Note : Les descriptions sont présentées dans la langue officielle dans laquelle elles ont été soumises.
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TITLE: VERTICAL AXIS WINDNIILL WITH WINGLETTED
AIR-TILTABLE BLADES
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a vertical axis windmill with wingletted
air-tiltable blades, and in particular to a vertical axis windmill that
employs
aerodynamic force to tilt or swivel the angle of the blades such that the
blades
are automatically set in a windward position to receive wind energy from
variable directions so as to cause the shaft to drive a power generator even
with a low wind speed (approximately 1-2m/s) and thereby realize optimum
power generation performance, where the blade structure and configuration is
not complicated, hence reducing the manufacturing costs thereof.
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 atmosphere. Thus, the
United Nations has issued regulations and commands and is coordinating the
fight against global warming. Recently, all 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 carries 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
windmill is apparently not an ideal solution for wind power stations.
Prior references discussing or disclosing windmill 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 camed out by aerodynamic force, so an additional device for
swiveling or tilting the blades is needed, such as a wind vane coupled to the
blades 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 blade
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 having 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, uses 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 on the electronic components by the temperature and/or
humidity of surrounding air. 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.
Thus, the known technology/devices are not good enough. The present
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inventor has devoted time and energy to the development of the windmill 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 windmill with wingletted air-tiltable blades.
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SUMMARY OF THE INVENTION
In accordance with the present invention, a vertical axis windmill is
provided, comprising: a generator, a shaft mounted to the generator, and a
plurality of blade sets. A blade set comprises a blade rod rotatably connected
to the shaft and canying blades arranged on opposite sides of the shaft. Each
blade is divided into first and second moment-inducing sections located on
opposite sides of the blade rod. The first moment-inducing section is greater
in area than the second moment-inducing section. Each blade is provided, at
a predetermined location thereof, with a winglet. Stops for limiting the
swiveling of the blade are arranged on the blade set. When the blade set is
moved so that the blades thereof are located in a windward position and
leeward position respectively, the blades are 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 speed to achieve optimum power
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generation performance. Further, no complicated swiveling structure is
needed for the blade.
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. Throughout the specification and drawings, identical reference
numbers refer to identical or similar parts.
Many other advantages and features of the present invention will be
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 windmill constructed in
accordance with a preferred embodiment of the present invention;
Figure 2 is an exploded view of the vertical windmill of the present
invention;
Figure 3 is an exploded view of a blade set of the vertical axis windmill in
accordance with the preferred embodiment of the present invention;
Figures 4 and 5 are perspective views illustrating the operation of the
vertical axis windmill of the present invention;
Figure 6 is a perspective view illustrating the first winglet of a blade of
the
blade set that receives wind pressure to swivel the blade upward;
Figures 7a, 7b, 7c illustrate the operation of the blades swiveling upward
from a horizontal state to a vertical state;
Figure 8 schematically demonstrates the blade in a horizontal state
receiving wind coming from a different direction to develop a lifting force;
Figure 9 is a perspective view illustrating the operation of the vertical axis
windmill of the present invention;
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Figures 10a,10b, l Oc illustrate the operation of the blades swiveling from
a vertical state to a horizontal state;
Figures 11 and 12 are perspective views illustrating the operation of the
vertical axis windmill of the present invention; and
Figure 13 is a perspective view illustrating a blade constructed in
accordance with another embodiment of the present invention.
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DETAILED DESCRIPTION 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
illustration for implementing exemplary embodiments of the invention.
Uarious 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 1-3, a vertical
axis windmill constructed in accordance with the present invention comprises
a generator 10, a shaft 20 mounted on the generator 10, a plurality of blade
sets 30, and a support frame 40. The blade set 30 comprises a plurality of
blade rods 31 each canying two blades 32 and rotatably mounted to the shaft
20, wherein the blades 32 are located on opposite sides of the shaft 20 and
are
provided with means for facilitating swiveling of the blades 32 so that the
blades 32, which are respectively on windward side and leeward side, can be
manipulated with aerodynamic force caused by air flows to automatically and
easily set in an optimum pressure-receiving position and least wind-resistance
position, respectively, for receiving of wind energy from variable directions
and thus providing optimum power generation performance even in low wind
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speed conditions. A detailed description for a preferred embodiment of the
present invention will be given as follows.
The generator 10 functions to convert rotary mechanical energy into
electrical power.
5 The shaft 20 is mounted on the generator 10 and functions to drive the
generator 10 for generation of power.
The blade sets 30 are arranged in such a way that an upper-level blade set
and lower-level blade set, which are stacked together in an altemate manner to
serve as a unitary module, are fixed to the shaft 20. If desired, either a
single
10 pair of upper-level and lower-level blade sets can be used or,
altematively,
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 30 comprises a plurality of blade rods 31 rotatably mounted to
the shaft 20 with bearings 311 arranged in the rotation connection to reduce
the likelihood of damage or breakdown. Each blade rod 31 is provided with
blades 32 on opposite sides of the shaft 20 and each blade 32 is divided into
two moment-inducing sections on the opposite sides of the blade rod 31 with
one moment-inducing section being greater in area than the other one. In
other words, the surface area "A" of the section of the blade 32 above the
blade rod 31 is greater than the surface area "a" of the section of the blade
32
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that is below the blade rod 31. Preferably, the blade rod 31 is set at a
location
approximately two-thirds of the widthwise dimension of the blade 32 so that
the surface area of two-thirds of the width of the blade 32, when facing
windward, receive a wind pressure greater than the surface area of the
remaining one-third of the width of the blade 32. When the blades 32 swivel
to a substantially vertical state, the lower edge of each blade 32 engages
with
the upper edge of the blade 32 below. Each blade 32 has an inner end on
which a first winglet 33 is formed at a preset intemal angle to concentrate
the
incoming wind pressure and thus induce moment on the blade 32 for
swiveling. The blade 32 also has an outer end forming a second winglet 34,
which is substantially normal to the blade 32 for receiving wind pressure and
preventing loss of wind pressure. Further, since the rotational axis of the
blade 32 is not set at the geometric center thereof, a counterweight is
selectively added to the lower surface section "a" of the blade below the
blade
rod 31 to set the center of gravity of the blade 32 at the rotational axis of
the
blade rod 31. This will set the blade 32 in a condition where the forces are
balanced when the blade 32 is in a horizontal state and thus allowing the
blade
32 to easily swivel, even when only being acted upon by the low wind
pressure of a light breeze. The second winglet 34 has a portion configured as
a lifting airfoil 341 similar to an airplane wing, serving to provide
additional
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lifting force to help rotation of the shaft 20 in the situation where the
blade 32
is rotated to a horizontal state. To enhance the stability and firmness of the
blade rod 31, the blade set 30 comprises a frame 35 that rotatably supports
the
ends of the blade rods 31 with bearings 312 set at the rotation connections.
