U.S. patent application number 11/279942 was filed with the patent office on 2007-10-18 for vertical axis wind turbine.
Invention is credited to Richard Baron.
Application Number | 20070243066 11/279942 |
Document ID | / |
Family ID | 38605001 |
Filed Date | 2007-10-18 |
United States Patent
Application |
20070243066 |
Kind Code |
A1 |
Baron; Richard |
October 18, 2007 |
VERTICAL AXIS WIND TURBINE
Abstract
A vertical axis sail-type wind turbine includes an array of
sail-like structures that are mounted on rotating main masts. The
sail-like structures can be oriented to interact with the wind. For
example, when the sail-like structures are moving in a downwind
direction, they are oriented to present a flat surface that is
perpendicular to the wind direction. On the other hand, when the
sail-like structures are moving in an upwind direction, they are
oriented to present a surface that is at an angle that creates an
upwind vector. The sail-like structures rotate about the sail
masts, which are mounted to transverse mounting arms that are
firmly mounted to a main mast. The main mast rotates, transferring
power through a gear and shaft drive to hydraulic pumps in the
tower. This hydraulic fluid pressure is then used to drive an
electrical generator.
Inventors: |
Baron; Richard; (St. Paul,
MN) |
Correspondence
Address: |
MOORE & HANSEN, PLLP
225 SOUTH SIXTH ST
MINNEAPOLIS
MN
55402
US
|
Family ID: |
38605001 |
Appl. No.: |
11/279942 |
Filed: |
April 17, 2006 |
Current U.S.
Class: |
416/132B |
Current CPC
Class: |
F03D 3/068 20130101;
Y02E 10/74 20130101; Y02B 10/30 20130101; F05B 2240/40 20130101;
F05B 2260/406 20130101 |
Class at
Publication: |
416/132.00B |
International
Class: |
B63H 1/06 20060101
B63H001/06 |
Claims
1. A wind turbine comprising: a main tower; at least two transverse
mounting arms mounted on and supported by the main tower; a sail
assembly mounted between the at least two transverse mounting arms,
the sail assembly comprising a main mast defining a vertical axis
of rotation, at least two sail arms mounted on and supported by the
main mast, and a sail mounted between the at least two sail arms,
the sail configured to rotate about the vertical axis of rotation
in response to wind; and a hydraulic pump configured and arranged
to generate a hydraulic output in response to rotation of the sail
about the vertical axis of rotation.
2. The wind turbine of claim 1, wherein the sail comprises a
plurality of vanes configured to be rotated to a first orientation
when the sail is moving in an upwind direction and to a second
orientation when the sail is moving in a downwind direction.
3. The wind turbine of claim 2, wherein the sail further comprises
a plurality of servo motors configured to selectively rotate the
vanes to the first and second orientations.
4. The wind turbine of claim 3, further comprising a
microprocessor-based system configured to control operation of the
vanes.
5. The wind turbine of claim 1, wherein the sail assembly
comprises: three pairs of sail arms; and three sails each mounted
between a corresponding pair of sail arms.
6. The wind turbine of claim 1, further comprising a flywheel
assembly operatively coupled to the sail assembly.
7. The wind turbine of claim 6, wherein the flywheel assembly is
sized and configured to function as a gyroscope.
8. The wind turbine of claim 6, further comprising a plurality of
hydraulic brakes, and wherein the flywheel is configured to act as
a brake disk for the hydraulic brakes.
9. The wind turbine of claim 1, further comprising a pill block
bearing drive mechanism configured and arranged to drive the
hydraulic pump in response to movement of the sails.
10. The wind turbine of claim 1, wherein the pill block bearing
drive mechanism comprises a shaft arrangement having a variable
effective length.
11. The wind turbine of claim 10, wherein the shaft arrangement
comprises a plurality of segments arranged in a slip fitting
arrangement.
12. The wind turbine of claim 10, wherein the shaft arrangement
comprises a plurality of segments connected to one another via a
universal joint.
13. The wind turbine of claim 1, further comprising a plurality of
guywires affixed to an upper portion of the main tower.
14. A wind turbine arrangement comprising: a plurality of wind
turbines each comprising a main tower, at least two transverse
mounting arms mounted on and supported by the main tower, and a
sail assembly mounted between the at least two transverse mounting
arms, the sail assembly comprising a main mast defining a vertical
axis of rotation, at least two sail arms mounted on and supported
by the main mast, and a sail mounted between the at least two sail
arms, the sail configured to rotate about the vertical axis of
rotation in response to wind, each wind turbine configured to
generate a hydraulic output in response to rotation of the sail
about the vertical axis of rotation, wherein the hydraulic outputs
of the wind turbines are linked together; an electrical generator,
and a hydraulic pump configured to receive the linked hydraulic
outputs of the wind turbines and to drive the electrical
generator.
