Abstract: To provide an electromagnetic clutch that prevents an armature from being reattracted to a rotor after a bridge wire is cut. Provided is an electromagnetic clutch 10 provided with a power interruption device 50 that forcibly interrupts power transmission to an electromagnetic coil 42. The power interruption device 50 includes a thermally-actuated member 51 attached to a rotor 21 and displaced at over a predetermined temperature, and a bridge wire 52 extending as a part of ground wire of the electromagnetic coil 42 and stretched across an area where the thermally-actuated member moves along with rotation of the rotor 21. The thermally-actuated member 51 is displaced to collide with and cut the bridge wire. The bridge wire 52 has a cutting region apart from a position where the displaced thermally-actuated member 51 collides with the bridge wire 52.

Abstract: Electromagnetic clutch having an electromagnetic coil 42 that causes magnetic attraction between a rotor and an armature is wound around bobbin 41. The bobbin includes: an inner wall 41d and an outer wall 41d, which extend opposite toward a bimetal; and an inner abutment portion 41g and an outer abutment portion 41f, which extend from each extension end of the inner wall 41d and the outer wall 41e toward inner and outer opening edges of a ring case 43 for accommodating the bobbin 41. The inner abutment portion 41f and the outer abutment portion 41g abut the inner and outer opening edges of the ring case 43, by which the bobbin 41 is positioned and accommodated in the ring case 43. In addition, a bridge wire 52 is stretched at the same height on the inner wall 41d and the outer wall 41e.

Abstract: In this electromagnetic clutch, a compressive force is generated in a plate spring when an armature plate is contact with a first rotor. Therefore, a force in the direction away from the first rotor acts on a first bent portion of a plate spring. However, an extension portion of a second rotor is capable of abutting to the first bent portion from the direction opposite to the first rotor. So a stress generated in the first bent portion is dispersed to the extension portion.

Abstract: When an armature plate is attracted to a rotor so that the turning force of the rotor is transmitted to the armature plate, the turning force of the armature plate is transmitted to a main shaft via a plate spring. An angle (hereinafter referred to as a slope angle) formed between the plate spring and the armature plate is set so as to be not smaller than 10° and not larger than 63°. Therefore, since the slope angle is larger than the slope angle (about 3°) of the general electromagnetic clutch, the torque increase effect increases about 5 percent as compared with the general electromagnetic clutch, and also an excessive pressing force of the plate spring does not develop.

Abstract: An electromagnetic clutch according to the present invention includes a rotor unit (11) intended to receive power from an engine of a vehicle. The rotor unit (11) has a pulley (111) around which an endless belt is passed, and a rotor (112) disposed inside the pulley (111). The pulley (111) and the rotor (112) are integrally joined together by fitting dowels (111c) projecting from an inner cylindrical surface of an inner rim (111a) of the pulley (112), into holes (112d) in an outer cylindrical surface of the rotor (112) and caulking the dowels to join the dowels and the holes (112d) together.

Abstract: In this electromagnetic clutch, only each of the plate springs is connected to the second rotor by first connecting members. Therefore, each of the first holes of the plate springs is accurately positioned to the position of each of the second holes of the extended portion. That is, it is not necessary to provide a useless gap between the first connecting members and the each of the holes. Also, the extended portion of the second rotor is opposed to the armature plate in the axial direction. Therefore, the inner diameter of the armature plate can be formed small irrespective of the extended portion.

Abstract: In this electromagnetic clutch, a compressive force is generated in a plate spring when an armature plate is contact with a first rotor. Therefore, a force in the direction away from the first rotor acts on a first bent portion of a plate spring. However, an extension portion of a second rotor is capable of abutting to the first bent portion from the direction opposite to the first rotor. So a stress generated in the first bent portion is dispersed to the extension portion.

Abstract: When an armature plate is attracted to a rotor so that the turning force of the rotor is transmitted to the armature plate, the turning force of the armature plate is transmitted to a main shaft via a plate spring. An angle (hereinafter referred to as a slope angle) formed between the plate spring and the armature plate is set so as to be not smaller than 10° and not larger than 63°. Therefore, since the slope angle is larger than the slope angle (about 30) of the general electromagnetic clutch, the torque increase effect increases about 5 percent as compared with the general electromagnetic clutch, and also an excessive pressing force of the plate spring does not develop.