| 摘要 |
PURPOSE:To reduce the effect of inertia of DC motor, reduction gear mechanism, etc., by obtaining a comparison torque smaller than a preset torque from the inputted preset torque and by switching the DC motor to low speed control, when a detected torque reaches the comparison torque. CONSTITUTION:When a screw is tightened and a load applied to a DC motor M increases, the torque of the motor increases as its number of revolutions lowers. Then, when its detected torque reaches a comparison torque, a first comparator TC1 outputs a second switching signal to a switching device CH. As a result, the switching device CH switches the output state of an operation stroke signal from an operation stroke setter OSS to the output state of a control signal from a constant-speed controller CC relative to a third comparator TC3. Then, the signal is compared with a triangular-waved voltage from a triangular wave oscillator TG in the third comparator TC3. The third comparator TC3 outputs a comparison output where the DC motor M is driven at a low and constant speed. |
