Wind energy conversion system with reaction torque for power control

A wind energy conversion system for converting wind energy into controlled wind turbine torque comprising a wind turbine with an essentially horizontally disposed shaft, a means, rotatably mounted to a chassis, for sensing and reacting to wind turbine torque such that reaction torque acting on the means causes angular displacement of the means, a driven machine drivenly connected to the shaft of the wind turbine, and a means for adjusting wind turbine efficiency which is drivenly connected to the first mentioned means in such a way as to prevent continual angular speed thereof. Angular displacement of the first mentioned means provides the power for the last mentioned means to adjust wind turbine efficiency. Because the system can be designed so as to provide a substantially constant torque to the driven machine over a significant range of wind speeds, the system is particularly useful for generating electrical power suitable for transfer to an alternating current power network of an electrical utility company.

BACKGROUND OF INVENTION 
As the world's supply of fossil fuels is further depleted, the need to 
harness the energy in the wind assumes ever increasing importance. 
Unfortunately, wide use of this clean, inexhaustible source of energy has 
not occured because of the high cost of wind energy conversion devices. 
In order to hold size and cost of wind turbines, towers, and machinery 
within bounds, almost all wind energy conversion systems utilize a means 
to limit the effect of high winds on the device. The American farm 
windmill has a tail vane which, when triggered by wind speeds exceeding 
its maximum set point, turns 90 degrees to the turbine shaft in order to 
rotate the turbine out of the wind. The 4-arm Dutch windmill relies on 
manual furling of canvas sails to accomplish the same effect. These 
devices are simple and inexpensive, but all the energy in the high winds 
is wasted. 
In the more sophisticated designs, various methods are used to regulate the 
output energy or torque or delivered power of the system to a 
substantially constant level for all wind speeds above a predetermined 
value, called "rated wind speed". This method allows economical design of 
the wind turbine, tower, and machinery while recovering a large portion of 
the energy available in the high speed winds. 
Many systems have been developed to perform this important function. 
Unfortunately, those that perform well are very complex and expensive 
while the low-cost units are generally applicable only to very small wind 
energy conversion devices. 
SUMMARY OF THE INVENTION 
The present invention is for a wind energy conversion system which is 
efficient and effective while being simple, reliable, and relatively low 
cost. 
In a further embodiment of this invention the system also provides a 
substantially constant level of output torque, or delivered power for all 
wind speeds above the rated wind speed of the system. 
In a still further embodiment of this invention the system provides a means 
for preventing excessive output torque, or delivered power from occurring 
so as to prevent system damage at wind speeds which are greater than the 
system's capability or design with regard to operational or safety 
criteria. 
This invention takes advantage of the principle that every action produces 
an equal and opposite reaction. For rotating machinery, this principle can 
be restated that every torque produces an equal and opposite reaction 
torque. 
In general the invention is for a wind energy conversion system in which 
wind turbine efficiency, wind turbine torque, wind turbine power, 
delivered torque, or delivered power, or a combination thereof is adjusted 
or controlled by reaction torque. By reaction torque herein is meant 
torque which is in opposition to and a function of torque developed by the 
wind turbine. 
In this invention, a wind turbine produces torque, or wind turbine torque, 
due to action of the wind, and wind turbine torque is transmitted to a 
driven machine, usually, although not necessarily, through a suitable 
speed increasing means. In other words, the driven machine is drivenly 
connected to the wind turbine. The reaction torque developed by the wind 
turbine acting on the driven machine, or load device, is utilized to sense 
the wind turbine torque magnitude and to provide the torque, or power, 
required to position a means for adjusting, or controlling, wind turbine 
efficiency, torque or power. A wide variety of wind turbine efficiency 
control means are known, including the following: 
1. Blade pitch control, in which the pitch of the wind turbine blades is 
varied from an optimum value, thereby reducing the turning force of the 
wind on the turbine and causing a reduction in turbine efficiency. 
2. Blade coning control, in which wind turbine blades are folded in a plane 
parallel to the turbine shaft, thereby reducing the area swept by the wind 
turbine and causing a reduction in turbine efficiency. 
3. Yaw angle control, in which the wind turbine shaft is caused to turn at 
a horizontal angle to the wind direction, thereby reducing the driving 
force of the wind on the turbine and causing a reduction in turbine 
efficiency. 
4. Vertical angle control, in which the wind turbine shaft is caused to 
tilt at a vertical angle to the wind direction, thereby reducing the 
driving force of the wind on the turbine and causing a reduction in 
turbine efficiency. 
