A roller system has a frame, a plurality of rollers (supported by the frame) forming a roller plane, and an external rotor motor (motor) spaced from the roller plane. As an external rotor motor, the motor has a stator and an external rotor radially outward of the stator to substantially circumscribe the stator. To kinetically couple the motor with the rollers, the system also has a transmission coupling coupled with the external rotor and at least one of the rollers. The transmission coupling and external rotor are configured so that rotation of the external rotor causes the at least one roller to rotate in response to a torque received through the transmission coupling.

A system for controlling an electric motor including a rotor supported by a lubricant upon a stator with a plurality of stator poles and stator windings includes monitoring a radial position and rotor angle of the rotor by a controller. The system includes generating adjustments by the controller to cause the stator poles to apply a net radial force to the rotor. This net radial force may be used, for example to cause the rotor to be centered upon a central axis of the electric motor and may be particularly advantageous for a lubricant supported rotor. A motor drive provides an AC current to the stator windings as well as phase current adjustments of the electrical current in one or more of the stator windings to apply the net radial force to the rotor in a direction perpendicular to the drive axis.

An electric motor has a first carrier having an array of electromagnetic elements and a second carrier having electromagnetic elements defining magnetic poles. The first and second carriers each define an axis. An airgap is formed between the first and second carriers when in an operational position. An inner thrust bearing connects the first and second carriers and is arranged to allow relative rotary motion of the carriers. An outer thrust bearing connects the first and second carriers and is arranged to allow relative rotary motion of the carriers. The electromagnetic elements of each of the first and second carriers are arranged radially inward of the outer thrust bearing and radially outward of the inner thrust bearing. The inner thrust bearing and the outer thrust bearing are arranged to maintain the airgap against a magnetic attraction of the electromagnetic elements of the first and second carriers.

A motor includes a bearing housing and a stator. The stator includes a stator core, an insulator, and a conductor. The insulator is an insulating body covering at least a part of the stator core. The conductor is wound around the stator core via the insulator. The bearing housing includes a first inner peripheral surface and a first outer peripheral surface. The first inner peripheral surface holds a bearing. The first outer peripheral surface is in contact with the insulator directly or via an adhesive. A surface roughness of the first outer peripheral surface is greater than a surface roughness of the first inner peripheral surface. Therefore, a friction coefficient between the first outer peripheral surface and the insulator increases. Therefore, it is possible to suppress position deviation of the stator with respect to the bearing housing.

This motor includes a stationary portion including a stator; and a rotating portion supported to be rotatable about a central axis extending in a vertical direction with respect to the stationary portion, and including a shaft arranged to extend along the central axis. The stationary portion includes a bearing arranged to rotatably support the shaft, and a base portion arranged to hold the stator. The rotating portion includes a rotor hub portion arranged to extend in an annular shape around the shaft; a magnet directly or indirectly fixed to the rotor hub portion, and arranged opposite to the stator; a flywheel arranged axially above the rotor hub portion; and a seal portion arranged to have a thickness smaller than the thickness of the magnet. At least a portion of an outer circumferential surface of the rotor hub portion is a metal surface. The metal surface has a reflectivity higher than the reflectivity of an outer circumferential surface of the flywheel and the reflectivity of a surface of the seal portion. The metal surface is covered with the seal portion.

A stator for a linear stepper motor includes four stator sheets and two stator windings. The four stator sheets are oriented towards each other, provided with bent polar arms, and have two inner stator sheets each defining a sheet recess and two outer stator sheets that are arranged in an offset manner. THE four stator sheets are joined into an integral coil body by a stator overmold. One of the stator windings is wound onto the coil body between one inner stator sheet and one outer stator sheet and connected with connector pins. The four stator sheets and the stator overmold including a stator flange and a pin socket are integrally formed such that radial envelope surfaces of the at least four stator sheets are free from the stator overmold. A stator recess inside the stator is arranged centrically in the stator overmold.

A rotating portion includes a hollow shaft extending along a central axis. The hollow shaft includes a through hole passing therethrough in an axial direction. The rotating portion includes an upper screw to close an upper opening that is an opening at an upper end portion of the through hole. The rotating portion includes a lower screw to close a lower opening that is an opening at a lower end portion of the through hole. The hollow shaft includes an upper groove portion into which the upper screw is screwed at the upper opening. The hollow shaft includes a lower groove portion into which the lower screw is screwed at the lower opening. A lubricating oil is in contact with the lower screw. The lower groove portion is shorter in axial length than the upper groove portion, and the lower screw is smaller in axial pitch than the upper screw.

A vibration motor includes a base portion arranged to extend perpendicularly to a central axis extending in a vertical direction; a shaft having a lower end fixed to the base portion, and arranged to project upward along the central axis; a circuit board arranged above the base portion; a single annular coil attached to the circuit board, and arranged to have the shaft arranged inside thereof; a bearing portion attached to the shaft to be rotatable with respect to the shaft above the coil; a rotor holder attached to the bearing portion; a magnet portion including a plurality of magnetic poles, and attached to the rotor holder; an eccentric weight attached to the rotor holder; a spacer attached to the shaft between the bearing portion and the coil, and including an upper surface arranged to be in contact with a lower surface of the bearing portion; and a cover portion arranged to cover, at least in part, upper and lateral sides of the rotor holder and the eccentric weight, and fixed to an upper end of the shaft and an outer edge portion of the base portion. The spacer includes a lower surface arranged opposite to an upper surface of the coil in the vertical direction.

A fluid dynamic bearing device includes a shaft disposed along a center axis, a sleeve cylindrically extending around the shaft, a thruster that closes a lower end of the sleeve, dynamic pressure grooves in the shaft or the sleeve, and a lubricating oil present therebetween. The shaft includes a shaft main body and a shaft flange extending radially outward from a lower end of the shaft main body. An inner peripheral surface of the sleeve includes a first inner peripheral surface that faces an outer peripheral surface of the shaft main body in the radial direction and a second inner peripheral surface that faces an outer peripheral surface of the shaft flange in the radial direction. The sleeve includes a sleeve inner lower surface and a circulation hole.

An axial flux motor includes a motor shaft, a double-row angular contact ball bearing, and a stator. The double-row angular contact ball bearing is sleeved on the motor shaft and is fixedly connected to the motor shaft through a bearing inner ring of the double-row angular contact ball bearing. The stator is sleeved on the motor shaft through the double-row angular contact ball bearing, and the stator is fixedly connected to a bearing outer ring, so that the motor shaft can rotate relative to the stator. In this application, the double-row angular contact ball bearing is used in the axial motor, the double-row angular contact ball bearing can bear axial force generated through interaction between the stator and a rotor.