Abstract:
A windmill for converting wind energy into electrical power and supplying it to a power grid, comprising a blade assembly, a generator housing, and a main shaft operatively coupled between the blade assembly and generator housing. The generator housing contains a first generator having a first generator output and a second generator having a second generator output. A hydraulic strut supports the generator housing and allows angular adjustment thereof. A hydraulic pump selectively pressurizes the hydraulic strut to effect adjustment thereof. A braking system is selectively actuable to slow rotation of the main shaft. A flyweight assembly and a four position speed sensing switch together detect rotational speed of the main shaft, selectively connect the generators with the main shaft, and selectively activate the braking system and hydraulic pump as appropriate according to the speed detected by the speed sensing switch.

Description:
BACKGROUND OF THE INVENTION  
         [0001]    The invention relates to a windmill having a speed-sensitive control system. More particularly, the invention relates to a windmill which is configured so as to make greatest use of available wind energy while increasing durability by reducing wear and tear which ordinarily occurs from high speed operation.  
           [0002]    Although utilization of wind energy has taken place for hundreds, if not thousands of years, only recently has cost effective large-scale generation of electric power been within reach. With the increasing concern over the cost and depletion of fossil fuel resources, effective solutions with regard to harnessing wind power are being demanded by scientists, politicians, and consumers.  
           [0003]    Currently, windmill generated electric power cannot compete with hydroelectric, nuclear, and fossil fuel based generation systems if compared on a cost basis alone. The primary reason is the cost of manufacturing and installing a new windmill. Typically then, one would expect that the cost of even an expensive windmill could be recouped, given enough time. However, current windmills are limited in durability, and thus fail long before they can generate enough electricity to pay for themselves.  
           [0004]    One of the major causes of windmill failure is unusually high wind velocity. High wind velocity causes increased stress on windmill blades and other components, and increases the speed of the windmill rotation. When windmill rotation speed exceeds design specifications, internal stresses and inertia can cause vibration throughout the windmill which will drastically cut its useful life. In severe wind situations, the windmill can even fail.  
           [0005]    Accordingly, in order to increase the durability of a windmill, the key area to focus upon seems to be speed management. In other words, configuring the windmill to either better withstand high blade velocities, or to reduce velocity—even in the face of strong winds.  
           [0006]    Others have sought to provide solutions to the problem of limited windmill durability and limited ability to withstand high winds, by promulgating alternative windmill designs. While these units may be suitable for the particular purpose employed, or for general use, they would not be as suitable for the purposes of the present invention as disclosed hereafter.  
         SUMMARY OF THE INVENTION  
         [0007]    It is an object of the invention to provide a windmill which is configured so as to have a long useful life. Accordingly, the windmill is configured to reduce the wear and tear normally encountered by windmills spinning at high rotational speeds resulting from unusually strong winds.  
           [0008]    It is another object of the invention to provide a windmill which reacts to varying wind conditions. Accordingly, the windmill senses the windspeed, and takes appropriate action in response thereto. The windmill employs a flyforce system which is operatively engaged with the main shaft of the windmill, the flyforce system operating a speed sensing four position switch in response to changes in rotational speed of the main shaft. The action taken, according to the status of the speed sensing four position switch either increases power output of the windmill, or takes steps to lower the blade speed.  
           [0009]    It is a further object of the invention to provide a windmill which makes greatest use of available wind energy to produce the greatest possible power output. Accordingly, the speed sensing system acts to engage the generator with the power grid when sufficient speed is present, and may act to engage a secondary generator when a further increase in speed warrants the use of the secondary generator.  
           [0010]    It is yet a further object of the invention to provide a windmill which acts to reduce the blade speed when high winds are present. Accordingly when the speed sensing switch detects an unsuitably rapid blade velocity, the blades are steered by a hydraulic system slightly away from the wind to slow down the blades. If the speed sensing switch detects an even greater velocity, a braking system is engaged to slow or stop the blade rotation.  
           [0011]    The invention is a windmill for converting wind energy into electrical power and supplying it to a power grid, comprising a blade assembly, a generator housing, and a main shaft operatively coupled between the blade assembly and generator housing. The generator housing contains a first generator having a first generator output and a second generator having a second generator output. A hydraulic strut supports the generator housing and allows angular adjustment thereof. A hydraulic pump selectively pressurizes the hydraulic strut to effect adjustment thereof. A braking system is selectively actuable to slow rotation of the main shaft. A fleeweight assembly and a four position speed sensing switch together detect rotational speed of the main shaft, selectively connect the generators with the main shaft, and selectively activate the braking system and hydraulic pump as appropriate according to the speed detected by the speed sensing switch.  
