GB1169873A - Improvements in or relating to Dental Handpieces - Google Patents

Abstract

1,169,873. Dental handpiece. DENTISTS' SUPPLY CO. OF NEW YORK. 19 Oct., 1966 [20 Oct., 1965; 5 Oct., 1966], No. 46863/ 66. Heading A5R. [Also in Divisions Fl and F2] A turbine cartridge for a dental handpiece comprises a rotor shaft 110 having a bore in one end to receive a dental tool 80, impeller means 96 upon the shaft, a pair of combination radial and thrust rotor bearings 112, 116 having conical outer bearing surfaces, and a pair of stator bearings 116, 124 having bearing surfaces complementary to those of the rotor bearings, the cartridge being characterised in that the rotor and stator bearings constitute air bearings supporting opposite ends of the rotor shaft the bearings being separable only axially to increase their clearance, the cartridge including resilient members 118, 122 disposed to urge the bearings of one pair only in an axial direction towards the other pair, the opposite end portions of the bearings of the. said one of said pairs having surfaces thereon engageable by positioning means in the head of the dental handpiece into which the cartridge may be fitted. As shown, the cartridge is assembled in the head (16) of a handpiece (Figure 1, not shown), the cartridge being held in the handpiece by a screw-sown cap 88 with a part spherical surface 128 of the lower stator bearing 116 engaging the handpiece housing 130 and a part spherical surface 128 of the upper stator bearing engaging a a positioning surface 132 on the screw-down cap. The stator bearings 116, 124 are formed of a self-lubricating material, e.g. compressed graphite or solid carbon. A spacer sleeve 120 surrounds the turbine impellor 96 and supports resilient spring washers 118, 122 which urge the stator bearings 116, 124 away from each other and the cartridge is initially assembled with the air bearing surfaces in contact with each other, further screwing down of the cap 88 causing the surfaces to separate against the thrust of the washers so as to form air bearing gaps. Filtered air for driving the impellor is provided through a tube (32) in the handpiece, through a plenum chamber (38) in the handpiece, and through a further bore (92) onto the impellor blades. Exhaust air passes away through the handpiece via a tube (42), a chamber (50), and a silencer muffle (160, 162) Air for the bearings is provided from the plenum chamber via bores 98, 100, manifolds 102, 104, and apertures 148 in the stator bearings, and is exhausted with both the air from the impellor and also through apertures 152, 158 in the top and bottom of the handpiece head. Further conduits (52, 54, 60, 62) supply air and water to a chamber 72 in the handpiece head so that it issues through bores 74, 78, together with the air from the aperture 158, as a spray of mist directed towards the end of the dental tool.