All of these means for adjusting wind turbine efficiency, or controlling 
wind turbine torque or power, are motivated by reaction torque in this 
invention. Therefore, this invention utilizes a reaction torque means 
drivenly connected to such wind turbine efficiency control means to 
adjust, or control, wind turbine torque, as will be further described 
below. 
Reaction torque may be utilized in at least two manners: 
1. A differential mechanism can be inserted between the wind turbine and 
the driven machine or load. Reaction torque is then available at a 
reaction shaft, or third shaft, of the differential mechanism. 
2. The frame of the driven machine or equipment, or the frame of any 
component directly in the drive train of the system such as a speed 
increasing means, is mounted in such a manner that it is free to rotate 
through a limited angle. 
Although such reaction shaft, or frame, is rotatable in response to 
reaction torque, it is connected to a means for adjusting, or controlling, 
wind turbine efficiency, torque, or power in such a way that the reaction 
shaft, or frame, is prevented from having continual angular speed. In 
other words, the reaction shaft, or frame, is permitted to rotate through 
a predetermined range of radians or degrees, for example 50.degree., but 
not permitted to continue to rotate. In other words, the means which is 
responsive to reaction torque can undergo angular displacement up to a 
predetermined number of degrees or radians, but is restricted from angular 
displacement in excess of the predetermined value. 
The reaction torque is then transmitted by the reaction torque means, or in 
one embodiment by the reaction shaft, or in another embodiment by the 
rotatable frame of the driven machine, to the means for adjusting, or 
controlling, wind turbine efficiency. 
The magnitude of the reaction torque can be equal to the torque of the wind 
turbine, the driven equipment, or if speed increasing or reducing means 
are employed, equal to neither but directly proportional to both. 
This invention has the advantage when the driven machine is an electrical 
generator of enabling or allowing the generation and transmission of 
electrical power directly into electrical power lines without the need for 
batteries, chargers, inverters, or other power conditioning equipment. 
The driven machine can be a generator. The generator can be any type but an 
induction generator is preferred because an induction generator 
facilitates wind turbine torque control by use of reaction torque 
particularly for small systems. An induction generator is easier to 
control, costs less to control, is cheaper to purchase, and has better 
reliability than a synchronous generator. However, an induction generator 
has a relatively poor power factor and therefore is slightly less 
efficient than a synchronous generator. Even though an induction generator 
has some disadvantages to a synchronous generator, the induction generator 
is preferred over the synchronous generator for relatively small wind 
energy conversion systems. 
Regardless of the type of driven machine, or generator, one embodiment of 
this invention has the advantage when applied to fixed pitch multi-blade 
wind turbines, of enabling or allowing effective yaw angle control for a 
wide range of wind speeds above rated value. 
A further embodiment of this invention which can be used with any of the 
various means for receiving and transmitting reaction torque, and any of 
the various means for adjusting or controlling wind turbine torque, 
comprises a means for sensing positive and negative torque magnitudes 
relative to a predetermined torque value corresponding to minimum "cut-in" 
wind speed. Another embodiment further comprises a means for sensing 
excessive or abnormal wind turbine torque magnitudes with respect to a 
predetermined torque value which corresponds to a maximum "cut-out" wind 
speed. In both of these embodiments the above means for sensing can be 
motivated by reaction torque or other sources of energy or power. 
In general, this invention is for a wind energy conversion system 
comprising a wind turbine for converting wind energy into wind turbine 
torque. An essentially horizontally disposed, first shaft is drivenly 
connected at one end thereof to the wind turbine. A first means is 
provided for reacting to wind turbine torque in such a way that, when the 
system is operating, wind turbine torque produces, in balance thereto, 
angular displacement of the first means. 
A chassis is provided to which the first means is rotatably mounted. By 
"rotatably mounted" herein is meant that the first means is not rigidly 
fixed to the chassis but is permitted to rotate. In one embodiment the 
axis of rotation of the first means is fixed in a specific location to the 
chassis. 
In general, however, a driven machine is provided which is drivenly 
connected to the first shaft of the wind turbine and supported by the 
chassis. A second means for adjusting wind turbine efficiency is provided 
which is drivenly connected to the first means in such a way that the 
first means is prevented from having continual angular speed, and further 
in such a way that angular displacement of the first means causes the 
second means to adjust wind turbine efficiency. By preventing the first 
means from having continual angular speed, the first means is not 
permitted to rotate or spin continuously no matter how slow or fast such 
rotation may be. 
In general, the system operates such that a change in reaction torque 
received by the first means causes the first means to undergo a change in 
angular displacement from its previously dynamically balanced position. 
