Patent GB-1238049-A (GB)
IPC: A61C17/02
Filed: 1968-07-31
Abstract: 1,238,049. Dental syringes. DENTSPLY INTERNATIONAL Inc. 31 July, 1968 [7 Aug., 1967], No. 36613/68. Heading A5R. Dental syringe. A dental syringe adapted to discharge air or water or a spray of both fluids comprises a cylindrical handle body 10, Fig. 1, a head portion 20 with a lateral extension 24 and a discharge conduit 22. Air and water are introduced under pressure into the handle via longitudinal conduits 16, 18 respectively which communicate with horizontal internally extending passages 42 in side cover plates 32, 34 leading to valve means. The valve means include two valves each of which comprises a blade-type gate valve member 64 pivoted in a vertical plane in the head portion on a shaft 30 and slidable between bevelled head surfaces of a pair of fluid transmission members 62 formed of synthetic self-lubricating resinous material and which include a head portion and an integral coaxial short stem portion with a relatively small diameter port extending entirely therethrough. The members are normally held in sealing arrangement against valve member blade 64 by 'o'-rings 78 which bear against the annular outside surfaces of the transmission member and annular recessed shoulders 50, 40, and also serve to seal the stem portions of the transmission members against leakage of fluid from the short recesses 52 in which they are disposed. A passage hole 66 in each valve member 64 is arranged so that it is aligned with the said ports when the valve is in the open position allowing the passage of air or water. The valve members 64 are provided with lateral extensions 68 which have extending transversely from them leaf-like finger pieces 70, shaped so as to receive the thumb or a finger. The members 70 are normally held coplanarly in the off position by coiled compression springs 74, and may be operated individually or simultaneously to provide a jet of air or water, or a spray of both. The exit side of each valve means communicates with the discharge conduits via passage 54, 56, and 54', 56'. Discharge nozzle. Air and water may be discharged either individually or together in a spray from a discharge conduit (22), Fig. 7, (not shown) comprising two coaxial tubes 82, 88, Fig. 6, tapering to a nozzle 106, water being fed from a first passage 56' into an extension 94 of tube 88, and air from a second passage 56 into a cavity 58 and through holes 86 in a collar means 80 fixed to tube 82, and thence through an annular passage 90. The discharge means is held against the head 20 by a knurled ring 98, Fig. 3, which has an externally threaded sleeve 104 which engages in cavity 58 and a recessed shoulder 100 which engages with an outer rim of locking collar 80. A thin washer 101 of self lubricating plastic is compressed between the shoulder 100 and collar 80. A sealing "o" ring 96 is compressed between end 84 of collar 80 and the innermost end of cavity 58 to seal the connection between the port 56 and the water transmitting tube 88. At the nozzle 106 water is discharged from an opening 110 in a central tube 108 projecting slightly beyond the end of the nozzle. The tube 108 is in short telescoping engagement at its inner end with the tube 88, and is held in place by a spider 112, Fig. 6. The passage 90 communicates with a short annular passage 109 of small radial dimension around the tube 108, which passage discharges air at a high speed concentrically around the water jet.