An electromechanical actuator, EMA, assembly operable in a plurality of modes, the EMA assembly comprising: an electrical motor having a motor shaft (201) extending along an axis (A) of the EMA, the motor driving the shaft to rotate about the axis; a gear assembly (401, 402) mounted around, and in geared connection with the shaft, to rotate with the shaft; an EMA output (300) connected to the gear assembly such that rotation of the motor shaft causes rotation of the output via the gear assembly, the output rotating at a speed which is a predetermined fraction of the speed of rotation of the motor shaft based on the gear ratio of the gear assembly; wherein the output is arranged to have a neutral position and to be rotatable away from the neutral position in a first, positive, extension direction to an extension position and away from the neutral position in a second, negative, retraction direction to a retracted position; a torque limiter (900) having a predetermined torque limit, wherein the torque limiter is arranged to limit torque transfer between the gear assembly and the output; an anti-extension mechanism (14, 140, 145) moveable between an engaged position in which it inhibits rotation of the output in the extension direction and a disengaged position wherein it allows rotation of the output in the extension direction, the anti-extension mechanism comprising a solenoid and a ratchet wheel and an anti-extension spring, wherein the anti-extension mechanism is in the disengaged position when the solenoid is energized to move the ratchet against the force of the anti-extension spring and is in the engaged position when the solenoid is not energized; wherein, in an active mode of the plurality of modes, the solenoid is energized and wherein rotation of the output shaft in either direction of rotation drives the output to rotate; wherein in an anti-extension mode, the solenoid is not energized and, when the output is at the neutral position or in the extension position, the output shaft is connected for rotation, via the ratchet, wherein the ratchet is arranged to prevent rotation of the output shaft in the extension direction of rotation; and wherein the torque limiter disengages the anti-extension mechanism in the event that the predetermined torque limit is reached; wherein in the anti-extension mode and when the output is in the retracted position, the torque limiter is adjusted to disengage the anti-extension mechanism at a torque lower than the predetermined torque limit., and/or when the output position is approaching an end stop position the torque limiter is adjusted to disengage the anti-extension mechanism at a torque lower than the predetermined torque limit.
EMA DROOP FUNCTION AND STOPS PROTECTION MANAGEMENT
STOPPSSCHUTZVERWALTUNG FÜR EINEN EMA MIT DROOP-FUNKTION
GESTION DE PROTECTION D'ARRÊT D'UN EMA AVEC POSITION NEGATIVE
2024-07-17
Patent
Electronic Resource
English
Automotive engineering | 1979
|Cathodic protection stops tank corrosion
Engineering Index Backfile | 1946
SAE Technical Papers | 1937
|