US3894252A — Electric motor with means for magnetically preven…

Claim 1

Independent Claim 262 words

In an electric motor including a permanent magnet stator magnetized radially to provide north and south poles alternating at equal angular spacing, a rotary shaft disposed coaxially with said permanent magnet stator, a rotor fixed to said rotary shaft and having a circular body portion lying in a radial plane through said shaft and pole teeth of soft teeth of soft magnetic material extending from the periphery of said body portion along the magnetized face of said permanent magnet stator keeping a gap therebetween, the number of said poles of the permanent magnet stator being an even multiple of the number of said pole teeth, an annular exciting coil concentric with said permanent magnet stator and said rotor and spaced from said rotor, and a casing including a yoke which forms a magnetic circuit interlinking said annular exciting coil with said pole teeth; the improvement comprising means relatively axially locating said rotor with respect to said permanent magnet stator and yoke for continuously applying a non-zero total net axial magnetic force to said rotor in only one axial direction during motor rotation, wherein said permanent magnet is spaced in said one axial direction from said rotor body portion such that the net direction of any axial magnetic force on said rotor by said permanent magnet stator is in said one direction and flux paths are providing between said yoke and rotor, rotor magnetic material portions at said flux paths being offset from the opposed yoke portion other than opposite said one axial direction and to urge said rotor in said one direction.

Claim 2

Dependent Claim 262 words

In an electric motor including a permanent magnet stator magnetized radially to provide north and south poles alternating at equal angular spacing, a rotary shaft disposed coaxially with said permanent magnet stator, a rotor fixed to said rotary shaft and having a circular body portion lying in a radial plane through said shaft and pole teeth of soft teeth of soft magnetic material extending from the periphery of said body portion along the magnetized face of said permanent magnet stator keeping a gap therebetween, the number of said poles of the permanent magnet stator being an even multiple of the number of said pole teeth, an annular exciting coil concentric with said permanent magnet stator and said rotor and spaced from said rotor, and a casing including a yoke which forms a magnetic circuit interlinking said annular exciting coil with said pole teeth; the improvement comprising means relatively axially locating said rotor with respect to said permanent magnet stator and yoke for continuously applying a non-zero total net axial magnetic force to said rotor in only one axial direction during motor rotation, wherein said permanent magnet is spaced in said one axial direction from said rotor body portion such that the net direction of any axial magnetic force on said rotor by said permanent magnet stator is in said one direction and flux paths are providing between said yoke and rotor, rotor magnetic material portions at said flux paths being offset from the opposed yoke portion other than opposite said one axial direction and to urge said rotor in said one direction.

Claim 3

Dependent Claim 122 words

An electric motor according to claim 1, in which said yoke includes a first portion in one part of said magnetic circuit and axially spaced also in said one direction from said rotor pole teeth by a magnetic flux gap, said yoke including a second portion in a remote part of said magnetic circuit and offset from an adjacent magnetic material portion of said rotor in a direction other than opposite said one axial direction wherein any net axial magnetic force therebetween urges said rotor in said one direction, and said yoke is free of portions magnetically gapped in the opposite axial direction from magnet material portions of said rotor for avoiding magnetic forces on said rotor in said opposite axial direction.

Claim 4

Dependent Claim 38 words

An electric motor according to claim 2, in which said yoke has a cutout spanning and facing said circular body portion of the rotor and a free end at said cutout facing said pole teeth of the rotor.

Claim 5

Dependent Claim 24 words

An electric motor according to claim 3, in which said free end of the casing extends in the axial direction of the rotary shaft.

Claim 6

Dependent Claim 61 words

An elelctric motor according to claim 2, in which said yoke has a cutout spanning said circular body portion of the rotor and said rotor has a plate member made of a magnetic material and radially extending beyond said cutout and over said second yoke portion, wherein said rotor is spaced in said one axial direction from said second yoke portion.

Claim 7

Dependent Claim 80 words

An electric motor according to claim 2, in which said yoke has a cutout spanning said circular body portion of the rotor, said rotor has a plate member at said cutout and made of a magnetic material and including a radially extending portion and an axially extending portion, and said second yoke portIon has a free end bounding said cutout and extending in the axial direction, facing said axially extending portion of the plate member across a radial magnetic gap.

