GB847262A - Improvements in or relating to a gas driven turbine or cartridg unit for a dental handpiece and the handpiece for such a unit - Google Patents

Abstract

847,262. Dental engines. DENTISTS'SUPPLY CO. OF NEW YORK. Aug. 29, 1957 [Jan. 18, 1957; Aug. 22, 1957 (2)], No. 27269/57. Class 81(2) [Also in Groups XXVI and XXXIV] The burr or tool 116, Fig. 4, of a dentists' handpiece is driven by a miniature air turbine housed in a head 28 obout 0À5 inch long and 0À375 inch outside diameter and carried by a metal tube 82 inserted in a handle 24. The turbine comprises a rotor 36, Fig 5, having integral blades 86 and upper and lower collars 74, 76 which serve to space the air-cooled ball bearings 38, 52 supporting the rotor. The outer race 42 of the lower bearing fits into a recess in the head 28 and is held in place by a threaded ring 48 having, in addition to its control bore, air outlet ports 134, while the outer race 58 of the upper bearing is a press fit in a flanged collar 60 held in place by a cap 62 screwed into the head and having an air outlet 78. The inner races of the bearings are press fits on the rotor 36 which has a threaded bore containing a plain nylon sleeve 114 the outer surface of which is pressed into the thread of the bore by the insertion of the shank of the tool 116. The turbine is driven by compressed air supplied through a tube 96 seated in a recess 82, Figs. 10, 11, in a plug 84 at the end of the tube 82 and communicating with an eccentrically disposed bore 86 which directs a tangential jet of air on to the turbine blades, the air being exhausted mainly through an axial slot 88 in the plug into the lower end of the tube 82 which is closed by a disc 100 having an air outlet port 106 which maintains a desired back pressure in the tube. The remainder of the air exhausts through the opening 78 in the cap 62 and inclined ports 80 in the bottom wall of the head after passing through the ball bearings. The air issuing through the ports 80 is directed on to the tool 116 together with a stream of water issuing from a jet tube 92 supplied through a tube 98 sealed in a second bore 90 in the plug 82. In assembling the turbine, the lower bearing is inserted in the housing and the 48 screwed home whereupon the rotor 36, with the upper bearing and the collar 60 mounted thereon, is pushed into the housing so that the rotor extends through the inner race of the lower bearing. The parts are held in place by the cap 62. In a modification, the turbine 218, Figs. 19, 20, its flanged casing 230, the upper and lower bearings, and a flanged collar 228 form a unit that is readily insertable in or removable from the housing. The casing is formed with air inlet and exhaust ports 276, 288 respectively. Numerous modifications in the constructial details of the turbine casing and bearings are described.