Therefore, the first means rotates in response to a change in reaction 
torque, which is caused by a change in wind turbine torque. The first 
means stops rotating when the new reaction torque is in dynamic balance 
with the system. The system is in dynamic balance when the second means, 
which is drivenly connected to the first means, has adjusted wind turbine 
efficiency so that the system is in dynamic balance with the new wind 
speed. If no change in the wind speed of the wind vector acting on the 
wind turbine occurs, the first means will, depending on the time constant 
and dampening of the system, come to rest and be in dynamic balance with 
the system. 
In a preferred embodiment of this invention the driven machine is spaced 
away from the chassis by a support means. The support means rotatably 
supports the driven machine in such a way that the frame of the driven 
machine, or frame of any component directly in the drive train of the 
system, is angularly displaceable about input shaft. By the expression 
"frame of the driven machine" is meant the frame of any component or 
machine which is directly in the drive train, such as for example a speed 
increasing means. In this embodiment the support means is fixed to the 
chassis as well as supported by the chassis. The frame is spaced away from 
the chassis by the support means so that the frame of the driven machine 
is angularly displaceable with respect to said chassis. 
An adjusting means for adjusting wind turbine efficiency is provided which 
is drivenly connected to the frame in such a way that the frame is 
prevented from having continual angular speed. The adjusting means is also 
drivenly connected to the frame in such a way that, when the system is in 
use, wind turbine torque produces, in balance thereto, angular 
displacement of the frame which in turn causes the adjusting means to 
adjust wind turbine efficiency. 
In this embodiment the system operates so that a change in reaction torque, 
due to a change in wind magnitude, is transmitted to the frame of the 
driven machine, and causes the frame to undergo a change in angular 
displacement from its previous dynamically balanced position. The frame 
rotates to a new position which is in dynamic balance with the new wind 
speed. This dynamic balance is accomplished by an adjusting means which is 
drivenly connected to the frame, and which is designed to adjust the wind 
turbine efficiency so that the system is in dynamic balance with the new 
wind speed. 
In an especially preferred embodiment the wind energy conversion system for 
converting wind energy into wind turbine torque comprises a wind turbine 
having blade pitch which is adjustable, an essentially horizontally 
disposed first shaft which is drivenly connected at one end thereof to the 
wind turbine, and a driven machine having an input shaft which is drivenly 
connected to the first shaft. A support means is provided for rotatably 
supporting the driven machine in such a way that the frame of the driven 
machine is angularly displaceable about the input shaft of the driven 
machine. A chassis is provided to which the support means is fixed. The 
frame of the driven machine is spaced away from the chassis by the support 
means so that the frame is angularly displaceable with respect to the 
chassis. An adjusting means is provided which is drivenly connected to the 
frame of the driven machine and supported by the chassis in such a way 
that said frame of the driven machine is prevented from having continual 
angular speed. The adjusting means is also drivenly connected to the frame 
of the driven machine in such a way that when the system is in use, wind 
turbine torque produces, in balance thereto, angular displacement of the 
frame of the driven machine which in turn causes the adjusting means to 
adjust blade pitch in such a way that wind turbine torque is controlled. 
In this embodiment a change in wind magnitude causes a change in wind 
turbine torque, which causes a change in reaction torque, which causes the 
frame of the driven machine to undergo a change in angular displacement 
from its previous position. The new angular displacement of the frame of 
the driven machine causes through various linkages or devices, which can 
include a dampening means or proportional control means to prevent 
undesirable system oscillation, an adjustment of blade pitch so that the 
system comes in dynamic balance with the new wind magnitude. 
In a further embodiment the driven machine is an electrical generator and 
the frame of the generator is angularly displaceable with respect to the 
chassis of the system. However, wind speed must exceed a predetermined 
lower value, which corresponds to a predetermined first value of wind 
turbine torque before angular displacement of the frame of the generator 
is permitted. When this embodiment of the system is in use, wind turbine 
torque which exceeds the predetermined first torque value produces, in 
balance thereto, angular displacement of the frame of the generator, which 
in turn causes the adjusting means to adjust blade pitch in such a way 
that wind turbine torque is adjusted to a predetermined second torque 
value which is substantially constant over a predetermined range of wind 
speeds. As in the previous embodiment, the "frame of the generator" is 
meant to include the frame of any component or machine which is directly 
in the drive train, such as for example the frame of a speed increasing 
means. 
For the predetermined second torque value to be substantially constant over 
a predetermined range of wind speeds means that the wind turbine torque at 
cut-out wind speed must be nearly equal to wind turbine torque at rated 
wind speed. For example, at rated wind speed the wind turbine torque may 
equal 100 torque units which will increase gradually to about 104 torque 
units at cut-out wind speed. In this example, the cut-out torque is 4 
percent higher than rated torque, and thus the wind turbine torque over 
the wind speed range illustrated is substantially constant. The increase 
in cut-out torque over rated torque may be higher or lower than the 4 
percent of the example, but, in any event, the percent change should be 
small so that the wind turbine torque over the range of rated to cut-out 
wind speeds is substantially constant. 
