| CPC F16D 63/004 (2013.01) [F16D 55/28 (2013.01); F16D 59/02 (2013.01); F16D 65/186 (2013.01); H01F 7/122 (2013.01); H02K 7/1025 (2013.01); F16D 55/08 (2013.01); F16D 2121/22 (2013.01); F16D 2129/065 (2013.01)] | 10 Claims |
|
1. An electromagnetic braking device for braking movement of a rotation shaft of a braking target, the electromagnetic braking device comprising:
a brake disk rotatable integrally with the rotation shaft and slidable along a central axis of the rotation shaft;
a fixed disk disposed facing one side of, and coaxially with, the brake disk;
an armature disposed facing another side of, and coaxial with, the brake disk, and slidable along the central axis;
a biasing member for biasing the armature in a direction in which the brake disk is disposed; and
a stator disposed with respect to the armature on a side opposite to a side where the brake disk is disposed, and capable of generating a magnetic force for attracting the armature in a direction away from the brake disk, wherein
the stator includes a coil and a stator magnetic circuit member, which includes a first yoke, a permanent magnet, and a second yoke,
the stator magnetic circuit member has a substantial U shape that surrounds the coil in a cross-sectional view of a surface obtained by cutting by a plane including the central axis, and is disposed so that one end surface on one end side, and another end surface on another end side, of the U shape face the armature,
elements of the stator magnetic circuit member are arranged, from one end to another end of the U shape, in order of the first yoke, the permanent magnet, and the second yoke,
at least one of the one end side and the another end side of the U shape stator magnetic circuit member includes a first portion having a first width and a second portion having a second width which is narrower than the first width of the first portion when viewed in the cross-sectional view of the surface obtained by cutting by the plane including the central axis of the stator,
a portion between the first portion and the second portion of the stator magnetic circuit member is stepped on a portion closer to the armature than a center of the coil,
the permanent magnet is in the first portion, and
the electromagnetic braking device is configured so that
in a rotatable state in which the rotation shaft is rotatable, the armature is held in contact with the one end surface and the other end surface of the stator magnetic circuit member even while energization to the coil is OFF,
when, while in the rotatable state, a current of a predetermined magnitude in a first direction flows through the coil, the armature moves toward the brake disk and contacts the brake disk to shift to a rotation braking state in which rotation of the rotation shaft is braked,
in the rotation braking state, the brake disk is held in a state of being sandwiched between the armature and the fixed disk while being in contact therewith even while energization of the coil is OFF, and
when, while in the rotation braking state, a current having a predetermined magnitude flows through the coil in a second direction opposite to the first direction, the armature moves toward the stator, and the brake disk is released from contact between the armature and the fixed disk to shift to the rotatable state.
|