Patent ID: 7927101

Claim:
A handpiece, comprising: a gripping portion to be gripped by an operator; a head mounted at a distal end of the gripping portion; and a wheel rotatably mounted in an interior of the head, said wheel comprising upper and lower turbine blades; wherein the head having an inlet from which pressurized air is supplied to the wheel and an outlet from which the pressurized air is discharged, the inlet and outlet being defined in the head; at least one buffer chamber defined in the head, where the pressurized air is forced in due to a centrifugal force applied thereto by rotations thereof with the wheel and then accumulated under positive pressure; a passage for guiding the accumulated air from a neighborhood of the rotating wheel to an atmosphere; and a circumferential wall extending circumferentially between the outlet and the wheel for providing a resistance to the air moving from the wheel toward the outlet, the circumferential wall substantially occupying a region where the outlet opposes the wheel, opposing an entire top to bottom part of a circumferential part of said lower turbine blades and defining an arcuate cavity between the circumferential wall and the outlet so that, during an operation in which the pressurized air is supplied from the inlet, the pressurized air from the wheel travels beyond the circumferential wall into the arcuate cavity and then into the outlet and, after halting a supply of the pressurized air from the inlet, the circumferential wall resists the pressurized air from the wheel from being directly forced into the outlet.