fit onto a cylindrical post (not shown). A set
screw 56 locks the mount 55 to the post. The mount may attach to
the base plate 54 with reinforcing brackets 57, welds, or other
attachments. Other mounts may be used according to installation
site. For example, the mount may be made integral to fence posts,
lamp posts, or any other object.
[0031] In the embodiment of FIG. 6, the housing has two parts. A
domed top part 51 a couples to and rotates with the blades 50a,
50b, 50c, and 50d. A cylindrical bottom part 51b couples to the
base plate 54 and remains stationary. The top and bottom parts
couple to one another through a bearing. A generator (not shown) is
located within the housing 51a, 51b. The generator rotor couples to
the housing top part 51a. The generator stator couples to the
housing bottom part 51b. The cap or fineal 52 of this embodiment is
a disc.
[0032] The embodiments described above are intended to be
illustrative but not limiting. Various modifications may be made
without departing from the scope of the invention. The breadth and
scope of the invention should not be limited by the description
above, but should be defined only in accordance with the following
claims and their equivalents.
* * * * *