Magnetic clutch

Claim 2

In a magnetic clutch comprising a main rotating unit rotated from a driving source, a rotary shaft concentric with said main rotating unit and rotatable independent of said main rotating unit and adapted to be connected to a driven member, an armature mechanically connected to said rotary shaft and placed opposite to said main rotating unit in the axial direction, said armature being movable in the axial direction between a first position where said armature is separated from said main rotating unit by a predetermined distance and a second position where said armature is engaged with said main rotating unit to rotate therewith, and energizeable electromagnetic means for attracting said armature from said first position to said second position when energized, the improvement comprising: a cylindrical elastic material concentric with said rotary shaft and having first and second cylindrical surfaces opposing to each other, first rigid means for mechanically connecting said first cylindrical surface to said armature and second rigid means for mechanically connecting said second cylindrical surface to said rotary shaft, said second rigid means and said second cylindrical surface of said elastic member being axially immovable when said electromagnetic means is energized but said first surface of said elastic member being then axially moved with said first rigid member and said armature when the latter moves to said second position to create thereby in said elastic material an axial elastic strain which is the sole force for returning said armature to said first position when said electromagnetic means is deenergized.

Claim 3

A magnetic clutch according to claim 1, further comprising a plurality of projecting heat radiation members provided on at least one of said first and second means.

Claim 4

A magnetic clutch according to claim 1, further comprising means for preliminarily providing a strain in said elastic material at said first position of said armature so as to produce an elastic force in a direction away from said rotating unit to help maintain said predetermined distance between said armature and main rotating unit while said armature is supposed to be in said first position.

Claim 5

A magnetic clutch according to claim 1 wherein said first means comprises a first retaining plate mechanically connected to said first cylindrical surface of said coupling member, means for mechanically connecting said first retaining plate to said armature and at least one member mounted intermediate to said first retaining plate and said armature so as to provide an air gap therebetween.

Claim 6

In a magnetic clutch comprising a main rotating unit rotated from a driving source, a rotary shaft concentric with said main rotating unit and rotatable independent of said main rotating unit and adapted to be connected to a driven member, an armature mechanically connected to said rotary shaft and placed opposite to said main rotating unit in the axial direction, said armature being movable in the axial direction between a first position where said armature is separated from said main rotating unit by a predetermined distance and a second position where said armature is engaged with said main rotating unit to rotate therewith, and magnetic means for attracting said armature from said first position to said second position, the improvement comprising: a coupling member comprising a cylindrical elastic material concentric with said rotary shaft and having first and second cylindrical surfaces opposing to each other, first means for mechanically connecting said first cylindrical surface to said armature, second means for mechanically connecting said second cylindrical surface to said rotary shaft, said coupling member being subject to an axial elastic strain when said armature is at said second position thereby exerting a force which causes said armature to return to said first position, and means for preliminarily providing a strain in said elastic material at said first position of said armature so as to produce an elastic force in a direction away from said main rotating unit to help maintain said predetermined distance between said armature and main rotating unit while said armature is supposed to be in said first position.

Claim 7

In a magnetic clutch comprising a main rotating unit rotated from a driving source, a rotary shaft concentric with said main rotating unit and rotatable independent of said main rotating unit and adapted to be connected to a driven member, an armature mechanically connected to said rotary shaft and placed opposite to said main rotating unit in the axial direction, said armature being movable in the axial direction between a first position where said armature is separated from said main rotating unit by a predetermined distance and a second position where said armature is engaged with said main rotating unit to rotate therewith, and magnetic means for attracting said armature from said first position to said second position, the improvement comprising: a coupling member comprising a cylindrical elastic material concentric with said rotary shaft and having first and second cylindrical surfaces opposing to each other, first means for mechanically connecting said first cylindrical surface to said armature, second means for mechanically connecting said second cylindrical surface to said rotary shaft, said coupling member being subject to an axial elastic strain when said armature is at said second position thereby exerting a force which causes said armature to return to said first position, and means for preliminarily providing a strain in said elastic material at said first position of said armature so as to produce an elastic force in a direction away from said main rotating unit to help maintain said predetermined distance between said armature and main rotating unit while said armature is supposed to be in said first position.

Claim 8

A magnetic clutch according to claim 5, wherein said first means comprises a first retaining plate mechanically connected to said armature and having a cylindrical surface firmly attached to the first cylindrical surface of said coupling member, and said second means comprises a second retaining plate having a portion opposed to said armature in the axial direction and mechanically connected to said rotary shaft and a cylindrical surface firmly attached to the second cylindrical surface of said coupling member, said second retaining plate being provided with said preliminary strain means in the form of a plurality of projections projected towards said armature and being in abutment under pressure with the same at a portion thereof opposing to said armature.

Claim 9

A magnetic clutch according to claim 6, wherein said projections comprise a plurality of pressing members made of an elastic material and securely mounted on said portion of said second retaining plate opposing to said armature.

Claim 10

A magnetic clutch according to claim 5, wherein said first means comprises a first retaining plate having a cylindrical portion formed as an integral part of said armature and concentric with said rotary shaft and the outer periphery firmly attached to the inner surface of said cylindrical portion, and said second means comprises a second retaining plate having a cylindrical portion mechanically connected to said rotary shaft and concentric therewith, said first and second cylindrical surfaces of said coupling member being respectively attached firmly to the inner periphery of said first retaining plate and the outer periphery of said cylindrical portion of said second retaining plate.

