Brake for motor

A brake for a motor comprising:

• a fixed-side engaging plate attached to a motor shaft subject to control, so as to rotate integrally with the motor shaft and not move in a direction of a center axis;
• a movable-side engaging plate coaxially facing the fixed-side engaging plate in the direction of the center axis;
• and
• a solenoid for moving the movable-side engaging plate along the direction of the center axis to a halt cancelation position where the movable-side gaping plate is set apart from the fixed-side engaging plate and to a halt position where the movable-side engaging plate is engaged with the fixed-side engaging plate,
• wherein
• the movable-side engaging plate comprises:
• a movable-side end face facing the fixed-side engaging plate;
• an annular protrusion protruding from the movable-side end face in the direction of the center axis;
• outer peripheral engagement protrusions protruding arcuately and radially outward, formed at a first angular interval along a circular outer peripheral surface of the annular protrusion;
• and
• inner peripheral engagement protrusions protruding arcuately and radially inward, formed at a second angular interval along a circular inner peripheral surface of the annular protrusion,
• wherein
• the fixed-side engaging plate comprises:
• a fixed-side end face facing the movable-side end face;
• an annular groove into which the annular protrusion can be inserted in the direction of the center axis, the annular groove being formed on the fixed-side end face;
• outer peripheral engagement recesses formed in a circular inner peripheral surface of the annular groove, the circular inner peripheral surface being a groove-side surface on an outer peripheral side of the annular groove, and the outer peripheral engagement recesses being formed at the first angular interval along the circular inner peripheral surface;
• and
• inner peripheral engagement recesses formed in a circular outer peripheral surface of the annular groove, the circular outer peripheral surface being a groove-side surface on an inner peripheral side of the annular groove, and the inner peripheral engagement recesses being formed at the second angular interval along the circular outer peripheral surface,
• wherein
• recess ends of the outer peripheral engagement recesses toward the outer peripheral engagement protrusions are opened so that the outer peripheral engagement protrusions can be inserted in the direction of the center axis;
• and
• recess ends of the inner peripheral engagement recesses toward the inner peripheral engagement protrusions are opened so that the inner peripheral engagement protrusions can be inserted in the direction of the center axis;
• and
• the annular protrusion of the movable-side engaging plate is provided with an annular distal-end portion protruding on a side of the fixed-side engaging plate to a greater extent than the outer peripheral engagement protrusions and the inner peripheral engagement protrusions, and
• wherein
• when the movable-side engaging plate is in the halt cancelation position, only the annular distal-end portion of the annular protrusion is inserted in the annular groove of the fixed-side engaging plate;
• the outer peripheral engagement protrusions and the inner peripheral engagement protrusions disengage from the outer peripheral engagement recesses and the toner peripheral engagement recesses, respectively, and the fixed-side engaging plate and the movable-side engaging plate are capable of rotating relative to each other;
• and
• when the movable-side engaging plate is in the halt position, the outer peripheral engagement protrusions and the inner peripheral engagement protrusions are respectively inserted in the outer peripheral engagement recesses and the inner peripheral engagement recesses, and the fixed-side engaging plate and the movable-side engaging plate are in an engaged state in which relative rotation therebetween is impossible.