GB809773A - Improvements in or relating to syringes - Google Patents

Abstract

809,773. Syringes. EVERETT & CO. Ltd., S. &R. J. Oct. 4, 1956 [July 6, 1955 ; Aug. 9, 1955 ; Aug. 19, 1955 ; Sept. 21, 1955], Nos. 19565/55, 22969/55, 24011/55 and 26992/55. Class 102(2). [Also in Group VI] A syringe having a casing 10 with a lateral aperture for loading with a cartridge 11, has an axially movable plunger rod 16 on which a sleeve 15 is axially slidable between a first position in which it is locked over one end of the cartridge 11 and a second position in which it is withdrawn for insertion or removal of the cartridge 11, a radiallymovable member 19 passing through the side wall of the sleeve 15 and projecting into a recess 20 in the casing 10 when the sleeve 15 is in the first position and into a recess 21 in the plunger rod 16 in other positions of the sleeve 15, the radially-movable member 19 being moved from one recess to the other when the recesses come into register during movement of the plunger rod 16, so that when the plunger rod 16 is moved into the cartridge 11, the sleeve 15 is moved into the first position and locked to the casing and when the plunger rod 16 is withdrawn the sleeve 15 is released and withdrawn. The cartridge 11 has a piston stopper 14 and a front stopper 13 pierceable by a double-ended needle 12. The plunger rod 16 engages the piston stopper 14 for discharging medicament from the cartridge 11. A cap 15 between the casing 10 and the plunger rod 16 has radial apertures 18 containing balls 19 of greater diameter than the thickness of the cap 15. When the balls 19 project into an annular groove 20 on the inside of the casing 10, the cap 15 fits over the rear end of the cartridge 11 which is thus fixed, the plunger 16 being free to effect an injection. On withdrawal of the plunger rod 16, the balls 19 move into the recess 21 in the plunger rod 16 when the recess 21 and the groove 20 are in register, so that the cap 15 is secured to the plunger rod 16. Further withdrawal of the plunger rod 16 carries the cap 15 rearwardly so that the cartridge 11 is freed for removal from the syringe. When the plunger rod 16 is projected, the balls 19 move into the groove 20 when the recess 21 and the groove 20 are in register. The plunger rod 16 comprises an outer tube 27, having a cylinder 28 secured at its forward end, and an inner rod 26 carrying at its forward end a cup 29 having radial apertures with balls 30. The inner rod 26 can be reciprocated within the outer tube 27 by a sleeve 32 at the rear of the plunger 16. A pin head 25 on the piston stopper 14 is held in the cup 29 by the balls 30 and can be released or secured in the cup 29 by withdrawing the inner rod 26 against a spring 31 so that the balls temporarily enter a groove 34 in the cylinder 28. Alternatively, the balls may be expanded into an undercut recess in the piston stopper (not shown) a screw or bayonet connection may be provided between the plunger rod and the piston stopper. An apertured plate (not shown) may be connected with the cap 15 and located across the front end of the cartridge so that as the cap moves rearwardly the plate removes the cartridge from the needle, a lostmotion device being provided to prevent movement of the plate until the cap is freed from the cartridge. Specification 809,774 [Group VI] is referred to.