Axial gap motor-generator for high speed operation

Abstract

An axial gap motor-generator of the type coupled to a shaft having an axis of rotation. The motor-generator comprises a rotor having a rotor body rotatably disposed about the shaft and having an outer region. The rotor includes a plurality of openings disposed in the outer region and spaced from one another. Each of the openings includes an outer edge. The motor-generator also includes a plurality of magnets equal in number to the openings. Each of the magnets includes an outer edge corresponding to the outer edge of a corresponding one of the openings. The outer edge of the magnets generally is non-conformal to and is slightly smaller than the outer edge of the openings, and each of the magnets is shaped to be inserted into the corresponding one of the openings. The motor-generator further includes a stator assembly positioned adjacent to the rotor. The stator assembly includes windings positioned to be adjacent to the magnets when the rotor is rotated. The outer edge of each of the magnets is dimensioned to substantially conform to the outer edge of the corresponding one of the openings when the axial gap motor-generator is operated at the operational speed and the outer edge of the corresponding one of the openings is thereby deformed. The motor-generator further includes a backiron assembly that is adapted to conform to the rotor when the rotor is operated at its operational state. A vibration isolator also is provided for isolating vibrations of the motor-generator from the shaft. Related methods also are provided.

What is claimed is:  
     
         1 . An axial gap motor-generator of the type coupled to a shaft having an axis of rotation, the motor-generator comprising: 
 a rotor having a rotor body rotatably disposed about the shaft and having an outer region, the rotor including a plurality of openings disposed in the outer region and spaced from one another, each of the openings including an outer edge;    a plurality of magnets equal in number to the openings, each of the magnets including an outer edge corresponding to the outer edge of a corresponding one of the openings, the outer edge of the magnets generally being non-conformal to and being slightly smaller than the outer edge of the openings, and each of the magnets being shaped to be inserted into the corresponding one of the openings; and    a stator assembly positioned adjacent to the rotor, the stator assembly including windings positioned to be adjacent to the magnets when the rotor is rotated.    
     
     
         2 . An axial gap motor-generator as recited in  claim 1 , further comprising an expandable hub between the rotor and the shaft.  
     
     
         3 . An axial gap motor-generator as recited in  claim 1 , wherein the rotor further includes a rim around the outer region.  
     
     
         4 . An axial gap motor-generator as recited in  claim 3 , wherein the rim comprises a composite material.  
     
     
         5 . An axial gap motor-generator as recited in  claim 1 , wherein: 
 the outer edge of each of the openings has a first resting radius when the axial gap motor-generator is at rest; and    the outer edge of each of the magnets has a second resting radius when the axial gap motor-generator is at rest, wherein the first resting radius is larger than the second radius.    
     
     
         6 . An axial gap motor-generator as recited in  claim 5 , wherein the second resting radius is about  80 % of the first resting radius.  
     
     
         7 . An axial gap motor-generator as recited in  claim 1 , wherein: 
 the outer edge of each of the openings has a first operating radius when the axial gap motor-generator is at an operational speed; and    the outer edge of each of the magnets has a second operating radius when the axial gap motor-generator is at the operational speed, wherein the first operating radius is substantially equal to the second operating radius.    
     
     
         8 . An axial gap motor-generator as recited in  claim 1 , wherein: 
 the axial gap motor-generator has an operational speed; and    the outer edge of each of the magnets is dimensioned to substantially conform to the outer edge of the corresponding one of the openings when the axial gap motor-generator is operated at the operational speed and the outer edge of the corresponding one of the openings is thereby deformed.    
     
     
         9 . An axial gap motor-generator as recited in  claim 1 , wherein: 
 each of the openings further includes an inner edge and a pair of side edges; and    each of the magnets further includes an inner edge and a pair of side edges respectively corresponding to the inner edge and the pair of side edges of the openings,    the inner edge of the magnets generally conforming to but being slightly smaller than the inner edge of the openings, and    the pair of side edges of the magnets generally conforming to but being slightly smaller than the pair of side edges of the openings,    
     
     
         10 . An axial gap motor-generator as recited in  claim 9 , wherein: 
 each of the magnets is shaped relative to the corresponding one of the openings so that, when inserted into the corresponding one of the openings,    the inner edge of the magnet and the inner edge of the opening form an inner edge gap,    each of the side edges of the magnet and the side edges of the corresponding one of the openings form a side edge gap, and    the outer edge of the magnet and the outer edge of the corresponding one of the openings form an outer edge gap.    
     
