Note: Descriptions are shown in the official language in which they were submitted.
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TITLE: VERTICAL AXIS WiND TURBINE WITH WIlNGLETTED
CAM-TILTABLE BLADES
BACKGROUND OF THE IIWENTION
1. Field of the Invention
The present invention relates to a vertical axis wind turbine with
wingletted cam-tiltable blades, and in particular to a vertical axis wind
turbine
that employs a guide means constituted of cams and crank arms, and
aerodynamic for-ce, to control the tilting or swiveling of the angle of the
blades,
such that is the blades are automatically set in a windward position to
receive
wind eneigy from variable directions so as to cause the shaft to drive a power
generator even in low wind speed conditions and thereby realize optiinum
power generation performance.
2. The Related Arts
Due to the increasing consumption of fossil fuel, reserves of fossil fuel are
gradually getting depleted and increasing levels of carbon dioxide are causing
a severe "greenhouse" phenomenon in the Earth's atinosphere. Thus, the
United Nations has issued regulations and commands and is coordinating the
fight against global wanning. Recently, many nations around the world have
put a lot of effort into developing renewable energies, among which wind
energy is one of the best. This is simply because wind power stations do not
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generate any carbon dioxide emissions and have absolutely no risk of nuclear
pollution.
Electrical power is considered "advanced" energy and has an extremely
wide range of applications. Electricity is also the foundation of modem
civilization, and is a must for modem society.
The known horizontal axis wind power station usually needs a tower as
high as 50 meters, which cames a generator and a blade assembly that drives
the generator at the top thereof. This makes the tower very bulky, costly and
difficult to maintain. Thus, the known construction of the horizontal axis
wind turbine is apparently not an ideal solution for wind power stations.
Prior references discussing or disclosing windmill or wind turbine power
generation include, for example, US Patent Nos. 4,496,283; 384,232; 440,266;
505,736; 685,774; 830,917; 1,076,713; 4,534,703; 4,679,985; 4,818,180;
5,256,034; 4,220,870; 7,118,344; 6,749,399; 963,359; 5,269,647; 6,000,907;
6,537,018; 5,083,902; 6,749,393; 863,715; 4,509,899; 4,421,458; 6,726,439;
5,195,871; and 4,245,958, but are not limited thereto. These known
references share at least the following drawbacks:
(1) The construction is complicated and assembly is difficult, both leading
to increased costs;
(2) Swiveling or tilting of the blades to face the direction of the incoming
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airflow is not carried out by aerodynamic force so an additional device for
swiveling or tilting the blades is needed, such as a wind vane coupled to the
blade by a transmission mechanism; and
(3) The design of the structure is poor because a huge initial driving force
is needed to swivel the blades to face the wind direction, such that the
blades
cannot be properly swiveled in low wind speed conditions, leading to low
power generation efficiency.
Other prior references are also known, including US Patent Nos.
3,995,170; 6,688,842; and 6,749,394, none of which discloses effective use of
the aerodynamic force, and all of which have the following drawbacks:
(1) All the blades are individually arranged in a vertical state, and are not
interconnected to facilitate swiveling thereof (the blades of US Patent No.
3,995,170 are interconnected, but a transmission mechanism is needed for the
interconnection), so that the initial driving force for swiveling the blades
is
huge;
(2) The blades have to be swiveled (by an angle of as much as 180
degrees) to face the wind direction by a huge initial driving force so that
the
blades cannot be swiveled in low wind speed conditions, leading to poor
power generation efficiency; and
(3) The blades are not of a design or construction good enough to
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facilitate swiveling of the blades with a small initial driving force.
Further prior references, such as US Patent No. 4,383,801, use a large
wind vane to facilitate swiveling of blade via a cam. This known device has at
least the following drawbacks:
(1) The construction is complicated and assembly is difficult, both leading
to an increase of costs; and
(2) The swiveling of the blades is driven by mechanical transmission, so
that the initial driving force for swiveling the blades is huge and the blades
cannot be swiveled in low wind speed conditions, leading to poor power
generation efficiency.
