Abstract:
A power generator including a rotating disc shaped permanent magnet. One magnetic pole is at the center of the disc and the other is at its circumference. A slip ring is carried on each face of the disc magnet and a crossover connects the slip rings. Fixed brushes and lead wires contact the two slip rings and make electrical connection through the slip rings and the crossover. The rotating disc causes a constant amplitude and direction magnetic field to continuously pass the lead wires and induce a DC voltage and drive a DC current through the lead wires.

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS  
         [0001]    Not Applicable.  
         STATEMENT REGARDING FEDERALLY SPONSORED RESEARCH OR DEVELOPMENT  
         [0002]    Not Applicable.  
         REFERENCE TO A MICROFICHE APPENDIX  
         [0003]    Not Applicable.  
         BACKGROUND OF THE INVENTION  
         [0004]    The present invention relates to rotating equipment for generating electrical power and more particularly to a generator having a rotating disc permanent magnet.  
           [0005]    Conventional electrical generators are based on Faraday&#39;s law which describes the induction of voltages by a time varying magnetic field. Energy conversion takes place when a change in magnetic flux is associated with mechanical motion. In rotating machines, voltages are generated in windings by rotating the windings through a magnetic field. Due to the motion, the flux linking a specific coil is changed cyclically and a voltage is generated.  
           [0006]    Several common types of direct current, DC, generators are based on these principles, but are in reality alternating current, AC, generators. For example, one type of DC generator has a series of coils on a rotor which turns in a magnetic field of a fixed stator winding. The series of coils actually produce an AC voltage, but are connected by a commutator to the power outputs to provide DC power. In a second type, referred to as an alternator, a rotor carries a coil which produces a rotating magnetic field, which alternately applies north and south poles to the stator. Coils in the stator produce an AC voltage as a result of the changing magnetic fields. The coils are connected through a diode bridge to provide a DC output.  
           [0007]    Thus, prior DC generators require complicated coils, time varying magnetic fields and some type of AC to DC conversion.  
         SUMMARY OF THE INVENTION  
         [0008]    A power generator according to the present invention includes a disc-shaped permanent magnet having one magnetic pole at its center and the other around its circumference. Each side of the disc has an electrically conductive slip ring. The disc also has a conductive crossover coupling the slip rings together. Lead wires are positioned in the magnetic field on each side of the disc and are electrically coupled to the rings on each side of the disc. Upon rotation of the disc magnet, a substantially constant magnitude magnetic field moves past both lead wires inducing voltages which drive current through the circuit including the lead wires, the slip rings and crossover. 
       
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0009]    [0009]FIG. 1 is a perspective view of a rotating disc magnet generator according to the present invention.  
         [0010]    [0010]FIG. 2 is a cross-sectional view of the generator shown in FIG. 1.  
         [0011]    [0011]FIG. 3 is a side view of an embodiment of the present invention having three generator discs coupled in series.  
         [0012]    [0012]FIG. 4 is a side view of an alternative disc magnet for the FIG. 1 embodiment.  
         [0013]    [0013]FIG. 5 is a cross-sectional view of an alternative permanent magnet arrangement for concentrating the magnetic field. 
     
    
     NOTATION AND NOMENCLATURE  
       [0014]    In the following discussion and in the claims, the terms “including” and “comprising” are used in an open-ended fashion, and thus should be interpreted to mean “including, but not limited to . . . ”. Also, the term “couple” or “couples” is intended to mean either an indirect or direct electrical connection. Thus, if a first device couples to a second device, that connection may be through a direct electrical connection, or through an indirect electrical connection via other devices and connections.  
       DETAILED DESCRIPTION OF THE INVENTION  
       [0015]    With reference now to FIGS. 1 and 2, a basic electrical generator according to the present invention is shown. The generator includes a disc, or wheel, shaped permanent magnet  10 . The disc  10  is mounted on, or attached to, a shaft  12  (shown in FIG. 2). The shaft  12  is supported to allow for rotation about the axis of the shaft. The shaft  12  may be driven by any available source, such as a motor, windmill or any other rotational motive device.  
