US Patent 9427852 Rotary impact tool

A rotary impact tool comprises: a motor that is a rotation driving source; an impact generation device for generating a pulse impact by rotation of the motor and applying a rotational torque to an output shaft by the impact; a torque sensor for measuring the torque applied to the output shaft; and a control means for halting the motor when the torque measured by the torque sensor has reached a target torque having been set. The control means is configured to change an increased torque value for one impact according to the target torque having been set.