Note: Descriptions are shown in the official language in which they were submitted.
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1 FIELD OF lNVENTION
This is a divisional application of Canadian
Patent Application Serial Number 392l524.
This invention relate.s to vertical axis wind
turbines and components useful therefor, including, hydraulic
suspension systems for supporting components of the vertical
axis wind turbine, braking systems and an overspeed safety
device.
BACKGROUND OF INVENTION
In co-pending application serial number 342,287
I disclosed an improved gear box assembly for a vertical
axis wind turbine, the vertical axis wind turbine having
a rotor having a centrally disposed axis oriented in the
vertical direction, a bull gear supporting the rotor, a
base below the bull gear, the bull gear and base presenting
a hollow housing and shaft terminating in an inner end
wall and end surface respectively, the housing Eor receiving
the shaft, one of said hollow housing or shaft being stationary
and the other being rotatable with respect thereto and
2~ secured to the bull gear, the shaft and housing when secured
together presenting a space between the inner end wall
and end surface, bearings supported between the housing
and shaft, a fluid passageway extending into the space
created between the inner end wall and end surEace for
feeding hydraul.ic fluid under pressure into the space for
hydraulically elevating the bull gear relative to the base,
means precluding the gear from rising more than a predetermined
distance or controlled distance, means for feeding the
fluid under pressure to, and means draining the 1uid from,
the space, and reservoir for such fluid.
While the aforesaid stxucture o~ercomes problems
discussed in the said application, I have discovered a ~J~
-- 1 --
1~33~Z~
1 more efficient approach to hydraulically supporting the
bull gear, rotor and/or guy wires of vertical axis wind
turbines and particularly the bull gear, rotors and guy
wires. Particularly, in the description of the embodiment
of the invention disclosed in the aforesaid patent application,
the rotor is wholly supported by the bull gear. Therefore,
when the bull gear is hydraulically lifted and supported,
the rotor is also lifted. In the larger wind turbines
(for example, wind turbines that generate greater than
one-third megawatt) the forces exerted between the end
of the rotor and seat, and resultant wear and tear of the
metal between the rotor and seat, increase dramatically
thereby increasing the intervals between maintenance and
decreasing the useful life expectancy of the wind turbine.
Additionally, when the rotor of the vertical
axis wind turbine is braked as described in the said co-pending
application, the guy tensioning ability of the wind turbine
ceases.
In the said co-pending application, I also disclosed
an emergency safety device for assisting to brake the wind
turbine when the angular velocity of the rotor exceeded
a predetermined velocity. In this regard, the opening
of a normally closed valve leading from the space between
the bulL gear and shaft ~over which the bull gear rotated
when elevated by the hydraulic fluid) occurred when the
weighted pendulum that rotated with the rotor reached a
predetermined extended position - when the angular velocity
of the rotor exceeded a predetermined angular velocity.
While this approach was an improvement to prior art approaches,
its reliability to open at a predetermined angular velocity
~L233~2~
1 could not be assured because of for example, friction.
It is therefore an object of this inventi.on to
provide an improved vertical axis wind turbine and components
therefor, including hydraulic suspension systems, braking
system, and an overspeed safety device wholly reliable
in emergency situations, and components therefor, which
overcome the aforementioned deficiencies found in prior
art structures. These improvements also include an improved
hydraulic suspension system for hydraulically supporting
the rotor shaft, bull gear and rotor shaft together and
in some embodiments maintain the tension of the guy wires
of the vertical axis wind turbines even when the bull gear
has been braked, and more efficient components for these
structures, and a reliable overspeed safety device which
operates in emergency situations to effectively shut down
the operation of the vertical axis wind turbine
Further and other objects of the invention will
be realized by those skilled in the art from the following
summary of the invention and detailed description of the
preferred embodiments thereof.
SUMMARY OF _NVENTION
According to one aspect of the invention, for
assisting to support a vertically oriented rotor shaft
of a vertical axis wind turbine for rotation, the combination
of a space below the rotor shaft to receive fluid injected
into the space, and means to feed fluid into, and drain
fluid from, the space are provided in a vertical axis wind
turbine.
In one embodime:nt the rotor shaft is carried
by a gear and the space to which the hydraulic :Eluicl is
~;~33~
1 fed is below both the rotor and gear.
~ ccording to one aspect of the invention, an
improved hydraulic suspension system is provided for supporting
a rotor shaft of a vertical axis wind turbine, the improvement
comprising the rotor shaft having a bottom surface sitting
on a bearing surface (preferably an annular spherical bearing
surface) supported for angular rotation by the bearing
surface, and hydraulic fluid presented to a space below
the bottom surface. In one embodiment, the space is created
between a support comprising an upstanding continuous wall
provided to support the rotor shaft for rotation, and the
bottom of the rotor. A fluid passageway leading into the
space for feeding hydraulic fluid into the space, means
for feeding the fluid into the space, sealing means for
sealing the space and a reservoir for the fluid are all
provided.
