Syringe needle protection device

Description

[0001] The present invention relates to a needle protection device and a dispensing assembly comprising a syringe and such a needle protection device.

[0002] Syringe needle protection devices, also referred to as needle shields, are known, including documents EP0429052, EP0976415, EP1208861, WO2015052417, WO2017051108, FR2816848, FR3011473, US2015174337, WO02074367 and US2004111066.

[0003] However, this type of protective device can have drawbacks.

[0004] Therefore, depending on the material used for the flexible part of the protective device, the withdrawal force required to remove the protective device may be too low, typically less than 5N. This may present reliability risks.

[0005] The present invention aims to provide a needle protection device which does not have the aforementioned drawbacks.

[0006] More particularly, the present invention aims to provide a needle protection device which requires a withdrawal force greater than 5N.

[0007] The present invention also aims to provide such a needle protection device which is simple and inexpensive to manufacture and assemble, and reliable to use.

[0008] The present invention therefore relates to a needle protection device comprising an elastic cap extending axially between an open rear end and a closed front end, said elastic cap defining an internal cavity delimited by a side wall and by a radial end wall, said end wall receiving in a sealed manner, in the assembled position, a tip of a needle of a syringe, said internal cavity comprising a first section connected to an opening of said rear end of said cap, a second section connected to said first section, said second section being cylindrical and having an internal diameter Dcav, and a third section connected to said second section, a radial annular projection being arranged between said first and second sections,said annular projection having an internal diameter Dproj and cooperating in a sealed manner with a front part of the body of said syringe when said protective device is assembled on a syringe, so that said annular projection forms a step having a radial dimension d corresponding to the difference between Dcav and Dproj, wherein said internal diameter Dcav of said second section is between 3.5 mm and 4.1 mm, said internal diameter Dproj of said radial annular projection is between 3.0 mm and 3.6 mm, said radial dimension d is greater than or equal to 0.50 mm, and said ratio d / Dcav is greater than or equal to 12%, to generate a withdrawal force of said protective device of at least 5.5 N.,

[0009] Advantageously, said third section is conical, narrowing towards said end wall.

[0010] Advantageously, a fourth section is connected to said third section and ends in said end wall.

[0011] Advantageously, said fourth section is cylindrical with a circular section and has a diameter substantially equal to the external diameter of a syringe needle.

[0012] Advantageously, the device comprises a rigid shell in which said elastic cap is housed.

[0013] Advantageously, said annular radial projection comprises at least one slot.

[0014] The present invention also relates to a dispensing assembly comprising a syringe comprising a body provided with a front part supporting a needle provided with a point, and a removable needle protection device as described above, removably attached to said syringe.

[0015] Advantageously, in the assembled state on said syringe, said second section receives said front part of the syringe.

[0016] These and other features and advantages of the present invention will become more apparent from the following detailed description, given with reference to the accompanying drawings, given as non-limiting examples, and in which: there Figure 1 is a schematic cutaway perspective view of a dispensing assembly comprising a syringe and a needle protection device, and the Figure 2 is a schematic cross-sectional view of a needle protection device according to an advantageous embodiment of the present invention.

[0017] In the following description, the terms "axial" and "radial" refer to the longitudinal central axis A of the device.

[0018] The figures show a protective device 10 for a syringe needle, or needle guard. This protective device 10 is intended to be removably assembled on a syringe 20.

[0019] Such a syringe 20 comprises a syringe body 21 containing a piston (not shown), the front part 22 of said syringe body 21 supporting a needle 23 provided with a point 24 defining the dispensing opening of the needle A. This front part 22 is also called the ball of the syringe, and it is this term which will be used below.

[0020] The needle guard 10 comprises an elastic cap 11 extending in a longitudinal axial direction between an open rear end and a closed front end. The elastic cap 11 defines an internal cavity 12 delimited by a side wall 13 and by a radial end wall 14. The elastic cap 11 is made of a flexible material, typically rubber.

[0021] The internal cavity 12 is composed of several sections extending from an opening 15 located at the open rear end of the cap 11, to the end wall 14.

[0022] Adjacent to the opening 15, the internal cavity 12 comprises a first section 12a which has a cylindrical shape of circular section in the figures. Il It should be noted that a truncated cone shape tapering towards the end wall 14 could also be used.

[0023] As illustrated, the first section 12a has a diameter substantially equal to the diameter of the opening 15.

