Patent ID: 6910540

Claim:
A torque control system for an electrically driven rotating tool, said tool comprising: a grip portion containing therein an electric motor, a driven shaft coupled to an output shaft of said electric motor via a speed-reduction mechanism so as to be used as a working shaft, a clutch mechanism equipped with a cam engaging section which makes a clutch operation that severs a coupling between said output shaft and said driven shaft when a load torque that exceeds a predetermined value acts on said driven shaft, a torque setting mechanism in which an actuation point of said clutch mechanism to sever a coupling between said output shaft and said driven shaft is adjusted as a set torque value, and a torque detection mechanism which detects said clutch operation in a cam engaging section of said clutch mechanism to sever a coupling between said output shaft and said driven shaft and which performs a drive stop control of said electric motor wherein said cam engaging section of said clutch mechanism is comprised of a combination of a clutch cam surface and a steel ball, said clutch cam surface being formed with a projecting portion that makes a clutch operation on a circumference of said driven shaft, and said steel ball facing and elastically engaging with said clutch cam surface via said torque setting mechanism; and said torque detection mechanism is comprised of a magnet and a magnetic sensor provided on a circumference of said driven shaft, so that said torque detection mechanism detects completion of clutch operation which occurs when a load torque that exceeds a predetermined value acts on said driven shaft and said projecting portion of said clutch cam surface rides over said steel ball to release a cam engagement thus performing said drive stop control of said electric motor.