Patent Abstract:
The invention relates to an alternate current power generator with a primary drive shaft having a set of two magnets and an armature and a governor. The governor moves the magnets and armature with respect to one another. In another embodiment, the alternate current power generator has a secondary drive shaft, weighted flexible strips attached to the secondary drive shaft with connectors such that the flexible strips&#39; weights cause the strips to move outward upon rotation, drawing the connectors closer together.

Full Description:
TECHNICAL FIELD OF THE INVENTION  
       [0001]     This invention relates generally to using a centrifugal governor and more specifically to a centrifugal governor in an alternate current power generator to regulate power output.  
       BACKGROUND OF THE INVENTION  
       [0002]     Windmills provide energy with limited environmental impact. However, since wind speeds are not constant from day to day or even throughout the course of a day, current wind generators are not always a dependable source of constant power. Specifically, currently available generators typically cannot generate power until a threshold of wind speed is met.  
         [0003]     To start the generator, the wind speed must be high enough to overcome inertial and frictional effects of the mechanical components and the resistive force caused by the movement of the magnetic flux in generating current in the generator windings. Thus, typical generators require high wind speed before sufficient rotational speed is obtained in the generator to generate power. This poses a problem for low wind speed locations and causes power loss in starting the generator initially. The present invention addresses these issues.  
       SUMMARY OF THE INVENTION  
       [0004]     The invention relates to an alternate current power generator with a primary drive shaft having a set of two magnets, an armature and a governor. The governor moves the magnets and armature with respect to one another. In one embodiment, the armature is fixed and the magnets move relative to the armature. In another embodiment, the governor includes a secondary drive shaft.  
         [0005]     In one embodiment, the governor has flexible strips with centrally located weights. In another embodiment, the flexible strips are attached to the secondary drive shaft with connectors. The weights on the flexible strips cause the strips to move outward upon rotation, drawing the connectors closer together. In other embodiments, one or more springs are located between the connectors. In yet another embodiment, the governor has two lever arms, connecting the connectors and the magnets. Each lever arm moves a respective magnet relative to the armature as the governor rotates.  
         [0006]     In another embodiment, the secondary and primary drive shafts are connected through either a belt or a gear assembly. In still another embodiment, the governor&#39;s flexible strips are positioned about the secondary drive shaft to permit balanced rotation. 
     
    
     BRIEF DESCRIPTION OF THE FIGURES  
       [0007]     The foregoing and other objects, aspects, features, and advantages of the invention will become more apparent and may be better understood by referring to the following description taken in conjunction with the accompanying drawings, in which:  
         [0008]      FIG. 1  is a schematic diagram of an embodiment of the centrifugal governor, constructed in accordance with the present invention;  
         [0009]      FIG. 1A  is a depiction of the key and groove portion of the connectors and secondary shaft of  FIG. 1 ;  
         [0010]      FIG. 1B  is a depiction of the lever arms and connectors of  FIG. 1 ;  
         [0011]      FIG. 2  is a perspective view of another embodiment of the centrifugal governor used in conjunction with a generator;  
         [0012]      FIG. 3  is a cross-sectional view in the plane A, A′ of  FIG. 2 ; and  
         [0013]      FIG. 4  is a graph of electromotive force versus wind speed for a generator constructed in accordance with the invention. 
     
    
     DETAILED DESCRIPTION OF THE INVENTION  
       [0014]     In brief overview and referring to  FIG. 1 , a generator with an alternate current power generator  4  constructed in accordance with the invention includes a generator portion  10  and a governor portion  12 . The generator portion  10 , in one embodiment includes a pair of magnetic disks  30 ,  30 ′ (generally  30 ) attached to a shaft  75 . Located between the magnetic disks  30  is a stationary armature  40 . In operation, the shaft  75  is driven into rotation by a mechanical source such as a crank or a windmill. As the shaft  75  rotates, so do the magnetic disks  30  relative to the armature  40 . The magnetic field lines between the two rotating magnetic disks  30  are cut by the armature  40 . The moving field lines caused by the rotating magnetic disks  40  induce a current in the armature  40  which is used to power external devices. In an alternate embodiment, the armature  40  is fixed to the rotating shaft  75  and the magnetic disks  30  are held stationary.  
