Torque control method for power rotary tool

Abstract

A torque control system for electrically driven rotating tools capable of always properly and efficiently effecting constant-torque tightening of screws or the like and capable of easily achieving the miniaturization of the whole device and the improvement in torque control accuracy, the torque control system comprising a clutch mechanism that, when a load torque of predetermined value or above acts on a driven shaft joined to the output shaft of an electric motor, operates to cut off the engagement between the output shaft and the driven shaft, a torque setting mechanism that adjusts the engagement point for the clutch mechanism, and a torque detecting mechanism (42) for detecting the clutch operation of the clutch mechanism to effect drive stop control of the electric motor, wherein the torque detecting mechanism (42) is set so that it effects drive stop control of the electric motor simultaneously with the detecting operation thereof in a state in which the clutch operation has been completed as the cam engagement at the cam engagement portion (40a) of the clutch mechanism is completely canceled.

Description

technical field [0001] The present invention relates to a torque control method of an electric rotary tool such as an electric screwdriver, and particularly relates to a torque control method of an electric rotary tool that is controlled in such a manner that a driven shaft of the electric rotary tool receives a load torque equal to or greater than a preset value Next, this state is detected by the operation of the clutch mechanism, and the driving of the electric motor is stopped appropriately. Background technique [0002] In the prior art, as an electric rotary tool for driving an electric screwdriver or the like by an electric motor, there has been proposed and put into practical use a tool of such a structure that when tightening a screw or the like, the screwdriver bit (driver bit) is applied In the case of a strong reverse load, the state of reaching the specified torque value is detected through the clutch mechanism that operates with a preset locking torque, and the...

AI Technical Summary

Problems solved by technology

[0013] Furthermore, when an electric rotary tool equipped with such a torque detection mechanism is provided with a torque setting mechanism, it is generally arranged in a structure concentric with the driven shaft in correspondence with the clutch mechanism. Frictional contact between the moving shafts tends to reduce the torque control accuracy of the torque setting mechanism to the clutch mechanism

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