According to another aspect of the invention,
a vertical axis wind turbine having a rotor having a centrally
disposed axis or rotor shaft oriented in the vertical direction,
and an improved hydraulic suspension system for supporting
the rotor shaft of the vertical axis wind turbine is provided,
the improvement comprising the rotor shaft having a bot-tom
surface sitting on a spherical bearing surface and supported
for angular rotation by the bearing surface and hydraulic
fluid presented under pressure to a space directly below,
and in communication with the bottom surface for providing
radial and vertical supportl respectively.
In one embodiment, a vertical axis wind turbine
may be provided wherein the spherical bearing surface comprises
an annular spherical bearing surface.
:12~3~L2~
1 In another embodiment, a vertical axis wind turbine
may be provided wherein the space is created between a
support provided to support the rotor shaft for rotation,
and the bottom of the rotor shaft, and further comprises
a fluid passageway leading into the space, means for feeding
fluid into the space, sealing means for sealing the space
and a reservoir for the fluid.
According to another aspect of the invention,
a braking system may be provided comprising brake pads
and a braking surface carried by the improved hydraulic
suspension system of the vertical axis wind turbine whereby
when the hydraulic fluid is drained from the space, the
brake pads are brought into engagement with the braking
surface to stop the motion of the rotor shaft and thus
the vertical axis wind turbine.
According to another aspect of the invention,
a braking system for a vertical axis wind turbine having
a vertically oriented rotor shaft may be provided, the
braking system comprising a braking surface and braking
pads, one of which components is adapted to rotate with
the rotor, relative to the other component, the rotor being
supportable for rotation by hydraulic fluid presented to
a space below the bottom surface of the rotor whereby when
the rotor is supported for rotation by hydraulic fluid
in the space, the braking surface and braking pads are
spaced from one another and whereby when the hydraulic
fluid is drained from the space, the braking surface and
braking pads are brought into engagement with one another
stopping rotation of the rotor shaft and thus the ~ertical
axis wind turbine.
;~33~
Accordin~.to another aspect of the invention,
a braking system for a vertical axis wind turbine, having
a rotor having a centrally disposed axis or rolor shaft
oriented in the vertical direction is provided comprising
a support for supporting the rotor and permitting the rotor
to be elevated, brake pads and a braking surface carried
by the vertical axis wind turbine r a space below the rotor
Eor receiving hydraulic fluid injected therein under pressure
to raise the rotor for rotation, and hydraulic circuitry
to feed hydraulic fluid into, and drain fluid from, the
space, whereby when the hydraulic fluid is drained from
the space, the rotor is lowered causing the brake pads
to engage the braking surface to stop the motion of the
rotor.
. According to another aspect of the invention,
a braking system for a vertical axis wind turbine having
a rotor having a centrally disposed axis or rotor shaft
oriented in the vertical direction, a support for supporting
the rotor and permitting the rotor to be elevated~ a gear
below the rotor and adapted to rotate therewith, a space
below the rotor for receiving hydraulic fluid injected
therein under pressure to raise the rotor for rotation,
the system comprising brake pads and a braking surface
carried by the vertical axis wind turbine, and hydraulic
circuitry to feed hydraulic fluid into, and drain fluid
from, the space whereby when the hydraulic fluid is drained
from the space, the rotor is lowered causing the brake
pads to engage the braking surface to stop the motion of
the roto.r.
In one embodiment of the .invention -the brake
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1 pads and braking surface are disposed below the bottom
of the gear. For assisting to support the vertically oriented
rotor shaft of a vertical axis wind turbine for rotation
and brake the rotor shaft, the following combination may
be provided: a space below the rotor shaft to receive
fluid injected into the space, and means to feed fluid
into, and drain fluid from, the space, and brake pads and
a braking surface carried by the vertical axis wind turbine
whereby when the hydraulic fluid is drained from the space,
the rotor is lowered causing the brake pads to engage the
braking surface to stop the motion of the rotor shaft.
In one embodiment, the rotor shaft is supported
by a gear and the gear carries on the bottom thereof either
the brake pads or braking surface which engages the other
component when the fluid is drained to stop the rotation
of the rotor shaft.
Where the rotor is mounted for angular rotation
in conjunction with a bull gear, the rotor shaft may be
supported by hydraulic fluid in a space between the bottom
of the rotor shaft and that part of the bull gear in which
the rotor shaft is secured. In this event, the bull gear
may be hydraulically supported as shown in co-pending application
serial number 342,287 or otherwise.
In this regard, and according to another aspect
of the invention, an improved hydraulic suspension system
is provided for supporting a rotor and bull gear of a vertical
axis wind turbine comprising a base, a bull gear adapted
to rotate above the base, the bull gear and base presenting
a housing and shaft terminating in an inner end wall and
end surface respectively, the housing for receivi.ng the
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l shaft, one of said housing or shaft being stationary and
the other being rotatable with respect thereto and secured
to the bull gear and having a centrally disposed circular
opening surrounded by an annular bearing surface (being
preferably an annular spherical bearing surface), the rotor
being of a diameter at its lower end to seat on the annular
bearing surface and close the centrally disposed circular
opening, the shaft, rotor and housing when secured together
presenting a space between the inner end wall, end surface,
and bottom of the rotor, bearing and sealing means between
the housing and shaft~ a fluid passageway opening into
the space between the inner end wall, end surface and bottom
of the rotor for feeding hydraulic fluid under pressure
into the space for hydraulically elevating the bull gear
and rotor, means precluding the bull gear and rotor from
rising more than a predetermined or controlled distance,
means for feeding the fluid under pressure to, and means
for draining fluid from, the space, and a reservoir for
such fluid
Preferably, means precluding the bull gear from
rising more than a predetermined or controlled distance
comprises the means for draining fluid from the space. In
this instance, when the bull gear and rotor are elevated
a predetermined distance, a drain is exposed to the space
which drains the fluid from the space.