15. The wind turbine arrangement of claim 14, wherein the
electrical generator and the hydraulic pump are housed in a control
building.
16. The wind turbine arrangement of claim 15, wherein the control
building comprises a pressure equalizer configured to equalize
fluid pressures between the linked hydraulic outputs of the wind
turbines.
17. The wind turbine arrangement of claim 15, wherein the control
building comprises: a plurality of electrical generators; a
plurality of hydraulic pumps; and a splitter arrangement to split
the linked hydraulic outputs of the wind turbines among the
plurality of hydraulic pumps.
18. The wind turbine arrangement of claim 14, wherein the sail
comprises a plurality of vanes configured to be rotated to a first
orientation when the sail is moving in an upwind direction and to a
second orientation when the sail is moving in a downwind
direction.
19. The wind turbine arrangement of claim 18, wherein the sail
further comprises a plurality of servo motors configured to
selectively rotate the vanes to the first and second
orientations.
20. The wind turbine arrangement of claim 14, wherein each wind
turbine further comprises a flywheel assembly operatively coupled
to the sail assembly.
21. The wind turbine arrangement of claim 20, wherein the flywheel
assembly is sized and configured to function as a gyroscope.
22. The wind turbine arrangement of claim 20, further comprising a
plurality of hydraulic brakes, and wherein the flywheel is
configured to act as a brake disk for the hydraulic brakes.
23. The wind turbine arrangement of claim 14, wherein each wind
turbine further comprises a pill block bearing drive mechanism
configured and arranged to drive the hydraulic pump in response to
movement of the sails.
24. The wind turbine arrangement of claim 23, wherein the pill
block bearing drive mechanism comprises a shaft arrangement having
a variable effective length.
25. The wind turbine arrangement of claim 14, wherein each wind
turbine further comprises a plurality of guywires affixed to an
upper portion of the main tower.
26. A wind turbine comprising: a main tower; a plurality of
transverse mounting arms mounted on and supported by the main
tower; a plurality of sail assemblies mounted between at least two
of the transverse mounting arms, each sail assembly comprising a
main mast defining a vertical axis of rotation, at least two sail
arms mounted on and supported by the main mast, and a sail mounted
between the at least two sail arms, the sail configured to rotate
about the vertical axis of rotation in response to wind; and a
hydraulic pump configured and arranged to generate a hydraulic
output in response to rotation of the sails of the sail assemblies
about the vertical axes of rotation.
Description
TECHNICAL BACKGROUND
[0001] The disclosure relates generally to electrical power
generation. More particularly, the disclosure relates to the
generation of electricity using wind power.
BACKGROUND
[0002] Wind turbines are known in the art for converting wind power
to electrical energy. Typically, wind turbines rotate around a
horizontal axis. Such wind turbines are known as horizontal axis
wind turbines and have a main rotor shaft and a generator mounted
on top of a tower. A gearbox may be used to convert the slow
rotation of the blades into a faster rotation that is more suitable
for generating electrical power. Horizontal axis wind turbines must
be pointed into the wind, for example, by a wind vane or a wind
sensor coupled with a servo motor.
[0003] While horizontal axis wind turbines are the most common type
of wind turbine, they suffer from certain drawbacks. For example,
horizontal axis wind turbines are typically velocity-governed. That
is, the power that they generate is dependent on the velocity of
the rotating blades. Thus, they generate low amounts of power at
low wind speeds. Indeed, at sufficiently low wind speeds, the
blades do not rotate at all. At high wind speeds, on the other
hand, the power generated is limited by a phenomenon known as the
Betz limit. Accordingly, the efficiency of velocity-governed wind
turbines is limited at both low and high wind speeds. Other
drawbacks that are particularly evident at high speeds include, for
example, high noise levels and large numbers of birds killed by
blade tips rotating at extremely high velocities. In addition,
increasing the speed of the rotating blades in order to extract
more energy from the wind creates centrifugal forces that impart
cyclic stresses, thereby leading to fatigue of the blades, axles,
and bearing material. These stresses are particularly problematic
under gusty or changing wind conditions.
[0004] Some wind turbines, known as vertical axis wind turbines,
rotate around a vertical axis. One example of a vertical axis wind
turbine is a Darrius or "egg beater" type wind turbine. In such
wind turbines, the main rotor shaft runs vertically, as contrasted
with the horizontal rotor shafts of horizontal axis wind turbines.
