| 摘要 |
1,034,867. Turbines. POWER BRAKE EQUIPMENT CO. April 4, 1963 [April 19, 1962], No. 13432/63. Heading FIT. [Also in Divisions A5 and F2] The invention relates to a dental handpiece of the kind comprising an air driven turbine. The assembly comprises a turbine casing C of open-ended cylindrical form which is formed integrally with a handle portion H, the ends of the casing C being closed by screwed-on cap members 33, 34. Mounted within the casing is the turbine rotor R which comprises a shaft 40 having a flange at its lower end, as seen in Fig. 3, the shaft being bored internally and screwed so as to receive a chuck 41 which is adapted to hold a drill 78. Mounted on the shaft are a rotor disc 62 and two journal members 43, 44 which are of frusto-conical form on their outer surfaces, the parts being secured on the shaft by means of a lock-nut 42. The rotor disc 62 is formed with axially-spaced grooves 62s, also with circumferentially spaced notches 51s (Fig. 4, not shown) around its periphery and with axially-extending holes 51b towards its inner periphery, high pressure air being directed on to the notches 51s to rotate the rotor, the air finally discharging through the holes 51b to the exhaust spaces 68, 69 at the sides of the rotor. The rotor journals 43, 44 co-operate with stator bearing assemblies 29, 30 which comprise bearing members 28, 27 which have frusto-conical surfaces which co-operate with the corresponding surfaces of the rotor journals to form capillary passages 48, 47 to which air under pressure is supplied so as to form a fluid type bearing. The bearing members 28, 27 are received in bearing rings 26, 25 which are supported within the turbine casing C by means of frusto-conical rings 24, 24s, 23, 23s of resilient rubber-like material reinforced with metal wires. The bearing rings 26, 25 are formed at their outer surfaces with circumferential grooves 38, 37 to which air under pressure is supplied through ducts 38, 37 and conduit 55 in the handle portion H, air from the grooves 38, 37 passing through restricted bores 58 in the rings 26, 25 thence through larger bores 59 in the bearing members 28, 27 and so to the capillary passages 48, 47. The air flows from the passages 48, 47 to the turbine exhaust air spaces 68, 69 also to the spaces 71, 70 within the end caps 34, 33 and thence to atmosphere through outlets 73, 72. Air under pressure from the conduit 55 also flows through the duct 51 so as to impinge on the notches 51s formed in the turbine rotor. |