Claim 8

Dependent Claim 20 words

An electric motor according to claim 6, in which said plate member is offset outwardly with respect to said casing.

Claim 9

Dependent Claim 59 words

An electric motor according to claim 2, in which said yoke has a cutout radially spacing said first and second yoke portions, said stator being formed as a disk and disposed in said cutout, said rotor being disk-like with said pole teeth radially extending, said yoke and stator being entirely offset in said one axial direction from said rotor.

Claim 10

Dependent Claim 142 words

An electric motor according to claim 2, in which said stator, rotor and coil define with said yoke a first motor unit and including a second motor unit offset along said shaft from said first motor unit and similar at least as to stator and rotor, said casing including a substantially radial partition separating same in separate rooms for each motor unit and incorporating said first yoke portion of said first motor unit as an axially offset annulus directed toward the pole teeth of the first rotor and away from the second rotor, and a further radial wall axiallly spaced by said second rotor from said partition and defining a portion of the yoke of said second motor unit, whereby said rotors of said first and second motor units each receive said total net axial magnetic force in the same axial direction.

Claim 11

Dependent Claim 44 words

An electric motor according to claim 2, in which said circular body portion of the rotor is made of a non-magnetic material and said second yoke portion is an axial projection radially facing said pole teeth of the rotor across a radial magnetic gap.

Claim 12

Dependent Claim 225 words

An electric motor comprising a permanent magnet stator magnetized radially to provide north and south poles alternating at equal angular spacings, a rotary shaft disposed coaxially with said permanent magnet stator, a rotor fixed to said rotary shaft and having a circular body portion lying in a radial plane through said shaft and pole teeth of soft magnetic material extending from the periphery of said body portion along the magnerized face of said permanent magnet stator keeping a gap therebetween, the number of said poles of the permanent magnet stator being an even multiple of the number of said pole teeth, an annular exciting coil concentric with side permanent magnet stator and said rotor and spaced from said rotor, a casing made of a non-magnetic material, and a yoke which forms a magnetic circuit interlinking with said annular exciting coil in cooperation with said pole teeth, wherein said yoke has a portion which faces said rotor through a further gap, said gaps being axial gaps, said casing including means locating said yoke and permanent magnet stator in one axial direction across said gaps from said rotor, with the magnetic flux interlinking said rotor and stator and yoke being in said gaps, for providing a continuous net axial magnetic force on said rotor in said one direction, whereby to magnetically bias said rotor against axial vibration.

Claim 13

Dependent Claim 225 words

An electric motor comprising a permanent magnet stator magnetized radially to provide north and south poles alternating at equal angular spacings, a rotary shaft disposed coaxially with said permanent magnet stator, a rotor fixed to said rotary shaft and having a circular body portion lying in a radial plane through said shaft and pole teeth of soft magnetic material extending from the periphery of said body portion along the magnerized face of said permanent magnet stator keeping a gap therebetween, the number of said poles of the permanent magnet stator being an even multiple of the number of said pole teeth, an annular exciting coil concentric with side permanent magnet stator and said rotor and spaced from said rotor, a casing made of a non-magnetic material, and a yoke which forms a magnetic circuit interlinking with said annular exciting coil in cooperation with said pole teeth, wherein said yoke has a portion which faces said rotor through a further gap, said gaps being axial gaps, said casing including means locating said yoke and permanent magnet stator in one axial direction across said gaps from said rotor, with the magnetic flux interlinking said rotor and stator and yoke being in said gaps, for providing a continuous net axial magnetic force on said rotor in said one direction, whereby to magnetically bias said rotor against axial vibration.

Claim 14

Dependent Claim 23 words

An electric motor according to claim 11, in which said permanent magnet stator is disposed between said annular exciting coil and said rotor.

Claim 15

Dependent Claim 99 words

An electric motor according to claim 12, said yoke is formed in E-shape in diametric cross section and secured to the casing, said E-shape yoke including a raised central part which serves as a bearing for the rotary shaft, an annular groove centered on said raised central part for receiving said annular exciting coil therein, and a free end facing said rotor in an overlapping relation thereto, said permanent magnet stator being substantially radially coplanar with said yoke free end, the remainder of said yoke being remotely spaced from said rotor in said one direction and by said coil.