Further references, such as Chinese Patent No. 96120092.8, disclose a
blade swiveling system that uses a wind vane to track the wind direction and
issue an electronic signal to control a servo motor which swivels the blades,
but the blades have to be driven all the way by the servo motor, leading to
consumption of electrical power and increased risk of breakdown caused by
undesired influences of temperature and/or humidity on the electronic
components. In addition, the motor is mounted on a rotary member and a
rotary joint has to be established to transmit electrical power, leading to
high
risk of failure.
Further references, such as Chinese Patent No. 02232245.0, also suffer
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various drawbacks, such as:
(1) A huge initial driving force is needed for tilting or swiveling the blades
to face the direction of the incoming air flows, and tilting or swiveling the
blades is generally impossible in low wind speed conditions, such that the
5 efficiency of power generation is quite low.
(2) The design of the blades is poor, including using additional winglets to
facilitate the tilting or swiveling of the blades, such that a huge initial
driving
force is needed for swiveling the blades.
Thus, the known technology/devices are not good enough. The present
inventor has devoted time and energy to the development of the wind turbine
with experiments and tests. The present invention is therefore aimed at
solving and/or alleviating the drawbacks of the known devices by providing a
vertical axis wind turbine with wingletted cam-tiltable blades.
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StJI!/IlVIARY OF THE INVENTION
In accordance with the present invention, a vertical axis wind turbine with
wingletted cam-tiltable blades is provided, comprising: a generator, a shaft
interconnected with the generator, and a plurality of blade sets coupled to
the
shaft. Cam members are provided inside the shaft and have guide sections of
pre-determined shapes. A blade set includes blades that are coupled to crank
arms in contact with the guide sections. Thus, when the blades are located in
a windward position and a leeward position respectively, the blades are caused
by the guide sections to automatically and easily set in an optimum
pressure-receiving condition and a least wind-resistance condition,
respectively, for receiving wind energy from variable directions, so that the
shaft is rotatable even with low wind speeds to achieve optimum power.
The foregoing object and summary provide only a brief introduction to
the present invention. To appreciate fully these and other objects of the
present invention as well as the invention itself, all of which will become
apparent to those skilled in the art, the following detailed description of
the
invention and the claims should be read in conjunction with the accompanying
drawings. Through the specification and drawings, identical reference
numbers refer to identical or similar parts.
Many other advantages and features of the present invention will be
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manifested to those versed in the art upon making reference to the detailed
description and the accompanying sheets of drawings, in which a preferred
structural embodiment incorporating the principles of the present invention is
shown by way of illustrative example.
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BRIEF DESCRIPTION OF THE DRAWINGS
The present invention will be apparent to those skilled in the art by
reading the following description of preferred embodiments thereof, with
reference to the attached drawings, wherein:
Figure 1 is a perspective view of a vertical axis wind turbine constructed
in accordance with the present invention;
Figure 2 is an exploded view of a blade set of the vertical axis wind
turbine in accordance with the present invention;
Figures 3 and 4 are perspective views illustrating the operation of the
vertical axis wind turbine of the present invention;
Figure 5 is a perspective view, partially sectioned, illustrating a cam shaft
of the vertical axis wind turbine of the present invention;
Figure 6 is a perspective view, partially sectioned, illustrating a cam driver
device of the vertical wind turbine of the present invention;
Figure 7 is a perspective view, illustrating the operation of the vertical
axis wind turbine of the present invention;
Figure 8 is a cross-sectional view taken along line A-A of Figure 7;
Figures 9a, 9b, 9c are cross-sectional views taken along line B-B of
Figure 7, illustrating the operation of the blades swiveling upward from a
horizontal state to a vertical state;
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Figures 10a, l Ob, 10c are cross-sectional views taken along line C-C of
Figure 7, illustrating the operation of the blades swiveling from a vertical
state
to a horizontal state;
Figure 11 is a perspective view, illustrating the operation of the vertical
axis wind turbine of the present invention;
Figure 12 is a perspective view, partially sectioned, illustrating the
operation of a shaft of the vertical axis wind turbine of the present
invention
driving a generator for power generation;
Figures 13 and 14 are perspective views, partially sectioned, illustrating a
cam driver device moving the fust cam member downwards on the vertical
axis wind turbine of the present invention; and
Figure 15 is a cross-sectional view illustrating the adjustment in the angle
of the blades by the downward movement of the first cam member.
