GB798827A - Improvements in needle-less hypodermic injectors - Google Patents

Abstract

798,827. Hypodermic injection devices. Z. & W. MACHINE PRODUCTS, Inc. Aug. 27, 1954, No. 6462/58. Divided out of 798,826. Class 81 (2). A needleless hypodermic injector has a plunger for discharging medicament from a medicament chamber, a reservoir carried by the body of the instrument for replenishing the medicament chamber and adjustable means for transferring a selected volume of medicament from the reservoir to the chamber. The plunger 6 and a plunger extension rod 15, which are slidable in a piston housing 3, have a bore 92 through which medicament passes into the medicament chamber A from the reservoir 104. The medicament chamber A is held between flanges 137 of a collet 136. The tip 124 of the plunger 6 forms a closure for the medicament chamber A and includes a ball valve through which medicament passes into the chamber A. The medicament reservoir 104 is threaded on the extension rod 15. On projection of a piston 107 within the reservoir 104 by rotation of a knob 116, medicament is transferred to the medicament chamber A. The face of the reservoir 104 adjacent the knob 116 has a cavity 118 containing a spring-pressed ball 119 and the knob 116 has four equally spaced depressions 117 which register in turn with the ball 119 as the knob 116 is rotated, thus giving an indication of the number of rotations completed by the knob 116 and the amount of medicament transferred to the medicament chamber A. Projection and retraction of the plunger 6 is brought about as described in Specification 798,826. The stroke of the plunger 6 is limited by abutment of a disc 102 secured to the extension rod 15 with an adjustable sleeve 98 threaded on the rear of the piston housing 3. A lever 140 pivoted on the housing 3 prevents inadvertent depression of a button 62 which is operated to release the plunger as described in Specification 798,826.