Abstract: When a control unit starts to supply power to an electromagnetic coil in a first direction, a magnetic force generated by a non-attracting magnetic circuit becomes larger than a magnetic attraction force generated by an attracting magnetic circuit. As a result, a movable member is guided by a guide portion of a yoke and moves to a second position from a first position. When the control unit starts to supply power to an electromagnetic coil in a second direction, the magnetic attraction force generated by the attracting magnetic circuit becomes larger than the magnetic force generated by the non-attracting magnetic circuit. As a result, the movable member is guided by the guide portion and moves to the first position from the second position. Accordingly, the movable member can reliably perform a moving operation when turning ON/OFF.

Abstract: 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.

Abstract: When a clutch relay connects between a control device and a vehicle electric power source in response to outputting of a clutch OFF signal from an electronic control device to the clutch relay, a timer circuit starts a control operation for energizing coil portions. When a predetermined time period elapses, the timer circuit terminates energization of the coil portions. When the clutch relay connects between the control device and the vehicle electric power source in response to outputting of a clutch ON signal from the electronic control device to the relay, the timer circuit starts a control operation for energizing the coil portions. When a predetermined time period elapses, the timer circuit terminates energization of the coil portions.

Abstract: When a clutch relay connects between a control device and a vehicle electric power source in response to outputting of a clutch OFF signal from an electronic control device to the clutch relay, a timer circuit starts a control operation for energizing coil portions. When a predetermined time period elapses, the timer circuit terminates energization of the coil portions. When the clutch relay connects between the control device and the vehicle electric power source in response to outputting of a clutch ON signal from the electronic control device to the relay, the timer circuit starts a control operation for energizing the coil portions. When a predetermined time period elapses, the timer circuit terminates energization of the coil portions.

Abstract: 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.

Abstract: An electromagnetic clutch provided with an armature in which two or more non-magnetic sections of differing radii are provided and which is installed on a rotary shaft, a rotor in which three or more non-magnetic section of differing radii that do not overlap with the non-magnetic sections are provided on a friction plate that faces the armature, and which rotates with respect to the rotation shaft by external force, a stator equipped with an electromagnetic coil for fixing the armature to the rotor by applying magnetic flux, which is generated by passage of an electric current, on the friction plate, and a control device for the electromagnetic coil.

Abstract: When a control unit starts to supply power to an electromagnetic coil in a first direction, a magnetic force generated by a non-attracting magnetic circuit becomes larger than a magnetic attraction force generated by an attracting magnetic circuit. As a result, a movable member is guided by a guide portion of a yoke and moves to a second position from a first position. When the control unit starts to supply power to an electromagnetic coil in a second direction, the magnetic attraction force generated by the attracting magnetic circuit becomes larger than the magnetic force generated by the non-attracting magnetic circuit. As a result, the movable member is guided by the guide portion and moves to the first position from the second position. Accordingly, the movable member can reliably perform a moving operation when turning ON/OFF.