Elevator safety brake, elevator and method for testing elevator safety brakes

An elevator comprising:

• an elevator car movable up and down along guide rails in an elevator shaft by an elevator driving machinery, the elevator driving machinery comprising:
• a drive motor;
• a traction sheave;
• and
• a brake assembly to stop the rotational motion of the traction sheave,
• wherein the brake assembly comprises a plurality of elevator safety brake units that are operatively associated with the drive motor and are spaced apart from each other, each elevator safety brake unit including:
• a frame part;
• a movable composition comprising a plurality of movable elements, the plurality of movable elements being movably supported on said frame part;
• a compression spring assembly associated with said movable composition, and configured to press each movable element in a first direction to cause the movable elements to be urged to activate a braking;
• and
• an electromagnet having a coil assembly is disposed in the frame part, the electromagnet being configured to, upon an electric current being applied to the coil assembly, apply a force to the movable elements in the movable composition in a second direction opposite to the first direction to cause the movable elements to deactivate the braking, and
• wherein, for each elevator safety brake unit, the elevator safety brake assembly is configured to:
• apply a first electric current to the coil assembly to cause at least one first movable element but not all movable elements of the movable composition to move in the second direction, pulled by the electromagnet, to selectively deactivate the braking activated by the at least one first movable element, and
• apply a second electric current, greater than the first electric current, to the coil assembly to cause at least one second movable element of the movable composition, other than the at least one first movable element, to move in the second direction, pulled by the electromagnet, to selectively deactivate the braking activated by the at least one second movable element.

A method for testing elevator safety brake units an elevator including:

• an elevator car movable up and down along guide rails in an elevator shaft by an elevator driving machinery, the elevator driving machinery comprising:
• a drive motor;
• a traction sheave;
• and
• a brake assembly to stop the rotational motion of the traction sheave, the brake assembly including at least two elevator safety brake units of the elevator driving machinery, each safety brake unit comprising N movable elements, where N is an integer greater than one, the method comprising:
• a) actuating less than N, movable elements of a first elevator safety brake unit among the at least two elevator safety brake units and providing, with a drive motor, a test torque to test the actuated movable elements of the first elevator safety brake unit;
• and
• actuating all movable elements of the other elevator safety brake units while keeping all movable elements of a first elevator safety brake unit open, and providing, with a drive motor, a test torque to test the actuated movable elements of the other elevator safety brake units.