| 摘要 |
A dental handpiece is disclosed with a turbine construction wherein a radial airflow into the turbine about the whole circumference of the turbine is created, which generates additional torque and simultaneously centralizes the turbine wheel. The turbine is supported by a pair of axially spaced air bearings which are controlled in such a way that the air bearings are floated before drive air is supplied to the turbine and after drive air to the turbine has been shut off. This ensures that the air bearings are always operational irrespective of the operational state of the turbine. The handpiece has an improved ergonomic shape, especially the shape and configuration of the front or head portion, which provides additional tooth clearance arid a better field of view. An angled swivel connection to the umbilical cord is provided to reduce physical strain on th e dentist's wrist. A lock and key type torque connection between the dental burr and chu ck is provided which accommodates both conventional burrs and the burr of the lock and key arrangement. An auto stop arrangement for the turbine is disclosed which prevents a vacuum build-up during run-down of the turbine. The specific construction of the auto stop valve in accordance with the invention closes both the drive and exhaus t air conduits. |
