IMPROVEMENTS RELATING TO INJECTION DEVICES

摘要

An injection device has a barrel (1) for housing and guiding a syringe (13) as it is urged forward to project its needle (14), while the dose is ejected, and as a return spring (22) retracts it. A firing mechanism (6) is connectable to the rear end of the barrel and is re-usable, whereas the barrel (1) with its spent syringe (13) is disposable. The connection (4) has limited freedom of axial movement so that, once made, forward pressure on the firing mechanism (6) moves the syringe (13) up to a ready position. A number of barrels (1) with syringes (13) can be housed in a common box (31) with a single firing mechanism (6), the forward end of each barrel (1) being screwed to a locator (32) on the base of the box. The engagement of the firing mechanism (16) with the rear end of each barrel (1) is also screw-threaded, but of opposite hand, so that screwing the firing mechanism (6) on and continuing to turn releases the complete device; and correspondingly the barrel (1) can be returned and located in the box (31) while the firing mechanism (6) is separated from it.