Motor including embedded permanent-magnet rotor
First Claim
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1. A rotor of cylindrical configuration for use in a motor having a high torque to size ratio, said rotor having an outer cylindrical peripheral surface and comprising:
- a central rotor shaft with a center axis;
at least first and second retainers securely mounted on said shaft in spaced opposed relation to one another;
a plurality of magnetically conductive segments arrayed around said shaft between said first and second retainers with each of said segments spanning a circumferential sector of said cylindrical configuration;
magnets disposed between each adjacent pair of said segments for providing magnetic flux through said adjacent segments for linking through a stator disposed around said peripheral surface;
each of said segments having an opening extending therethrough in generally spaced parallel relation to said shaft, each of said openings being of a cross-section which is elongated radially, namely having a length as measured parallel to a radial plane through the center axis of said shaft which is significantly greater than the width of said opening as measured normal to such radial plane; and
a non-magnetic securing bar extending through each of said openings and engaging the respective segment at the radially inward side of said opening to support said segment at least in a radial direction, each of said securing bars being a separate element spaced from said shaft and being in radial support engagement with said retainers whereby said bars and said retainers support said segments in predetermined positions in said rotor.
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Accused Products
Abstract
An electric motor including a permanent-magnet rotor having embedded magnets held in place by several segments. The embedded magnets are secured by segments including non-circular openings near their centers. Several non-magnetic, non-conductive bars extend through the non-circular openings of the segments to secure the segments in relation to the shaft. The motor is capable of producing high torque while only requiring a minimum amount of space.
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Citations
61 Claims
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1. A rotor of cylindrical configuration for use in a motor having a high torque to size ratio, said rotor having an outer cylindrical peripheral surface and comprising:
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a central rotor shaft with a center axis; at least first and second retainers securely mounted on said shaft in spaced opposed relation to one another; a plurality of magnetically conductive segments arrayed around said shaft between said first and second retainers with each of said segments spanning a circumferential sector of said cylindrical configuration; magnets disposed between each adjacent pair of said segments for providing magnetic flux through said adjacent segments for linking through a stator disposed around said peripheral surface; each of said segments having an opening extending therethrough in generally spaced parallel relation to said shaft, each of said openings being of a cross-section which is elongated radially, namely having a length as measured parallel to a radial plane through the center axis of said shaft which is significantly greater than the width of said opening as measured normal to such radial plane; and a non-magnetic securing bar extending through each of said openings and engaging the respective segment at the radially inward side of said opening to support said segment at least in a radial direction, each of said securing bars being a separate element spaced from said shaft and being in radial support engagement with said retainers whereby said bars and said retainers support said segments in predetermined positions in said rotor. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 10, 11, 12, 13, 14, 15, 16, 17, 22)
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9. The rotor as set forth in claim i wherein each of said openings is formed generally in a diamond shape.
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18. A rotor of cylindrical configuration for use in a motor having a high torque to size ratio, said rotor having an outer cylindrical peripheral surface and comprising:
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a central rotor shaft including a center axis; at least first and second retainers securely mounted on said shaft in spaced opposed relation to one another; a plurality of magnetically conductive segments arrayed around said shaft between said first and second retainers with each of said segments spanning a circumferential sector of said cylindrical configuration; magnets disposed between each adjacent pair of said segments and extending radially from closely adjacent said shaft to adjacent the outer peripheral surface of said rotor for providing magnetic flux through each of said segments adjacent thereto for linking through a stator disposed around said peripheral surface, said magnets being formed as substantially thin plates and being magnetized through their thickness so that their poles are at their major planar side surfaces facing said segments; each of said segments having an opening extending therethrough in generally spaced parallel relation to said shaft, each of said openings being of a cross-section which is elongated radially, namely having a length as measured parallel to a radial plane through the center axis of said shaft which is significantly greater than the width of said opening as measured normal to such radial plane; and a non-magnetic and electrically non-conductive securing bar extending through each of said openings and engaging the respective segment at the radially inward side of said opening to support said segment at least in a radial direction, each of said securing bars being spaced from said shaft and being supported by said retainers whereby said bars support said segments in predetermined positions in said rotor. - View Dependent Claims (19, 20, 21, 23, 24, 25, 26, 27)
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28. A rotor of cylindrical configuration for use in a motor having a high torque to size ratio, said rotor having an outer cylindrical peripheral surface and comprising:
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a central rotor shaft with a center axis; at least first and second retainers securely mounted on said shaft in spaced opposed relation to one another; a plurality of magnetically conductive segments arrayed around said shaft between said first and second retainers with each of said segments spanning a circumferential sector of said cylindrical configuration; magnets disposed between each adjacent pair of said segments for providing magnetic flux through segments for linking through a stator disposed around said peripheral surface; each of said segments having an opening extending therethrough in generally spaced parallel relation to said shaft, each of said openings being generally of a diamond shape; and