Claim 16

Dependent Claim 228 words

An electric motor comprising, in combination, yoke means formed of a casing and a partition which is provided in said causing to define rooms in cooperation with said casing: a rotary Shaft rotatably supported by said casing: a plurality of motors mounted in the respective rooms defined by said partition and each including a permanent magnet stator magnetized radially to provide north and south poles alternating at equal angular spacings, a rotor fixed to said rotary shaft and having a circular body portion lying in a radial plane through said shaft and pole teeth of a soft magnetic material extending from the periphery of said body portion along the magnetized face of said permanent magnet stator keeping a gap therebetween, the number of said poles of the permanent magnet stator being an even multiple of the number of said pole teeth, and an annular exciting coil concentric with said permanent magnet stator and said rotor and spaced from said rotor through another gap, said yoke means forming a magnetic circuit interlinking with said annular exciting coil in cooperation with said pole teeth, means relatively axially locating the rotor of each motor with respect to its stator and yoke for continuously applying a non-zero total net axial magnetic force to said rotor in only one axial direction during motor rotation, said one direction being the same for both motors.

Claim 17

Dependent Claim 228 words

An electric motor comprising, in combination, yoke means formed of a casing and a partition which is provided in said causing to define rooms in cooperation with said casing: a rotary Shaft rotatably supported by said casing: a plurality of motors mounted in the respective rooms defined by said partition and each including a permanent magnet stator magnetized radially to provide north and south poles alternating at equal angular spacings, a rotor fixed to said rotary shaft and having a circular body portion lying in a radial plane through said shaft and pole teeth of a soft magnetic material extending from the periphery of said body portion along the magnetized face of said permanent magnet stator keeping a gap therebetween, the number of said poles of the permanent magnet stator being an even multiple of the number of said pole teeth, and an annular exciting coil concentric with said permanent magnet stator and said rotor and spaced from said rotor through another gap, said yoke means forming a magnetic circuit interlinking with said annular exciting coil in cooperation with said pole teeth, means relatively axially locating the rotor of each motor with respect to its stator and yoke for continuously applying a non-zero total net axial magnetic force to said rotor in only one axial direction during motor rotation, said one direction being the same for both motors.

Claim 18

Dependent Claim 25 words

An electric motor according to claim 14, in which said motors mounted in the respective rooms are staggered from each other by predetermined electric angle.

Claim 19

Dependent Claim 22 words

An electric motor according to claim 14, in which said circular body portion of the rotor is made of a non-mgnetic material.

Claim 20

Dependent Claim 47 words

An electric motor according to claim 14, in which said circular body portion of the rotor is made of a magnetic material and said yoke means has a projection extending in an overlapping relation to the pole tooth along the inner periphery of the annular exciting coil.

Claim 21

Dependent Claim 28 words

An electric motor according to claim 14, in which said yoke means has a projection formed in the position opposite to the tip end of the pole tooth.

Claim 22

Dependent Claim 127 words

An electric motor according to claim 14, in which the axial interlocation of the rotor, stator and yoke is the same for both motors, such that said motors are stacked on said shaft in series rather than opposed relation, each said motor having its stator and one portion of its yoke axially spaced in one said axial direction from opposed portions of its rotor to define at least an axial yoke-rotor magnetic flux path, each motor having no yoke portion spaced in the opposite axial direction from a magnetic material portion of the rotor through an effective magnetic flux gap, each said yoke having a further flux path to its rotor orienting the magnetic attractive force therethrough on the rotor other than toward said opposite axial direction.

Annuity Stage	Window Opens	Payment Deadline	Surcharge Period Until	Estimated Fee	Status
3.5 Years (Year 4)	1978-07-07	1979-01-06	1979-07-08	$2000.00	Window Closed / Lapsed
7.5 Years (Year 8)	1982-07-07	1983-01-06	1983-07-08	$3760.00	Window Closed / Lapsed
11.5 Years (Year 12)	1986-07-07	1987-01-06	1987-07-08	$7700.00	Window Closed / Lapsed

Electric motor with means for magnetically preventing axial vibration

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