| 摘要 |
<p>The invention relates to a power screwdriver (10) comprising a motor (12) as the drive, a desired torque default element (52) and an actual torque determination element (46), a torque gradient determination element (48) and a motor control (40) which controls the motor (12) depending on the torque gradient (dmd_lst/dt). The invention is characterized by a torque threshold determination element (50) which provides a torque threshold value (Md_Lim, Md_Lim1, Md_Lim2) that depends on the torque gradient (dmd_lst/dt) and lies below the desired torque value (Md_Soll). If the actual torque value (md_Ist) exceeds the torque threshold value (Md_Lim, Md_Lim1, Md_Lim2), a motor control (40) presets a speed reduction for the motor (12) or already completely switches off the motor (12). The power screwdriver (10) according to the invention avoids torque overshoots and yet allows the desired torque value (Md_Soll) to be exactly reached in the shortest time possible.</p> |
