Hypodermic syringe

Claim 1

A hypodermic syringe comprising: (i) a tubular syringe body having a first open longitudinal end and a second open longitudinal end, said body having adjacent its first longitudinal end a transverse wall with a conical bore, said body having an internal thread between said transverse wall and said first open end, (ii) a cylindrical ampoule disposed in said syringe body and having a first longitudinal end and a second longitudinal end, said ampoule having a piston slidable within it, (iii) a connecting means projecting axially at said first end of the ampoule and having a first conical surface and a coaxial second conical surface of lesser cross-section than said first conical surface extending from the end of said first conical surface, said connecting means including a passage through it, said connecting means having its first conical surface seated into said conical bore of said syringe body, (iv) a retaining member axially adjustable on said second open end of the syringe body and including presser means bearing against the second end of the ampoule such that the ampoule is firmly held, against longitudinal movement relative to the syringe body, between said transverse wall and said retaining member, and (v) a coupling member carrying a cannula, said coupling member having an internal chamber communicating with said cannula, said internal chamber being bounded by an internal conical surface engaged over said second conical surface of the connecting means, said coupling member extending into said syringe body at the first longitudinal open end thereof and coacting with said internal thread, such that by rotation of said coupling member with respect to said syringe body the internal conical surface of the coupling member may be firmly engaged in fluidtight manner on the second conical surface of the connecting means.