There is provided a power transmission device to switch a coupled state and an uncoupled state between a first member and a second member which are arranged in a transmission path of a driving force to thereby control transmission of the driving force. The device includes a movable body having ferromagnetic property, a first magnetic path and a second magnetic path, and a permanent magnet. The device also includes a driving portion to excite the electromagnet in the forward direction and then increases an attraction force on a side on which a magnetic flux is increased or decreased.

An axially oriented, two-position linear actuator includes a fixed stator having a single stator coil and a linear movable translator. The linear actuator is oriented axially in that the stator and the translator are axially offset from one another and the translator is axially movable between first and second end positions toward and away from the stator. For the translator to move between the end positions, the stator coil attracts or repels the translator depending on the polarity of the electrical current of the stator coil. The linear actuator may be part of a clutch assembly, such as a dynamically controllable clutch, for use in controlling coupling members of the clutch assembly.

An electrically and mechanically driven automotive accessory including a housing, an electric motor, a pulley, and a pulley assist mechanism. The electric motor comprises a stator assembly that is mounted to the housing and a rotating assembly that is mounted to a shaft. The electric motor creates a primary torque flow path that drives rotation of the rotating assembly relative to the stator assembly. The pulley is rotatable relative to the shaft and the rotating assembly. The pulley assist mechanism includes a plurality of circumferentially spaced teeth nested with a conductive body, a rotor body fixedly mounted to the shaft, and an electromagnet that is configured to induce a magnetic field between the circumferentially spaced teeth, the rotor body, and the pulley, which creates a secondary torque flow path between the pulley and the rotor body.

An electrically and mechanically driven automotive accessory including a housing, an electric motor, a pulley, and a pulley assist mechanism. The electric motor comprises a stator assembly that is mounted to the housing and a rotating assembly that is mounted to a shaft. The electric motor creates a primary torque flow path that drives rotation of the rotating assembly relative to the stator assembly. The pulley is rotatable relative to the shaft and the rotating assembly. The pulley assist mechanism includes a plurality of circumferentially spaced teeth nested with a conductive body, a rotor body fixedly mounted to the shaft, and an electromagnet that is configured to induce a magnetic field between the circumferentially spaced teeth, the rotor body, and the pulley, which creates a secondary torque flow path between the pulley and the rotor body.

An electronic locking differential that includes a movable electromagnet to selectively operate a dog clutch for locking a side gear to a carrier. The dog clutch includes a dog member having a plurality of legs that extend through leg apertures in the carrier. A cam mechanism is employed on the legs and the carrier to generate and apply a force to the dog member to maintain the dog member in an engaged position when torque is transmitted through the cam mechanism. The carrier is configured with an annular rib that surrounds a pocket. The annular rib has a frustoconical shape that matches that of a pole piece on the electromagnet. The electromagnet is received into the pocket when the electromagnet is operated and the dog member is in its engaged position.

In some examples, an electromagnetic clutch assembly. The assembly includes a pair of clutch plates including a first clutch plate configured to rotate around a rotational axis; and a second clutch plate configured to rotate around the rotational axis. The assembly further includes an electromagnetic coil circumferentially surrounding the air gap, wherein the electromagnetic coil is configured to generate a magnetic flux passing through the first clutch plate and the second clutch plate, wherein the pair of clutch plates define an air gap between the first clutch plate and the second clutch plate in the absence of the magnetic flux, and wherein the magnetic flux is configured to cause at least one of the first clutch plate or the second clutch plate to move to close the air gap.

A bistable electromagnetic clutch is provided that includes a first part, a second part and an spring part. The first part includes a yoke with a plurality of iron cores, and an electromagnetic coil on each of the iron cores. The second part includes a moving carrier disc and a magnetic conductive disc that is fixed on a side of the moving carrier disc that is away from the yoke. Several magnets are fixed on the moving carrier disc, and the iron cores and the magnets are provided in a correspondence relation. The spring part is configured to keep the moving carrier disc and the yoke in normally separated positions. Two adjacent electromagnetic coils form a group, two electromagnetic coils in a same group are wound to form a group of windings with identical magnetic polarities, and corresponding two magnets form a group of magnetomotive forces with identical magnetic polarities.

A ring insertion groove is formed between adjacent two of circular plates, which are made of a magnetic material and are arranged concentric with each other, and a ring, which is made of a non-magnetic material and has a larger deformation resistance in comparison to the magnetic material of the plates, is press fitted into the ring insertion groove. Thereafter, a peripheral part around an opening of the ring insertion groove is plastically flowed, so that a compression stress is left in the ring.

An inner peripheral surface of an outer cylindrical tubular portion and an outer peripheral surface of an inner cylindrical tubular portion of a rotor are respectively shaped into a stepped form. A radial distance between the outer cylindrical tubular portion and the inner cylindrical tubular portion at a counter-armature side location is larger than that of an armature side location in the rotor. An outer peripheral surface of an outer cylindrical tubular portion and an inner peripheral surface of an inner cylindrical tubular portion of a stator are respectively shaped into a stepped form. A radial distance between the outer peripheral surface of the outer cylindrical tubular portion and the inner peripheral surface of the inner cylindrical tubular portion at the counter-armature side location is larger than that of the armature side location in the stator.

An electromagnetic brake includes a hub disposed about a shaft and configured for rotation with the shaft about a rotational axis. An electromagnet assembly is fixed against rotation about the axis and includes a housing defining axially extending, radially spaced inner and outer poles and a brake plate extending radially therebetween. A conductor is disposed between the poles on one side of the brake plate. An armature is disposed on the other side of the brake plate and coupled to a body driven by the shaft. The electromagnet assembly, armature and hub form an electromagnetic circuit when the conductor is energized urging the armature towards the brake plate. A portion of the magnetic flux in the circuit travels radially inwardly across a first radial air gap from the inner pole to the hub and then radially outwardly across a second radial air gap from the hub to the brake plate.