           [0012]    To the accomplishment of the above and related objects the invention may be embodied in the form illustrated in the accompanying drawings. Attention is called to the fact, however, that the drawings are illustrative only. Variations are contemplated as being part of the invention, limited only by the scope of the claims.  
       
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0013]    In the drawings, like elements are depicted by like reference numerals. The drawings are briefly described as follows.  
         [0014]    [0014]FIG. 1 is a diagrammatic side view, illustrating various components of the windmill.  
         [0015]    [0015]FIG. 2 is a block diagram, illustrating interconnection of various components of the windmill and associated speed sensing mechanisms.  
     
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS  
       [0016]    [0016]FIG. 1 illustrates a windmill  10 , having a mast  12 , and a generator housing  14  mounted thereupon with a swivel joint  16 . A blade assembly  18  is operatively connected to the generator housing  14  with a main shaft  20 . The generator housing  14  contains two generators coaxially linked to the main shaft  20 , including a first generator, having a first generator output  21 , and a second generator, having a second generator output  22 . The windmill  10  supplies energy to a power grid  25 . Typically numerous windmills  10  are connected to said power grid  25  which allows distribution of electricity to electrical consumers in a manner which is well known, and is thus beyond the scope of the present discussion.  
         [0017]    The generator housing  14  is angularly braced with a hydraulic strut  50  which allows angular adjustment of the generator housing  14  and thus the blade assembly  18 . Accordingly, the generator housing  14  typically extends horizontally, and the blade assembly  18  typically extends vertically. However, the hydraulic strut  50  allows angular adjustment varying from said typical positions. Like a hydraulic shock absorber, the hydraulic strut  50  has an internal cavity into which hydraulic fluid may be pumped in order to alter its load bearing ability, and thus alter its position. An hydraulic fluid pump  52  is connected to the hydraulic strut  50  by a hydraulic line  54 . A braking system  60  is also provided, which is electrically operated, and acts to slow the main shaft  20  either directly, or indirectly by steering the entire generator housing  14  away from the wind.  
         [0018]    A fleeforce assembly  30  is operatively coupled to the main shaft  20 , fully opposite from the blade assembly  18 . Referring to FIG. 2, a four position speed sensing switch  40  is located adjacent to the fleeforce assembly  30 . The speed sensing switch  40  has a housing  41  and a plunger  42  movable to four different positions with respect to the housing. The fleeforce assembly  30  has a fleeforce plate  32  which is capable of contacting the plunger  42  of the speed sensing switch  40  and altering the selected position of said speed sensing switch  40 . The fleeforce plate  32  is positioned in accordance with the rotational speed of the main shaft  20  in a manner which will be described hereinafter. Accordingly, the position of the speed sensing switch  40  is thereby dependent on the rotational speed of the main shaft  20 .  
         [0019]    The fleeforce assembly  30  comprises a cross bar coupler  33  having a pair of cross bar ends  34 . The fleeforce assembly  30  also comprises a pair of fleeweights  36  which are each pivotally attached at one of the cross bar ends  34 . Each fleeweight  36  comprises a major arm  37  and a minor arm  38  which are joined at an elbow  39 . The major arms  37  are oriented away from each other, and the minor arms  38  are oriented toward each other. The cross bar coupler  33  is attached onto the main shaft  20  and spins therewith. As the main shaft  20  spins, centrifugal force causes the major arms  37  to pivot outward, which in turn causes the minor arms to pivot outward and press upon the fleeforce plate  32 . As the main shaft  20  spins faster, the minor arms  38  push the fleeforce plate  32  further toward the speed sensing switch  40 . The fleeforce plate  32  may be biased toward the fleeforce assembly  30  and away from the plunger  42  with a fleeforce assembly spring  31 . Accordingly, as the main shaft  20  slows down, the fleeforce assembly spring  31  helps restore the fleeforce plate  32  toward the generator housing  14  and away from the switch  40 .  