Unlike horizontal axis wind turbines, vertical axis wind turbines
can incorporate the generator and gearbox near the bottom of the
structure. As a result, the tower does not need to support the
generator and gearbox, and the turbine does not need to be pointed
into the wind. Some conventional vertical axis wind turbines also
suffer from some drawbacks, such as a pulsating torque produced
during each revolution. In addition, mounting vertical axis
turbines on towers is relatively difficult. As a result, vertical
axis turbines typically operate in the slower, more turbulent air
flow near the ground. With the air flow slower and more turbulent
relative to higher altitudes; vertical axis wind turbines may
extract energy from wind less efficiently than horizontal axis wind
turbines. In addition, vertical axis wind turbines, like horizontal
axis wind turbines, are typically velocity-governed and suffer from
many of the same problems exhibited by horizontal axis wind
turbines, including, for example, efficiency limitations at both
high and low wind speeds and stresses imparted by centrifugal
forces.
SUMMARY OF THE DISCLOSURE
[0005] According to various example embodiments, a vertical axis
sail-type wind turbine includes an array of sail-like structures
that are mounted on rotating sail masts. The sail-like structures
can be oriented to interact with the wind. For example, when the
sail-like structures are moving in a downwind direction, they are
oriented to present a flat surface that is perpendicular to the
wind direction. On the other hand, when the sail-like structures
are moving in an upwind direction, they are oriented to present a
surface that is at an angle that creates an upwind vector. The
sail-like structures rotate about the sail masts, which are mounted
to transverse mounting arms that are firmly mounted to a main mast.
The main mast transfers power through a gear and shaft drive to
hydraulic pumps in the tower. This hydraulic fluid pressure is then
used to drive an electrical generator.
[0006] One embodiment is directed to a wind turbine. At least two
transverse mounting arms are mounted on and supported by a main
tower. A sail assembly is mounted between the at least two
transverse mounting arms. The sail assembly comprises a main mast
defining a vertical axis of rotation. At least two sail arms are
mounted on and supported by the main mast. A sail is mounted
between the at least two sail arms. The sail is configured to
rotate about the vertical axis of rotation in response to wind. A
hydraulic pump is configured and arranged to generate a hydraulic
output in response to rotation of the sail about the vertical axis
of rotation.
[0007] In another embodiment, a wind turbine arrangement includes a
number of wind turbines. Each wind turbine includes a main tower
and at least two transverse mounting arms mounted on and supported
by the main tower. A sail assembly is mounted between the at least
two transverse mounting arms. The sail assembly comprises a main
mast defining a vertical axis of rotation. At least two sail arms
are mounted on and supported by the main mast. A sail is mounted
between the at least two sail arms. The sail is configured to
rotate about the vertical axis of rotation in response to wind.
Each wind turbine is configured to generate a hydraulic output in
response to rotation of the sail about the vertical axis of
rotation. The hydraulic outputs of the wind turbines are linked
together. A hydraulic pump is configured to receive the linked
hydraulic outputs of the wind turbines and to drive an electrical
generator. The hydraulic pump and the electrical generator may be
housed in a control building, along with other components, such as
a microprocessor-based system for controlling the operation of the
wind turbine arrangement.
[0008] Another embodiment is directed to a wind turbine comprising
a main tower. Transverse mounting arms are mounted on and supported
by the main tower. Sail assemblies are mounted between at least two
of the transverse mounting arms. Each sail assembly has a main mast
defining a vertical axis of rotation and at least two sail arms
mounted on and supported by the main mast. Sails are mounted
between the sail arms. The sails are configured to rotate about the
vertical axis of rotation in response to wind. A hydraulic pump is
configured and arranged to generate a hydraulic output in response
to rotation of the sails of the sail assemblies about the vertical
axes of rotation.
[0009] Various embodiments may provide certain advantages. The wind
turbine disclosed herein is torque-governed rather than
velocity-governed and can therefore generate power at a wide range
of wind speeds. Also, compared to the blades in a horizontal axis
wind turbine, the sail-like structures of the vertical axis wind
turbine disclosed herein are less susceptible to flexion and
extension under even gusty or changing wind conditions. Thus, the
need for maintenance and replacement parts is significantly
reduced. In addition, the wind turbine disclosed herein can extract
energy from the wind in both downwind and upwind directions. Also,
the wind turbine is both laterally and vertically scalable to
enable power generation on a larger scale than has previously been
realized, particularly with horizontal axis wind turbines.
[0010] Additional objects, advantages, and features will become
apparent from the following description and the claims that follow,
considered in conjunction with the accompanying drawings.
BRIEF DESCRIPTION OF THE DRAWINGS
[0011] FIG. 1 is a plan view of a wind turbine arrangement
according to one embodiment.
[0012] FIG. 2 is a plan view of a portion of the wind turbine
arrangement of FIG. 1.
[0013] FIG. 3 is an elevational view of a wind turbine forming part
of the wind turbine arrangement of FIG. 1, according to another
embodiment.
