Drive mechanism for oscillatory dental tool

摘要

A dental tool assembly having a driving mechanism with interengaging camming surfaces shaped for continuous contact during use. The mechanism includes a drive shaft having a drive surface and a driven shaft having a driven surface. The cam surfaces are shaped and the shafts are transversely juxtaposed with respect to each other such that the drive surface and driven surface are in continuous contact during rotation of the drive shaft to impart oscillatory rotation to the drive shaft. Specifically, the drive surface is conical and preferably has a cone axis that is at an approximately 45 DEG angle with respect to the rotation axis of the drive shaft. The driven surface has alternating hills and valleys that are shaped for continuous engagement with the drive surface as the drive shaft rotates. Preferably a pair of juxtaposed valleys are provided with juxtaposed hills formed therebetween. Rotation of the drive shaft causes the drive surface to ride alternately along the hills and valleys, continuously in contact with the driven surface. When the drive surface moves along a valley, the driven shaft is in a rest position. When the drive surface moves along a hill, the driven shaft is rotated approximately 45 DEG from the rest position, contact with oppositely positioned hills causing rotation in opposite directions. Oscillatory rotation is thereby imparted to the driven shaft as the drive surface alternately engages the alternating hills and alleys.