,non-magnetic securing bars extending through each of said openings and being supported by said retainers whereby said bars support said segments in predetermined positions in said - View Dependent Claims (29)
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30. An electrical motor including a rotor having a high torque to size ratio, said motor comprising:
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a stator including a centrally located longitudinal opening; a bearing mechanism fixedly disposed relative to said stator; and a rotor of cylindrical configuration, said rotor having a central shaft supported by said bearing mechanism and disposed at least partially within said centrally located opening of said stator, magnetically conductive segments disposed around said central shaft, each of said segments having an arcuate outer surface distal from said central shaft and an inner edge proximal to said central shaft, each of said segments further defining an opening extending therethrough in generally parallel relation to said central shaft, each of said openings being of a radially elongated cross-section, namely having a length as measured parallel to a radial plane through the center axis of said shaft which is greater than the maximum width of that opening as measured normal to such radial plane, and wherein said cross-section includes a mid-portion having said maximum width and narrows near the outer surface and near the inner edge of the respective segment, magnets located between each adjacent pair of said segments for providing magnetic flux through each of the adjacent segments, said flux linking at least partially through said stator disposed around said segments, and securing bars structurally coupled to and spaced from said shaft and extending through said openings in said segments to retain said segments in predetermined position around said shaft. - View Dependent Claims (31, 32, 33, 34)
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35. An electrical motor having a high torque to size ratio, said motor including a rotor having a central longitudinal axis of rotation, a stator defining a centrally located longitudinal opening, and a bearing mechanism fixedly disposed relative to said stator for supporting said rotor at least partially in said stator for rotation about the central longitudinal axis of said rotor, said rotor comprising:
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magnetically conductive segments disposed around said central longitudinal axis, each of said segments having an arcuate outer surface distal to said axis and an inner surface proximal to said axis, each of said segments defining an opening therethrough in generally parallel relation to said axis; magnets located between each adjacent pair of said segments and being engaged with the adjacent segments for retention therebetween and for providing magnetic flux through each of the adjacent segments, said flux linking at least partially through said stator disposed around said segments; retainers adjacent each end of said segments; and
,securing bars spaced from said axis, extending through said openings in said segments and engaging each of the respective segments at a radially inward side of said opening therein, said securing bars engaging and being supported by said retainers to retain said segments in predetermined positions around said axis, each of said securing bars being a separate element, said securing bars holding said segments and magnets radially and maintaining radially inward compressive forces on said segments and thereby forming a prestressed cylindrical structure which includes said bars, retainers, segments and magnets. - View Dependent Claims (36, 37, 38, 39, 40)
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41. A rotor of cylindrical configuration for an electrical motor having a high torque to size ratio, said rotor comprising:
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a central shaft; magnetically conductive segments disposed around said central shaft, each of said segments having an arcuate outer surface distal to said central shaft and an inner edge proximal to said central shaft, said segments defining openings therethrough in generally parallel relation to said central shaft; magnets located between each adjacent pair of segments for providing magnetic flux through each of the adjacent segments for linking at least partially through a stator widen disposed around said segments; a plurality of separate securing bars extending through said openings in said segments and each disposed in spaced and generally parallel relation to said shaft, said bars engaging said segments and structurally coupled to said shaft to retain said segments in respective predetermined positions around said shaft, said securing bars maintaining said segments in radial compression against said central shaft, whereby said bars, said shaft, said magnets and said segments form a prestressed rigid rotor structure. - View Dependent Claims (42, 43, 44, 45, 46, 47, 48, 49, 50, 51, 52, 53, 54, 55, 56)
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57. A rotor of cylindrical configuration for use in a motor having a high torque to size ratio, said rotor having an outer cylindrical peripheral surface and comprising:
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a central rotor shaft with a center axis; at least first and second retainers securely mounted on said shaft in spaced opposed relation to one another; a plurality of magnetically conductive segments arrayed around said shaft between said first and second retainers with each of said segments spanning a circumferential sector of said cylindrical configuration; magnets disposed between each adjacent pair of said segments for providing magnetic flux through each of the adjacent segments for linking through a stator disposed around said peripheral surface; each of said segments having an opening extending therethrough in generally spaced parallel relation to said shaft; and a securing bar which is non-magnetic and electrically non-conductive extending through each of said openings and engaging the respective segment at the radially inward side of said opening therein to support said segment at least in a radial direction, each of said securing bars being spaced from said shaft and being supported by said retainers whereby said bars support said segments in predetermined positions in said rotor. - View Dependent Claims (58, 59, 60, 61)
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Specification