GB1014685A - Improvements in or relating to hypodermic injection apparatus - Google Patents

Abstract

1014685 Needleless injection devices NATIONAL RESEARCH DEVELOPMENT CORPORATION 14 Nov 1963 [14 Aug 1962] 31096/62 Headings F1A A1A7 A1B8B A1C1 A3F1A A4L A454 and A4Y In a needleless injection device, the propulsive force is provided by a spring-loaded plunger assembly 4, the plunger assembly being held in a restrained position by a sear 17 of a release mechanism, the sear 17 being pivoted about a point 21 behind its point of contact with the plunger assembly, whereby the arc of movement of the point of contact of the sear when the sear is free to move under the force of the plunger assembly is in a partly forward and partly sideways direction out of the path of the plunger assembly. The device comprises a chamber 3 for holding medicament, connected to nozzle 10 with orifice 11, through non-return value 14, and to medicament supply (not shown) through non-return valve 15, and plunger 5 slidably mounted in chamber 3 and tube 7 and urged forward by spring 8, the tube 7 having projections 6 which can be engaged by a recocking device. The release mechanism com- prises sear 17 having roller 16, which is urged into contact with the plunger assembly by spring 18, and trigger 19 urged into contact with sear 17 by spring 20. In use, trigger 19 is pressed and moves out of contact with sear 17, which is then pushed forward and sidewards by the power of the plunger assembly. Plunger 5 moves forwards and medicament is ejected from chamber 3 via passage 9, valve 14 and nozzle 10 out of orifice 11. The device may be recocked by a device comprising a cylindrical body 30 having chambers 32, 33 and 34. Mounted in chamber 34 is piston 37 into which is screwed shaft 46. Slidably mounted on shaft 46 is mount 50 having flexible prongs 51, 52. In recocking, the injection device is rested on flange 35 of chamber 32, and piston 37 normally urged into a forward position by spring 38, is withdrawn by pressing lever 45. The mount 50 is initially prevented from moving by the action of spring 55, such that shaft head 47 moves through prong heads 53, 54, forcing them outwards. The heads 53, 54 come into contact with the injection device and, at this stage, the mount 50 begins to move rearwards with the piston 37, such that heads 53, 54 contact the projections 6 of the injection device and hence pull the plunger assembly rearwards till it is in a position to be held by the release mechanism. The pressure on lever 45 is then released and the piston 37, mount 50 and prongs 51, 52 return to their original positions under the action of spring 38, such that the injection may be removed from the recocking device.