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DETAILED DESCRIPTTON OF THE PREFERRED EMBODIMENTS
The following descriptions are of exemplary embodiments only, and are
not intended to limit the scope, applicability or configuration of the
invention
in any way. Rather, the following description provides a convenient
5 illustration for implementing exemplary embodiments of the invention.
Various changes to the described embodiments may be made in the function
and arrangement of the elements described without departing from the scope
of the invention as set forth in the appended claims.
With reference to the drawings and in particular to Figures 1-6, a vertical
10 axis wind turbine constructed in accordance with the present invention
comprises a generator 10, a shaft 20, a first cam member 31, a second cam
member 32, a plurality of blade sets 40, a cam driver device 50, and a support
frame 60. The blade set 40 comprises blades 43 each coupled to a crank arm
44 that is engaged to guide sections 311, 321 of the fust and second cam
members 3 l, 32. When the blades 43 are in a windward position and a
leeward position respectively, they can be manipulated by the guide sections
311, 321 to automatically and easily set in an optimum pressure-receiving
condition and least wind-resistance condition, respectively, for receiving of
wind energy from variable directions and thus providing the optimum power
generation perfomlance. A detailed description of a preferred embodiment
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of the present invention will be given as follows.
The generator 10 functions to convert rotary mechanical energy into
electrical power.
The shaft 20 is coupled to the generator 10 by gears 11, 12 and rotation of
the shaf120 functions to drive the generator 10 for generation of power. The
shaft 20, which is hollow, contains a cam shaft 21 and an outerjacket 22
fitted
over the cam shaft 20.
The first cam member 31 and the second cam member 32 are vertically
aligned and are fitted over the outer jacket 22. The first cam mernber 31 and
the second cam member 32 are fixed to the cam shaft 21 and the jacket 22 by
fasteners. The jacket 22 forms a slot 221 at the location where each fastener
extends to allow the cam shaft 21 to move the first cam member 31 downward
a pre-determined distance. The first and second cam members 31, 32 have
opposing faces between which there is a guide channel 33. The opposing
faces also act, respectively, as the guide sections 311, 321, which, at two
diametrically opposed points, have inclined sections 312, 322.
The blade sets 40 are an anged in such a way that an upper-level blade set
and lower-level blade set, which are stacked together in an alternate manner
to
serve as a unitary module, are fixed to the shaft 20 and the blade set 40 of
each
pair comprises portions arranged in an opposite manner on opposite sides of
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the shaft 20. If desired, a single pair of upper-level and lower-level blade
sets
can be used, or alternatively, based on the local topography and wind field,
one or more additional pairs of blade sets can be further stacked to increase
power generation efficiency. The blade set 40 comprises a frame 41 located
on each side of the shaft 20 and having a remote, free end forming a winglet
411 to reduce wind resistance. The fi-a.me 41 rotatably supports a plurality
of
blade rods 42 each of which is provided with a blade 43. Each blade rod 42
has a proximal end fornling the crank arm 44 that extends into the
corresponding guide channel 33 to engage the guide sections 311, 321 in a
movable manner. The proximal, inner end of the blade 43 forms a secondary
winglet 45 that is set at a pre-detennined angle and facilitates the
concentration
of incoming wind pressure.
The cam driver device 50 comprises a wind vane assembly 51 housed in
the shaft 20 with a wind vane projecting upward out of the shaft 20, a wind
direction sensor 52 arranged below the wind vane assembly 51, a stand 53 to
which a lower-end threaded section 211 of the cam shaft 21 is coupled in a
threading engagement manner, a first motor 54 and a second motor 55, of
which the first motor 54 drives axial movement of the cam shaft 21 that is
provided with the threaded section 211 via gears 541, 542 and the second
motor 55 drives, via gears 551, 552, rotation of the jacket 22 and the cam
shaft
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21 in association with the rotation of the wind vane and change of direction
thereof. The second motor 55 is activated by the wind direction sensor 52
when the wind vane assembly 51 is rotated by air flows or winds.