[0014] FIG. 4 is an elevational view of a portion of the wind
turbine of FIG. 3.
[0015] FIG. 5 is a sectional view taken along lines 5-5 of FIG. 3,
showing certain details of the wind turbine of FIG. 3.
[0016] FIG. 6 is a sectional view taken along lines 6-6 of FIG. 5,
showing certain details of the wind turbine of FIG. 3.
[0017] FIG. 7 is a diagrammatic top plan view of a wind turbine
showing selected sail positions with a given wind direction,
according to another embodiment.
[0018] FIG. 8 is a diagrammatic top plan view of a wind turbine
showing transitions between sail positions as the sail rotates in
one direction.
[0019] FIG. 9 is a diagrammatic top plan view of a wind turbine
showing transitions between sail positions as the sail rotates in
another direction.
DESCRIPTION OF VARIOUS EMBODIMENTS
[0020] According to various example embodiments, a vertical axis
sail-type wind turbine includes an array of sail-like structures
that are mounted on rotating sail masts. When the sail-like
structures are moving in a downwind direction, they are oriented to
present a flat surface that is perpendicular to the wind direction.
When the sail-like structures are moving in an upwind direction,
they are oriented to present a surface that is at an angle that
creates an upwind vector. The sail-like structures rotate about the
sail masts, which are mounted to transverse mounting arms that are
firmly mounted to a main mast. The main mast transfers power
through a gear and shaft drive to hydraulic pumps in the tower.
This hydraulic fluid pressure is then used to drive an electrical
generator. The use of a hydraulic power transfer eliminates the
transmission and planetary gear system that are characteristic of
many conventional wind turbines.
[0021] In the following description, numerous specific details are
set forth in order to provide a thorough understanding of various
embodiments. It will be apparent to one skilled in the art that
some embodiments may be practiced without some or all of these
specific details. In other instances, well known components and
process steps have not been described in detail.
[0022] Various embodiments may be described in the general context
of processor-executable instructions, such as program modules,
being executed by a processor. Generally, program modules include
routines, programs, objects, components, data structures, etc.,
that perform particular tasks or implement particular abstract data
types. The invention may also be practiced in distributed
processing environments in which tasks are performed by remote
processing devices that are linked through a communications network
or other data transmission medium. In a distributed processing
environment, program modules and other data may be located in both
local and remote storage media, including memory storage
devices.
[0023] Referring now to the drawings, FIG. 1 is a top plan view of
a wind turbine array 100 according to one embodiment. The wind
turbine array 100 is illustrated in FIG. 1 as including six wind
turbines 102. Persons of ordinary skill in the art will appreciate
that the wind turbine array 100 may include more or fewer wind
turbines 102 than are illustrated in FIG. 1, and that the wind
turbines 102 may be arranged in a configuration that is either
similar to or different from the configuration shown in FIG. 1.
[0024] The wind turbine array 100 also includes a control building
104. The control building 104 is illustrated as being located
proximate the geographic center of the wind turbine arrangement
100. Locating the control building 104 in this position facilitates
monitoring the operation of the wind turbines 102. In addition, in
this configuration, the control lines and hydraulic fluid lines
between the various wind turbines 102 and the control building 104
can be made substantially uniform. In this way, the control and
hydraulic fluid lines between any individual wind turbine 102 and
the control building 104 are prevented from being excessively long.
However, persons of ordinary skill in the art will appreciate that
the control building 104 may be located in another position
relative to the wind turbine arrangement 100.
[0025] FIG. 2 is a plan view illustrating the control building 104.
The control building 104 includes two generators 106 and two
hydraulic pumps 108 that are hydraulically coupled with the wind
turbines 102 via hydraulic fluid lines (not shown). It will be
appreciated by those of ordinary skill in the art that the control
building 104 may incorporate more or fewer generators 106 and
hydraulic pumps 108 than are shown in FIG. 2. In some embodiments,
the control building 104 may have a door 110 that is sized and
arranged to allow the generators 106 to be pulled out on wheels
should the need to replace or service the generators 106 arise.
[0026] When the wind turbines 102 extract mechanical energy from
wind, hot hydraulic fluid is pumped through the hydraulic fluid
lines at high pressure to the control building 104. The hydraulic
fluid outflows from the various wind turbines 102 are combined into
a single hydraulic fluid line using pressure equalizers (not shown)
to equalize the fluid pressure in the hydraulic fluid outflows from
the various wind turbines 102. Equalizing the fluid pressure in
this way prevents hydraulic fluid from flowing backward through the
hydraulic fluid lines. By linking hydraulic outputs, the same
number of generators can be used for multiple towers in a wind
farm, thereby facilitating expansion of the wind farm. A splitter
(not shown) splits the hydraulic fluid output of the combined
hydraulic fluid line into multiple lines that drive the generators
106.