The range of wind speeds can be, for example, from the predetermined lower 
value or rated wind speed to a wind speed equal to at least two times the 
predetermined lower value wind speed. For example, the predetermined lower 
value wind speed can be 20 miles per hour (mph) and the predetermined 
range of wind speeds can be from 20 to at least about 40 mph. In this 
range of wind speeds, the system adjusts wind turbine efficiency in such a 
manner that wind turbine torque is substantially constant. 
In another preferred embodiment, the predetermined range of wind speeds 
over which wind turbine torque is substantially constant is from a 
predetermined lower value to a wind speed equal to about four times the 
predetermined lower value. For example, the predetermined lower value wind 
speed can be 15 mph and the predetermined range of wind speeds over which 
wind turbine torque is essentially constant can be from about 15 to about 
60 mph. 
Preferably the predetermined second value of wind turbine torque is nearly 
equal to, but slightly greater than, the predetermined first value of wind 
turbine torque. For example, the predetermined first value of wind turbine 
torque corresponds to the rated wind speed which can be assigned a value 
of 100 torque units, and the predetermined second value of wind turbine 
torque corresponds to the wind speed between rated and cut-out wind speed 
which can correspond to a wind turbine torque range of between about 100 
to 104 torque units. Thus, the average predetermined second value of wind 
turbine torque, in this example, is about 102 torque units which is 
slightly greater than the predetermined first value of wind turbine 
torque, or 100 torque units in this example. 
In another embodiment of this invention the wind energy conversion system 
comprises a wind turbine for converting wind energy into wind turbine 
torque, and an essentially horizontally disposed first shaft, one end of 
which is drivenly connected to the wind turbine. A differential mechanism 
means is provided which has an input or second shaft drivenly connected to 
the first shaft, a power or third shaft for transmitting wind turbine 
torque to a driven machine, and a reaction or fourth shaft for 
transmitting a reaction torque to an adjusting means. The differential 
mechanism means is fixed to a chassis. The driven machine is fixed to the 
chassis and has an input shaft which is drivenly connected to the third 
shaft of the differential mechanism means. The adjusting means is drivenly 
connected to the fourth shaft in such a way that the fourth shaft is 
prevented from having continual angular speed. When the system is in use, 
wind turbine torque produces, in balance thereto, an angular displacement 
of said fourth shaft which in turn causes the adjusting means to adjust 
wind turbine efficiency. In this embodiment the system operates so that a 
change in reaction torque, due to a change in wind magnitude, is 
transmitted to the fourth shaft of the differential mechanism means, and 
causes the fourth shaft to undergo a change in angular displacement from 
its previous dynamically balanced position. The fourth shaft rotates to a 
new position which is in dynamic balance with the new wind speed. This 
dynamic balance is accomplished by an adjusting means which is drivenly 
connected to the fourth shaft, and which is designed to adjust the wind 
turbine efficiency so that it is in dynamic balance with the new wind 
speed. 
In a further embodiment, the fourth shaft of the differential mechanism 
means is drivingly connected to a yaw control means in such a way that the 
fourth shaft is prevented from having continual angular speed. The yaw 
control means is supported by the chassis. When the system is in use, wind 
turbine torque produces, in balance thereto, angular displacement of the 
fourth shaft which in turn causes the yaw control means to adjust wind 
turbine yaw in such a way that wind turbine torque is controlled. 
Therefore, in this embodiment, when the fourth shaft rotates to a new 
position which is in dynamic balance with a new wind speed, the yaw 
control means, which is drivenly connected to the fourth shaft, adjusts 
wind turbine yaw so that wind turbine torque is in dynamic balance with 
the new wind speed. 
In a still further embodiment, in which the driven machine is an electrical 
generator, wind speed which exceeds a predetermined first value, such as 
the rated wind speed, produces in balance thereto angular displacement of 
the fourth shaft of the differential mechanism means. The angular 
displacement of the fourth shaft which is drivingly connected to the yaw 
control means causes the yaw control means to adjust wind turbine yaw. In 
this embodiment wind turbine yaw is adjusted in such a way that wind 
turbine torque is adjusted to a predetermined second torque value which is 
substantially constant over a predetermined range of wind speeds. As in 
the earlier embodiment, this means that the wind turbine torque between 
rated and cut-out wind speeds is substantially constant. Wind turbine 
torque will increase slightly as the wind speed increases from rated to 
cut-out wind speed. 