The support frame 60 is composed of a plurality of horizontal and vertical
bars 61 that form a multi-level framework to support the shaft 20.
Also referring to Figures 7 and 8, when the wind turbine of the present
invention is acted upon by wind, [as indicated by the arrows], the first cam
member 31 and the second cam member 32 are set in pre-d.etem.lined
positions in accordance with the direction indicated by the wind vane
assembly 51. The blades 43 of one side of the upper-level blade set 40 are
guided by the fust cam member 31 and the second cam member 32 and
caused by aerodynamic force to swivel automatically to a vertical state where
the vertical blades 43 receive the greatest wind pressure. Meanwhile the
blades 43 on the other side of the upper-level blade set 40 are guided by the
first cam member 31 to set an initial swiveling angle and thence, due to the
wind pressure acting upon the blades 43, automatically swivel to the
horizontal state, which is the state of least wind resistance, so that the
blade set
40 drives the shaft 20 to rotate in, for example, a counter-clockwise
direction.
At the same time, the lower-level blade set 40 is substantially parallel to
the air
flow of the wind thereby losing wind pressure (and thereby losing power), but
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the blades 43 on one side of the lower-level blade set 40 are in a horizontal
state, getting ready to be acted upon by the aerodynamic force of the wind to
start swiveling to a vertical state.
Figure 9 shows the condition succeeding from that shown in Figure 7.
With the upper-level and lower-level blade sets 40 further rotating
counter-clockwise, the blades 43 of the lower-level blade set 40 that are in a
horizontal state ready to receive the aerodynamic force of the wind (the
blades
43 of the other side of the lower-level blade set 40 being in a vertical
state)
cause the crank arms 44 thereof to move along the inclined sections 322 of the
second cam members 32 and thus their initial angle is changed by the
camming action. After that change of angle, the blades 43 are subject to
wind pressure which allows them automatically and easily to swivel upward.
When the blades 43 swivel and approach a vertical state, the blades 43 engage
with the inclined sections 322 of the guide sections 311 of the first cam
members 31 and are thus automatically stopped. At this point, the blades 43
together form a vertical surface that serves as an optimum wind-receiving
surface that effectively receives wind pressure for driving rotation of the
shaft
20.
Figure 10 also demonstrates the condition succeeding Figure 7. When
the blades 43 on one side of the lower-level blade set 40 start to receive
wind
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pressure and swivel to form a vertical surface, the blades 43 on the other
side
of the lower-level blade set 40, that were originally in a vertical state,
start to
get to a leeward position. The crank anns 44 thereof reach the inclined
sections 312 of the guide sections 311 of the first cam members 31 and are
5 induced thereby to change their angle so that the blade 43 that was in a
vertical
state easily swivels to a horizontal state, a less wind-resistant condition.
Referring to Figures 11 and 12, when the blades 43 of one side of the
lower-level blade set 40 are in a vertical state and are subject to the
greatest
wind pressure, the blades 43 of the other side of the lower-level blade set 40
10 are located in a leeward position and provide the least wind resistance. At
this moment, the upper-level blade set 40 is substantially parallel to the
direction of air flow of the wind, thus losing wind pressure (and thereby
losing
power), and the lower-level blade set 40 succeeds the rotation force of the
upper-level blade set 40. As such, wind energy of variable directions can be
15 intersected and optimum power generation performance can be ensured for
rotating the shaft 20 to drive the generator 10 even at low wind speeds.
Referring to Figures 13, 14, and 15, the cam shaft 21 is rotated by the first
motor 54 of the cam driver device 50 in order to move the threaded section
211 within the stand 53 in a vertical direction downwards and thus causing a
pre-determ.ined distance of travel of the first cam member in a vertical
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direction downwards for reducing the width of the guide channel 33. This
reduces the range of motion of the blades 43. In case of high wind speeds,
the range of motion of the blades 43 can be adjusted to regulate wind pressure
in order to prevent damage caused by excessive wind speeds.
Although the present invention has been described with reference to the
preferred embodiments thereof, it is apparent to those skilled in the art that
a
variety of modifications and changes may be made without departing from the
scope of the present invention which is intended to be defined by the
appended claims.
