| 摘要 |
<p>A system to prevent the effect of suction in dental handpieces with a turbine (5) envisages the application of second valve means (13) on a second exhaust duct (11) synchronized with first valve means (12) for supplying drive air. The second valve means (12) can be switched between two working positions, one of which allows air to flow through in an exhaust direction (Fs) when the first valve means (12) are open, and the other connecting the second duct (11) with means (14) that supply air under pressure, simultaneously or with a slight delay after the first valve means (12) reach the closed position. The means (14) supply air flowing in a direction (Fp) opposite the exhaust direction (Fs) in such a way as to create a counterpressure in a chamber (4) of the turbine (5) at least until the turbine stops completely. <IMAGE></p> |
