GB920096A - Improvements in or relating to dental handpieces - Google Patents

Abstract

920,096. Dental handpieces. R. A. WHITE. April 29, 1960, No. 15243/60. Class 81 (2). [Also in Groups XXVI and XXVIII] The head of a dental handpiece includes a tool driving shaft Y which is rotatably mounted along the axis of the head and is driven by a fluid-operated engine comprising a stator A which receives fluid entering an inlet port at an angle to the axis of the head and directs it axially of the head and a rotor B carried by the shaft. The stator A comprises an annular channel 42 disposed circumferentially against the internal bore of the head, compressed air passing through a port 44 being delivered through openings between blades 48 fixed to the channel. The compressed air flows from the channel upwardly and radially inwardly and then downwardly through diverging channels formed between pitched blades 61, 62 of the rotor, which is thus caused to rotate, and is exhausted through a port 65 in the head into a duct 118 in the handpiece. The shaft Y is inserted through the lower part of the head and has a slot which after engagement with a pin 29 fixed to the rotor receives a plug 31, the rotor and shaft thus being secured together. The shaft rotates in bearings 14, 15 and has on its lower part rings 67 which engage with rings 66 on the lower part of the head to form a labyrinth seal preventing the escape of air exhausted from the rotor. The tool T is fitted into a bore 26 in the shaft, relative rotation being prevented by a shoulder 28 on the shaft engaging a corresponding recess in the tool. The tool is prevented from slipping out of the shaft by a stop 87 which engages a groove in the tool, the stop being carried by a yoke-shaped lever 81 which surrounds the shaft and is pivotal on a ring 80 attached to the shaft. The lever 81, which is of greater weight on the side remote from its pivot is normally held by its weight and a spring 83 in a horizontal position so that the stop secures the tool. For release of the tool an operator sleeve 82 at the bottom of the head is unscrewed so that it engages a lug 88 which tilts the lever and the stop against the spring thus disengaging the groove in the tool. The rotor may be braked as desired on pressing a plate 71 at the top of the head against a spring 72, brake blocks 70 attached to the plate then engaging the flat annular top surface of the rotor. A connector S (Fig. 10) for a flexible tube 124 is rotatably secured to the end of the handpiece remote from the head by balls 108 held between opposite channels in the connector and the handpiece. This end of the handpiece is of stepped formation and engages in a stepped bore in the connector to define annular or cylindrical chambers 113, 116 and 104. The chambers interconnect ducts 119, 121 and 118 in the handpiece with corresponding passages in the flexible tube for the supply of compressed air for driving the rotor and cooling the tool and for the exhaust of air from the rotor.