Abstract:
The present invention relates to an aerodynamic dead zone-less triple-rotor integrated wind power driven system wherein control rotor  81  disposed at up-wind is rotated at a high speed. It induced the air flowing into the hub of extenders  71  of the auxiliary rotor  71  to the outside of the extenders  71 - 1  of the auxiliary rotor  71 , thereby forming an aerodynamic annular stream tube zone and increasing the air density therein, the main rotor  11  disposed at down-wind, is aerodynamically accelerating and improving the system efficiency. In addition, the rotor  52  and stator  51  of the electromagnetic attraction dragging rotational torque of the auxiliary generator by the load assists to rotate main rotor  11 , thereby the triple rotors integrating rotational torque generates the twin generators  4  and  4 - 1 ″ of the wind turbine.

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
       [0001]    This application claims the benefit of U.S. Provisional Application No. 61/353,679 filed Jun. 11, 2010, which is incorporated herein in its entirety. 
     
    
     FIELD OF THE DISCLOSURE 
       [0002]    The present invention relates generally to a wind turbine system for generating electricity and more specifically to a wind turbine system for generating electricity that includes two up-wind rotors and one down-wind rotor structure. 
       BACKGROUND OF THE INVENTION 
       [0003]    Existing large scale wind turbine systems for utilizing wind energy to generate electricity have certain disadvantages. 
         [0004]    For example, when the diameter of a wind turbine rotor exceeds twelve (12) meters, the wind input at its center has no effect on the rotation of the rotor thereby creating “an aerodynamic dead zone.” Accordingly, a large scale wind turbine system has its corresponding large aerodynamic dead zone. 
         [0005]    Another disadvantage involves the coupling the rotational forces of two or more rotors with different RPMs, where the force generated is limited by the gear ratio of each rotor&#39;s RPM and the total rotational force is decreased by the drag force created between the rotors of different tip speed rotor. 
         [0006]    Furthermore, when the input wind speed is above the rated wind speed, a mechanical stress can be created that exceeds the point where the wind turbine system can operate safely without breaking. 
         [0007]    Another challenge to a developer of a wind turbine system is avoiding aerodynamic interference between the counter-rotating rotors. 
       SUMMARY OF THE INVENTION 
       [0008]    Accordingly, it is an object of the present invention to provide an improved wind turbine system for generating electricity. 
         [0009]    Another object of the present invention is to provide a high speed small control rotor placed in front of auxiliary rotor in an up-wind position to create an aerodynamic dead zone-less system. 
         [0010]    The control rotor increases the rotational speed of both auxiliary rotor in the up-wind position and main rotor in the down-wind position during low wind speed as well as during rated wind speed. 
         [0011]    Another object of the present invention is to provide a flexible electromagnetic torque coupling where the rotational force of two or more rotors of different RPM is not limited by the gear ration of the RPMs of each rotors. 
         [0012]    When the tip speed ratio of each rotors are different, rotation of one rotor acts as a drag force on each other thereby decreasing the total rotational force. Coupling of electromagnetic torque of the current invention is flexible and is not dependent on the gear ratio of the rotors and the drag force created by the different tip speed is avoided. 
         [0013]    Further, the present invention is can operate under variable system capacity (i.e. variable load) corresponding to different input wind energy. 
         [0014]    The variable system capacity improves the generators efficiency through the load share ratio of a large-sized generator in accordance with the magnitudes of the energy caused by the variation of input wind speed. 
         [0015]    Other objects and the scope of applicability of the present invention will become apparent from the detailed description given hereinafter. It should be understood, however, that the detailed description and the specific examples, while indicating preferred embodiments of the invention, are given by way of illustration only since various changes and modifications within the spirit and scope of the invention will become apparent to those skilled in the art from this detailed description. 
     
    
     
       BRIEF DESCRIPTION THE DRAWINGS 
         [0016]    The present invention will become more fully understood from the detailed description given herein below and the accompanying drawings which are given by way of illustration only, and thus are not (imitative of the present invention, and wherein: 
           [0017]      FIG. 1  is a perspective view of a wind turbine system embodying the present invention. 
           [0018]      FIG. 2  is a side view of the annual stream tube depicting in detail the present invention. 
           [0019]      FIG. 3  is a side view of gear box with its twins generators. 
           [0020]      FIG. 4  is a detailed view of the section along the A-A′ or C-C′ line of the dual input gear box shown in  FIG. 7 . 
           [0021]      FIG. 5  is a side view of the auxiliary generator. 
           [0022]      FIG. 6  is a cross sectional view along B-B′ line shown in  FIG. 5 . 
           [0023]      FIG. 7  is a side view of the dual axis inputs gear box. 
           [0024]      FIG. 8  is a detailed view of the section along the D-D′ line shown in  FIG. 7 . 
           [0025]      FIG. 9  is a side view of the rotor hub, the control rotor, and the auxiliary rotor. 
       
