| 摘要 |
PROBLEM TO BE SOLVED: To provide an impact rotary tool capable of controlling fastening torque without complicatedness in constitution and an increase in cost. SOLUTION: In this impact rotary tool, a position detecting means 52 detects leading edges and trailing edges of rectangular wave magnetic detection signals outputted by magnetic sensors 12a to 12c, and generates and outputs pulses synchronous with the respective edges. In a speed detection means 22, the rotating speed of a brushless motor 1 is computed from the interval of pulses outputted by the position detecting means 52, and a detection pulse with a pulse duration corresponding to the detected speed is outputted. An impact of a hammer is detected based upon the detected speed of the brushless motor 1 detected by the speed detecting means 22 by an impact detecting means 24. Thus, the impact of an output shaft 3 caused by the hammer is detected based upon the detection result of the position detecting means 52 used for controlling the drive of the brushless motor 1, whereby it is not necessary to provide a rotary sensor 4 only for detecting the impact of the hammer as in a prior art, and the fastening torque can be controlled without complicatedness in constitution and an increase in cost. COPYRIGHT: (C)2007,JPO&INPIT
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