In another aspect of the invention, an improved
hydraulic suspension system is provided for supporting
a rotor and bull gear of a vertical axis wind turbine,
the vertical axis wind turbine comprising a base, a bull
gear adapted to rotate above the base, a rotor oriented
~233~L2~
1 in the vertical direction coupled to the bull gear to rotate
therewith, the base supporting a stationary centrally disposed
cylindrical vertical shaft having an upper end, the bull
gear having a centrally disposed annular hub of a predetermined
inner diameter, the vertical shaft of a slightly lesser
outer diameter than the internal diameter of the hub, the
annular hub having a top having a circular opening centrally
disposed therein surrounded by an annular bearing surface,
(preferably an annular spherical bearing surface) surrounding
the circular opening, the rotor being of a diameter at
its lower end to sit against the annular bearing surface
and close the opening, bearing and sealing means between
the annular hub of the bull gear and stationary shaft,
a fluid passageway opening into the space between the upper
end of the shaft, top of the hub of the bull gear, and
bottom of the rotor, for feeding hydraulic fluid under
pressure i.nto the space for hydraulically elevating the
bull gear and rotor relative to the base, means precluding
the bull gear and rotor rising more than a predetermined
or controlled distance (in one embodiment comprising, the
guy wires secured to the guy wire coupling secured to the
upper end of the rotor, and/or a drain for draining fluid
from the space, the drain being exposed to the space when
the bull gear and rotor have been elevated a predetermined
distance), means for feeding the fluid under pressure to
the space, means for draining fluid from the space, and
a reservoir for such fluid.
According to another aspect oE the invention,
the means for draining fluid may comprise a passageway
in the annular huh wall of the bull gear which opens in-to
~33~Z~
1 the space between the hub and shaft after the bull gear
and rotor have been raised a predetermined level.
According to another aspect of the invention,
brake pads may be interposed between the bottom of the
bull gear and base to stop the motion of the bull gear
relative to the base when the gear is lowered onto the
base.
Therefore, by having both the bull gear and rotor
supported by the hydraulic fluid, the load transmitted
at the bearing surface between the rotor and bull gear,
can be selected for optimal efficiency and depending upon
the ratio of area (A) of the opening through the bull gear
through which the rotor protrudes into the space divided
by the cross-sectional area (B) of the space created between
the bottom of the rotor, inner end wall and end surface
proximate the opening.
In this regard, the total load transmitted (Lt)
that must be supported
= Lg + WR + WB
where Lg = downward load from the guys
WR = Weight of Rotor and WB = Weight of the bull
gear.
This load is supported by the hydraulic fluid
(PO x B) where PO = incoming pressure.
Therefore, PoB = Lg + WR + WB.
The load that is transmitted at the metal to
metal contact between the bull gear and rotor for the purposes
herein: Lm = PoB - PoA - WB.
Therefore, Lm a Po ( B-A ) ~Wg ~
~ccorcling to another aspect oE -the invention,
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1 the upper end of a wind turbine comprises an upper head
assembly for securing the guy wires of the wind turbine
thereto, the upper head assembly comprising a guy wire
coupling to which the guy wires are secured, a support
for supporting the guy wire coupling, the guy wire being
vertically displacable relative to the support, the guy
wire coupling and support presenting a housing and shaft,
the shaft for being received in the housing and presenting
a space therebetween for receiving fluid therebetween for
vertically displacing the guy wire coupling from the support,
a fluid passageway opening into the space, means for supplying
fluid through the fluid passageway to elevate the coupling
relative to the support, sealing means for sealing the
space between the shaft and housing and means to drain
the fluid from the space.
While the guy wires themselves limit the vertical
displacement of the shaft relative to the housing, a drain
may also be provided which is exposed to the space to drain
the space when the shaft is displaced more than a given
amount from the housing.
According to another aspect of the invention,
the upper end of a rotor of a wind turbine may include
a fluid passageway opening proximate the upper end of the
rotor into a space between the rotor and a guy wire coupling
tpreferably opening through the top surface of the rotor
into a head to which the guy wires may be secured or a
guy wire coupling seated over the upper end of the rotor),
means for supplying fluid through the fluid passageway
to elevate the coup.ling relative to the rotor end, sealing
means preEerably between the coupling and the upper end
3 233~
1 of the rotor, and means to drain the fluid from the space.