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
     Triple Rotor System 
       [0026]      FIG. 1  shows overall system of the present invention. The present invention can be divided into seven parts. Part  1  in a down wind position comprises of main rotor  11  (“MR”) and its hub  1 . Part  2  comprises of a gear box  2  which increases the speed of MR  11 . Part  3  comprises of a gear box  3  which combines the rotational forces of control rotor  81  (“CR”), auxiliary rotor  71  (“AR”) and MR  11 . 
         [0027]    Part  4  comprises of twin generators  4 ,  4 - 1 . Part  5  comprises of the auxiliary generator  5  which combines rotational forces of CR  81  and AR  71 . Part  6  comprises of dual axis input gear box  6  which combines the rotational forces of CR  81  and AR  71 . Part  7  comprises of CR hub  7  and AR hub  8  in a up wind position. 
       Aerodynamic Dead Zone 
       [0028]    A wind turbine obtains its power input by converting the force of the wind into a torque on the rotor blades. The amount of energy which the wind transfers to the rotor depends on the density of the air, the rotor area, and the wind speed. 
         [0029]    The kinetic energy of a moving body is proportional to its mass or weight. The kinetic energy in the wind thus depends on the density of the air. In other words, the “heavier” the air, the more energy is received by the turbine. 
         [0030]    At normal atmospheric pressure and at 15 Celsius air weighs some 1.255 kg per cubic meter. The greater the diameter of a wind turbine rotor, the greater the effect of tip speed to limit and reduce revolutions per minute (“RPM”). This creates an “aerodynamic dead zone” in part of the hub where no lift force is generated due to its low RPM. 
         [0031]    More specifically, the aerodynamic dead zone is about 30% of the blade from the center axis, which no wind energy can be converted into mechanical energy. 
         [0032]    Fast spinning CR  81  is placed directly in front of AR  71  blade extender hubs so that the wind inputs into this aerodynamic zone of the AR blades extenders is diverted outside of the dead zone thereby increasing the air density and directing this increased air density to the tips of the AR blade where the sweeping speed is the greatest. 
         [0033]      FIG. 2  shows an air stream line  107  of AR  71  according to Betz&#39;s disk analogy model. Then an annular stream tube  104  with increased air density is created between an air stream line  107  of AR  71  and air stream line  106  of MR  11 . Then, this increased air density of annular stream tube  104  is applied to the outer tips of MR  11  blades. 
         [0034]    This phenomenon depends on the diameter of CR  81 , the distance between CR  81  and AR  71 , the diameter of AR  71 , and the distance between AR  71  and MR  11 . This phenomenon has been tested and proved numerous times with smaller model in a experimental field tests as well as actual sized scaled model field tests. 
         [0035]      FIG. 1  shows the direction of rotation of each part indicated by the big arrows, and the direction of rotational force indicated by the small arrows. Keeping CR  81 , AR  71  and MR  11  rotational force combining gear box  3  as the point of reference, will describe in order the upwind portion starting with  FIG. 9  toward the gear box  3 , then downwind portion starting with MR  11  towards the gear box  3 . 
         [0036]    When there is wind speed 1.8-2.2 m/s, CR  81  rotates in the direction as shown in  FIG. 1 . As shown in FIG  9 , when CR  81  rotates, it causes the hollow shaft  76 - 3 , the coupling plate  76 - 4  and the spline coupling  76 - 2  to rotate in the same direction. 
         [0037]    Then in FIG  7 , this rotational force of CR  81  further extends and rotates rotational shaft  76  and spline coupling  76 - 1 . This rotational force is transferred then to the CR-AR dual axis input gear box  6  where it rotates the input rotation shaft  66  and the Input member planet gear carrier  67 . 
         [0038]    As shown in  FIG. 8 , the second sun gear  62 - 2  attached to the input member planet gear carrier  67  will also rotate. This will rotate the second planet gears  62 - 3  and the second ring gear  62 - 4  in the opposite direction. 
         [0039]    As CR  81  starts to rotate the second sun gear  62 - 2  attached to the input member planet gear carrier  67  also rotates. This sun gear  62 - 2  rotation will cause to counter rotate the second ring gear  62 - 4  which is attached to the second ring gear cylinder  62 - 5 . Since the second ring gear cylinder  62 - 5  is coupled to AR  71 , CR  81  rotation will eventually make AR  71  rotating in the opposite direction of CR  81 . 
         [0040]    Hence, the rotational force of CR  81  transfers to AR  71  adds to the direct natural wind input and assist AR  71  rotate more easily. The inverse rotational forces of these two rotors CR  81  and AR  71  creates the air stream tube  105  as shown in  FIG. 2  with its increased the air density. This increased air density is directed at the tips of MR  11  and assist MR  11  rotate even at a low wind speed. 
       Dual Axis Inputs GearBox 
       [0041]    As shown in  FIG. 7 , when the difference in the rotational force of CR  81  and AR  71  spinning in opposite direction is inputted into the dual axis inputs gearbox  6 , then the ring gear  63  and the planet gear carrier  67  rotating in opposite direction will rotate the sun gear  61  in clockwise direction according to the given gear ratio. 
         [0000]      CR  81  Input RPM: N1 X {1+(ZR1/ZS1)}  (1)
 