In another embodiment of the present invention, a wind turbine having blade 
pitch which is adjustable is drivingly connected to a horizontally 
disposed first shaft which is drivenly connected to the input or second 
shaft of the differential mechanism means. As in the previous embodiment, 
the power or third shaft of the differential mechanism is drivingly 
connected to a driven machine. The reaction or fourth shaft of the 
differential mechanism means, however, is drivingly connected to an 
adjusting means for adjusting blade pitch of the wind turbine, thereby 
controlling wind turbine torque. In this embodiment a change in wind speed 
causes a change in the angular displacement of the fourth shaft of the 
differential mechanism means, which in turn causes movement of the 
adjusting means, which in turn causes blade pitch to be adjusted, thereby 
controlling wind turbine torque. 
In all embodiments of the present invention, a speed increasing means may 
be inserted in the drive train of the system between the first shaft of 
the wind turbine and the input shaft of the driven machine. In the 
embodiments using a differential mechanism means, the speed increasing 
means can be an integral part of the differential mechanism means. 
In a preferred embodiment wind turbine torque is controlled so that it is 
substantially constant for all wind speeds between a first predetermined 
wind speed and a second predetermined wind speed which is at least two 
times greater than the first predetermined wind speed. For example, the 
range of wind speeds can be between rated and cut-out wind speed. In a 
still further embodiment the second predetermined wind speed is about four 
times greater than the first predetermined wind speed, while the wind 
turbine torque within such a range of wind speeds is maintained 
essentially constant. 
In these embodiments the speed of the input shaft of the driven machine or 
generator is directly proportional to the speed of the wind turbine shaft 
or first shaft as referred to herein. 
In further embodiments of the above-described embodiments, neither the 
first means for reacting to wind turbine torque and the second means for 
adjusting wind turbine efficiency; nor the frame of the driven machine or 
generator and the adjusting means drivenly connected to the frame; nor the 
reaction shaft, or fourth shaft as referred to herein, of the differential 
mechanism means and the adjusting means, or yaw control means, drivenly 
connected to the fourth shaft, are elements of the drive train of the 
system. 
In another further embodiment of the present invention there is provided a 
connecting means for transmitting electrical power from the generator into 
an electrical power source, and a breaking means for breaking electrical 
connection between the generator and the power source when the wind 
turbine torque is less than a predetermined absorbing torque value 
required for transmitting electrical power from the generator to the power 
source. In this embodiment when the wind speed is less than cut-in wind 
speed, the system is not able to generate sufficient voltage for feasible 
or economical transfer of power to the electrical power source, and 
therefore a breaking means is used to prevent the power source from 
causing the wind turbine to motor. In a still further embodiment an 
excessive wind speed means is provided which reduces the drag on the wind 
turbine when the wind speed exceeds a predetermined high value, which 
corresponds to predetermined high torque value, which could cause damage 
to the system if the system were to be allowed to continue operation in 
its normal mode. 
If needed or desired, a suitable dampening means, proportional control, or 
the like can be added to the system to reduce any system oscillation. 
In general the system is rotatably mounted on a support structure so that 
it normally faces directly into the wind, at least for all wind speeds no 
greater than rated wind speed. Furthermore, an aerodynamic shroud can be 
used to enclose the various components of the system to protect such 
components from the weather and to reduce drag on the structure which is 
not beneficially converted into useful torque. 
Other objectives and features of the present invention will become apparent 
from a detailed description and consideration of the preferred embodiments 
thereof taken in conjunction with the accompanying drawings in which like 
elements or parts have like numerals throughout the several views and 
embodiments.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
FIG. 1 shows a schematic view of one embodiment of the present invention 
which uses a differential mechanism means to sense and respond to reaction 
torque and a yaw control means drivenly connected to the differential 
mechanism means to adjust the efficiency of the wind turbine system. 
In particular, wind turbine 10 is coupled to an essentially horizontally 
disposed first shaft 12 which is also the input shaft to differential 
mechanism means 14 which has an output power shaft 16 and reaction torque 
shaft 18. Output power shaft 16 is also the input shaft to driven machine 
20 which can be an electrical generator. Reaction torque shaft 18 is 
drivingly connected to torque arm 22a. Differential mechanism means 14 is 
mounted on chassis 30 shown in phantom detail for aiding this description. 
Torque arm 22a is drivingly coupled to yaw control vane arm 26 by means of 
suitable yaw linkage mechanism 24 which comprises elements 24a, 24b, 24c 
and 24d. Yaw control vane 28 is drivenly attached to yaw control vane arm 
26 which is free to rotate on bearings 32a and 32b which are mounted on 
chassis 30. Chassis 30 is free to rotate (not shown) on support tower 34. 
