A rotor for an electric machine, especially a generator of a direct drive wind turbine, includes a cylindrical rotor housing with several magnet means arranged at the inner housing surface, wherein each magnet means includes several magnet elements arranged in a row parallel to an axis of rotation, wherein the inner housing surface is provided with at least one groove-like recesses extending parallel to the axis of rotation, wherein each recess is covered by the magnet elements of a row, and wherein at least two magnet elements in at least some of the rows are arranged with at least one gap extending in the circumferential direction, which gap communicates with the respective recess.

A slot-less motor includes a rotor and a stator which is equipped with a coil assembly made of a combination of a plurality of coils. Each of the coils is designed as an air core coil which includes a pair of effective coil portions and a pair of coil ends. The coils assembly has the effective coil portions each of which is disposed in air cores of the respective adjacent coils. The coils include first coils each of which is not located between a center line and each of outer outlines of a respective adjacent one of the first coils.

A slot-less motor includes a rotor and a stator which is equipped with a coil assembly made of a combination of a plurality of coils. Each of the coils is designed as an air core coil which includes a pair of effective coil portions and a pair of coil ends. The coils assembly has the effective coil portions each of which is disposed in air cores of the respective adjacent coils. The coils include first coils each of which is not located between a center line and each of outer outlines of a respective adjacent one of the first coils.

A rotor includes a rotor hub including a through-hole to which the shaft is fixed. An upper end and a lower end of an opposing region where an outer peripheral surface of the shaft and an inner peripheral surface of the through-hole oppose each other in a radial direction are respectively provided with an upper gap portion and a lower gap portion opposing each other through a space in the radial direction. The upper gap portion and the lower gap portion each include a bottom portion extending in a direction intersecting the center axis and a peripheral wall portion connected to a radial outer edge of the bottom portion and extending along the center axis.

A rotor includes a rotor hub including a through-hole to which the shaft is fixed. An upper end and a lower end of an opposing region where an outer peripheral surface of the shaft and an inner peripheral surface of the through-hole oppose each other in a radial direction are respectively provided with an upper gap portion and a lower gap portion opposing each other through a space in the radial direction. The upper gap portion and the lower gap portion each include a bottom portion extending in a direction intersecting the center axis and a peripheral wall portion connected to a radial outer edge of the bottom portion and extending along the center axis.

An electric work machine includes coils formed reliably. The machine includes a stator, a rotor rotatable about a rotation axis, and an output unit drivable by the rotor. The stator includes a stator core including a cylindrical yoke and teeth protruding radially outward from the yoke, an insulator fixed to the stator core, and coils each wound around a corresponding one of the teeth with the insulator in between. The insulator includes a first cover covering a first end face of the yoke in a first axial direction and a rib on the first cover and supporting a wire connecting the coils. The rotor includes a rotor core outside a periphery of the stator and a magnet fixed to the rotor core.

An electric work machine includes coils formed reliably. The machine includes a stator, a rotor rotatable about a rotation axis, and an output unit drivable by the rotor. The stator includes a stator core including a cylindrical yoke and teeth protruding radially outward from the yoke, an insulator fixed to the stator core, and coils each wound around a corresponding one of the teeth with the insulator in between. The insulator includes a first cover covering a first end face of the yoke in a first axial direction and a rib on the first cover and supporting a wire connecting the coils. The rotor includes a rotor core outside a periphery of the stator and a magnet fixed to the rotor core.

An electric work machine can appropriately detect rotation of a rotor. The electric work machine includes a stator including a stator core, an insulator fixed to the stator core, and a coil attached to the insulator, a rotor rotatable about a rotation axis and including a rotor core and a magnet fixed to the rotor core, a stator base supporting the stator, a sensor board supported by the stator base and including a magnetic sensor that detects the magnet, and an output unit drivable by the rotor.

An electric work machine can appropriately detect rotation of a rotor. The electric work machine includes a stator including a stator core, an insulator fixed to the stator core, and a coil attached to the insulator, a rotor rotatable about a rotation axis and including a rotor core and a magnet fixed to the rotor core, a stator base supporting the stator, a sensor board supported by the stator base and including a magnetic sensor that detects the magnet, and an output unit drivable by the rotor.

An electric power generator is provided for a human-powered vehicle. The electric power generator includes an axle, a stator, a rotor and a first electrical cable. The axle has a first axial end, and a second axial end. The stator has a first axial stator-end that faces the first axial end of the axle with respect to the rotational center axis and a second axial stator-end that faces the second axial end of the axle with respect to the rotational center axis. The rotor is rotatably mounted on the axle to rotate around a rotational center axis of the electric power generator. The first electrical cable is electrically connected to the stator on the first axial stator-end of the stator. The first electrical cable extends axially through the stator toward the second axial stator-end of the stator with respect to the rotational center axis.