         [0015]     The governor portion  12 , in one embodiment, includes a secondary shaft  71  to which are attached weights (generally  72 ) by way of connectors  73 . The secondary shaft  71  is driven by the shaft  75  of the generator portion  10 . As the secondary shaft  71  rotates, the weights  72  move outward away from the secondary shaft  71  by centrifugal force, pulling the connectors  73  toward one another. The motion of the connectors  73 , by way of lever arms  50 ,  50 ′ (generally  50 ), causes the magnetic disks  30  to move toward the armature  40 , decreasing the air gap between the magnetic disks  30  and the armature  40 , and thereby changing the magnetic field flux experienced by the armature  40 . The increase in field flux experienced by the armature  40  as the magnets  30  are moved toward the armature  40  causes the current induced in the armature  40  to increase.  
         [0016]     The governor portion  12  need not be driven by the secondary shaft  75 . In another embodiment, the generator portion  10  and the governor portion  12  are on the same shaft  75 , connected through a mechanical linkage.  
         [0017]     Referring also to  FIG. 1A , considering the governor portion  10  in more detail, two connectors  73 ,  73 ′ (generally  73 ) are slidably attached to the secondary shaft  71 . Each connector  73 ,  73 ′ includes a key  72  which slidably fits within a groove  76  that is cut along the longitudinal surface of the secondary shaft  71 . In this way, the connectors  73  may move freely and longitudinally along the secondary shaft  71  and yet rotate with the secondary shaft  71  as the secondary shaft  71  rotates.  
         [0018]     Referring back to  FIG. 1 , the connectors  73  are biased toward the ends of the secondary shaft  71  by springs  74 ,  74 ′ (generally  74 ). In the embodiment shown, each connector  73  is associated with a respective spring  74 . The springs  74  enable the weights  72  to be biased toward their initial positions at the ends of the secondary shaft  71  as the governor&#39;s  12  rotational speed decreases. In one embodiment, one end of the spring  74  is in contact with its respective connector  73  while the other end of the spring is in contact with a respective one of two stops  56 ,  56 ′ (generally  56 ), located near the center of the secondary shaft  71 . In another embodiment, both springs  74  are connected to one centrally located stop.  
         [0019]     Considering the weights  72  in more detail, the weights  72  are attached to flexible strips  70 . Each flexible strip  70  is in contact with a respective connector  73  at each end of the flexible strip  70 . The flexible strips  70 , and attached weights  72  are positioned about the secondary shaft  71  to ensure balanced rotation. In one embodiment, two flexible strips  70  are diametrically opposed about the secondary drive shaft  71 ; one hundred eighty degrees apart. In another embodiment, three flexible strips are positioned about the secondary shaft  71 ; each being one hundred twenty degrees apart.  
         [0020]     The flexible strips  70  are made of any flexible material that will bow in response to an outward force on the strip  70 . In one embodiment, the flexible strips  70  are composed of metal. In another embodiment, the flexible strips  70  are composed of plastic. In one embodiment, the weights  72  are separate attachments to the outside of the flexible strips  70 , which accentuate the centrifugal force. In another embodiment, the same effect can be achieved through using variable thickness flexible strips where the strips have a greater mass in the center, similar to attaching a weight.  
         [0021]     Considering the lever arms  50  in more detail, two lever arms  50  connect the connectors  73  with respective magnets  30 . Thus, when the rotating secondary shaft  71  moves the connectors  73  toward one another, the lever arms  50  are also pulled toward one another, pulling the magnetic disks  30  closer together.  
         [0022]     Referring also to  FIG. 1 B , considering the lever arms  50  in more detail, the lever arms  50  may be affixed to the connectors  73  by means of two bolts  77  and  77 ′ (generally  77 ). The bolts  77  attach the lever arms  50  to the outer surface of the connectors  73 , such that the connectors  73  are free to slide longitudinally along the secondary shaft  71 . In one embodiment, a stabilizing bar  78  may be secured via additional bolts  79  and  79 ′ to the lever arms  50 . This stabilizing bar  78  stabilizes the lever arms  50  as they move in response to the governor.  