According to another aspect of the invention,
an upper head assembly for securing to the top of a rotor
shaft of a vertical axis wind turbine is provided for securing
the guy wires thereto, the upper head assembly and rotor
shaft presenting a housing and shaft terminating in an
end wall and end surface respectively, the housing for
receiving the shaft, one of said housing or shaft secured
to the upper end of the rotor shaft and the other for securing
the guy wires, the housing and shaft being vertically displacable
with respect to one another by fluid being fed into a space
between the end wall and end surface, a fluid passageway
opening into the space through which fluid is fed into
the space, means for precluding the guy wire coupling rising
more than a predetermined or controlled distance, means
for feeding the fluid under pressure to elevate the member
secured to the guy wires and means for draining the fluid
to lower the last member, and a reservoir for such fluid.
Preferably, the fluid passageway of the upper
head assembly is connected to the space created by, the
end wall, end surface and bottom of the rotor of the vertical
axis wind turbine to which space hydraulic fluid is fed
for hydraulically supporting the bull gear and rotor.
In this regard, according -to another aspect of the invention,
the fluid passageway may lead from the space between bull
gear, rotor and top of the shaft, to open into the space
created in the upper head assembly and the fluid passageway
may include a pressure regulating valve and one-way check
valve between the pressure regulating valve and top of
the wind turbine to preclude ~luid transmitted to the upper
lZ33~2~
1 end of the rotor from returning via said passageway when
fluid is drained from the space created between the shaft,
hub and rotor.
According to another aspect of the invention,
a hydraulic damper may be provided between the check valve
and upper head assembly the hydraulic damper for dissipating
energy in the system.
According to another aspect of the invention,
the hydraulic damper may comprise a restriction in a conduit.
According to another aspect of the invention,
the hydraulic damper may include a restriction and a hydraulic
accumulator connected in parallel to the restriction for
dissipating energy.
As in the earlier application, hrake pads can
be interposed between the base ~above which the bull gear
will rotate), and bull gear, for braking the bull gear
as the bull gear is lowered by the drainage of fluid from
the space. In an emergency situation, when the angular
velocity of the rotor exceeds a predetermined angular velocity,
an overspeed safety device can be provided, secured to
the rotor, to cause the rapid drainage of the fluid from
the space between the bottom of the rotor, inner end wall
and end surface lowering the bull gear onto the brake pads,
the overspeed safety device comprising a passageway leading
from the space containing the fluid between the inner end
wall, end surface, and bottom of the rotor for permitting
the fluid to leave the space via the passageway when the
angular velocity of the rotor exceeds a predetermined angular
velocity, means closing the passageway cornprising a pivotal
arm, pre~erably including means on the end of the arm for
- 13 -
~Z33~2~
l closing the passageway, the last means preferably pivotable
with respect to the arm, the pivotal arm pivotable about
a pivot point on the end of the arm remote the means closing
the passageway in a direction away from the rotor from
a position closing the passageway to a position opening
the passageway, a housing or tube secured to and spaced
from the pivotable arm to pivot therewith in a direction
away from the rotor when the passageway is opened, the
housing or tube being angled radially away from the rotor
from the bottom of the tube or housing to the top and containing
a rolling element or fluid capable of moving along the
housing or tube as the case may be, from the bottom towards
the top when the rotor exceeds a given predetermined angular
velocity, thus causing the centre of gravity of the housing
or tube to move towards the top of the tube or housing
to cause the tube or housing to pivot the pivotable arm
thus opening the passageway, draining the fluid from the
passageway. In use, the overspeed device is enclosed to
catch the fluid and a drain is provided to drain fluid
collected for reuse.
Preferably, the housing contains a rolling element
(either a cylinder or sphere) for rolling up the length
of a wall surface of the housing or tube when the predetermined
angular velocity is reached.
Preferably the housing or tube is square in cross-section.
When the wind turbine is operating normally with
the passageway closed by the pivotal arm (when the angular
velocity of the rotor does not exceed a predetermined angular
velocity) a resultant force is exerted on the fluid or
rolling element made up of a gravitational force and a
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~;233~Z'~
1 centrifugal force directed away from the rotor of the wind
turbine. When the angular velocity of the rotor is small,
the resultant force holds the fluid or element on the bottom
of the tube maintaining the pivotal arm in a position closing
the passageway. In the case of the rolling element (which
is more precise), as the angular velocity of the rotor
increases, the centrifugal force increases tending to urge
the element to roll up the inclined surface of the housing
surface away from the rotor. However, the resultant force
is not sufficient to cause the element to roll up the incline
of the housing until the rotor reaches a predetermined
angular velocity. At this point, the resultant force made
up of the gravitational force and centrifugal force is
directed above the centre of rotation of the rolling element
(when looking from the bottom o~ the tube or housing) causing
the rolling element to roll up the surface of the housing
on which it lies to the upper end of the housing. (A similar
result is arrived at though less precisely, using a fluid).
At that point, the force eXerted by the element (or fluid)
is sufficient to cause the housing to pivot causing the
pivotal arm to pivot about the pivot point opening the
passageway, releasing the fluid.
Preferably, the rolling element sits on a hard
steel plate in the housing to preclude the wearing away
of the surface where it would normally seat precluding
the creating of a rut in which the rolling element could
become lodged.
Therefoxe, the normally closed passageway is
centrifugally opened by the overspeed safety device when
the rotor exceeds a predetermined angular velocity. Activation
- 15 -
33~2~
1 is not dependent on weather conditions but only on the
setting. Because there is little to wear out in the construction
of the device, the safety device has a long, useful life
and provides substantially 10Q~ reliability.
