Abstract: An armature includes an inner plate located on an inner side of a groove and an outer plate located on an outer side of the groove. The hub includes: an outer hub; an inner hub that is coupled to a shaft; and a primary elastic member that is interposed between the inner hub and the outer hub and is configured to exert an elastic force to the outer hub in a direction away from a rotor. The outer hub includes an outer side coupling portion that is opposed to the outer plate and the inner plate and is coupled to the outer plate. The hub includes a secondary elastic member that is clamped between: the outer plate and the inner plate located on one side of the secondary elastic member; and the outer side coupling portion located on another side of the secondary elastic member.

Abstract: A power transmission device includes an electromagnet, a rotor, an armature and a hub that couples the armature to a shaft of a driving target device. The hub includes an outer hub coupled to the armature, an inner hub coupled to the shaft, and an elastic member interposed between the outer hub and the inner hub. An outer peripheral side of the inner hub includes plural extending parts each extending outward in a radial direction. An inner peripheral side of the outer hub includes an inner peripheral side wall that overlaps with the extending parts in a rotational direction and surrounds the extending parts. The elastic member is disposed in an unbonded state with respect to at least one of the inner hub and the outer hub between the outer peripheral side of the inner hub and the inner peripheral side of the outer hub.

Abstract: An armature includes an inner plate located on an inner side of a groove and an outer plate located on an outer side of the groove. The hub includes: an outer hub; an inner hub that is coupled to a shaft; and a primary elastic member that is interposed between the inner hub and the outer hub and is configured to exert an elastic force to the outer hub in a direction away from a rotor. The outer hub includes an outer side coupling portion that is opposed to the outer plate and the inner plate and is coupled to the outer plate. The hub includes a secondary elastic member that is clamped between: the outer plate and the inner plate located on one side of the secondary elastic member; and the outer side coupling portion located on another side of the secondary elastic member.

Abstract: A power transmission device includes an electromagnet, a rotor, an armature and a hub that couples the armature to a shaft of a driving target device. The hub includes an outer hub coupled to the armature, an inner hub coupled to the shaft, and an elastic member interposed between the outer hub and the inner hub. An outer peripheral side of the inner hub includes plural extending parts each extending outward in a radial direction. An inner peripheral side of the outer hub includes an inner peripheral side wall that overlaps with the extending parts in a rotational direction and surrounds the extending parts. The elastic member is disposed in an unbonded state with respect to at least one of the inner hub and the outer hub between the outer peripheral side of the inner hub and the inner peripheral side of the outer hub.