Syringe with a barrel having a sealing cap to hold a fluid medium within the barrel

[0002] The invention relates to a syringe with a Barrel having a Sealing Cap to a Fluid Medium within the Barrel.

[0003] Such a syringe is known from EP 0 723 784 A, incorporated in its entirety by reference. The barrel has a lug that extends in the peripheral direction with an inclined side facing the outlet and a rear shoulder that is almost perpendicular to the peripheral direction. On its inside, the cap that is to be put on has sections that are formed as undercuts and that extend in the peripheral direction, and the cap engages in the projecting section of the barrel when the cap is pushed on. Since the outside diameter of the projecting section of the barrel is larger than the inside diameter of the cap, a considerable compressive force can be used when the cap is put on. This is all the more true as the projecting element must be relatively large so that deviations from the container dimensions can be compensated for.

[0004] The object of the invention is to provide an improved syringe of the type mentioned above.

[0005] It is achieved by this design that the compressive pressure can be lower to put on the sealing cap, which in turn has the result that the number of cases in which the container is damaged during closing is reduced.

[0006] Other features and the suitability of the invention follow from the description of the embodiments based on the figures. Here, the figures show:

[0007] FIG. 1 a section through the outlet-side end of a barrel and through the sealing cap that is to be put on, and

[0008] FIG. 2 a second embodiment of the outlet-side end of the barrel.

[0009] FIG. 1 shows the outlet-side end of a barrel 1, on which a sealing cap 2 is put for outlet-side sealing. In a known way, barrel 1 has a seal on its inlet side and a sealable plunger in the inside to extrude the medium that is to be held in the barrel. Barrel 1 is designed as a glass barrel, and sealing cap 2 is preferably made of a chlorobutyl rubber or another elastic material having similar properties.

[0010] Sealing cap 2 is designed cup-shaped and has a cylindrical wall section 3, which is open to the end facing the barrel and has a cover 4 on the opposite end, whereby the cover has a sealable outlet 5 in a known way. Inside of the cover, a seal 6 is provided. Sealing cap 2 is pushed open to seal the syringe body in the direction of arrow 7 on the outlet-side end of barrel 1.

[0011] At a predetermined distance from its outlet-side end, barrel 1 has a first locking element 8 that projects from and extends around the entire periphery thereof. The locking element 8 and which has a cross-section of a sawtooth shape and is tilted like a ramp on its shoulder 9 that faces the outlet-side end, while second shoulder 10 that faces away from the outlet-side end, extends almost perpendicularly to the barrel surface. In other words, the projection has a first surface that converges toward the barrel in the direction of the barrel opening to form a ramp and a second surface 10 that extends transverse to the axis of the barrel 1 to form an abrupt shoulder.

[0012] At a predetermined distance from open end 11 of the cap 2, a large number of second locking elements 12 that are placed against one another in peripheral direction are provided on the inside wall. The cross-sections of said locking elements are also designed in an approximately sawtooth shape and have a shoulder that is in turn inclined on its side that faces open end 11 and a shoulder that runs almost perpendicular to the wall of the wall section on its side that faces away from open end 11. The second shoulders lie in a plane that runs perpendicular to the axis of symmetry of the sealing cap. The distance of this plane from open end 11 or from the base of seal 6 is selected in such a way that the sealing cap can be pushed on just to the outlet-side end of barrel 1 so that when the free edge of the barrel adjoins seal 6, second locking elements 12 are slid over first locking element 8, and the two elements make contact and lock with their almost perpendicular shoulders.

[0013] As FIG. 1 shows, a longitudinal slot 13 that extends parallel to the axis of symmetry in the wall of the sealing cap is provided between, in each case, two adjacent second locking elements 12. The sealing cap is arranged symmetrically between, in each case, two adjacent locking elements and extends both upward to the sealed bottom of the sealing cap and also downward to open end 11 over the length of locking elements 12.

[0014] At least six second locking elements are preferably provided placed against one another in peripheral direction. An embodiment with a number from eight to ten and corresponding longitudinal slots 13 arranged in between in each case is quite especially advantageous.

[0015] The embodiment that is shown in FIG. 2 is distinguished from the one first described only in that instead of first locking element 8, an annular undercut 14 is provided, which is designed in such. a way that second locking elements 12 project inwardly to engage in the undercut to ensure locking when sealing cap 2 is pushed on.

[0016] Longitudinal slots 13 are used as expansion sections and facilitate pushing the sealing cap onto the end of the barrel. The above-discussed number of second locking elements 12 that are arranged according to peripheral direction also contributes to the fact that together with the longitudinal slots, a pushing with less pressure is possible.

[0017] In the above-described embodiment, the expansion sections that are formed by longitudinal slots 13 are designed as recesses that extend through the entire wall. As an alternative, it can also be provided that the expansion strips are made only as recesses that do not go through the entire wall. In both cases, the axial length and the width of the expansion strips is selected based on the material that forms the sealing cap and its elasticity properties. In this case, the barrel itself is preferably made of glass.

[0018] The requirements for the materials of glass plunger, inlet-side seal, outlet-side sealing cap and plunger, which together form a glass cartridge, are high, since they are sterilized both in unassembled state and as assembled syringes at about 120° C. over an extended period of, for example, 30 minutes with superheated water.

[0019] The entire disclosure of all applications, patents and publications, cited above and below, and of corresponding European Application No. 00121060.8, filed Sep. 27, 2000 is hereby incorporated by reference.

[0020] From the foregoing description, one skilled in the art can easily ascertain the essential characteristics of this invention and, without departing from the spirit and scope thereof, can make various changes and modifications of the invention to adapt it to various usages and conditions.