Rotor vibration suppressing apparatus for miniature electric motors

Claim 2

An electric motor having a rotor vibration-suppressing apparatus, comprising; a motor casing; an annular coil fixed in the casing and adapted for connection to a source of A.C. potential; an annular magnet fixed in said casing and being opposed to and spaced from said coil; a rotor having a portion disposed in the space between said coil and said magnet so that said rotor is rotated in synchronism with the frequency of the A.C. potential source when said coil is energized; a rotatable shaft concentric with said magnet, said rotor being fixed to said shaft for conjoint rotation therewith; first and second axially spaced bearings fixed in said casing and rotatably supporting said shaft; a compression coil spring surrounding said shaft and located between said bearings, said coil spring bearing at one end thereof against one of said bearings and bearing at the other end thereof against said rotor to continuously urge said shaft axially toward the other bearing, said other bearing having a central opening into which is received one end portion of said shaft, a member of hard material disposed in said opening and contacting the end wall of said one portion of said shaft, said compression coil spring continuously pressing said end wall against said member whereby said shaft is continuously supported by said member, thereby suppressing axial vibration of said shaft and said rotor and minimizing generation of vibration sound.

Claim 3

An electric motor according to claim 1, in which said member is a spherical member fitted into said opening.

Claim 4

An electric motor according to claim 1, in which said member comprises a trapezoidal portion fitted into said opening and a conical portion whose tip is centrally located in said opening and contacts said end wall of said shaft.

Claim 5

An electric motor having a rotor vibration-suppressing apparatus, comprising; a motor casing; an annular coil fixed in the casing and adapted for connection to a source of A.C. potential; an annular magnet fixed in said casing and being concentric with, disposed within, radially spaced from and opposed to the radially inner side of said coil; a rotor having an annular portion concentric with said coil and disposed in the space between the radially inner side of said coil and the periphery of said magnet so that said rotor is rotated in synchronism with the frequency of the A.C. potential source when said coil is energized; a rotatable shaft concentric with said magnet, said rotor being fixed to said shaft for conjoint rotation therewith; first and second axially spaced bearings fixed in said casing and rotatably supporting said shaft; a compression coil spring surrounding said shaft and located between said bearings, said coil spring bearing at one end thereof against one of said bearings and bearing at the other end thererof against said rotor to continuously urge said shaft axially against the other bearing, thereby suppressing axial vibRation of said shaft and said rotor, said casing having a cover closing one end of said casing and disposed over corresponding ends of said coil and said magnet, said cover having said one bearing mounted therein and also having inwardly bent pieces underlying and supporting said magnet, said magnet having a notch on one end thereof and said cover having a projection extending into said notch, whereby said magnet is supported on said cover.

Claim 6

An electric motor having a rotor vibration-suppressing apparatus, comprising; a motor casing; an annular coil fixed in the casing and adapted for connection to a source of A.C. potential; an annular magnet fixed in said casing and being concentric with, disposed within, radially spaced from and opposed to the radially inner side of said coil; a rotor having an annular portion concentric with said coil and disposed in the space between the radially inner side of said coil and the periphery of said magnet so that said rotor is rotated in synchronism with the frequency of the A.C. potential source when said coil is energized; a rotatable shaft concentric with said magnet, said rotor being fixed to said shaft for conjoint rotation therewith; first and second axially spaced bearings fixed in said casing and rotatably supporting said shaft; a compression coil spring surrounding said shaft and located between said bearings, said coil spring bearing at one end thereof against one of said bearings and bearing at the other end thererof against said rotor to continuously urge said shaft axially against the other bearing, thereby suppressing axial vibRation of said shaft and said rotor, said casing having a cover closing one end of said casing and disposed over corresponding ends of said coil and said magnet, said cover having said one bearing mounted therein and also having inwardly bent pieces underlying and supporting said magnet, said magnet having a notch on one end thereof and said cover having a projection extending into said notch, whereby said magnet is supported on said cover.

Claim 7

An electric motor having a rotor-vibration suppressing apparatus, comprising; a motor casing; an annular coil fixed in the casing and adapted for connection to a source of A.C. potential; an annular magnet fixed in said casing and being concentric with, disposed within, radially spaced from and opposed to the radially inner side of said coil; a generally cup-shaped rotor comprising a base wall and an annular portion concentric with said coil and disposed in the space between the radially inner side of said coil and the periphery of said magnet so that said rotor is rotated in synchronism with the frequency of the A.C. potential source when said coil is energized; a rotatable shaft concentric with said magnet, said rotor being fixed to said shaft for conjoint rotation therewith; said base wall of said rotor extending transverse to said shaft and being disposed adjacent to one axial end of said magnet, said base wall having a central opening therethrough; a boss fixed to said shaft and said base wall and extending through said central opening in said base wall; first and second axially spaced bearings fixed in said casing and rotatably supporting said shaft; a compression coil spring surrounding said shaft and located between said bearings, said coil spring bearing at one end thereof against one of said bearings and bearing at the other end thereof against said boss too continuously urge said shaft axially against the other bearing, said shaft extending through said boss into said other bearing, one axial end of said spring bearing against said boss and said spring extending axially through the central opening of said magnet and its other axial end bears against said one bearing adjacent to the opposite axial end of said magnet, thereby suppressing axial vibration of said shaft and said rotor.

Claim 8

An electric motor having a rotor-vibration suppressing apparatus, comprising; a motor casing; an annular coil fixed in the casing and adapted for connection to a source of A.C. potential; an annular magnet fixed in said casing and being concentric with, disposed within, radially spaced from and opposed to the radially inner side of said coil; a generally cup-shaped rotor comprising a base wall and an annular portion concentric with said coil and disposed in the space between the radially inner side of said coil and the periphery of said magnet so that said rotor is rotated in synchronism with the frequency of the A.C. potential source when said coil is energized; a rotatable shaft concentric with said magnet, said rotor being fixed to said shaft for conjoint rotation therewith; said base wall of said rotor extending transverse to said shaft and being disposed adjacent to one axial end of said magnet, said base wall having a central opening therethrough; a boss fixed to said shaft and said base wall and extending through said central opening in said base wall; first and second axially spaced bearings fixed in said casing and rotatably supporting said shaft; a compression coil spring surrounding said shaft and located between said bearings, said coil spring bearing at one end thereof against one of said bearings and bearing at the other end thereof against said boss too continuously urge said shaft axially against the other bearing, said shaft extending through said boss into said other bearing, one axial end of said spring bearing against said boss and said spring extending axially through the central opening of said magnet and its other axial end bears against said one bearing adjacent to the opposite axial end of said magnet, thereby suppressing axial vibration of said shaft and said rotor.