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AssigneeHitachi, Ltd.
InventorsSatosi Uno, Sueo Akashi, Katsutoshi Nii, Kazuhiko Kawaike, Hiroo Hiroyama, Kosho Ishizaki
Estimating the term…
A motor provided with a magnetic fluid bearing device for suppressing vibration and irregular rotation as well as preventing the magnetic fluid from being scattered from a bearing portion and the inside of the motor. The motor includes a rotor having a polygon mirror mounted thereon, a stator unit having driving coils, a rotor position detector and a rotor revolution detector attached thereto, a magnetic fluid bearing unit having a magnetic seal and a dynamic pressure seal attached thereto and a magnetic bearing. A triple seal structure for magnetic fluid which includes a first fluid seal constituted by the seals of the bearing unit, a second fluid seal constituted by a magnet of the rotor and a third fluid seal constituted by a magnet of the seal magnet is provided in the motor.
A polygon mirror motor including a stator, a rotor, stator coils and radial bearings provided on said stator, said rotor including a rotor shaft, a collar provided on said rotor shaft, and a motor magnet and a polygon mirror provided on said collar, said motor magnet and said stator coils being disposed to face each other, said radial bearings being slide bearings and rotatably supporting said rotor shaft, and wherein a magnetic fluid is applied as a lubricating oil for lubricating sliding surfaces between said radial bearings and said rotor shaft, and said motor further including a magnetic fluid seal in the form of a permanent magnet which is disposed to surround the outer periphery of said rotor shaft, and wherein said collar is formed of a material having a greater coefficient of thermal expansion than that of said rotor shaft with said collar being joined to said rotor shaft by heat shrinkage fit, and said rotor further comprising a magnetic thrust bearing for restricting movements of said rotor in a thrust direction, said magnetic thrust bearing comprising a stator thrust magnet and a rotor thrust magnet, said stator thrust magnet being provided on said stator and said rotor thrust magnet being provided on said rotor, and said stator thrust magnet and said rotor thrust magnetic being disposed to face each other, in a direction perpendicular to the axial direction of said rotor shaft, whereby said polygon mirror motor rotates during operation with relatively low vibration and relatively low irregularity of rotation.
A polygon mirror motor including a stator, a rotor, stator coils and radial bearings provided on said stator, and rotor including a rotor shaft, a collar provided on said rotor shaft, and a motor magnet and a polygon mirror provided on said collar, said motor magnet and said stator coils being disposed to face each other, said radial bearings being slide bearings and rotatably supporting said rotor shaft, and wherein a magnetic fluid is applied as a lubricating oil for lubricating sliding surfaces between said radial bearings and said rotor shaft, and said motor further including a magnetic fluid seal in the form of a permanent magnet which is disposed to surround the outer periphery of said rotor shaft, and wherein said collar is formed of a material having a greater coefficient of thermal expansion than that of said rotor shaft and said motor magnet is formed of a material having a greater coefficient of thermal expansion than that of said collar with said collar joined to said rotor shaft by heat shrinkage fit and said motor magnet joined to said collar by heat shrinkage fit, and said rotor further comprising a magnetic thrust bearing for restricting movements of said rotor in a thrust direction, said magnetic thrust bearing comprising a stator thrust magnet and a rotor thrust magnet, said stator thrust magnet being provided on said stator, said rotor thrust magnet being provided on said rotor and said thrust magnets being disposed to face each other in a direction perpendicular to the axial direction of said rotor shaft, whereby said polygon mirror motor rotates during operation with relatively low vibration and relatively low irregularity of rotation as.
A polygon mirror motor including a stator, a rotor, stator coils and radial bearings provided on said stator, said rotor including a rotor shaft, a collar provided on said rotor shaft, and a motor magnet provided on said collar, said motor magnet and said stator coils being disposed to face each other, said radial bearings being slide bearings and rotatably supporting said rotor shaft, and wherein a magnetic fluid is applied as a lubricating oil for lubricating sliding surfaces between said radial bearings and said rotor shaft, and said motor further including a magnetic fluid seal in the form of a permanent magnet which is disposed to surround the outer periphery of said rotor shaft, and wherein said collar is formed of a material having a greater coefficient of thermal expansion than that of said rotor shaft with said collar being joined to said rotor shaft by heat shrinkage fit, and said motor further comprising a magnetic thrust bearing for restricting movements of said rotor in a thrust direction, said magnetic thrust bearing comprising a stator thrust magnet and a rotor thrust magnet, said stator thrust magnet being provided on said stator, said rotor thrust magnet being provided on said rotor, and said thrust magnets being disposed to face each other in a direction perpendicular to the axial direction of said rotor shaft, whereby said polygon mirror motor rotates during operation with relatively low vibration and relatively low irregularity of rotation as.
Dependencies are inferred from the claim text.