Patent ID: 8485273

Claim:
An electric assembly device for tightening threaded fasteners, comprising: a housing; a variable speed rotation motor; an output shaft connected to the motor and rotatable about a rotation axis; coupling means provided on the output shaft for coupling the output shaft to a threaded fastener to be tightened; wherein the housing is arranged to be manually supported by an operator and is angularly displaceable relative to the rotation axis; determining means for determining an angular displacement of the housing relative to the rotation axis during tightening of the threaded fastener; and a control unit which controls a rotation speed of the motor during tightening in relation to the determined angular displacement of the housing; wherein the rotation speed of the motor is arbitrarily determinable by the operator by angularly displacing the housing relative to the rotation axis in one of a rotation direction of the output shaft and a direction opposite to the rotation direction of the output shaft, to thereby correspondingly determine a tightening speed of the fastener; and wherein the control unit is configured to: (i) increase the rotation speed of the motor to thereby increase the tightening speed of the fastener if a displacement of the housing about the rotation axis in one of the rotation direction of the output shaft and the direction opposite to the rotation direction of the output shaft is detected, and (ii) decrease the rotation speed of the motor to thereby decrease the tightening speed of the fastener if a displacement of the housing in the other of the rotation direction of the output shaft and the direction opposite to the rotation direction of the output shaft is detected.