         [0020]    Referring to FIG. 2, the four position switch  40  has a position one output  401 , a position two output  402 , a position three output  403 , and a position four output  404 . The four position speed sensing switch  40  operates such that when in its first position, the position one output  401  is enabled. However, when the switch  40  is in its second position, the position one output  401  and the position two output  402  are enabled. Further, when the switch  40  is in its third position, the position one output  401 , the position two output  402 , and the position three output  403  are enabled. Still further, when the switch  40  is in its fourth position, the position one output  401 , the position two output  402 , the position three output  403 , and the position four output  404  are enabled.  
         [0021]    A first relay  501  is controlled by the position one output  401 . A second relay  502  is controlled by the position two output  402 . A third relay  503  is controlley by the position three output  403 . A fourth relay  504  is controlled by the position four output  404 . Each of the relays have an open position and a closed position.  
         [0022]    The first relay  501  selectively connects the first generator output with the power grid  25 . The second relay  502  selectively connects the second generator output  22  with the power grid  25 . The third relay  502  selectively connects the hydraulic pump  52  with a general power source  80 . The fourth relay  504  selectively connects the braking system  60  with said general power source. The general power source is any power source capable of reliably supplying sufficient power to operate the hydraulic pump and the braking system. The general power source may be one or both of the generator outputs, may be the power grid, or may be a storage battery.  
         [0023]    During operation then, at a relatively low rotational speed of the main shaft  20 , the switch  40  will be in a first position. When the switch  40  is in the first position, the position one output  401  is enabled, and the first relay  501  is thereby closed, connecting the first generator output  21  with the power grid  25 . Accordingly, wind power is harnessed by the blade assembly  18 , is converted to electricity by the first generator, and is tendered to the power grid  25 .  
         [0024]    As increased wind force causes the rotational speed of the main shaft  20  to increase, the fleeforce assembly  30  increases pressure upon the fleeforce plate  32  which moves the plunger  42  to put the switch  40  into its second position. When the switch  40  is in its second position, the position two output  402  is enabled, and the second relay  502  is closed, connecting the second generator output  22  with the power grid  25 . Accordingly additional electricity is generated by the second generator, and is tendered to the power grid  25 .  
         [0025]    If the wind force causes the rotational speed of the main shaft to increase to an undesirably high level, the fleeforce assembly continues to increase pressure upon the fleeforce plate  32  and moves the plunger  42  so as to put the switch  40  in its third position. When the switch  40  is in the third position, the position three output  403  is enabled, and the third relay is closed  503 , connecting the hydraulic pump with the general power source  80 . Accordingly, hydraulic fluid is pressurized by the hydraulic pump  52 , and is fed to the hydraulic strut  50 , causing the strut to expand in length, thus pitching the blade assembly  18  upward. Preferably the movement of the blade assembly  18  brings the blades into position which causes the blade assembly  18  and thus the main shaft  20  to slow down. Meanwhile, both generators continue generating electric power and supplying the same to the power grid  25 . The hydraulic strut  50  can be configured so that it typically rests in an optimum position when unpressurized, and that it slowly bleeds hydraulic fluid until it reaches its optimum position. Accordingly, after a high rotation speed situation has been dealt with, the hydraulic strut  50  will slowly automatically bring the blade assembly  18  back into optimum position.  
         [0026]    If the wind force continues to increase, the resulting increased rotation of the main shaft can be detrimental to the windmill. Accordingly, slowing the blade assembly becomes of critical importance. At this point, the fleeforce assembly  30  will have brought the switch  40  into its fourth position. When the switch  40  is in its fourth position, the position four output  404  is enabled, and the fourth relay  504  is closed, connecting the braking system  60  with the general power source  80 . The braking system  60  operates to slow the windmill operation. If the braking system  60  is configured to directly slow the main shaft, then some oscillation may naturally occur as the main shaft is repeatedly slowed by the braking system such that the braking system is disengaged, then sped up again by the wind—causing the braking system to re-engage. Hopefully, if the extreme rotational speed is caused by a momentary gust, then no such oscillation of the braking system will occur.  
         [0027]    In conclusion, herein is presented a windmill system which responds to increased wind velocity and corresponding increases in windmill component rotation by various actions which seek to increase utilization of wind energy, and to decrease damage caused by excessive wind speeds.  
         [0028]    It should be noted that the invention is illustrated by example in the accompanying drawings figures, and throughout the discussion. Howeve it should be appreciated that innumerable variations may be promulgated while adhering to the inventive principles. Such variations are contemplated as being a part of the present invention.