Furthermore, because of its structure, it will
not trip prematurely. Particularly, in a preferred embodiment
employing a rolling element, nothing can happen to move
the rolling element up the angled incline until the predetermined
velocity is reached. Only then will it roll up the incline
to the top end of the housing creating a large enough clockwise
movement about the centre of rotation causing the housing
to pivot, thus pivoting the arm opening the passageway.
The enclosure then collects the discharged fluid and directs
it for reuse.
. Of broader scope, this invention also provides
an overspeed safety device for ensuring the operational
safety of a body rotating about in a vertically oriented
axis which body for safety reasons should not exceed a
predetermined angular velocity, the safety device comprising
a housing or tube pivotable about a pivot point proximate
a lower end of the tube, or housing, radially away from
the centre of the rotating body, the housing or the tube
having a surface inclined radially upwardly away from the
rotating body from the bottom to the top to support a rolling
element or fluid thereon, which element or fluid moves
radially to the upper end of the tube or housing, when
the rotating body exceeds a predetermined angular velocity
causing the tube to pivot about the pivot point, and means
preferably connected to the tube activated by the pivoting
oP the tube ko operate in a predetermined manner, as for
- 16 -
~33~
1 example, a valve opened by the pivoting of the tube.
According to another aspect of the invention,
the rotor shaft is preferably tapered at the ends from
a broader central portion. While any cross-sectional shape
of the rotor shaft is satisfactory (symmetrically octagonal
for example), it is preferable that the rotor shaft be
circular in cross-section. For ease of manufacture, it
is preferable the rotor shaft be manufactured in two or
more sections. Where two sections are employed, each section
preferably comprises a broader end tapering to a narrower
end. Annular flanges may extend radially or laterally
oE the section, from the broader end of each section for
use in joining the sections together.
The advantage of this configuration is that the
wind loading under storm conditions is less. Additionally,
because the rotor shaft of a vertical axis wind turbine
can create aerodynamic interference with the blade passing
behind the rotor shaft with respect to the wind direction,
the use of the tapered shaft produces only a series of
variable frequency vortices which provide less interference
to the performance of the blade passing in the shadow of
the rotor shaft than the vortices created by the constant
diameter rotor. A further advantage is the cost of shipping
~~ the ability to carry two or more sections of the rotor
by truck with the tapered end of one section next to the
broader end of another section.
BRIEF DESCRIPTION OF THE DRAWINGS
The invention will now be illustrated with reference
to the following drawings of preferred embodiments of the
invention, in which:
- 17 -
~Z~3~
1 Figure 1 ls a perspective view of a Darrieus
vertical axis wind turbine incorporating preferred embodiments
of the lnvention.
Figures 2 to 5 inclusive are views of parts of
the rotor in assembled, disassembled and close-up views
according to another embodiment of the invention.
Figures 6 and 7 (shown with Figure 4) illustrate
cross-sections of two different rotor sections according
to embodiments of the invention.
Figure 8 is a side view of part of a gear box
assembly accordiny to a preferred embodiment of the invention,
partly in section with component parts cut away.
Figure 9 is a close-up schematic view of part
of the gear box assembly according to a preferred embodiment
f the inventiOn.
Figure 10 is a detailed schematic side view of
a valve shown diagrammatically in Figure 5.
Figure 11 is a side schematic view of part of
an assembly according to a preferred embodiment of the
invention.
Figure 12 is a side schematic view of part of
an assembly according to a preferred embodiment of the
invention.
Figures 13A, 13B and 14 are detailed schematic
side views of component parts incorporated in the assembly
shown in Figures 11 and 12.
Figure 15 illustrates the tensioning of the guy
wires of a vertical axi.s wind turbine.
Figure 16 is a close-up sectional view of part
of the assembly shown in Figure 9, with portions removed.
- 18 -
~23~
1 Figure 17 is a perspective view partly in section
of the assembly shown in part in Figure 16.
Figures 18 and 19 illustrate schematically the
operation of the assembly in Figure 17.
Figure 20 is a top view of the assembly' of Figure
16.
Figure 21 is a schematic illustrating the forces
on component parts of part of the assembly of Figure 17
in various positions.
DETAILED DESCRIPTION OF THE EMB~DIMENTS OF THE INVENTION
With reference to Figure 1, Darrieus vertical
axis wind turbine 30 comprises vertical rotor shaPt 32
and rotor blades 34 and 36 spaced from and secured to shaft
32, by connectors at 31 and 33. Four (4) guy wires shown
as 38, 40, 42 and 44 are connected to, and support, wind
turbine 30, through upper head assembly 46. The lower
end of shaft 32 is secured for rotation in gear box assembly
50 (see Figures 8, 9, and 11) mounted in tower 52.
With reference to Figure 2, rotor shaft 32 has
been replaced by shaft 321 tapered from a broader central
portion at 52 to reduced end portions at 54 and 56. Shaft
321 is made up of two tapered sections 58 and 60 (see also
Figure 4) having angular flanges 61 extending radially
from the sections at the broader ends 62 and 64 respectively
for connecting the sections. Curved blades 34 and 36 are
connected to shaft 321 proximate the ends in the same manner
as in Flgure 1.