Stops 351, 352 are formed at upper and lower intemal edges of the fiame 35
(or altematively, the stops are formed on the shaft 20) to automatically stop
the
swiveling of the uppermost and lowermost blades 32 when they approach a
vertical state, thereby fixing the blades.
The support frame 40, serving to support the shaft 20 in position,
comprises a plurality of horizontal and vertical bars 41 that form a multi-
level
framework, each level containing diagonal bars 42 interconnecting each other
at an intersection in which a bore 43 is defined to receive and retain a
bearing
44 for the extension and rotation of the shaft 20.
Also referring to Figure 4, when the windmill of the present invention is
acted upon by wind, as indicated by the arrows, the blades 32 on one side of
the upper-level blade set 30 are acted upon by the aerodynamic force of the
wind to swivel automatically to a vertical state where the vertical blades 32
receive the greatest wind pressure, while the blades 32 on the other side of
the
upper-level blade set 30, also due to aerodynamic force, automatically swivel
to a horizontal state, which is the state of the least wind resistance, so
that the
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blade set 30 drives the shaft 20 to rotate in, for example, a counter-
clockwise
direction. At the same time, the lower-level blade set 30 is substantially
parallel to the air flow of the wind thereby losing wind pressure (and thereby
losing power), but the blades 32 on one side of the lower-level blade set 30
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.
Also referring to Figures 5, 6, and 7, with the upper-level and lower-level
blade sets 30 further rotating counter-clockwise, the blades 32 of the
lower-level blade set 30 that are in a horizontal state ready to receive the
action
of the aerodynamic force of the wind (the blades 32 of the other side of the
lower-level blade set 30 being in a vertical state) receive the incoming wind
pressure with the first winglets 33 thereof. This, together with the fact that
the surface area of the one section of the blade 32 on one side of the blade
rod
31 is greater than that of the other section of the blade 32 on the other side
of
the blade rod 31, as well as the counterweight added to the blade 32, provides
the blade 32 with enhanced moment acting thereon, allowing the blades 32
that are in a horizontal state to automatically and easily swivel upward.
When the blades 32 swivel and approach a vertical state, the blades 32 engage
and fix against each other with the uppermost and lowermost blades 32 being
brought into contact with and automatically stopped and fixed by the stops
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351, 352. At this time, the blades 32 together form a vertical surface that
serves as an optimum wind-receiving surface which, with the aid of the
second winglets 34, effectively receives the wind pressure for driving the
rotation of the shaft 20.
Referring to Figure 8, when the blades 32 on one side of the upper-level
blade set 30 are in a leeward position, the blades can reduce the wind
resistance due to the horizontal state thereof at that moment, and further,
the
second winglets 34 that at this moment are in a vertical state and extending
downward so that the second winglets 34 can receive wind coming from a
different direction and induce an upward lifting force according to the
principles of aerodynamics to thereby generate a rotation force for assisting
rotation of the blade set 30 about the shaft 20.
With reference to Figures 9 and 10, which demonstrate the operation of
the windmill of the present invention succeeding that shown in Figure 7, when
the blades 32 on one side of the lower-level blade set 30 start to receive
wind
pressure, swiveling to form a vertical surface, the blades 32 on the other
side
of the lower-level blade set 30 that were originally in a vertical state start
to get
to a leeward position. Since the surface area of one section of the blade 32
on one side of the blade rod 31 is greater than the other section, an enhanced
moment is induced, which helps the blade 32 that is in a vertical state to
easily
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swivel to a horizontal state, a less wind-resistant condition.
Referring to Figure 11, when the blades 32 of the side of the lower-level
blade set 30 become vertical and are set to receive the greatest wind
pressure,
the blades 32 of the other side of the lower-level blade set 30 are located in
a
5 leeward position and provide the least wind resistance. At this moment, the
upper-level blade set 30 is substantially parallel to the direction of air
flow of
the wind, thus losing wind pressure (losing power) and the lower-level blade
set 30 succeeds the rotation force of the upper-level blade set 30.
Referring to Figure 12, when the lower-level blade set 30 is acted upon by
10 the wind to rotate further, the upper-level blade set 30 will be moved to a
windward position again, causing the blades 32 on one side thereof, which
were originally in a horizontal state, to swivel to a vertical state, while
the
blades 32 of the other side of the upper-level blade set 30, which were
originally in a vertical state swivel to a horizontal state, whereby the
15 upper-level blade set 30 succeeds the rotation. As such, wind energy from
variable directions can be intercepted 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 Figure 13, if desired, ribs 321 can be formed on the surface
of the blade 32 to increase the structural strength thereof and also to help
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receive wind pressure.