         [0000]      AR  71  Input RPM: N2 X (ZR2/ZS2)   (2)
 
         [0000]      Total RPM of Sun Gear output shaft  61 - 1 : 
         [0000]      Tn1n2=[N1 X {1+(ZR1/ZS1)}]+N2 X (ZR2/ZS2)   (3)
 
         [0000]      ZS1: number of first sun gear teeth 
         [0000]      ZS2: number of second sun gear teeth 
         [0000]      ZR1: number of first ring gear teeth 
         [0000]      ZR2: number of second ring gear teeth 
         [0042]    Above equation ( 1 ) only applies when the RPMs of the sun gear  61  and the ring gear  63 , and the input torque are same. Based on the characteristic of dual axis gearbox  6 , the larger torque AR  71  s rotational speed and CR  81  s rotational speed are determined by the the gear ratio of the second sun gear  62 - 2  and the second ring gear  62 - 4 . 
         [0043]    In order to make CR  81  and AR  71  s tip speed ratio the same, the size of the CR  81 , and the gear ratio of the second sun gear  62 - 2  and the second ring gear  62 - 4  are adjusted so that the speed of AR  71  rotation is optimized to increase the efficiency of the system at the dual axis inputs gearbox  6 . 
         [0044]    However, since CR  81  performs the pitch control at the wind speed greater than the rated wind speed, rotational speed of CR  81  acts as a drag force on the rotational speed of AR  71  through the second planetary gear assembly shown in  FIG. 8  of the dual axis inputs gearbox  6 . 
         [0045]    This slows down the rotational speed of the rotor  53  of auxiliary generator  5 , and weakens the electromagnetic torque of the rotating stator  51  thereby decreasing the rotational speed of the MR  11  allowing the overall system to operate more safely. 
       Electromagnetic Torque 
       [0046]    The rotational force of CR  81  and AR  71  combined at the dual axis inputs gearbox  6  is transferred via the high speed output shaft  61 - 1 , the connection plate  62 - 6 , and the connection plate  59 - 1  of the auxiliary generator  5  to the rotor  52  attached to the rotor shaft  53  thereby rotating the rotor  52  clockwise as shown in  FIG. 6  and generating rated RPM in accordance with the pole numbers of the auxiliary generator  5 . 
         [0047]    Then the electromagnetic coupling torque of the load is created. This causes the slow rotating stator  51  that is rotating in the same direction as the high speed rotating rotor  52  to rotate in the same direction, thereby increasing the rotational speed of the MR  11 . 
         [0048]    This mechanism is summarized as follows: 
         [0000]      Torque of CR  81 +Rotational Torque of AR  71 =generation power of the auxiliary generator  5   
         [0000]      Electromagnetic torque from the load between the rotor  52  of the auxiliary generator  5  and the rotation stator  51 +rotational torque of MR  11 =generation power of the twins generators  4 ,  4 - 1 
 
