Permanent magnet rotor having magnet positioning and retaining means

A permanent magnet rotor assembly comprising:

• a substantially cylindrical rotor core having an axis of rotation and an outer radius of curvature;
• a plurality of arcuate magnetic elements each of which has a radial thickness bounded by an inner surface having a radius of curvature substantially equal to the radius of curvature of said rotor core, an outer surface substantially concentric to said inner surface, and longitudinal side surfaces;
• a plurality of ribs on said rotor core extending radially outwardly a distance substantially less than the radial thickness of said magnetic elements, said ribs being equal in number to said magnetic elements and being substantially equally circumferentially spaced about said rotor core and extending substantially parallel to said axis of rotation, said ribs having longitudinal side surface which converge toward each other in the radial direction from said core,
• annular sheet means disposed about and securing said magnetic elements on said rotor core between said ribs, said magnetic elements having arcuate tolerance ranges which create radial cavities between said longitudinal side surfaces on said magnetic elements, said magnetic elements having inner longitudinal edge surfaces configured to form cavities between said edge surfaces and said converging side surfaces on said ribs which communicate with said radial cavities, said magnetic elements being positioned to establish substantially equal radial cavities between said magnetic elements;
• and
• a hardenable adhesive material substantially filling said radial cavities and said cavities between said magnetic elements and said ribs;
• said ribs and hardenable material being cooperative with said shell means to maintain said magnetic elements in fixed equally spaced relation on said rotor core and prevent circumferential movement of said magnetic elements relative to the rotor core during rotation of the rotor assembly.

A permanent magnet rotor assembly comprising, in combination:

• a substantially cylindrical core having an axis of rotation and an outer radius of curvature;
• a plurality of magnetic elements each of which has an inner surface having a radius of curvature substantially equal to the radius of curvature of said core, an outer surface substantially concentric to said inner surface, and two longitudinal side surfaces connecting said inner and outer surfaces, said core having an axial length greater than the axial lengths of said magnetic elements;
• a plurality of ribs on said core and extending radially outward a distance significantly less than the radial thickness of said magnetic elements, said ribs extending along the outer surface of said rotor core substantially parallel to said axis of rotation, said ribs having side surfaces which taper toward each other as they extend outwardly from said core;
• said ribs being substantially equally spaced about said core substantially parallel to said axis of rotation, and equal in number to said magnetic elements;
• said inner surface of each of said magnetic elements being positioned between and substantially filling the space between adjacent ribs, said magnetic elements being positioned to define substantially equal radial cavities between the longitudinal side surfaces of adjacent magnetic elements and having inner edge surfaces spaced from said tapered side surfaces on said ribs to define cavities therebetween communicating with the corresponding radial cavities,
• a hardenable adhesive material substantially filling said cavities, and
• at least one end plate having a central aperture larger than the cross section of said core such that said end plate is slidable over said core toward said magnetic elements, said at least one end plate having a chamfer along the outer periphery thereof, said chamfer being an acute angle with the periphery adjacent said magnetic elements being larger than the periphery remote from said magnetic elements,
• said ribs and adhesive material maintaining equal spacing of said magnetic elements and precluding deleterious movement of said magnetic elements relative to the core under high speed rotation of the rotor assembly.

A permanent magnet rotor assembly comprising:

• a substantially cylindrical rotor core having an axis of rotation and an outer radius of curvature;
• a plurality of magnetic elements of substantially equal radial thickness and each having an inner surface having a radius of curvature substantially equal to the radius of curvature of said rotor core, an outer surface substantially concentric to said inner surface, and two longitudinal side surfaces connecting said inner and outer surfaces;
• a plurality of ribs extending radially outwardly from said rotor core a distance significantly less than the radial thickness of said magnetic elements, said ribs extending along a significant portion of the outer surface of said rotor core substantially parallel to said axis of rotation, said ribs having generally planar side surfaces converging toward each other in the direction outwardly from said core;
• said inner surface of each magnetic element being positioned between and substantially filling the space between a corresponding pair of adjacent ribs, said magnetic elements having arcuate tolerance ranges which create radial cavities between said longitudinal side surfaces of said elements and having inner chamfered longitudinal edge surfaces disposed in spaced relation with the side surfaces of said elements and having inner chamfered longitudinal edge surfaces disposed in spaced relation with the side surfaces of corresponding ribs to define cavities therebetween which communicate with said radial cavities;
• said magnetic elements being positioned on said core so as to establish substantially equal radial cavities between said elements;
• a hardened viscous adhesive material interposed between said core and the inner surfaces of said magnetic elements and substantially filling each of said cavities;
• and
• an outer shell axially positioned around and contacting said magnetic elements to press said magnetic elements toward said rotor core;
• said hardened adhesive cooperating with said shell, said magnetic elements and said ribs to maintain said magnetic elements in fixed equally spaced relation on said core with said converging sides of said ribs and the chamfered edge surfaces of adjacent magnetic elements providing a reactive camming action wherein any attempted circumferential rotation of said magnetic elements relative to said rotor core is resisted by said ribs.

A permanent magnet rotor comprising:

• a substantially cylindrical rotor core having an axis of rotation and an outer radius of curvature;
• a plurality of ribs spaced substantially equidistantly about said rotor core and extending along a substantial portion of the outer surface of said rotor core in parallel relation to said axis of rotation, said ribs having side surfaces which converge toward one another as they extend outwardly from said rotor core;
• a plurality of magnetic elements each of which is positioned between a pair of said ribs and has an inner surface having a radius of curvature substantially equal to the outer radius of curvature of said rotor core, an outer surface substantially concentric to said inner surface, and longitudinal side surfaces, said magnetic elements being contoured to cooperate with said side surfaces of said ribs to form cavities therebetween;
• an outer shell axially positioned over said magnetic elements and said rotor core to retain said magnetic elements radially against said rotor core;
• a hardenable material disposed within said cavities between said magnetic elements and said ribs and being cooperative with said magnetic elements, said shell and said ribs to prevent circumferential movement of said magnetic elements relative to the rotor core during rotation of the rotor assembly;
• said rotor core having a longitudinal length greater than the longitudinal lengths of said magnetic elements;
• at least one end plate in the form of a ring having a central aperture and secured to an end of said rotor core and overlying said magnetic elements and at least a portion of said rotor core including said ribs and said cavities, said end plate having a chamfer about its outer periphery, said chamfer being an acute angle with the periphery of said ring adjacent said magnetic elements being larger in diameter than the outer periphery of said ring furthest from said magnetic elements;
• said outer shell having an end surface bent over the chamfered periphery of said at least one plate so as to retain said end plate in position against said rotor core, whereby the corresponding ends of said magnetic elements are enclosed by said outer shell and said at least one end plate.