Patent ID: 8720162

Claim:
A motor-driven power tool, in particular a hand-held power tool, comprising: a tool; a motor including a drive shaft driven by the motor, wherein the drive shaft defines a drive shaft axis about which the drive shaft rotates; an output shaft on which the tool is accommodated; an eccentric coupling device configured to transmit the rotary motion of the drive shaft to the output shaft; and a mass-compensation device provided for oscillation compensation purposes, which is operatively connected to at least one of the drive shaft and the output shaft, and which executes a compensating motion in opposition to an eccentric coupling motion, wherein the mass-compensation device includes a stroke mass part that is movably supported in a slot guide with a rotary bearing defining a rotary bearing axis about which the rotary bearing rotates, the rotary bearing axis being displaced from the drive shaft axis, the slot guide including a surrounding closed frame that encompasses an eccentric cam affixed to the drive shaft for coaxial rotation therewith, with the stroke mass part executing a non-linear compensating motion inside the slot guide, the non-linear compensating motion of the stroke mass part being independent of motion of the slot guide and the eccentric cam acting as a drive element for the stroke mass part which has a recess into which the eccentric cam protrudes, and wherein the stroke mass part and the eccentric cam execute movements in a shared common plane which is perpendicular to axes of rotation of the output shaft and of the drive shaft axis, which are perpendicular to one another and wherein the rotary bearing axis remains at a fixed location with respect to the drive shaft axis during rotation of the drive shaft.