[0027] The hydraulic fluid drives the generators 106, thereby
generating electrical power as the wind turbines 102 rotate in
response to the wind. As the hydraulic fluid drives the generators
106, its fluid pressure decreases, while its temperature remains
hot. The hot hydraulic fluid output by the generators 106 is then
cooled, for example, using a cooling system 112. The cooling system
112 may incorporate exhaust fans 114, a radiator, and an intake
filter 116. Air from the outside environment is drawn in under
negative pressure by the exhaust fans 114 through the intake filter
116. The air cools the hydraulic fluid and is returned to the
outside environment. The cooled hydraulic fluid is then returned to
the wind turbines 102.
[0028] The control building 104 also includes a control tower 118,
which may be located on an upper floor of the control building 104.
The control tower 118 may have a hexagonal profile as shown in FIG.
2 to facilitate monitoring the operation of the wind turbines 102.
Alternatively, the control tower 118 may have a circular or
substantially circular profile. The control tower 118 controls and
monitors various aspects of the operation of the wind turbine array
100, including, for example, the hydraulic system, the individual
wind turbines 102, and the generator output.
[0029] The control tower 118 incorporates a microprocessor-based
system (not shown) that executes software to control the operation
of the wind turbine array 100. The microprocessor-based system is
typically configured to operate with one or more types of processor
readable media. Processor readable media can be any available media
that can be accessed by the microprocessor-based system and
includes both volatile and nonvolatile media, removable and
non-removable media. By way of example, and not limitation,
processor readable media may include storage media and
communication media. Storage media includes both volatile and
nonvolatile, removable and nonremovable media implemented in any
method or technology for storage of information such as
processor-readable instructions, data structures, program modules,
or other data. Storage media includes, but is not limited to, RAM,
ROM, EEPROM, flash memory or other memory technology, CD-ROM,
digital versatile discs (DVDs) or other optical disc storage,
magnetic cassettes, magnetic tape, magnetic disk storage or other
magnetic storage devices, or any other medium that can be used to
store the desired information and that can be accessed by the
microprocessor-based system. Communication media typically embodies
processor-readable instructions, data structures, program modules
or other data in a modulated data signal such as a carrier wave or
other transport mechanism and includes any information delivery
media. The term "modulated data signal" means a signal that has one
or more of its characteristics set or changed in such a manner as
to encode information in the signal. By way of example, and not
limitation, communication media includes wired media such as a
wired network or direct-wired connection, and wireless media such
as acoustic, RF, infrared, and other wireless media. Combinations
of any of the above are also intended to be included within the
scope of processor-readable media.
[0030] According to certain embodiments, the microprocessor-based
system obtains and interprets real-time input parameters relating,
for example, to the wind velocity and direction, the rotation of
the sails, power generation, and hydraulic fluid pressure levels.
Based on these input parameters, the microprocessor-based system
adjusts various aspects of the operation of the wind turbine array
100. For example, the microprocessor-based system may adjust the
orientation of the sails to obtain maximum power in both downwind
and upwind movements. In addition, the microprocessor-based system
maintains a substantially constant rotational speed of the wind
turbines at, for example, 20 revolutions per minute, by adjusting
the load on the generators 106. To accomplish this adjustment, the
microprocessor-based system may adjust the armature strength upward
or downward in real time.
[0031] FIG. 3 is an elevational view of one of the wind turbines
102 forming part of the wind turbine array 100. The wind turbine
102 includes a main tower 130 supported on a base 132. In one
embodiment, the main tower is approximately 250 feet tall. A main
mast is bearing mounted to the main tower 130 via transverse
mounting arms 134, 136, and 138. The main tower 130, which remains
substantially stationary during operation of the wind turbine 102,
supports transverse mounting arms 134, 136, and 138, which also
remain substantially stationary during operation of the wind
turbine 102. Rotatable main masts 140 are mounted on and supported
between transverse mounting arms 134 and 136 and transverse
mounting arms 136 and 138, respectively. In addition, a third main
mast (not visible in FIG. 3) is mounted on and supported between
each pair of transverse mounting arms, such that each pair of
transverse mounting arms is associated with three main masts and
three sails. The rotatable main masts define vertical axes of
revolution. Sails 144 are mounted to the main masts and rotate
about the axes of revolution defined by the main masts 140. The
structure and operation of the sails 144 are described more fully
below in connection with FIG. 4. Four such assemblies of sails 144
and main masts 140 are mounted at 90 degree intervals around the
main tower 130.
[0032] Near the bottom of the wind turbine 102, flywheel assemblies
146 maintain a constant rotational velocity and provide gyroscopic
stabilization for the rotating sail assemblies and provide a
braking surface for four hydraulic brakes. The structure and
operation of the flywheel assemblies 146 are described more fully
below in connection with FIG. 5.