         [0016]    Conductive slip rings  14  and  16  are carried on sides  18  and  20  of the disc magnet  10 . At least one conductive crossover  22  is carried on the outer edge, or circumference,  24  of the disc  10 . The cross-over  22  electrically couples the slip rings  14  and  16  to each other to allow current to flow from slip ring  14  to slip ring  16 . As used herein the term “carried on” means that the slip rings  14 ,  16  and the crossover  22  are mechanically coupled to the disc magnet  10  so that they move with the disc magnet  10 . Crossover  22  may be positioned in a hole through the disc  10  if desired, but this may cause interference with the magnetic characteristics of the disc  10 .  
         [0017]    In this embodiment, the disc  10  is made of a ceramic magnetic material which is essentially nonconductive electrically. Some magnetic materials are electrically conductive, e.g. iron. If disc  10  is made of such an electrically conductive material, then the slip rings  14  and  16  may simply be selected circular surface areas on the sides  18  and  20  of the disc  10 . In that case the disc  10  itself would also provide electrical conductivity between the two slip ring areas  14  and  16  and would therefore form the crossover  22 . Thus the disc  10  may form a rotatable permanent magnet, the slip rings  14 ,  16  and the crossover  22  simultaneously.  
         [0018]    A first set of brushes  26  and  28  are positioned on opposite sides of disc  10  to make sliding contact with slip rings  14  and  16  respectively. Lead wires,  30  and  32  are coupled to brushes  26  and  28 , respectively. A second set of brushes  34  and lead wires  36  are also shown in contact with the slip rings  14  and  16 . A plurality of additional brushes  34  and lead wires  36  may be used, subject to space limitations. The brushes  26 ,  28 ,  34  may be any type of sliding contact, including conventional graphite brushes, roller or ball bearing contacts which may provide reduced friction, etc.  
         [0019]    The magnetic orientation of the disc  10  is shown by the N, north, and S, south, magnetic pole designations. The magnet is radially magnetized to have a north pole near its center and a south pole around its circumference  24 . The opposite polarization may be used if desired. This magnetic orientation produces magnetic flux paths  38  outside of the disc itself. These flux lines  38  run from the circumference  24  of the disc  10  to both sides  18  and  20 . The shape and density distribution of the flux lines  38  is generally uniform about the entire circumference of the disc  10 . Rotation of disc  10  therefore does not generate alternating or time varying flux fields. The flux lines  38  pass through the brushes  26 ,  28  and  34  and their respective lead wires  30 ,  32  and  36 .  
         [0020]    In operation, the brushes  26 ,  28 ,  34  are held in a fixed position while disc  10  is rotated. The lines of flux  38  therefore move past each of the brushes and lead wires. Since the flux  38  is generally constant, there is no time-varying magnetic field as required by prior art generators. In the present invention the magnitude and direction of flux  38  passing through the brushes and lead wires remains generally constant. However, as the disc  10  rotates, the flux field  38  rotates with it. The moving magnetic field produces a force on the electrons in the brushes  26 ,  28 ,  34  and their respective lead wires which produces a voltage, e.g. between lead wires  30  and  32 . A current can flow between lead wires  30  and  32  because the brushes  26  and  28  are electrically coupled by the slip rings  14  and  16  and the crossover  22 . Since the slip rings  14 ,  16  and the crossover  22  move with the disc  10  and consequently its magnetic field, the electrons within these conductors do not experience a force from the moving magnetic field.  
         [0021]    Note that in FIG. 2, the flux lines  38  cross lead wires  30 ,  32  in generally the same direction. As a result, when the disc  10  rotates, the induced voltages in the two lead wires will be in the same direction, e.g. the voltage on lead wire  30  will be positive when the voltage on lead wire  32  is negative with reference to cross-over  22 . The direction of voltage is dependent on the polarity of the magnetization of disc  10  and the direction of rotation.  