Chassis 30 therefore carries the entire mechanism and is rotatably mounted 
atop support tower 34. 
In this embodiment the driven machine 20 is shown as an alternating current 
generator which transmits electrical energy directly into power line 36. 
Torque arm 22c is preloaded by a means comprising spring 40 and stop 42. 
In this embodiment the wind turbine is normally oriented downwind of the 
tower, so that wind forces acting on the wind turbine create a drag which 
keeps the wind turbine directed into the wind. Other methods of keeping 
the wind turbine directed into the wind can be used if desired. Yaw 
control vane 28 is normally oriented parallel to the wind, as shown in 
FIG. 1, so that the wind exerts a negligible force on it. 
As the wind speed increases, generator 20 is energized and begins supplying 
power directly into power line 36 and a retarding or reaction torque is 
created which is transmitted through the reaction shaft 18 to the yaw 
control means comprising elements 26 and 28, and linkage mechanism 24. The 
yaw control means is, in this embodiment, designed to maintain the wind 
turbine system at constant or nearly constant torque. 
As the developed wind turbine torque exceeds the set point, which is 
predetermined by the design of spring 40 and stop 42, the reaction torque 
exerted through torque arm 22c overcomes the retarding torque represented 
by preloading spring 40 and begins to rotate, that is, undergo angular 
displacement. Springs 40 and 42 are fixed (not shown) to the chassis 30. 
Rotation of torque arm 22a is translated through linkage mechanism 24 
which causes yaw control arm 26 and vane 28 to rotate, thereby presenting 
a greater surface area of yaw control vane 28 to the wind. The force of 
the wind acting on yaw control vane 28 causes the entire assembly to 
partially rotate out of the wind until a point is reached in which the 
developed wind turbine torque is reduced to, or slightly above, a 
predetermined value or rated value which corresponds to the set point 
value represented by spring 40 and stop 42. 
The differential mechanism means shown in FIG. 1 shows three distinct 
shafts for connection to the wind turbine, generator, and torque arm. The 
differential mechanism means can be a bevel gear type, planetary gear 
type, or a type employing chains and sprockets or belts and pulleys. The 
depicted shafts represent the three power connections normally available 
in such a differential mechanism means. 
With slow-turning wind turbines, a speed increasing means is often desired 
or required. Although a speed increasing means is not shown in FIG. 1, 
this device could be located between wind turbine 10 and differential 
mechanism means 14, or between the differential mechanism and generator 
20. The speed increasing means can be separate or integral with the 
differential mechanism means. 
In this embodiment of the present invention, a wind coming from the 
direction shown in FIG. 1 creates a drag on the wind turbine which tends 
to keep the wind turbine oriented downstream but directed into the wind. 
Rotation of the wind turbine causes rotation of power shaft 16 and 
generation of electrical power by generator 20. Reaction torque is sensed 
by reaction shaft 18. As the wind speed increases reaction torque 
increases, but reaction torque arm 22c remains seated against stop 42 due 
to the force of spring 40 until the reaction torque is greater than that 
exerted by spring 40. The point where reaction torque and the torque 
exerted by spring 40 are equal is the "rated" torque of the wind turbine 
system which corresponds to the "rated" wind speed. As the wind speed 
exceeds rated wind speed, torque arm 22a rotates a limited amount in the 
direction shown in FIG. 1. The angular displacement of torque arm 22a 
causes, through linkage mechanism 24, yaw control arm 26 to rotate in the 
direction shown, thereby causing yaw control vane 28 to present more of 
its surface to the wind. The drag exerted on yaw control vane 28 causes 
the wind turbine to be partially rotated out of the wind to a point where 
the wind speed which exceeds rated wind speed is in dynamic balance with 
the system. Dynamic balance results in a controlling of wind turbine 
torque so that it is just slightly greater than rated torque for all wind 
speeds greater than rated wind speed. It will be appreciated that as wind 
speed increases to a much greater extent over rated wind speed, the wind 
turbine must rotate to a larger degree out of the wind in order for the 
system to maintain wind turbine torque substantially constant, that is 
just slightly greater than rated torque. 
FIGS. 2 and 3 illustrate a physical arrangement of a wind turbine with 
variable pitch blades 50 supported from a central hub 52 which is direct 
coupled to the shaft 12 of a generator 54. Generator frame 56 is free to 
rotate by means of a special mounting arrangement in which the generator 
front and rear shaft extensions are separately and rotatably supported by 
pedestal bearings 58a and 58b which are fixed to chassis 30. Generator 
shaft 12 is hollow to accept control rod 60 which extends through the 
center of generator shaft 12 and protrudes therefrom at both ends. 
