Patent ID: 7168505
Filing Date: 2007-01-30
Classification: B25B

Abstract:
1. A rotary tool comprising: a motor, a tool bit driven by the motor, a driving-side clutch element rotated by the motor, a driven-side clutch element disposed opposite to the driving-side clutch element and can move between a power transmission allowed position in which the driven-side clutch element is allowed to transmit rotating torque to the tool bit by moving toward the driving-side clutch element into engagement and a power transmission prevented position in which transmitting of the rotating torque to the tool bit is prevented by moving away from the driving-side clutch element into disengagement, a biasing spring disposed in a compressed state on the outer peripheral side of the driving-side clutch element and the driven-side clutch element to extend between the driving-side clutch element and the driven-side clutch element, wherein the biasing spring biases the driven-side clutch element toward the power transmission prevented position, a rotation preventing member that engages with the driven-side clutch element in the power transmission prevented position to prevent rotation of the driven-side clutch element, wherein during driving rotation of the driving-side clutch element, in the power transmission prevented position, the driven-side clutch element is engaged with the rotation preventing member by the biasing force of the biasing spring so as to be prevented from rotation, while, when the driven-side clutch element moves from the power transmission prevented position to the power transmission allowed position, the driven-side clutch element is disengaged from the rotation preventing member and released from the rotation prevention of the rotation preventing member, whereby the driven-side clutch element rotates following rotation of the driving-side clutch element via the biasing spring and engages with the driving-side clutch element, an enclosure that encloses the biasing spring, wherein at least part of the biasing spring in its circumferential and axial directions in the outer peripheral region of the biasing spring is enclosed by the enclosure and a sliding contact area between the biasing spring and the driving-side clutch element or between the biasing spring and the driven-side clutch element, wherein lubricant deposited on the inner wall surface of the enclosure is supplied to the sliding contact area by rotation of the biasing spring.