         [0022]    Since there are no time-varying electric fields, the present invention generates no electromagnetic radiation which can interfere with other equipment and which may represent a loss of energy. Another advantage is that there are no significant induced eddy currents which may also cause energy loss. Likewise, there should be little or no hysteresis losses.  
         [0023]    The electromotive force, or voltage, generated by rotation of disc  10  is proportional to the product of the velocity of the magnetic field  38  times the strength of the field  38  times the length of the conductors, e.g. brush  28  and lead wire  32 , exposed to the moving magnetic field  38 . The voltage can therefore be increased by increasing the speed of rotation of shaft  12 . It can also be increased by using a stronger magnet. The flux  38  may also be increased by providing different shaped discs or by adding elements to concentrate the flux, as discussed below. Generator output voltage may be increased by coupling the brushes and lead wires in series on a single disc or by using multiple discs on one shaft.  
         [0024]    [0024]FIG. 3 illustrates the use of three magnetic discs  40 ,  42 ,  44  on one shaft  46 . The discs  40 ,  42 ,  44  may be identical to disc  10  of FIG. 1. Brush  48  is coupled to a slip ring on the left side of disc  40 . Two brushes and a lead wire shown at  50  couple the right slip ring on disc  40  to the left slip ring on disc  42 . In similar fashion, at  52  two brushes and a lead wire couple the right slip ring on disc  42  to the left slip ring on disc  44 . A brush  54  makes a contact to the right slip ring on disc  44 . Lead wires  56  and  58  are coupled to brushes  48  and  54  to provide power outputs for the generator. The slip rings are not shown to simplify the figure, but are the same as the rings  14 ,  16  of FIG. 1. Each disc  40 ,  42 ,  44  also includes a crossover like crossover  22  of FIG. 1 to couple its slip rings together electrically.  
         [0025]    When the shaft  46  is rotated to rotate the discs  40 ,  42 ,  44 , a voltage is generated across output leads  56 ,  58  which is the sum of voltages generated by each of the discs  40 ,  42 ,  44 . In this case, the output voltage is at least three times the voltage generated by a single disc generator. Any number of discs can be place in series on one shaft to further increase the output voltage. This multiple disc arrangement also helps concentrate the field passing through lead wires, e.g. lead wires  50  and  52  and thereby tends to increase the generated voltage.  
         [0026]    The current generated by the devices of FIG. 1 or FIG. 3 can be increased by increasing the number of additional brushes  34  and lead wires  36  as illustrated in FIG. 1. Each set of brushes and lead wires will provide the same current capacity. Since they are electrically coupled through the same slip rings  14 ,  16  and crossover  22 , their output leads must be coupled in parallel.  
         [0027]    [0027]FIG. 4 illustrates an alternative disc arrangement which allows series connection of outputs, and resulting increased voltage, with only one disc. Disc  60  may be essentially identical to disc  10  of FIG. 1. It is carried on a shaft  62 . Disc  60  carries two slip rings  64 ,  66  on each side. Only one side is illustrated. The opposite side may be identical. Slip ring  64  is electrically coupled to its corresponding slip ring on the opposite side by a crossover  68 . Slip ring  66  is electrically coupled to its corresponding slip ring on the opposite side by a crossover  70 . Crossover  70  passes under and is electrically insulated from slip ring  64 .  
         [0028]    At least one pair of brushes, e.g. brushes  34  of FIG. 1 are placed into contact with each of the conductive rings  64 ,  66 . When the disc  60  is rotated, the brushes and their respective lead wires provide separate outputs which may be coupled in series to double the output voltage of the generator. By increasing the number of brushes and lead wires on each slip ring  64 ,  66 , the device current capacity may be increased.  
