Electric motor arrangement adapted for use in an actuator and an actuator including the motor arrangement

A method of braking an actuator included in a linear type safety actuator unit, said actuator unit (100), including an electric motor (1) driving a linear actuator (2) of, said motor (1) having a casing (11), a stator (14, 15) fixed to the casing, a rotor (13) fixed to a rotary part (10), a rotary motor shaft (10), wherein said rotary part (10) is arranged to be operatively connected to a reduction gear (5) which drives the mechanical output of the actuator (2), a separate magnetic brake unit (3), said magnetic brake (3) including a rotating brake member (30, 31) connected to the motor shaft (10), directly or indirectly, and a plurality of fixed brake members (32, 33), wherein said magnetic brake (3) produces a torque that will strive to position a rotary member (10, 20) with said rotating brake member (30, 31) into one or more specific angular positions in relation to the fixed brake members (32, 33), characterized by providing said rotating brake member (30, 31) in the form of a separate permanent magnet annulus (30, 31) attached to said rotary member (10, 20) combined with having said fixed brake members (32, 33) in the form of separate magnetic pole pieces (32, 33) apart from the stator (14, 15) that brakes the motor at low rotational speeds and by providing the actuator unit (100) with a circuitry (101) including a short circuiting arrangement (113, 103) enabling braking of the motor (1) at rotational speeds above low rotational speeds.