[0033] According to some embodiments, the wind turbine 102 is both
horizontally and vertically scalable to promote efficiently
capturing the mechanical energy contained in the wind. The wind
turbine 102 may be horizontally scaled by increasing the width of
the sails 144. Additionally, the wind turbine 102 may be vertically
scaled by adding one or more further levels of sails 144. As the
wind turbine 102 is constructed to great heights, guywires 150 may
be used to stabilize the wind turbine 102.
[0034] FIG. 4 is an enlarged elevational view of a lower portion of
the wind turbine 102. Among other structures, FIG. 4 illustrates
the sails 144 in greater detail. It should be noted that, while two
sails 144 are visible in FIG. 4, each main mast, such as the main
mast 140 shown in FIG. 4, preferably has three sails 144 mounted
thereon. Each sail 144 includes a number of vanes 160 mounted
between two crossbeams, one of which is shown as sail arm 162 in
FIG. 4, and the other of which is not visible in FIG. 4.
Preferably, each sail 144 includes two vanes 160 on each side of
the sail 144, promoting symmetry and thereby enabling the sail 144
to balance itself. Also mounted between these two crossbeams is a
sail mast 164. The sail masts 164 are mounted on a crossbeam 166,
which is itself fixedly mounted to the main mast 140.
[0035] The vanes 160 can be rotated using individual hydraulic
servo motors 168. In this way, the orientation of the sails 144 is
precisely controlled by the hydraulic servo motors 168 as the sails
144 rotate about the axes of rotation defined by the sail masts. In
particular, the vanes 160 are oriented to create a flat surface
perpendicular to the wind direction when a sail 144 is moving
downwind. When the sail 144 is moving upwind, the vanes 160 are
oriented to create a surface at an angle that creates an upwind
vector.
[0036] FIG. 7 illustrates one particular scheme according to which
the vanes 160 may be rotated. In order to avoid unnecessarily
complicating the disclosure of the operation of the vanes 160, only
a selected set of orientations is disclosed herein in connection
with FIG. 7. In the example shown in FIG. 7, a wind originates from
the south, indicated at the bottom of FIG. 7.
[0037] In response to the wind from the south, certain sail
assemblies will rotate clockwise, while others opposed 180 degrees
will rotate counterclockwise. In both cases, there are four
possible transition points at which the orientation of the vanes
160 may change. These transition points occur at 90 degree
intervals throughout the 360 degree rotational cycle. Whether a
given sail assembly rotates clockwise or counterclockwise,
transitions will occur at the 0 degree and 180 degree points.
Further, if the sail assembly is rotating clockwise, a transition
will also occur at the 90 degree point, but not at the 270 degree
point. On the other hand, if the sail assembly is rotating
counterclockwise, a transition will occur at the 270 degree point,
but not at the 90 degree point.
[0038] FIG. 8 illustrates the transition points when the sail
assembly rotates counterclockwise with a wind from the south. At
each transition point, solid lines indicate the position of the
vanes immediately before the transition point, while dashed lines
indicate the position of the vanes immediately after the transition
point. Immediately before the 0 degree point, the vanes are
oriented at a 45 degree angle. As the sail assembly rotates
counterclockwise through the 0 degree point, the vanes are oriented
essentially flat, e.g., at 10 degree angles canted toward the sail
mast. No transition occurs at the 90 degree point, but as the sail
assembly rotates through the 180 degree point, the vanes change in
orientation from an essentially flat angle to a 45 degree angle. As
the sail assembly rotates through the 270 degree point, the vanes
change orientation again, this time from a 45 degree angle to a 45
degree angle in an opposite direction. The vanes remain in this
orientation until the sail assembly rotates through the 0 degree
point.
[0039] FIG. 9 illustrates the transition points when the sail
assembly rotates clockwise with a wind from the south. At each
transition point, solid lines indicate the position of the vanes
immediately before the transition point, while dashed lines
indicate the position of the vanes immediately after the transition
point. Immediately before the 0 degree point, the vanes are
oriented at a 45 degree angle. As the sail assembly rotates
clockwise through the 0 degree point, the vanes are oriented
essentially flat, e.g., at 10 degree angles canted toward the sail
mast. No transition occurs at the 270 degree point, but as the sail
assembly rotates through the 180 degree point, the vanes change in
orientation from an essentially flat angle to a 45 degree angle. As
the sail assembly rotates through the 90 degree point, the vanes
change orientation again, this time from a 45 degree angle to a 45
degree angle in an opposite direction. The vanes remain in this
orientation until the sail assembly rotates through the 0 degree
point.
