Patent GB-1049162-A (GB)
Title: Improvements in and relating to dental equipment
Inventor: BOULSOVER GEOFFREY
IPC: A61C17/02
Filed: 1964-01-31
Abstract: 1,049,162. Dental syringes. AMALGAMATED DENTAL CO. Ltd. April 30, 1965 [Jan. 31, 1964], No. 4307/64. Heading A5R. A dental syringe, which is capable of producing an air jet, a water spray or a water jet and which comprises a body portion and an offset nozzle portion, the nozzle portion having separate passageways for air and water and incorporating an electric heater element disposed in heat exchange relationship with both the air and the water passageways, incorporates separate valves in the air and water passageways and also a constrictor for limiting the flow of water actuable when the air valve is opened. The heater element, which may be carried either by a support at the inner end of the nozzle portion or by the outer end of the body portion itself, extends into the nozzle portion towards the nozzle and protrudes into the air passageway. The water passageway adjacent to the heater either may be concentric to, and embrace, the air passageway or may be in the form of a tube extending alongside and in heat exchange with the air passageway. The constrictor may be brought into an operative condition automatically by actuation of the air valve or by the conjoint operation of both valves; alternatively, the constrictor may require separate actuation, actuating means being disposed for ready operation at the same time as the water and air valves are actuated. The constrictor is preferably arranged to operate automatically when the water valve is only partially opened, the water valve being constructed to open, stepwise or progressively, in association with means for locating the actuating member of the water valve in a predetermined partially opened position; this means may comprise a stop limiting the fully opened position of an adjacent actuating member for the air valve so that the step is operative for both actuating members when these members are operated in unison. As shown in Figure 2, the syringe comprises a body portion 1 at one end of which is a thread 4 to hold in position the nozzle portion (not shown). Air- and water-operating levers 13 and 14 pivoted to the body portion serve to actuate respective spring loaded plungers 15 and 16 which in turn actuate respective rockers (not shown) which in turn actuate respective plungers 19 and 27. The rockers also actuate a switch (not shown) for the heater element in the nozzle portion. Air passes through connection 21 and chamber 22 and, on displacement of valve body 20, passes through outlet 23 leading to the nozzle portion. Water passes through inlet 24 and parallel chambers 25 and 26 and, on displacement of valve body 28, passes through outlet 29 leading to the nozzle portion. On operating the air lever, the constrictor 30 approaches seating 31 to effectively constrict the supply of water to the nozzle. The connection between the air chamber and the air passageway incorporates an air by-pass 32 leading to the connection between the second water chamber and the water passageway; this by-pass enables the water passageway to be blown clear of water when the syringe is used as an air jet. In a modification of the valve assembly, Fig. 3 (not shown), the water valve comprises a valve spindle formed with a reduced portion adjacent to a small flat, the throughput of the valve being determined by whe whether the reduced portion or the flat is in register with an O-ring seal.