A low impedance power disc is provided. The power disc is connected to a crankshaft of an engine, and includes a rotor, a connecting shaft, and a permanent magnet. The rotor is disposed separately from the permanent magnet. The connecting shaft is locked inside the rotor. A unidirectional bearing is provided and fitted on the connecting shaft. The permanent magnet is fitted on the unidirectional bearing. When the engine is running, the rotor and the permanent magnet are rotated at the same speed to generate electricity and supply the electricity to the vehicle and to charge the battery. When the engine decelerates, the rotor and the connecting shaft are decelerated synchronously with the engine, while the permanent magnet and the unidirectional bearing are continuously rotated at the speed before deceleration in order to facilitate the engine to accelerate again, so that the rotor can be quickly rotated.

A motor of a ceiling fan includes a shaft, a bearing sleeve, a limiting member, a stator and a rotor. The shaft has a first shoulder and a second shoulder. The bearing sleeve receives a first bearing and a second bearing for supporting the shaft and has an inner flange, with the inner flange and the first shoulder jointly clamping and positioning the first bearing. The limiting member and the second shoulder jointly clamp and position the second bearing. The stator is arranged around the shaft. The rotor couples with the bearing sleeve.

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 is defined by a closed shape including at least three or more straight sides, and a radius of an inscribed circle of the closed shape of the through hole is larger than a radius of the portion of the rotor received in the through hole.

Described herein are methods and system for welding, for example, girders. The method may include activating a homopolar generator. The method may include applying a force to two metal girders at a desired coupling joint. The method may include generating an electrical pulse using the homopolar generator and conducting the electrical pulse to the desired coupling joint to increase a temperature of the girders. The method may include forming a weld at the desired coupling joint attaching the two metal girders at the desired coupling joint. In some embodiments, the homopolar generator may include a radial bearing rotor including a rotatable shaft and a bearing assembly. The bearing assembly may include nonmagnetic bearings. The homopolar generator may include a field coil. The homopolar generator may include a brush actuation mechanism which when activated engages a plurality of brush devices to the radial bearing rotor.

A mine explosion-isolating hoisting device with a built-in type permanent magnet motor includes a spindle fixed on the ground; a permanent magnet motor stator fixed on the spindle; a drum rotating relative to the spindle, the drum surrounding the spindle circumferentially; and a permanent magnet motor external rotor fixed by a spoke plate and rotating relative to the spindle; the drum is connected to the permanent magnet motor external rotor via an isolating disc; and a radial distance between an outer circumferential surface of the permanent magnet motor external rotor and an inner wall of the drum is greater than a preset value.

A housing for an electric motor includes a tubular wall extending in an axial direction of the housing, and closures at opposite axial ends of the tubular wall to rotatably support opposite axial end portions of a rotor. At least one of the closures is separate from the tubular wall and includes a radially inner portion and a radially outer flange that, in an assembled state, is in physical contact with a radially inner surface of the tubular wall and extends from the radially inner portion of the separate closure towards the opposite axial end of the tubular wall.

A ratio W1/W2 of a circumferential width W1 of each of inclined hill portions G2 of a radial dynamic pressure generating portion G and a circumferential width W2 of each of inclined groove portions G3 is 1.2 or larger. And when an inner diameter of a bearing member is D, the circumferential width W2 of each of the inclined groove portions satisfies 0.2D≦W2≦0.4D.

The present invention provides a motor shell, comprising a hollow metal shaft and a plastic shell, wherein the hollow metal shaft is fixedly connected to the plastic shell, and the connection between the hollow metal shaft and the plastic shell is one of injection molding connection, glue connection and interference connection. By using the motor shell according to the present invention, problems in the prior art such as low processing precision of the motor shaft, poor wiring structure, low structural strength, no limiting for the magnetic ring and tending to deform after loading are solved.

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.

An electrical machine includes a stator with a stator body supporting an electrical stator and a rotor. The rotor is supported by a bearing having a radial bearing section forming a radial gas bearing and an axial bearing section forming an axial gas bearing, the stator side parts of these bearing sections being a stator side radial bearing part and a stator side axial bearing part that are rigidly connected to one another and together form a stator bearing structure. The stator bearing structure is mounted to the other parts of the stator by either the stator side radial or axial bearing part being rigidly mounted to these other parts, and the other bearing part are connected to these other parts by an elastic support or not at all.