Figures 6 and 7 illustrate two cross-sections
that shaft 321 may take. The circular cross-section shown
in Figure 6 is preferred to the octagonal cross-section
-- 19 --
~;~33~
1 shown in Figure 7.
Shaft 321 is preferrred to shaft 32 in the construction
of Darrieus vertical axis wind turbine 30. This is because
constant diameter shaft 32 creates aerodynamic interference
with each of the rotor blades 34 and 36 as each passes
behind the rotor with respect to wind direction, reducing
the efficiency of the rotor. The reason is tl~e cumulative
effect of Von Karman vortex generation - ~he Von Karman
vortex generation caused by the rotor shaft in the windstream
is a function of shaft diameter. Since the diameter of
the shaft 32 is constant, the frequency of the Von Karman
vortices generated along the length of shaft 32 is constant,
the vortices reinforce one another. The use of tapered
shaft 321 tapering from a broader central portion to narrower
ends produces a series of independent variable frequency
vortices which are less disruptive to the performance of
the blades passing in the "shadow" of the column.
Figure 3 illustrates schematically the independent
variable frequency vortices produced in the shadow of shaft
321.
An additional benefit results from the use of
two tapered sections 58 and 60 connected to form shaft
321. By producing tapered shaft 321 in two sections, they
may be shipped as shown in Figures 4 and 5. Particularly,
highway regulations, regulate the maximum width of a vehicle
and its capacity to carry oversized structures of large
diameter. Where the load is oversized, special permits
and/or a police escort are required. Because the diameter
of large constant diameter rotors in excess of 120 feet
is about 5 Eeet, it is not ordinarily possible to ship
- 20 -
~;~33~2~
1 the rotor in two sections loaded on one truck side by side.
~owever, because the diameter of the section 58 and 60
taper from 5 feet to narrower 2 foot end portions, the
sections may be shipped side by side as shown in Figure
5.
With reference to Figures 8, 9 and 11, gear box
assembly 50 is shown, incorporating a hydraulic suspension
system for supporting rotor shaft 32 or 821 (for simpllfying
description, rotor shaft 32 has been used) and bull gear
70 for rotation, and, for tensioning and supporting guy
wires 38, 40~ 42 and 44, under a constant tension whether
or not the bull gear and rotor are operational.
Particularly, bull gear 70 has circular openlng
72 at the top thereof surrounded by annular spherical bearing
1~ surface 74 for supporting the bottom surface 76 of shaft
32 proximate its radially outer bottom edge, shaft 32 seats
in opening 32 on bearing surface 74 as shown.
Bull gear 70 comprises (a) central hub 78 overlying
.end 80 of stationary shaft 82 (of lesser diameter than
20 hub 78), shaft 82 being secured to base 84 above which
bull gear 70 will rotate, (b) bottom plate 86 secured to
hub 78; (c) gear ring 88 secured to the periphery of bottom
plate 86; and (d) triangular stiffening webs 90 secured
between plates 86 and hub 78.
Base 84 supports brake pads 92 proximate the
periphery of plate 86 for seating on brake pads 92 when
the Darrieus vertical axis wind turbine is not operational.
When plate 86 seats on brake pads 92, end surface 80 of
shaft 82 is either spaced from the inner end of hub 78
or in contact with it. Hydrodynamic bearings (not shown)
- 21 -
~;~33:~2~
1 are secured between the inner side wall of hub 78 and the
outer side surface of vertical shaft 82 for sealing the
space created between the end 80 of shaft 82, inner end
wall of hub 94 and the bottom surface 72 of rotor shaft
32 when bull gear 70 is raised relative to shaft 82.
Hub 78 and rotor shaft 32 are free to rise with
respect to shaft 82 limited by guy wire reaction and the
hydraulic fluid permitted to enter space 102 between the
shaft, hub and rotor, to support the hub and rotor as descrlbed
herein. Bull gear 70 meshes with pinion gear 96 coupled
to generator 98 for driving generator 98. Annular dam
wall 100 sits on base 84 and separates the interior space
under gear 70 from generator 98 and the remainder of equipment
(not shown).
Hub 70 and rotor shaft 32 are hydraulically supported
with respect to stationary shaft 82 by hydraulic fluid
fed into the space 102 created between the bottom surface
76 of rotor shaft 32, inner end 94, and end surface 80,
as bull gear 70 and rotor 32 are elevated by fluid fed
20 into space 102 from passageway 104 fed from reservoir 107
by hydraulic circuitry shown schematically in Figure 9.
With reference to Figure 9, hydraulic fluid is fed into
space 102 from reservoir 107 through passageway 104 by
pump 110 operated by electric motor 112. Pump 114 operated
25 on a common axis as pump 110 by motor 112 pumps fluid through
passageway 116 to lubricate the gear/pinion mesh. Fluid
passing do~n from the lubrication of the gear 88/pinion
96 mesh is collected through passageways 118 and 120 by
returns 122 and 124.