         [0029]    It may appear that the voltage generated by brushes on slip ring  66  would be less than for brushes on slip ring  64  because of the different velocity of the flux field at different radii. However, this effect is offset by the fact that the field strength at slip ring  66  is greater than the field strength at slip ring  64 . That is, the total field is the same, but it is contained in a smaller space at slip ring  66 .  
         [0030]    As noted above, the disc magnet  60  may be made of an electrically conductive material. If such a material is used for the FIG. 4 embodiment, then the slip rings  64 ,  66  and crossovers  68 ,  70  may be attached to the disc magnet  60  with an electrical insulating layer. Alternatively, one of the slip rings, e.g. slip ring  66 , and its crossover, e.g. crossover  70 , may be replaced by the disc  60  itself. The other slip ring  64  and its crossover  68  could then be applied to the disc magnet  60  with an electrical insulator so that two independent generator outputs are available and may be connected in series.  
         [0031]    With reference to FIG. 5, an alternative disc magnet arrangement is illustrated. A disc magnet  72  is mechanically different from the disc magnet  10  of FIG. 1, in that it has a central hole to facilitate mounting on a shaft  74 . Otherwise, disc magnet  72  may be functionally equivalent to the magnet  10 . It has a north polarity near its center and a south polarity at its circumference. A magnetic ring  76  is attached to the outer circumference  78  of the disc  72 . The magnetic ring  76  is shaped like a section of a hollow cylinder or pipe. The magnetic ring  76  is preferably made of a high-permeability material. It is also preferred that the shaft  74  be made of a high-permeability material.  
         [0032]    The purpose of magnetic ring  76  and the use of high-permeability material for shaft  74  is to concentrate magnetic flux in the area where the brushes and lead wires, e.g. brushes  34  and lead wires  36  of FIG. 1, will be positioned. As illustrated by flux lines  80 , the magnetic flux from disc  72  will tend to be concentrated in ring  76  and shaft  74  and pass through the closest air space between them. That is, the air gap is reduced by use of ring  76 .  
         [0033]    In FIG. 5, the magnetic ring  76  has a length substantially greater than the thickness of disc  72 . The magnetic ring  76  may be shorter if desired and may have a length the same as the thickness of disc  72 . The effective air gap will still be reduced. In addition, the magnetic ring  76  may serve as an electrical crossover  22  of FIG. 1, especially in a system with a single slip ring  14 ,  16  on each side as shown in FIGS. 1 and 2. It is also possible for the ring  62  to serve as both slip rings and crossover. That is, brushes  34  of FIG. 1 could be positioned to make sliding contact with the opposite edges of the magnetic ring  76 , if it has sufficient electrical conductivity and wear properties. Where multiple crossovers are used, e.g. the FIG. 4 embodiment, the crossovers may pass under or over the magnetic ring  76 .  
         [0034]    With further reference to FIG. 5, it will be recognized that the magnetic ring  76  can be replaced with an extension of the magnet  72  itself. That is, the magnet need not have a flat disc, or hockey puck, shape. Its outer circumference  78  can be formed with a greater thickness than the rest of the disc. The effect of such a shape would again provide a desirable concentration of flux in the areas on the sides of the disc where it will provide the most effective electromotive force to electrons in the brushes and lead wires.  
         [0035]    With further reference to FIGS. 1 and 2, it will be appreciated that the slip rings  14 ,  16  and crossover  22  may be implemented in several different ways. As illustrated, these elements may be cut from sheet metal, e.g. copper, and bonded to the surfaces of the disc  10 . They may also be plated onto the disc  10 . When a single slip ring set  14 ,  16  is used, the entire outer surface of the disc  10  may be covered with a conductive material, e.g. plated with copper. If the disc  10  is made of an electrical conductor, it may provide the functions of the slip rings  14 ,  16  and the crossover  22 .  
         [0036]    While the present invention has been illustrated and described in terms of particular apparatus and methods of use, it is apparent that equivalent parts may be substituted of those shown and other changes can be made within the scope of the present invention as defined by the appended claims.