Electromagnetic clutch
View Patent ↗An electromagnetic clutch ( 20 ) capable of connecting and disconnecting a driving power source and a rotary shaft ( 22 ) includes a rotor ( 25 ) rotated by the driving power source, and an armature ( 40 ) capable of being attracted to the rotor ( 25 ) by electromagnetic force to produce a transmission force transmitted from the rotor ( 25 ) to the rotary shaft ( 22 ). The electromagnetic clutch ( 20 ) further includes leaf springs ( 52 ) urging the armature ( 40 ) in such a direction as to separate the armature from the rotor ( 25 ). The leaf springs ( 52 ) each assume an orientation such that a boost force assisting the attractive force acting upon the armature ( 40 ) is produced based on the transmission force when the armature ( 40 ) is attracted to the rotor ( 40 ).
1. An electromagnetic clutch capable of connecting and disconnecting a driving power source and a rotary shaft, comprising:
a rotor arranged around the rotary shaft coaxially therewith and adapted to be rotated by the driving power source;
an electromagnetic force generator including an electromagnetic coil arranged inside the rotor, the electromagnetic force generator producing an electromagnetic force when the electromagnetic coil is energized;
an armature arranged close to the rotor and capable of being attracted to the rotor by the electromagnetic force to produce a transmission force transmitted from the rotor to the rotary shaft; and
a coupler coupling the armature and the rotary shaft to each other, the coupler including a connecting member coupled to the rotary shaft, and leaf springs coupling the connecting member and the armature to each other and urging the armature in such a direction as to separate the armature from the rotor,
wherein each of the leaf springs has a portion inclined with respect to the armature, the inclined portion being inclined at an angle falling within a range in which the armature is separable from the rotor when the electromagnetic coil is de-energized during rotation of the armature together with the rotor, and the connecting member has mounting portions to which inner ends of the respective leaf springs are attached, each of the mounting portions being inclined at an angle corresponding to the angle of inclination of the leaf springs, and
wherein each of the leaf springs has inner and outer ends as viewed in a radial direction of the armature, the inner end of each of the leaf springs is located more forward than the outer end, as viewed in a rotating direction of the armature, and separated farther from the armature than the outer end, and the inner end of each of the leaf springs is formed as a folded portion, the folded portion clamping the corresponding mounting portion therein, and
wherein the leaf springs each assume an orientation such that a boost force assisting an attractive force acting on the armature is produced based on the transmission force when the armature is attracted to the rotor.
2. The electromagnetic clutch according to claim 1 , wherein the armature has fixing holes into which the outer ends of the respective leaf springs are inserted.