An electric propulsion system, comprising a propeller and a motor arranged to rotate the propeller, the motor comprising an axial flux motor comprising a rotor disc and a stator disc mounted in face-to-face relationship with an air gap defined therebetween, the rotor disc driven to rotate relative to the stator disc to cause magnetic flux in the air gap to cause rotation of the propeller, characterised in that the propeller is directly attached to the rotor disc to rotate with the rotor disc.

A rotor for an electric motor, comprising a rotor magnet and a bearing for the rotatable support on a fixed axle, the bearing comprising first and second bearing half-shells, wherein at least the first bearing half-shell is moveably arranged within the rotor body with respect to the second bearing half-shell, and wherein the first bearing half-shell is supported against the rotor body by a resilient element tangentially arranged with respect to the axle. The resilient element, at both its side surfaces facing in an axial direction of the axle, has at least one respective first protrusion extending in the axial direction, and the first bearing half-shell, on a side facing away from its bearing surface, includes at least two axially spaced second protrusions each extending in a radial direction and cooperating with the first protrusions for aligning the resilient element.

A generator for a wind turbine has a rotor and a stator separated radially by an air gap, wherein the stator includes at least one stator segment, which includes a stack of lamination sheets and at least one stator winding, and a stator support structure supporting the at least one stator segment, wherein the generator further includes a cooling arrangement for providing cooling fluid at least to the air gap, wherein the cooling arrangement further includes a cooling fluid flow dividing element for dividing an incoming cooling fluid flow to the stator into a first partial cooling fluid flow directed to the air gap and a second partial cooling fluid flow directed to the stator support structure.

According to one embodiment, a disk device includes a housing including a base with a bottom wall, a drive motor including a pivot erected on the bottom wall and a hub rotatably supported around the pivot, ten or more magnetic disks attached to the hub and stacked on a flange of the hub, and spacer rings attached to the hub and each disposed between each respective adjacent pair of two magnetic disks. A number of the spacer rings is one less than the magnetic disks. At least one spacer ring has a thickness different from that of the other spacer rings, and a difference between a maximum thickness and a minimum thickness of the spacer rings is 0.01 mm or more and 0.09 mm or less.

An embodiment may provide a motor including a shaft, a rotor including a rotor core and a coil disposed on the rotor core, a stator disposed outside the rotor, a substrate electrically connected to the coil, and a first housing in which the substrate is disposed and which is coupled to the shaft and the rotor, wherein the substrate includes a sensor and a coil connected to the sensor, the first housing includes a hole, the stator includes a yoke and a magnet disposed on the yoke, the yoke includes a plurality of protrusions, and the protrusions and the hole are disposed to overlap the coil in an axial direction.

An electric motor includes a housing with a tubular wall extending in an axial direction of the housing and a closures positioned at opposite axial ends of the tubular wall, a stator fixedly mounted inside of the housing, a rotor rotatably mounted inside of the housing, and a bearing rotatably supporting the rotor. At least one of the closures includes a rotor supporting portion. The rotor supporting portion includes a through hole configured to receive a portion of the rotor. The through hole has a triangular or polygonal shape, and a radius of an inscribed circle of the triangular or polygonal shape of the through hole is larger than a radius of the portion of the rotor received in the through hole.

According to one embodiment, a disk device includes a housing including a base with a bottom wall, a drive motor including a pivot erected on the bottom wall and a hub rotatably supported around the pivot, ten or more magnetic disks attached to the hub and stacked on a flange of the hub, and spacer rings attached to the hub and each disposed between each respective adjacent pair of two magnetic disks. A number of the spacer rings is one less than the magnetic disks. At least one spacer ring has a thickness different from that of the other spacer rings, and a difference between a maximum thickness and a minimum thickness of the spacer rings is 0.01 mm or more and 0.09 mm or less.

A spindle motor is provided, the motor comprising: a base plate, a PCB on the base plate, a bearing assembly arranged on the base plate, a stator coupled to a periphery of the bearing assembly, a rotor rotationally coupled to the bearing assembly, the rotor including a yoke and a magnet, and a rotation shaft rotationally coupled to the bearing assembly. The base plate includes a planar portion and a protruding portion arranged along with a periphery of the yoke, the protruding portion being apart from the yoke. The base plate is partially covered with the PCB in a region where the stator is arranged. And, a height from the planar portion to an upper surface of the protruding portion is smaller than a height from the planar portion to a lower surface of the periphery of the yoke.

A magnetic disk device includes a disk, first and second heads, a motor, and a controller. The disk includes a first surface and a second surface opposite to the first surface. The first head is configured to perform reading and writing with respect to the first surface. The second head is configured to perform reading and writing with respect to the second surface. The motor is configured to move the first and second heads with respect to the first and second surfaces, respectively, along a radial direction of the disk. The controller is configured to alternately activate the first and second heads to perform writing of a plurality of spiral patterns on the first and second surfaces of the disk, respectively, while controlling the motor to move the first and second heads at a predetermined constant speed with respect to the first and second surfaces in the radial direction.

A motor assembly includes a first bearing installed on a rotating shaft adjacent to an impeller to support a first support part of the rotating shaft, a second bearing installed on the rotating shaft adjacent to the rotor to support a second support part of the rotating shaft, a bearing bracket receiving the first and second bearings therein, an elastic member inserted between the first bearing and the bearing bracket or between the second bearing and the bearing bracket to press either the first bearing or the second bearing to get closer to each other, and a separation preventing member installed on the bearing bracket to fix the first bearing, the second bearing and the elastic member to an inner space of the bearing bracket such that at least one portion of the separation preventing member overlaps with one of the first bearing, the second bearing and the elastic member.