         [0049]    The general principle behind the generators is based on the rotational force created between the stator and the rotor. Energy is generated when one or other rotates or when they rotate in opposite direction to one another. 
         [0050]    However, the generator of the present invention generates energy even though both the rotor and the stator are rotating in the same direction. The number of poles of auxiliary generator has a prescribed RPM&#39;s. 
         [0051]    It is the difference of this prescribed RPM&#39;s in effect acts as though either the stator  51  or the rotor  52  is in a fixed position thereby generating energy. If the RPM of the rotor  52  is defined as V1, RPM of the stator  51  rotating in same direction is defined as V2, and the prescribed RPM of the number of poles of the auxiliary generator  5  is defined as V0: 
         [0000]      V0=V1−V2   (4)
 
         [0052]    RPM of V2 is accelerated by predetermined number of rotation of MR  11 &#39;s gearbox  2 . This RPM V2 inputs to a horizontal input shaft  39  of CR-AR rotational force combining gearbox  3  which is coupled to the rotation stator  51 . The energy generated from the auxiliary generator  5  is drawn out by the slip ring  54 . And this energy also rotates the bearings  58 ,  55  which are mounted on the drive train pad  17  of the auxiliary generator  5 . 
       Total Rotational Force Integrating Gearbox 
       [0053]    Rotational force generated by MR  11  and rotational force generated by the electromagnetic coupling torque created between rotor  52  and stator  51  of the auxiliary generator  5  by the load combined at the gearbox  3 . As shown in  FIG. 1 , the rotational force of MR  11  is inputted into the gearbox  2  and generates energy based on a prescribed number of rotation. 
         [0054]    In  FIG. 5 , the rotational force generated by the combined electromagnetic coupling torque in the auxiliary generator  5  is transmitted via rotation shaft  56  and rotational plate  57 . Then it is sent to the rotational force connection plate  39 - 2 . Finally, these rotational force are combined at the horizontal input shaft  39  of the twins planetary gear of the gearbox  3  as shown in  FIG. 3 . 
         [0055]    Such sun gear and planetary gear assembly is known from the Applicant&#39;s U.S. Pat. No. 5,876,181, the contents of which are hereby incorporated in their entirety. 
         [0056]    In  FIG. 3 , the right-sided bevel gear  37 - 1  and left-sided bevel gear  38 - 1  rotates in the direction as indicated by the arrow. This causes the bevel gear  38  and the bevel gear  37  to rotate in opposite direction to one another. 
         [0057]    Further, the bevel gear  38  is attached to the planet gear input shaft  36  on each twin planetary gear system. In each twin planetary gear system, the planet gear carrier  36 - 1 , the ring gear cylinder input shaft  35  and the ring gear cylinder  35 - 1  are attached to the ring gear  33 . 
         [0058]    The ring gear  33  rotates in the opposite direction to the planet gears  32  as indicated by the arrows as shown in  FIG. 4  thereby obtaining the gear ratio and the RPM as follows: 
         [0000]      Z0={(1+ZR/ZS)+(ZR/ZS)}X n   (5).
 
         [0000]      Z0 is the total output RPM 
         [0000]      ZS is the number of sun gear teeth 
         [0000]      ZR is the number of ring gear teeth 
         [0000]      n is the input RPM 
       Variable Load Capacity System 
       [0059]    The sun gear  31  accelerated to the rated output RPM rotates the output shaft  34 , thereby rotating the twin generators  4 ,  4 - 1 . The gearbox  3  is a twin planetary gearbox system with symmetrical gearbox on either side of horizontal input shaft  39 . 
         [0060]    The rotational forces of MR  11 , AR  71  and CR  81  are combined at this horizontal input shaft  39 . Depending on the variable forces of the input wind energy, one or both generators can be operated. 
         [0061]    When the input wind energy from cut-in wind speed is up to 10 m/s, about 60% of the full system is operated where the auxiliary generator  5  and the twin generator  4  operates. When the wind speed ranges from 10.1 m/s to rated wind speed of 12 m/s, the twins generator  4 - 1  is added to the auxiliary generator  5  and the twin generator  4 . 
         [0062]    Accordingly, the present invention includes the auxiliary generator&#39;s electromagnetic coupling torque, the triple rotor-irtegrating force, and aerodynamic dead zone-less wind power generating system, thereby increasing the system&#39;s potential capacity to a maximum degree and providing high efficiency aerodynamic operation. 
         [0063]    No doubt many other effective alternatives will occur to the skilled person. It will be understood that the invention is not limited to the described embodiments and encompasses modifications apparent to those skilled in the art lying within the sprit and scope of the claims appended hereto.