GB979124A - An injection or hypodermic syringe - Google Patents

Abstract

979,124. Hypodermic syringes. INTERNATIONALE TREUHAND A.G. May 30, 1961 [June 10, 1960; March 21, 1961], No.19503/61. Heading A5R. A hypodermic syringe comprises a medicament-containing cylinder 11a having a forward extension 11b, through which passes a needle 15, and a piston 13 with a central bore, in which a rod 14 carrying the needle is slidable under the control of a sleeve 10b, which is slidable on the cylinder, resilient means restraining the rod and a compression spring 18, which is locked until the rod has been released for projection of the needle and which is then released for projection of the piston to discharge medicament through the needle. A polyethylene medicament ampoule 11 is closed at one end by a bored rubber piston 13 and at the other end has an aperture sealed by a removable cap 12. A rod 14 slidable in the piston is operatively connected at the rear to a metal cartridge 10, which is slidable on the ampoule, and carries an hypodermic needle 15 which extends through the ampoule. An aperture 14a between the ampoule and the needle bore is covered by the piston bore when the syringe is inoperative. A compression spring 18 is held between the rear end of the cartridge and a locking disc 21, which is prevented from forward movement by spring arms 21a having bent portions 21b which engage the rear edge of the ampoule. A spring 20 connected with the disc 21 engages a peripheral recess 14b in the rod. In use, the cap is removed and the forward end of the ampoule is pressed against the skin. Hand pressure on the cartridge overcomes the spring 20 to allow the cartridge to slide over the ampoule and thus permit projection of the rod and the needle which then penetrates the skin, the aperture 14a thus being exposed to the medicament. Further pressure overcomes the locking effect of the spring arms 21a, so that the compression spring is released to cause projection of the piston and discharge of medicament through the needle. Movement of both the rod and the piston is limited by abutment against a tapering forward portion of the ampoule. After the injection, pressure on the cartridge is released and residual expansion of the spring withdraws the needle from the skin. The forward end of the rod may be spherical (Fig. 6, not shown) and engage a corresponding recess in the piston bore to lock the rod in inoperative position. In an alternative construction (Fig. 7, not shown), the locking disc is secured to the rod and is spaced from the piston so that, on expansion of the spring, the rod and needle are projected before the piston is engaged for discharge of medicament. The locking disc may have rearwardly extending spring arms (Figs. 9 and 10, not shown) which are held in engagement with the rear end of the rod by a sleeve fixed to a rearward extension of the ampoule. As the rod and locking disc are projected, the spring arms move out of the fixed sleeve and release the rod, so that further expansion of the spring causes only projection of the piston.