Fluid is normally drained from space 102 by outlet
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9 ~
~33~
1 port 106 (of the same dimensions as passageway 104) through
drain passageway 108 in hubs 78 and returned to the reservoir
107 when bull gear 70 is elevated a predetermined distance
above stationary shaft 82 exposing outlet port 106 to space
102. Therefore, gear 70 and rotor 32 cannot be elevated
more than a predetermined distance because the feeding
of hydraulic fluid into space 102 is maintained at a flow
rate not to exceed the flow rate draining fluid through
port 106 for return to reservoir 107.
When bull gear 70 and rotor shaft 32 are to be
lifted hydraulically, fluid is pumped from reservoir 107
under pressure by pump 110 through passageway 120, 122
and 104 into space 102 elevating both gear 70 and rotor
32 enlarging space 102 comprising the volume between inner
end wall 94 of hub 78, the bottom surface 76 of rotor shaft
32 and end surface 80 of shaft 82 as the fluid elevates
gear 70 and rotor shaft 32. At the same time, fluid attempts
to move through passageway 124 through valve 126. However,
valve 126 -- electrically operated two-way direct pilot
operated valve ~manufactured by Sperry Vic~ers) shown in
cross-section in Figure 10 -- is normally closed and opens
only upon electrical failure to the Darrieus vertical axis
wind turbine 30. To this end, with reference to Figure
10, valve 126 is electrically powered to normally repel
magnetic moveable core 128 from stationary core 130 so
long as electrically connected to a power source, compressing
spring 132 of spring loaded sealing disc 134 to seal port
136 by stainless steel seat 138. When the electric power
i.s shut off in, for example, an electrical power failure
to the wind turbine, the force of spring 132 forces core
iz33~
1 128 away Erom sealing disc 134 releasing seat 138 opening
communication between the two ports 136 and 137 drainin~
all fluid from space 102 through passageway 104 and outlet
140 to reservoir 107.
In cases where the angular velocity of the rotor
exceeds the prescribed maximum safe angular velocity, overspeed
safety device 142 and associated components come into play.
With reference to Figures 9 and 16 to 21 inclusive, device
142 and associated components including passageway 144,
10 leading from space 102 in rotor shaft 132 through branched
portion 146 to device l.42 are shown. Device 142 is secured
by support bracket 145 to rotor 32 to rotate therewith,
and is enclosed by housing 150 made up of reservoir 152
(see Figure 16) and weighted cl.osure 154. Oil return and
hold down pipe 156 extends upwardly through the bottom
158 o~ reservoir 152 and is releasably secured to top 154
by threaded bolt 160 secured into threaded end of pipe
156. Washer 163 compressingly seals the opening in top
154 through which bolt 160 extends and gasket 164 is positioned
20 between top 154 and the top of continuous wall 166 of reservoir
152 to seal the space in housing 150 against lsakage between
the reservoir 152 and top 154.
Pipe 156 has been notched at 162 to permit oil
to drain from reservoir 152 to the sump (oil reservoir)
25 107.
Oil inlet 146 is secured -to metal tube 168 passing
through top 154 (see Figure 17) sealed by washer 155 and
is closed by ball valve 170 supported on arm 172 to urge
bal.]. 170 to close tube 168 as shown in Figure 17. Arm
172 is in turn supported in pivotable upper valve lever
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1 arm 174 laterally pivotable in channel 180 of lower valve
lever arm 182 with respect to arm 182. Channel 180 extends
radially from rotor 32~ Lower lever arm 182 is flxedly
secured to rotatable shaft 184 (see Figure 20) passing
therethrough to rotate therewith radially away from rotor
shaft 32 from the position shown in Figure 17. Shaft 184
is fixed for rotation in support 186 secured to top 154.
Shaft 184 is in turn fixed to hollow square tubing 188
comprising elongated rectangular walls 190, 192, 194 and
10 196 so that when tubing 188 rotates, shaft 184 and arm
182 all rotate together away from the rotor shaft 32.
Stop bolts 198 and 200 are secured across the
centre of the open ends of tubing 188 for stopping metal
ball 202 from passing through the ends. Plate 204 (see
Figures 18 and 21) is positioned on the inside surface
of wall 192 proximate bolt 190. Tube 188 is secured to
shaft 184 at an angle of 75 degrees to the vertical when
ball valve 170 closes the opening 206 of inlet 168 sloping
upwardly and radially out~ardly from rotor shaft 32 (looking
from the bottom of tubing 188) to provide radially upwardly
angled ramp 208 on the inside surface of wall 192.
With reference to Figure 21, as the rotor xotates
at a safe angular velocity, less than a predetermined given
unsafe angular velocity, two forces are exerted on ball
202, gravity (G) and a centrifugal force (C) radially outwardly.
The resultant (R) of the two forces does not cause the
ball to move. However, as the angular velocity of the
rotor increases, the resultant (R) approaches a position
normal (N) to the plate until at the predetermined angular
3~ velocity, the resultant (R) passes the normal (N~ exerting
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~;~33~2~
1 a clockwise movement about the centre of gravity on sphere
202 causing sphere 202 to roll up ramp 208 altering the
centre of gravity of tubing 188, causing tubing 188 to
rotate radially away from rotor shaft 32 on shaft 184 rotating
shaft 184 and arm 182 thus opening inlet 168 (see Figure
g) permitting fluid in space 102 to drain through outlet
162, through passageway 156 to reservoir 107, causing bull
gear 70 to settle on brake pads 92 stopping rotor 32 and
bull gear 70.
