GB710795A - Improvements in or relating to dental engines - Google Patents

Abstract

710,795. Turbines. NORLEN, P. I. Jan. 28, 1952 [April 10, 1951], No. 2249/52. Class 110(3) [Also in Group VI] A turbine for operating a dental handpiece is rotated by a pressure medium, such as compressed air, supplied through a flexible hose, and is arranged on a shaft so that a rotary motion is transmitted to a burr in the handpiece, the pressure medium being regulated by a manually operable member arranged between the burr and the turbine casing, the pressure medium passing to the turbine casing through a valve so that it flows through the turbine in a direction away from the burr. A turbine wheel 2 is fixed on a shaft 3 connected by a claw coupling 8, 9 with a handpiece shaft 10. Compressed air entering a portion 12 of the turbine casing through a nozzle 17 passes through a valve opening 22 controlled by a rubber sealing member 23 which is held against a cylindrical valve body 19 by a ring 24. The rubber sealing member 23 normally closes the valve opening 22. the valve body 19 being pressed forwardly by a helical spring 21. A partition 13 is provided in the turbine casing and is provided with conical nozzles 14 through which air which, has passed through the valve opening 22 is conveyed to the turbine wheel 2. a sound absorber 74 being provided. The burr end of the handpiece shaft 10 is screwed into the reat end of a burr fixing sleeve 38, which rear end 39 is square in cross-section. A control key 40 of a bellcrank projects entirely or partially from the outer sleeve 33 of the handpiece and 'regulates the 'valve opening 22 and consequently the speed of rotation of the turbine wheel 2. On depression of the control key 40 a forked arm 42 of the bellcrank bears against a sleeve 43 which surrounds the handpiece shaft 10 and presses it rearwardly so that two parallel pins 44, attached to the rear end of the sleeve 43. press against a sealing diaphragm 29 which, in turn moves a valve nut 20 and the valve body 19 rearwardly thus opening the valve opening 22 against the closing action of the helical spring 21. A burr is secured in the handpiece when the control key 40 has been swung upwardly so that the forked arm 42 engages the rear portion 39 of the burr fixing sleeve 38, fixing of the burr being accomplished by turning a button 6, Fig. 1, at the rear end of the turbine shaft 3.