Claim 11

A magnetic clutch according to claim 5, wherein said first means comprises a retaining plate mounting member attached to said armature and having a cylindrical retaining plate mounting portion concentric with said rotary shaft and a cylindrical portion adjacent to and around the space between said armature and said main rotating unit and a first cylindrical retaining plate having an outer periphery thereof firmly attached to the inner periphery of said cylindrical retaining plate mounting portion, and said second means comprises a second retaining plate having a cylIndrical portion mechanically connected to said rotary shaft and concentric therewith, said first and second cylindrical surfaces of said coupling member being respectively attached to the inner periphery of said first retaining plate and the outer periphery of said cylindrical portion of said second retaining plate.

Claim 12

A magnetic clutch according to claim 5, further comprising a plurality of projecting heat radiation members provided on at least one of said first and second means.

Claim 13

A magnetic clutch according to claim 5, wherein said first means comprises a first retaining plate mechanically connected to said first cylindrical surface of said coupling member, means for mechanically connecting said first retaining plate to said armature and at least one member mounted intermediate to said first retaining plate and said armature so as to provide an air gap therebetween.

Claim 14

A magnetic clutch according to claim 5, wherein said first means comprises a first retaining plate having a cylindrical portion firmly attached to said first cylindrical surface of said coupling member, means for mechanically connecting said first retaining plate to said armature and at least one member mounted intermediate to said first retaining plate and said armature so as to provide an air gap therebetween; and said second means comprises a second retaining plate having a portion mechanically connected to said rotary shaft, a cylindrical portion firmly attached to the second cylindrical surface of said coupling member and a flange portion radially extending from the circumferential edge of said cylindrical portion and opposing to said coupling member.

Claim 15

A magnetic clutch according to claim 12, wherein said member mounted intermediate to said first retaining plate and said armature is made of an heat insulating material.

Claim 16

A magnetic clutch according to claim 5, wherein said first means comprises a first retaining plate having an annular portion firmly attached to the first cylindrical surface of said coupling member and a flange portion integrally formed on and radially extending from said annular portion, means for mechanically connecting said flange portion to said armature and at least one member mounted intermediate to said flange portion and said armature so as to provide an air gap therebetween; and said second means comprises a second retaining plate having a portion connected to said rotary shaft and a cylindrical portion firmly attached to the second cylindrical surface of said coupling member; said annular portion being formed into a V-shaped section opening towards its center and in cooperation with said cylindrical portion of said second retaining plate so as to radially compress said coupling member at its portions near its opposing sides thereby reducing the heights of said portions.

Claim 17

A magnetic clutch according to claim 14, wherein said member mounted intermediate to said flange portion and said armature is made of a heat insulating material.

Claim 18

In a magnetic clutch comprising a main rotating unit rotated from a driving source, a rotary shaft concentric with said main rotating unit and rotatable independent of said main rotating unit and adapted to be connected to a driven member, an armature mechanically connected to said rotary shaft and placed opposite to said main rotating unit in the axial direction, said armature being movable in the axial direction between a first position where said armature is separated from said main rotating unit by a predetermined distance and a second position where said armature is engaged with said main rotating unit to rotate therewith, and magnetic means for attracting said armature from said first position to said second position, the improvement comprising: a coupling member comprising a cylindrical elastic material concentric with said rotary shaft and having first and second cylindrical surfaces opposing to each other, first means for mechanically connecting said first cylindrical surface to said aRmature, second means for mechanically connecting said second cylindrical surface to said rotary shaft, said coupling member being subjected to an axial elastic strain when said armature is at said second position thereby exerting a force which causes said armature to return to said first position, and wherein said first means comprises a first retaining plate mechanically connected to said first cylindrical surface of said coupling member, means for mechanically connecting said first retaining plate to said armature and at least one member mounted intermediate to said first retaining plate and said armature so as to provide an air gap therebetween.

Claim 19

In a magnetic clutch comprising a main rotating unit rotated from a driving source, a rotary shaft concentric with said main rotating unit and rotatable independent of said main rotating unit and adapted to be connected to a driven member, an armature mechanically connected to said rotary shaft and placed opposite to said main rotating unit in the axial direction, said armature being movable in the axial direction between a first position where said armature is separated from said main rotating unit by a predetermined distance and a second position where said armature is engaged with said main rotating unit to rotate therewith, and magnetic means for attracting said armature from said first position to said second position, the improvement comprising: a coupling member comprising a cylindrical elastic material concentric with said rotary shaft and having first and second cylindrical surfaces opposing to each other, first means for mechanically connecting said first cylindrical surface to said aRmature, second means for mechanically connecting said second cylindrical surface to said rotary shaft, said coupling member being subjected to an axial elastic strain when said armature is at said second position thereby exerting a force which causes said armature to return to said first position, and wherein said first means comprises a first retaining plate mechanically connected to said first cylindrical surface of said coupling member, means for mechanically connecting said first retaining plate to said armature and at least one member mounted intermediate to said first retaining plate and said armature so as to provide an air gap therebetween.