With reference to Figures 9 and 11 to 15 inclusive,
fluid fed through passageway 144 from space 102 normally
passes through passageway 212 past pressure regulating
valve 214, check valve 216 and hydraulic damper 218 in
passageway 212.
, With reference to Figure 11, upper head assembly
46 includes a shaft 220 secured to the top of rotor shaft
32 of lesser diamter than shaft 32 having passageway 222
passing therethrough in communication with passageway 212
.and annular dam wall 223 surrounding shaft 220 spaced therefrom.
Head 224 seats over shaft 220 and comprises annular wall
226, top 228 and downwardly opening annular endless channel
230 in wall 226 to accommodate dam wall 223. Annular seals
232 are positioned between dam wall 223 and annular channel
wall 234 closes shaft 220 to seal a space between head
224 and 220. Hydrodynamic bearings 235 are secured between
the inner surface of wall 226 and outer surface of shaft
220 for sealing the space created between the end of shaft
220 and the inner surface of top 228. Four triangular
webs 236 extend from head 224 and secure guy wires 38,
40, 42 and 44 thereto.
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1 Drain 238 dralns fluid from controlled bearing
leakage past hydrodynamic bearings 235 from the space between
seals 232 and hydrodynamic bearings 235.
With reference to Figure 12, upper head assembly
461 comprises housing 300 secured to the top of shaft 32,
housing 300 comprising base 301, annular wall 302 upstanding
therefrom surrounding wall 303 and passageway 304 connecting
passageway 212 and well 303. Mounted and sealed by annular
seals 306 within well 303 for vertical displacement relative
to housing 303 and seals 306 is shaft 305. Fluid fed through
passageways 212 and 304 against the bottom 307 oE shaft
305 elevates shaft 305. Holes through top 308 of shaft
305 are used to secure the guy wires 38, 40, 42 and 44.
Hydrodynamic bearings are also secured between the shaft
305 and inner wall of the housing 303.
Drain 310 drains fluid from controlled bearing
leakage past the hydrodynamic bearings from well 303.
Fluid pumped up passageway 144 entering passageway
212 and fed to head assembly 46 or 461 elevates head 224
relative to shaft 220 or shaft 305 from housing 300 respectively,
thereby tensioning guy wires 38, 40, 42 and 44.
To ensure guy tension is maintained relatively
constant, direct acting pressure reducing valve 214 (see
Figure 9~ has been inserted into passageway 212 and permits
2~ only enough oil to flow therethrough to maintain fluid
pressure in the head assembly at the desired pressure.
To this end, valve 214 comprises housing 240, spool 242,
inlet port 244, outlet port 246, pressure sensing passage
248, compression spring 250, adjustment screw 252 extending
through housing 240 and bleed passage 254.
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~12;~31~
1 Valve 214. is held normally open by the force
exerted by spring 250 ~set by set screw 252) against spool
242. As the pressure in outlet port 246 increases (sensed
by passage 248) the pressure of the fluid in passage 248
on the face 256 of spool 242 compresses spring 250 when
the pressure exceeds the force of the spring, moving spool
242 to close outlet port 244. When valve 214 closes completely,
a small quantity of fluid drains through passageway 258
to bleed passageway 254 to reservoir 107 (not shown) preventing
reduced pressure from increasing because of valve leakage.
Fluid passing valve 214, passes upwardly through one-way
check valve 216 comprising housing 260 holding ball 262
at the bottom under compression by compression spring 264,
under greater pressure than the pressure exerted by compression
15 spring 264 tending to seat ball 262, through passageway
222 to raise head 224 or shaft 305 a predetermined amount
as limited by the guys, tensioning the guys and maintaining
the tension in the guys.
When the fluid is removed from passageway 212
(as for example when bull gear 70 is braked), one way check
valve 216 precludes fluid from returning past valve 216
by closing under the compression force of spring 264 thereby
maintaining the pressure in head assembly 210 and the guy
tension in guy wires 38, 40, 4~ and 44. Additionally,
the "floating" of head 46 supplies damping to the entire
rotor gear box assembly. For regulating this damping (as
for example when the guys fluctuate under fluctuating loads)
hydraulic damper 218 comprising air hydraulic accumulator
270 with hydraulic restrictor 272 is prov.ided. In this
case fluid Eorced back through passagewa~ 222 in instances
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> ~q ~ ~
~3~
1 of increased pressure through passage 212 enters restrictor
272 (see Figure 13) creating heat (thereby acting as a
damper) and then into the hydraulic accumulator 270, against
diaphragm 274 held under the action of compression spring
276 (see Figure 12). If the diaphragm is forced against
the spring by the fluid, compressing the spring, the excess
fluid is accumulated until the fluid pressure in assembly
46 or 461 eases and the diaphragm is restored to its normal
position by spring 276.
Figure 15 illustrates the tensioning of the guys
employing head assembly 46 or 461.
As many changes could be made in the embodiments
without departing from the scope of the invention, it is
intended that all matter contained herein be interpreted
as illustrative of the invention, and not in a limiting
sense.
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