     
         11 . An axial gap motor-generator as recited in  claim 10 , wherein a bonding material is disposed in a portion of the side edge gaps.  
     
     
         12 . An axial gap motor-generator as recited in  claim 11 , wherein the bonding material is excluded from the inner edge gaps.  
     
     
         13 . An axial gap motor-generator as recited in  claim 11 , wherein the bonding material is excluded from the outer edge gaps.  
     
     
         14 . An axial gap motor-generator as recited in  claim 1 , wherein: 
 the outer edge of the magnets and the outer edge of the corresponding ones of the openings form an outer edge gap; and    the outer edge gap is free of any bonding material.    
     
     
         15 . An axial gap motor-generator as recited in  claim 1 , wherein: 
 the rotor includes a first side and a second side; and    the axial gap motor-generator further includes a backiron assembly coupled to the rotor and rotatably mounted about the axis, the backiron assembly including 
 an attachment device rotatably disposed about the axis,  
 first and second couplers coupled to the attachment device, the first coupler being positioned on the first side of the rotor and the second coupler being positioned on the second side of the rotor, and  
 first and second backiron plates disposed adjacent to but spaced from the windings of the stator assembly, the first backiron plate being coupled to the first coupler and being positioned on the first side of the rotor, and the second backiron plate being coupled to the second coupler and being positioned on the second side of the rotor.  
   
     
     
         16 . An axial gap motor-generator as recited in  claim 15 , wherein each of the first and second couplers comprises an annular tube.  
     
     
         17 . An axial gap motor-generator as recited in  claim 15 , wherein the attachment device is coupled to the rotor body.  
     
     
         18 . An axial gap motor-generator as recited in  claim 17 , wherein the attachment device is threadably engaged with the rotor body.  
     
     
         19 . An axial gap motor-generator as recited in  claim 15 , wherein: 
 the axial gap motor-generator operates at an operational speed;    the first rotor side is disposed in a first rotor plane and the second rotor side is disposed in a second rotor plane substantially parallel to the first rotor plane; and    the first backiron plate is disposed in a first backiron plane and the second backiron plate is disposed in a second backiron plane, the first and second backiron plates being disposed with respect to the first and second rotor planes when the rotor is at rest so that the first backiron plane is substantially parallel to the first rotor plane and the second backiron plane is substantially parallel to the second rotor plane when the axial gap motor is operated at the operational speed.    
     
     
         20 . An axial gap motor-generator as recited in  claim 15 , wherein: 
 the first rotor side is disposed in a first rotor plane; and    the first backiron plate is disposed in a first backiron plane, the first backiron plate being disposed with respect to the first rotor plane when the rotor is at rest so that the first backiron plane forms an angle of about 1 to 3 degrees with respect to the first rotor plane.    
     
     
         21 . An axial gap motor generator as recited in  claim 20 , wherein the angle is about 2 degrees.  
     
     
         22 . An axial gap motor-generator as recited in  claim 15 , wherein: 
 the second rotor side is disposed in a second rotor plane; and    the second backiron plate is disposed in a second backiron plane, the second backiron plate being disposed with respect to the second rotor plane when the rotor is at rest so that the second backiron plane forms an angle of about 1 to 3 degrees with respect to the second rotor plane.    
     
     
         23 . An axial gap motor as recited in  claim 22 , wherein the angle is about 2 degrees.  
     
     
         24 . An axial gap motor-generator as recited in  claim 15 , wherein the first and second backiron plates have a conical inclination toward the rotor.  
     
     
         25 . An axial gap motor-generator as recited in  claim 1 , further including a vibration isolator for coupling the shaft to a housing, the apparatus comprising: 
 an inner sleeve for coupling to the shaft and bearing assembly, the inner sleeve having an exterior surface and a pair of longitudinal edges, each of the longitudinal edges including a plurality of stanchions;    an outer sleeve for coupling to the housing, the outer sleeve having an interior surface and a pair of longitudinal edges, each of the outer sleeve longitudinal edges including a plurality of outer sleeve stanchions corresponding in number and location to the inner sleeve stanchions and thereby forming a plurality of stanchion pairs, the inner sleeve being disposed within the outer sleeve to form an annular cavity between the exterior surface of the inner sleeve and the interior surface of the outer sleeve;    a vibration absorbing material disposed in the annular cavity; and    a plurality of couplers, each of the couplers corresponding to one of the stanchion pairs, and each of the couplers coupling the corresponding stanchion pair together.    
     
     
         26 . An axial gap motor-generator as recited in  claim 25 , wherein each of the couplers comprises a C flexure.  
     
