Method for Monitoring the Output of an Electromechanical Actuator of the Rotary-Linear Type

Method for monitoring the output of an electromechanical actuator of the rotary-linear type in order to detect gradual seizing of said actuator, said actuator comprising:

• a casing (1),
• rotary electric motor means (M) including at least one field winding (4),
• at least one nut (2) rotatably supported in bearings (3) of said casing (1) and integral in rotation with said motor means (M),
• at least one actuator rod (6) arranged coaxially with the nut (2), said nut (2) and said actuator rod (6) being coupled in rotation by axial helical meshing means (7, 9),
• means (17) for locking the actuator rod (6) in rotation relative to the casing (1) so that the rotation of the nut (2) leads to a linear displacement of the actuator rod (6),
• means (13) provided on the casing (1) for fastening the casing (1) to a fixed or displaceable component, and
• means (16) provided on the actuator rod (6) for fastening the free end (15) of the actuator rod (6) to a component that is respectively displaceable or fixed, this method being characterized by the following steps:
• a)—the intensity of the electric current powering the field winding (4) is measured, said intensity being representative of the motor torque, and
• a stress representative of the axial stress to which the actuator rod (6) is subjected, is measured,
• b) from these measurements, the [axial stress to which the actuator rod is subjected/motor torque] ratio, which is representative of the overall output of the actuator and representative of the present state of the actuator, is calculated,
• c) an evaluation of the present state of health of the actuator is produced that is based on the present state of the actuator and optionally on previous stored states of the actuator and/or on external parameters.