[0040] As a particular example, the sail assembly located at the
south position on FIG. 7 rotates clockwise. The sail 144a at the 0
degree position initially has its vanes 160 oriented inward toward
the center of the sail 144a at a 10 degree angle so as to present a
substantially flat surface perpendicular to the wind direction.
This orientation promotes capturing the mechanical energy of the
wind, and is maintained as the sail 144a rotates clockwise through
the 270 degree position. As the sail 144a continues to rotate
clockwise through the 180 degree position, however, the sail 144a
transitions from moving downwind to moving upwind. Accordingly, as
the sail 144a rotates through the 180 degree position, the vanes
160 are rotated to a 45 degree orientation, so as to create an
upwind vector. In this way, energy may be captured during both the
downwind movement and the upwind movement. This vane orientation is
maintained until the sail 144a rotates through the 90 degree
position, at which point the vanes 160 are rotated to a 45 degree
orientation in the opposite direction, such that the upwind vector
is maintained. This new orientation is maintained until the sail
144a rotates through the 0 degree position, at which point the
vanes 160 return to the orientation shown in the sail 144a at the 0
degree position. The sail assembly located at the east position on
FIG. 7 also rotates clockwise, like the sail assembly located at
the south position. Accordingly, the movement of the vanes 160 is
similar between these two sail assemblies.
[0041] As another example, the sail assemblies located at the north
and west positions on FIG. 7 rotate counterclockwise and likewise
exhibit similar movement of the vanes 160. In this case, turning to
the sail assembly located at the north position on FIG. 7, the sail
144d at the 0 degree position initially has its vanes 160 oriented
inward toward the center of the sail 144d at a 10 degree angle so
as to present a substantially flat surface perpendicular to the
wind direction. This orientation promotes capturing the mechanical
energy of the wind, and is maintained as the sail 144d rotates
counterclockwise through the 90 degree position. As the sail 144d
continues to rotate counterclockwise through the 180 degree
position, however, the sail 144d transitions from moving downwind
to moving upwind. Accordingly, as the sail 144d rotates through the
180 degree position, the vanes 160 are rotated to a 45 degree
orientation, so as to create an upwind vector. In this way, energy
may be captured during both the downwind movement and the upwind
movement. This vane orientation is maintained until the sail 144d
rotates through the 270 degree position, at which point the vanes
160 are rotated to a 45 degree orientation in the opposite
direction, such that the upwind vector is maintained. This new
orientation is maintained until the sail 144d rotates through the 0
degree position, at which point the vanes 160 return to the
orientation shown in the sail 144d at the 0 degree position.
[0042] In some embodiments, the hydraulic servo motors 168 are
further controlled by the microprocessor-based system, which
analyzes real-time sensor-obtained information on wind speed, wind
direction, sail position, and sail mast position. The
microprocessor-based system then continuously moves the vanes and
sails using the hydraulic servo motors to resist the maximum wind
force. The microprocessor-based system is also programmed to cause
the wind turbine 102 to generate increased torque, rather than
increased velocity, as the wind speed increases.
[0043] The generator 106 is driven by a hydraulic motor that is
connected to the hydraulic pumps from the mainsail masts. The
microprocessor-based system uses real-time sensor monitoring of
wind velocity, hydraulic fluid output pressure, and generator field
output power to continuously adjust the armature strength to
maintain the mainsail mast and armature of the generators 106 of
FIG. 2 at a constant speed, for example, 20 revolutions per minute.
The generator field is wound so as to create a 60 Hz AC current
when the armature is maintained at 20 revolutions per minute. This
power can then be stepped up via a transformer to transmission
voltage and uplinked to a power grid.
[0044] As the sails 144 rotate, asymmetric power loading on the
main masts during downwind versus upwind rotation would cause a
lateral oscillation in at least two directions. This problem is
resolved by the following means: First, downwind sail rotations on
opposite sides of the main tower 130 are counter-rotating. For
example, in FIG. 7, the north sail assembly and the south sail
assembly rotate in opposite directions. Similarly, the east and
west sail assemblies rotate in opposite directions. As a result,
equal and opposite oscillation forces on the main tower 130 are
generated.
[0045] Second, the flywheel assemblies 146 at the lower end of each
main mast serve as a gyroscope preventing any remaining oscillation
forces and generating a smooth, constant power output. FIG. 5 is a
sectional view taken along lines 5-5 of FIG. 3. While only one
flywheel assembly 146 is visible in FIG. 5, it will be appreciated
that the wind turbine 102 includes four flywheel assemblies 146
surrounding the lower end of the main tower 130. Each flywheel
assembly 146 acts as a gyroscope to resist extraneous oscillation
forces. With four flywheel assemblies 146 surrounding the lower end
of the main tower 130, the main tower is extremely stable.