     
         27 . An axial gap motor-generator of the type coupled to a shaft having an axis of rotation, the motor-generator comprising: 
 magnetic field generating means for generating a magnetic field, the magnetic field generating means including a force bearing means for bearing stress on the magnetic field generating means created when the axial gap motor-generator is operated at an operational speed;    rotor means for rotatably supporting the magnetic field generating means about the axis of rotation, the rotor means including means for securing the magnetic field generating means to the rotor, the securing means including means for conforming to the force bearing means when the axial gap motor-generator is operated at the operational speed; and    stator means positioned adjacent to the magnetic field generating means for interacting with the magnetic field to generate an electric voltage.    
     
     
         28 . An axial gap motor-generator as recited in  claim 27 , wherein the rotor means further includes coupling means for coupling the rotor means to the shaft.  
     
     
         29 . An axial gap motor-generator as recited in  claim 27 , wherein the securing means comprises means for bonding the magnetic field generating means to the rotor means.  
     
     
         30 . An axial gap motor-generator as recited in  claim 27 , wherein the bonding means is excluded from the force bearing means.  
     
     
         31 . An axial gap motor-generator as recited in  claim 27 , wherein the rotor means includes means for concentrating the magnetic field toward the stator means, the concentrating means including means for aligning the concentrating means with the rotor means when the axial gap motor-generator is operated at the operational speed.  
     
     
         32 . A method for securing a magnet in a rotor having an opening with an outer edge, the outer edge of the opening having a deformed shape when the rotor is in an operational state, the method comprising: 
 providing the magnet with an outer edge corresponding to the outer edge of the opening and sized to fit within the opening; and    shaping and dimensioning the outer edge of the magnet so that the outer edge of the magnet substantially conforms to the outer edge of the opening when the outer edge of the opening has the deformed shape.    
     
     
         33 . A method for rotating a rotor about an axis of rotation, the method comprising: 
 providing the rotor with a rotor body having an outer region and a plurality of openings disposed in the outer region and spaced from one another, each of the openings including an outer edge;    disposing a magnet into each of the openings, each magnet including an outer edge corresponding to the outer edge of a corresponding one of the openings,    the outer edge of the magnets generally being non-conformal to and being slightly smaller than the outer edge of the openings, each of the magnets being shaped to be inserted into the corresponding one of the openings; and    rotating the rotor at an operational speed so that the outer edge of the openings deform to thereby conform to the shape of the outer edge of the magnets.    
     
     
         34 . A method for rotating a rotor having first and second rotor sides and a backiron assembly having first and second backiron plates, the method comprising: 
 positioning the first and second backiron plates at an angle of about 1 to 3 degrees with respect to the respective first and second rotor sides when the rotor and backiron assembly are at rest.    
     
     
         35 . A method as recited in  claim 34 , wherein the angle is about 2 degrees.  
     
     
         36 . A rotor for use in an axial gap motor-generator of the type coupled to a shaft having an axis of rotation, the rotor comprising: 
 magnetic field generating means for generating a magnetic field, the magnetic field generating means including a force bearing means for bearing stress on the magnetic field generating means created when the axial gap motor-generator is operated at an operational speed; and    means for securing the magnetic field generating means to the rotor, the securing means including means for conforming to the force bearing means when the axial gap motor-generator is operated at the operational speed.    
     
     
         37 . A backiron assembly for use in an axial gap motor-generator of a type coupled to a shaft having an axis of rotation and having a rotor with first and second sides and a stator assembly, the backiron assembly comprising: 
 attachment means disposed about a backiron assembly axis corresponding to the axis of rotation for attaching the backiron assembly to the rotor,    first and second magnetic field concentrating means positioned on the first and second sides respectively of the rotor when the backiron assembly is operated with the rotor for concentrating a magnetic field from the rotor to the stator assembly; and    first and second coupling means for coupling the respective first and second magnetic field concentrating means to the attachment means.    
     
     
         38 . An apparatus for coupling a shaft and bearing assembly to a housing, the apparatus comprising: 
 outer sleeve means for coupling to the housing; and    inner sleeve means disposed annularly within the outer sleeve means for coupling to the shaft and bearing assembly, the outer and inner sleeve means forming an annular gap, the annular gap comprising vibration absorbing means for absorbing vibrations between the outer and inner sleeve means;    the outer and inner sleeve means including coupling means for coupling the outer and inner sleeves to one another, the coupling means comprising stanchion means and fastening means for fastening the stanchion means to one another.