On the rear of control rod 60 is fitted an idler bearing 62 which allows 
control rod 60 to be moved into and out of generator shaft 12 by action of 
torque arm 22a, fastened to rotatable generator frame 56. Torque arm unit 
22 comprises right angle element 22b which is slidingly and drivingly 
connected to linkage mechanism element 24a. Linkage mechanism 24 comprises 
elements 24a, 24b, 24c and 24d, which is slidingly and drivingly connected 
to pin element 62b which is fixed to annular element 62a of idler bearing 
62. Therefore, torque arm 22 and idler bearing 62 are coupled by means of 
a linkage mechanism 24 which is supported by bearings 64 which are mounted 
to chassis 30. 
The turbine end of control rod 60 is fastened to rotatable blade spars 66 
through linkage mechanism 68 which comprises elements 68a, 68b, 68c, 68d 
and 68e, thus allowing spars 66 to be rotated and blade pitch to be 
altered as the axial position of control rod 60 is changed in response to 
movement torque arm 22. 
In the embodiment shown in FIGS. 2 and 3, torque arm 22c of this 
arrangement is preferably preloaded by means of spring 40 and stop 42 
similar to those elements shown in FIG. 1. Preferably stop 42 is 
adjustable. 
In this embodiment drag on the wind turbine tends to keep the wind turbine 
oriented downstream but directed into the wind. As the wind speed exceeds 
rated wind speed, torque arm element 22c rotates slightly off of stop 42. 
Torque arm element 22b which is slidingly and drivingly connected to 
linkage mechanism 24 rotates linkage mechanism 24 in the direction shown 
in FIG. 2. Idler bearing 62 which is drivenly connected to linkage 
mechanism 24 is drivingly connected to control rod 60 which is drivingly 
connected to rotatable blade spars 66 through linkage mechanism 68. Blade 
spars 66 change blade pitch (not shown on FIGS. 2 and 3) to a point where 
wind turbine torque is in dynamic balance with the system and wind speed 
acting on the system. Dynamic balance results in a controlling of wind 
turbine torque so that it is just slightly greater than rated torque for 
all wind speeds greater than rated wind speed. As wind speed increases the 
efficiency of the wind turbine is therefore decreased by blade pitch 
adjustment so as to maintain wind turbine torque substantially constant; 
that is, just slightly greater than rated torque. Therefore, this 
embodiment operates to change the pitch of the wind turbine blades when 
the torque applied to the generator exceeds rated torque. 
Furthermore, in this embodiment the frame of a driven machine in the driven 
train, specifically the frame of the generator, senses and transmits 
reaction torque to an adjusting means which adjusts wind turbine 
efficiency, specifically by adjusting the blade pitch of the wind turbine. 
FIG. 2 depicts a small wind turbine in which the speed thereof is high 
enough to drive the generator directly. For larger slower-speed wind 
turbines, speed increasing devices can be inserted between the turbine and 
generator, in which case only the low speed turbine shaft need be hollow 
to accept the pitch changing control rod. 
FIGS. 4 and 5 illustrate another embodiment of the present invention in 
which reaction torque, sensed and transmitted by a component in the drive 
train of the system, is used to drive an adjusting means which adjusts 
wind turbine efficiency by adjusting the blade pitch of the wind turbine. 
This embodiment, which may be oriented into the wind as in the embodiment 
of FIG. 1, has first shaft 12 which is drivenly connected to the wind 
turbine. A speed increasing means 80 is drivenly connected to the first 
shaft. An output shaft 82 of the speed increasing means is coupled to 
input shaft 84 of generator 54. The details of the gear mechanism or the 
like between shaft 12 and 82 are not shown since any suitable means known 
to those skilled in the art can be used. The shaft of generator 54 extends 
through the generator and is rotatably mounted in pedastal bearings 58a 
and 58b which are mounted on chassis 30. Generator frame 56 is free to 
rotate relative to the chassis. 
As wind speed exceeds rated wind speed, frame 56 rotates slightly in the 
direction shown in FIG. 5 causing torque arm 22c to lift off stop 42. 
Spring 40 prevents rotation of frame 56 for all wind speeds less than 
rated wind speed which corresponds to rated wind torque. As frame 56 
rotates so does torque arm 22a which in this embodiment is a chain 
fastened to frame 56 by fastening means 85. Chain 22a is drivingly 
connected to sprocket 86 which is permitted to rotate but not permitted to 
have substantial axial movement by bearing means 88 which is contained in 
bearing mount 89 which is mounted to chassis 30. Rotation of sprocket 86 
causes control rod 60 to move axially through the hollow shaft of wind 
turbine shaft 12. Rotation of control rod 60 is prevented by spline means 
90. Control rod 60 is drivingly connected to rotatable blade spars 66 
through linkage mechanism 68 which changes blade pitch (not shown in FIGS. 
