GB1005869A - Improvements in or relating to hypodermic injection apparatus - Google Patents

Abstract

1,005,869. Syringes. F. WANTOCH, and L. G. WRAY. Dec. 5, 1961 [Dec. 5, 1960; Jan. 18, 1961 (2); Oct. 31, 1961; Nov. 9, 1961], Nos. 41702/60, 2021/61, 2022/61, 38886/61 and 40159/61. Heading A5R. A hypodermic syringe comprises a glass barrel 10 containing a plunger 11 from which a reduced stem 19 extends rearwardly through an aperture in a rear cover 20 and terminates in a knob 21. The plunger is formed with a through passage 25 provided intermediately with a valve seat dosed by a spring-biased ball 26. A disc 27, screwed to the front end of the plunger, is spaced from the front end of passage 25. An elastomeric gland 17 is bonded to the interior of the front end of the barrel and also to the interior of a sleeve 30. Secured to the latter and embedded in the gland are an inner disc 31 and an outer disc 32 from which extends a bayonet socket 33. Also embedded in the gland between discs 31 and 32 are a pair of past-circular metal collets 34. The front inner wall of the barrel is constituted by a frustoconical surface 36 of the gland, which latter is formed with a central passage 35. Sleeve 30 is surrounded by a clamp ring 40 carrying diametrically-opposed pins 41 and 42 which pass through holes in the sleeve to engage the collets. The stem of pin 42 is screw-threaded through ring 40 and has a knurled knob 43. A hypodermic needle 14 is fixed either permanently or detachably to a mount 15 provided with a radially-projecting pin 15A which passes through the wall of a flexible sac 16 attached to mount 15 to prevent leakage therebetween. The diameter of sac 16, when the latter is expanded, equals the interval diameter of the barrel. The sac is initially folded and is disposed, together with the mount 15 and needle 14, within a tubular sheath 50 formed with a longitudinal slot in which the pin 15A is disposed. Sheath 50 is pushed through the passage 35 with the pin 15A moving in the arial slot of the bayonet connection in socket 33. The sheater is then turned to locate pin 15A in the circumferential slot of said connection, and is finally withdrawn. Rotation of knob 43 then serves to distort gland 17 for clamping mount 15 therein. At the inward stroke of of plunger 11, sac 16 is compressed into the frusto-conical space, and air in the barrel escapes through the passage 25. During the outward stroke, valve 26 closes the passage 25. In a modification passage 25 is continued through the stem 19 and opens in the knob 21, whereby the open end can be closed by a finger or thumb. In a further modification. Fig. 8, the surface of the plunger 111 is formed with helical grooves and also with a circumferential groove 112 housing a washer 120. The latter collapses during the inward stroke to allow escape of air, and lies rigidly against the inner surface of groove 112 during the outward stroke.