Patent GB-697643-A (GB)
Title: Injection assembly
IPC: A61M5/24
Filed: 1949-05-26
Abstract: 697,643. Hypodermic syringes. HE IN, G. N. May 26, 1949 [May 29, 1948], No. 14182/49. Class 81 (ii). A hypodermic injection apparatus comprises manually operable force-multiplying mechanism provided for contracting an element of an accumulator which is initially under pressure to increase the pressure thereof, means being provided for releasing the said additional pressure to expel medicament from a chamber or ampoule and subjecting the said medicament to substantial pressure which at all times during such expulsion exceeds 1,000 lb. per square inch. As shown applied to a needleless type syringe. Fig. 1, within the bore 14 of the extension 13 of the hypodermic body 10 is disposed a collapsable rubber member 38 which envelopes a collapsable ampoule 40 both the member and the ampoule being firmly held within the bore 14 by the retaining collar 15 and cap 16. Disposed within the body 10 is a chamber enclosing an inverted rubber cup 33 and disc 36 filled with gas under pressure the upper end of the chamber being defined by a plate 20 formed with a passage 23 through which acts a spring 35 bearing against a disc 34. A passage 21 connects a cylinder 18 to the passage 23 and to a passage 22 which leads to the bore 14. A spring pressed poppet valve 24 mounted on a spindle 25 normally seals the passage 22 but it may be unseated by the operation of a cam 26. Movable within the cylinder 18 is a piston 17 actuation of which is by oppositely screw threaded operating stem 29 and handle 31 the screw threads engaging respectively with threads in the upper part of the syringe and the piston 17. The cylinder 18, passages 21, 22, 23, and the bore 14 are filled with water so that in operation compressive movement of the piston causes compression and partial collapse of the gas filled cap 33 the valve 24 being closed. When injection of the medicament is desired through the nozzle 41 the valve 24 is opened so allowing the compressed liquid to flow into the bore 14 and effect the collapse of the member 38 with subsequent collapse of the ampoule 40. In a modification the ampoule is sealed at one end by a covering which is ruptured by the nozzle portion on the application of sudden pressure on the ampoule walls. In the modification shown in Fig. 4, the piston 57 is actuated by a lever pivoted at 54 to the main body a spring pressed pawl 55 engaging teeth 56 of a ratchet forming part of the piston. A holding pawl 58 mounted on the pivot 54 prevents retraction of the piston. In a further modification of the piston actuating mechanism that portion of the operating lever surrounding the pivot 54 is cam-shaped such that downward movement of the lever causes compressive movement of the piston. In a further embodiment a valve is fitted on. the nozzle 41 for controlling injection when the valve 24 is open. By controlling the amount of downward movement of the piston within the cylinder 18 any desired dosage of the medicament within the ampoule may be injected. The pressure may be relieved by the insertion of a cannula 43 into the rubber disc 36 sealing the gas cup 33. Conversely the cannula 43 may be used to charge the cup 33 with gas or air under pressure. In the Specification as open to inspection under Sect. 91, a further embodiment is described, Fig. 7 (Cancelled), in which flow of the compressed fluid is through a passage 71 and control valve 72. A passage 76 is'provided within the main body 70 between which and the collar 77 is a collapsable member 81 firmly secured by means of the collar 77 and cap 78. A spherical ampoule 83 is arranged between the member 81 and the cap 78. This discharge structure may be utilised with any of the hydraulic units described above or it may be connected to any source of compressed fluid. In a further modification a needle may be fitted to the cap 16 the accumulator fluid pressures being according reduced. This subject-matter does not appear in the Specification as accepted.