[0046] Each flywheel assembly 146 includes a flywheel 170, which
may be approximately 12 feet in diameter. The flywheel 170 has an
upper surface that also serves as a brake disk for hydraulic brakes
172. In one embodiment, the flywheel assembly 146 has four
hydraulic brakes 172, two of which are visible in FIG. 5. The
flywheel 170 is weighted to contain four times the energy of one
main mast revolution.
[0047] FIG. 5 also illustrates an example drive mechanism for
transferring the mechanical energy extracted from the wind by the
sails 144 to the hydraulic pumps contained in the main tower 130.
These hydraulic pumps are in turn hydraulically coupled to
hydraulic motors in the control building 104. As the sails 144
rotate about the rotational axis defined by the main mast 140, they
drive a ring gear 174, which interacts with a pinion gear 176
affixed to a shaft 178 to cause the shaft 178 to rotate. In some
embodiments, the shaft 178 is capable of expanding and contracting
without adversely affecting the operation of the gears 174 and 176.
This capability may be provided by a slip fitting or spline joint,
as shown in FIG. 5, or by a universal joint, which would be
considerably more expensive to implement than a slip fitting.
[0048] As the shaft 178 rotates, a pinion gear 180 at the opposite
end of the shaft 178 relative to the gear 176 rotates and drives a
double ring gear 182 in the main tower 130. The double ring gear
182 drives the hydraulic pumps (not shown in FIG. 5) at the base of
the main tower 130. In addition, linking the outputs of the sail
assemblies in this way maintains synchronization between the
rotating sail assemblies. The hydraulic pumps are coupled to
hydraulic motors in the control building 104, which drive the
generators 106 in the control building 104, thereby generating
electrical energy.
[0049] FIG. 6 is a sectional view taken along lines 6-6 of FIG. 5.
As shown in FIG. 6, the shafts 178a and 178b that are driven by
sail assemblies on opposite sides of the main tower 130 rotate in
opposite directions. Accordingly, to ensure that the rotation of
the gears 180a and 180b causes the double ring gear 182 to rotate
in a single direction, the gears 180a and 180b are located on
opposite sides of the double ring gear 182. That is, while the gear
180a is located above the double ring gear 182, the gear 180b is
located below the double ring gear 182. As the double ring gear 182
rotates, it drives hydraulic pumps 184. Ports 186 on the hydraulic
pumps 184 permit the inflow and outflow of hydraulic fluid from the
hydraulic pumps 184. Hydraulic fluid is conveyed to the control
building 104 via a hydraulic fluid line 148 of FIG. 3, which is
located underground proximate the base 132 to wind turbine 102.
[0050] As demonstrated by the foregoing discussion, various
embodiments may provide certain advantages, particularly when
compared with horizontal axis wind turbines. With the vertical
axis, the wind turbine described herein is both laterally and
vertically scalable. For example, by stacking sails vertically with
guywire stabilization, the wind turbine can be built to heights of
up to 1000 feet. At such high altitudes with higher wind speeds and
greater laminar flow, significantly more power can be generated
than with horizontal axis wind turbines, which cannot use guywires.
In addition, the need for certain structures at the top of the wind
turbine, such as the transmission, generator, and yaw mechanism
characteristic of horizontal axis wind turbines, is avoided,
thereby promoting stability and facilitating repair. The reduced
number of mechanical parts may result in a lower initial cost,
lower operating costs, greater reliability, and lower cost per
kilowatt hour.
[0051] In addition, the use of sails may realize a number of
advantages relative to both horizontal axis wind turbines and
conventional vertical axis wind turbines. Because the sails move
symmetrically, for example, the wind turbine is particularly
stable, especially in view of the use of the flywheel/gyroscope for
balancing. Further, sails can extract far greater wind energy
relative to lift-type wind turbines. Gusty or changing wind loads
at different tower heights do not cause bending or torturing of
sails as they do to propellers on horizontal axis wind turbines. As
a result, even under high wind conditions, the sails cannot hit the
main tower as propellers can.
[0052] The relatively slow rotation speed (20 rpm) of the sails may
also produce a number of advantages. Torque generating sails
revolving at only 20 rpm will generate significantly less noise as
compared with propeller driven wind turbines, whose wingtip
velocity can exceed 180 mph and create a noise in excess of 90 dB.
Also, because of their low speed, the sails will be visible to
birds that can avoid flying into them. By contrast, millions of
birds are killed each year by high speed propeller tips that cannot
be seen by birds.
[0053] It will be understood by those who practice the embodiments
described herein and those skilled in the art that various
modifications and improvements may be made without departing from
the spirit and scope of the disclosed embodiments. The scope of
protection afforded is to be determined solely by the claims and by
the breadth of interpretation allowed by law.
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