         [0023]      FIG. 2  depicts in more detail another embodiment of a generator  4  with a centrifugal governor  12 . This embodiment is substantially similar to  FIG. 1 , but includes two gear trains,  11  and  61 . The first gear train  11  includes a small gear  20  and a large gear  10  located between a handle  80  and the shaft  75 . Large gear  10  has more teeth and has a larger circumference than small gear  20 . In one embodiment, in which the large gear  10  has eighty teeth and small gear  20  has twenty five teeth, the small gear  20  rotates at almost three times for each rotation of the large gear  20 . This gear train  11  permits a relatively slow turning of the handle  80  to be converted into a higher rotational speed of the shaft  75 .  
         [0024]     The second gear train  61  includes three gears: first gear  50 , second gear  60  and third gear  65  connecting the shaft  75  with the secondary shaft  71 . First gear  50  is largest gear and the third gear  65  is the smallest gear. In one embodiment, the first gear  50  has one hundred twenty seven teeth, the second gear  60  has seventy teeth and the third gear  65  has twenty five teeth. This gear train permits the governor portion to be activated at low rotational speeds of shaft  75 .  FIG. 3  is a cross-section of  FIG. 2  in the plane A, A′.  
         [0025]     It should be noted that it is not necessary that the secondary shaft  71  be driven by a gear train. Instead, shaft  75  may drive shaft  71  by a belt or other means known to one skilled in the art.  
         [0026]     Considering the magnetic disks  30  and armature  40  in greater detail, in one embodiment, shown in  FIG. 2 , twenty two magnets  33 ,  33 ′ (generally  33 ) are attached to aluminum disks  31 ,  31 ′ (generally  31 ) to form the magnetic disks  30  on the shaft  75 . The magnets  33  are arranged on one disk  31  such that they are the same polarity as the corresponding magnet on the other disk  31 ′: i.e. N-N, S-S. This arrangement makes the two sets of magnets  33 ,  33 ′ repel each other. This repulsion in conjunction with the force of the governor  12  pushing the sets of magnets  33 ,  33 ′ toward the armature  40 , keeps the sets of magnets  33 ,  33 ′ at a specific location on the shaft  75  for a given shaft rotational speed.  
         [0027]     In more detail, the air gap between the sets of magnets  33 ,  33 ′ and armature  40  is larger at low wind speeds. Since the distance between the magnets  33 ,  33 ′ is larger, the repulsion between the two sets of magnets  33 ,  33 ′ is less. Thus, with less magnet repulsion, less force is required to initiate rotation of the shaft  75 . Therefore, the shaft  75  can begin rotation at lower wind speeds and as a result produce power at lower wind speeds. As the wind speed increases, the governor decreases the air gap. This changes the magnetic flux and thus produces more power output of the generator. Therefore, this invention allows a wind generator to start producing power at lower wind speeds and also increases power output at moderate to high wind speeds through a variable air gap.  
         [0028]      FIG. 4  is a graph of electromotive force (EMF) produced by the invention for various wind speeds. W 2  represents the starting wind speed of a conventional wind powered generator. That is, the windspeed necessary to cause the generator shaft to start spinning and an EMF to be generated. W 1  represents the starting wind speed for the current invention. As  FIG. 4  indicates, this invention produces electromotive force at lower wind speeds than conventional wind generators. This enables the wind generator operator to derive power from the generator at low wind speeds. The area (A) is the amount of EMF that the present invention generates in excess of conventional generators.  
         [0029]     The invention may be embodied in other specific forms without departing from the spirit or essential characteristics thereof. The present embodiments are therefore to be considered in all respects as illustrative and not restrictive, the scope of the invention being indicated by the appended claims rather than by the foregoing description, and all changes which come within the meaning and range of equivalency of the claims are therefore intended to be embraced therein.

Technology Classification (CPC): 7