AN INJECTION APPARATUS

Abstract: In an injection apparatus having a removable cap (65), said cap, in addition to screwing-on threads (66), having threads (69) of greater pitch to cooperate with threads (61) on a needle holder (55) in such a manner that, when the cap is applied, the needle (57) is pulled out of the rubber membrane (53) of a cartridge (51) inserted in the apparatus, and is moved through the membrane when the cap is removed. When the apparatus is not in use, the free end of the needle is surrounded by a protective case (63), which is affected by a compression screw spring (73), inserted in the cap, to engage the needle holder, so that said holder with applied cap remains in position for renewed insertion of the needle into the cartridge when the cap is screwed off again.

Description: An injection apparatus The invention concerns an injection apparatus of the type defined in the introductory portion of claim 1. In the prior art injection apparatus of said type the thread of the needle holder and the screwing-on thread of the cap are oppositely directed so that one of said threads has a screwing-on direction opposite to the usual one, which is felt awkward by most users. The object of the invention is to provide an injection apparatus of the present type in which the thread of the needle holder and the screwing-on thread of the cap have the same, conventional direction of rotation. This object is achieved in that the injection apparatus is constructed as stated in the characterizing portion of claim 1. The embodiment defined in claim 2 provides effective protection of the needle against contamination by means of the protective case, which after removal of the cap remains in it and is kept by the spring-loaded case hol- der in a position which facilitates subsequent screwing on of the cap. The invention will be explained more fully below with reference to the drawing, in which fig. 1 shows a longitudinal section through the end of an embodiment of the injection apparatus according- to the invention which is provided with a needle, and with the cap removed, fig. 2 is a longitudinal section through the same with applied cap, and fig. 3 is a side view of the cap in removed state. In the drawing, 50 is one end of a jacket accommodating a cartridge 51 consisting of a cylindrical glass case provided with a beaded metal collar 52 which secures a rubber membrane 53. On a reduced diameter end part 54 of the jacket 50 there is slidably mounted a bowl- shaped needle holder 55 made from an elastic plastics material and having a hub 56 through which a needle 57 is passed. The cylindrical wall of the needle holder is formed with two fingers 58 which are disposed diame¬ trically opposite each other and have on the outer end and inwardly directed, hemispherical boss 59 which can slide in an axial groove in the jacket end part 54, which has moreover a hole 60 to receive the boss 59 at each end of each groove. On the outer side, the cylindrical part of the needle holder has threads 61 of great pitch. The bottom of the needle holder is formed with a ring- shaped protrusion 62 having an angular cross-section. This protrusion forms a well to receive the inner end of a protective case 63, figs. 2 and 3, for the outer end of the needle 57. The injection apparatus is provided with a cap 65, which is threaded on the jacket 50 by threads 66 at the open end. A clip 68 is secured in the end member 67 of the cap. The inner side of the cap is formed with threads 69 for cooperation with the threads 61 of the needle holder 55 and with three axial grooves 70 to receive guide fins 71 on a needle case holder 72 which is slidably movable in the cap. This holder forms a cylindrical well to receive the outer end of the needle protective case 63 and is under the action of a compression screw spring 73 which is embedded in ring-shaped tracks in the holder and the end member 67. When the cap is removed as shown in fig. 3, the movement of the holder 72 in an outward direction is limited by the engagement of the guide fins 71 with a spring ring 74, which is embedded in the cap at the inner end of the threads 66. Another spring ring 75, which is embedded in the outer end of the needle case holder 72, serves to grip the case 63 with such friction that the case remains in the cap when the cap is removed. When the cap 65 is screwed on the jacket 50 with the cartridge 51 positioned in it, the threads 69 engage the threads 61 of the needle holder 55. The screwing-on threads 66 have a relatively great pitch, but the needle holder threads 61 and the corresponding cap threads 69 have a so much greater pitch and are so positioned in the cap that when the cap is screwed on, the needle holder 55 is pulled from the position shown in fig. 1 in which the needle 57 extends through the rubber membrane 53 of the cartridge, to the position shown in fig. 2 in which the needle is pulled out of the membrane. It is noted in this connection that the engagement of the bosses 59 with the grooves of the jacket end part 54 prevents the needle holder from rotating with respect to the jacket. When the cap is applied, first the needle protective case 63 accommodated in it is passed inwardly over the exposed needle and into the well formed by the needle holder protrusion 62, and during the continued application movement the case holder 72 is urged backwards against the action of the spring 73. When the cap is screwed off, the two threads 61 and 69 move the needle holder back to the position shown in fig. 1, in which the inner end of the needle is present in the liquid contained in the cartridge.

Claims: P a t e n t C l a i m s 1. An injection apparatus having a cylindrical jacket to receive a cartridge, and a cap which can be applied and removed by screwing movement, as well as a double needle placed in a needle holder which can be so connected with a cartridge, inserted in the cap, by screwing movement that one end of the needle penetrates the rubber membrane of the cartridge in one end position of the needle holder, the threads causing the two screwing movements being so shaped and arranged with respect to each other that a needle positioned in said end position is pulled out of the rubber membrane of the cartridge by application of the cap, c h a r a c t e r i z e d in that the needle holder is adapted to be mounted on the cartridge in such a manner as to be slidable, but non-rotatable thereon, and that the needle holder is provided with an external thread for cooperation with an internal thread of the cap, the pitch of said threads being substantially greater than that of the screwing-on threads of the cap. 2. An injection apparatus according to claim 1, c h a ¬ r a c t e r i z e d in that it has a needle protective case which is adapted to be placed as a slight friction fit in an axially movable and spring loaded case holder contained in the cap.

Inventors: EJLERSEN HENNING MUNK, TULLIN FLEMMING, EJLERSEN, HENNING, MUNK, TULLIN, FLEMMING
Applicants: NORDISK GENTOFTE, NORDISK GENTOFTE A/S
Application year: 1988
Main classification: A61M5
IPC codes: A61M5