4 and 5) to a point where wind turbine torque is in dynamic balance with 
the system and wind speed acting on the system. 
As in the embodiment shown in FIGS. 2 and 3, the embodiment in FIGS. 4 and 
5 of the present invention adjust the blade pitch of the wind turbine for 
all wind speeds greater than rated wind speed which corresponds to rated 
wind torque so that wind turbine torque is just slightly greater than 
rated wind turbine torque and is substantially constant over all wind 
speeds between rated and cut-out wind speed. 
Another embodiment of the present invention is similar to the embodiments 
shown in FIGS. 2 and 4 except that a means for rotatably supporting the 
frame of the driven machine or generator is provided which is different 
than that shown in FIGS. 2 and 4. In this embodiment, instead of using 
pedestal bearings to support the shaft of the driven machine or generator, 
a pedestal bearing or bearings can be used to directly support the frame 
of the driven machine or generator rather than the shaft thereof. This 
embodiment has the advantage of not subjecting the pedestal bearing to the 
constant and relatively high-speed rotation of the shaft, but rather the 
intermittent and slight rotational motion of the frame. Although bearing 
life is enhanced in this embodiment this design is more costly to 
construct and therefore is not preferred where a cheaper initial 
investment is of principal concern. 
If desired or necessary, all embodiments of the present invention can have 
as a further embodiment a dampening means, proportional control means, or 
the like, to prevent undesirable system oscillation as the various control 
means react to a change in wind speed. Such means are additionally 
beneficial when wind speeds are varying rapidly. Dampening means can be, 
for example, a shock absorber means, or dash pot, working in parallel with 
spring means 40. 
FIG. 6 depicts schematically a further embodiment of the present invention 
which can be used with all the embodiments set forth above. A torque arm 
122 is rigidly connected to a reaction torque device 100 which can be 
either a rotatable frame of the driven machine, such as frame 56 in FIGS. 
2 and 4, or the reaction shaft of a differential mechanism means, such as 
reaction shaft 18 in FIG. 1. Cradle device 125, preloaded by means of 
spring 40 and stop 42, allows torque arm 122 some freedom to move 
clockwise or counterclockwise. When the reaction torque on torque arm 122, 
acting on cradle device 125, exceeds that exerted by large spring 40, 
cradle device 125 is free to move to the left, to position the particular 
turbine efficiency control means employed. For example, to position a yaw 
control vane as in the embodiment of FIG. 1, or blade pitch as in the 
embodiment of FIGS. 2 and 4. 
When the wind turbine produces "positive" torque, torque arm 122 moves 
clockwise to trip switch 131. When the torque arm turns counterclockwise, 
the turbine is being driven by the load device and switch 133 is tripped. 
Switch 131 can be used to make connection with an electrical power source 
thus allowing electrical connection when the wind speed reaches cut-in 
wind speed which corresponds to cut-in wind turbine torque. Switch 133 can 
be used to break the electrical connection with the electrical power 
source when wind speed is below cut-in wind speed which corresponds to 
cut-in wind turbine torque thereby preventing the generator from acting as 
a motor to drive the turbine. 
Increases in wind speed are acceptable until the maximum safe torque of the 
generator or other system components is approached. Therefore, when the 
system is exposed to excessive wind speed and an excessive torque is 
produced by the wind turbine, switch 135 is actuated by the cradle device 
125. Switch 135 can be used to initiate feathering of the wind turbine to 
prevent its operation when the wind speed becomes excessive and the system 
becomes unsafe or the torque exceeds the maximum safe design level for the 
generator or other system components or the like. By feathering the wind 
turbine is meant any method which essentially drastically reduces the drag 
on the wind turbine, such as for example, blade coning or vertical 
rotation of the entire wind turbine system. 
Small springs 141 and 143 may be attached between cradle device 125 and 
torque arm 122 to prevent operation of switches 131 and 133 until the 
positive and negative torques are of the desired magnitude. 
The switches depicted may be electrical, mechanical, or pneumatic. The 
switches can be used to indicate, or to initiate control functions, when 
the wind turbine is producing torque, absorbing torque or producing 
excessive torque. 
Although the present invention has been described with reference to the 
preferred embodiments thereof, many modifications and alternations may be 
made, and equivalents employed, within the scope of the appended claims 
without departing from the spirit or sacrificing any of the advantages of 
the present invention.