GB756957A - Hypodermic injector - Google Patents

Abstract

756,957. Hypodermic syringes. LABORATOIRE D'HYGIENE SCIENTIFIQUE HYGISCIENT. Oct. 9, 1953 [Nov. 24, 1952], No. 27860/53. Class 81(2). [Also in Group XXVIII] A hypodermic injector comprises a casing within which is a pump cylinder which has an inlet communicating with a container for injection liquid removably secured on the casing and which comprises a first chamber for receiving a piston member with an annular clearance and a second chamber which is in alignment with and adjacent the first chamber and is adapted to receive the piston member with a tight sliding fit, the second chamber communicating with an injection outlet at one end of the casing, the piston member being so positioned that, as it reciprocates, it alternately enters and leaves the second chamber through the first chamber and the piston member being operatively connected with an electromagnetic vibrating means in the casing and fed with alternating current through a control switch. The device comprises a body 1 on which an injection head is screwed. A nipple 3 connected with a flexible hose 4 through which liquid may be supplied from an external container such as a syringe 5, communicates through a duct 6 with a cylindrical feed chamber 7 and a delivery chamber 8 which leads to a calibrated hole 9 through which the injection is made. A piston 11 caused to vibrate by electromagnetic means alternately sucks liquid from the container 5 and forces it through the hole 9. The electromagnetic vibrating means comprises an electromagnet 28 energised by alternating current and an armature 12 mounted on a rod 39 which passes axially through the electromagnet 28 and bears against a head 37 of the piston 11 which is held in bearing engagement by a spring 38. Two discs 15, 16 are secured to the rod 39 on screw threads 17, 18 of opposite pitches and are mounted so that they can slide on guide rods 19. Opposite compression springs 20, 21 bear at their outer ends against the discs 15, 16 and at their inner ends against an annular flange 22 which is slidably mounted on a rod 23 and is in screwthreaded engagement with another rod 24. The position of the latter rod 24 may be adjusted by its sunk head 25 to vary the neutral position of the annular flange 22 and thus vary the air gap between the armature 12 and the electromagnet 28. The rod 39 carrying the armature 12 may also be adjusted by its rear end to vary the interval between the discs 15, 16 and therefore the stress in the compression springs 20, 21. Alternative constructions of electromagnet and armature may be provided (not shown). A hand grip 33 contains a switch 34 operated by a trigger-like part 35 and pins 36 on which a female connector may be plugged.