[0024] This first section 12a is extended by a second section 12b intended to receive the ball 22 of the syringe 20 when the needle guard 10 is assembled on the syringe 20, this second section 12b having a cylindrical shape of circular section and having an internal diameter Dcav less than the diameter of the opening 15.

[0025] This second section 12b is in turn extended by a third section 12c whose diameter gradually narrows towards the end wall 14.

[0026] Near this end wall 14, this third section 12c is extended by a fourth cylindrical section 12d of circular section having a diameter substantially equal to the external diameter of the needle 23 of the syringe 20.

[0027] Between the first and second sections 12a and 12b of the internal cavity 12, a radial annular projection 16 is provided, such as a bead, forming an internal bulge of material. This annular projection 16 has an internal diameter Dproj less than the diameter Dcav of the second section 12b of the internal cavity 12.

[0028] This projection 16 forms a step having a radial dimension d corresponding to the difference between Dcav and Dproj. It also forms a mechanical retaining cord. When passing through an autoclave, it improves the retention of the ball 22 of the syringe 20 in the housing 12 of the elastic cap 11.

[0029] In order to facilitate, during passage in the autoclave, the passage of pressurized water vapor out of the internal cavity 12 and to improve the deformability of this annular projection 16, the latter is provided with a plurality of slots 17, advantageously four, extending in the axial direction, preferably in a rectilinear manner.

[0030] It is of course possible to provide any number of slots 17, which may have a greater or lesser depth. If there are a large number of them, these slots 17 separate from each other a large number of portions of the projection 16 which each form a small protuberance. Likewise, these slots 17 may be more or less wide.

[0031] In the embodiment shown in the figures, the protective device 10 for a syringe needle comprises, in addition to the elastic cap 11, a rigid shell 19 in which the elastic cap 11 is housed. The presence of this rigid shell 19 is however not obligatory for the present invention.

[0032] This type of shell 19 is conventionally used to reinforce the protection of the user of the syringe against a needle prick by providing additional rigid external protection which is difficult to pierce by the needle 23. This rigid shell 19 is mounted coaxially with respect to the cap 11. The rigid shell 19 is dimensioned to allow the insertion and locking of the cap 11. For this purpose, the rigid shell 19 has an internal shape which substantially follows the external shape of the cap 11. In order to retain the cap 11 inside the rigid shell 19, means for retaining the cap 11 are advantageously provided, which may comprise a retracting rim 18, preferably annular.

[0033] As illustrated on the Figure 1, when the needle guard 10 is in the protective position around the needle 23, the free end, i.e. the tip 24, of the needle 23 is planted in the end wall 14 of the cap 11 while the ball 22 of the syringe 20 penetrates into the internal cavity 12 of the cap 11, and cooperates in a sealed manner with said annular projection 16.

[0034] In a manner known in particular from document EP1208861, the annular projection 16 cooperates with a side wall of the ball 22 of the syringe 20, which achieves the sealed closure of said internal cavity 12 with respect to the atmosphere. At the moment of insertion of the ball 22 of the body 21 of the syringe 20 into the internal cavity 12 of the cap 11, there is a crushing of the annular projection 16 by the ball 22 of the syringe, and the slots 17 therefore do not prevent the sealed closure of the cavity 12.

[0035] An aim of the present invention is to ensure a withdrawal force of the needle protection device of at least 5.5N.

[0036] Comparative tests of several internal geometries have surprisingly revealed that the main parameter for increasing this withdrawal force is not the tightening of the elastic cap 11 on the ball 22 of the syringe, but the importance of the "step" formed between the part of the cap receiving said ball, namely the second section 12b, and the annular projection 16.

[0037] The table below illustrates these comparative tests: Needle Guard withdrawal force results as a function of geometries Dcav (mm) Dproj (mm) d (mm) Withdrawal force (N) d / Dcav (%) 3.80 3.60 0.20 4.50 5.3 4.00 3.60 0.40 5.00 10.0 3.60 3.20 0.40 5.15 11.1 4.10 3.60 0.50 5.50 12.2 3.50 3.00 0.50 5.95 14.3 4.00 3.40 0.60 6.70 15.0

[0038] From these results, we observe that the higher the d / Dcav ratio, the greater the withdrawal forces. This ratio is the most important parameter for defining the withdrawal force.

[0039] Thus, a simple increase in the tightening of the cap on the ball 22 of the syringe, by a reduction in the diameters Dcav and Dproj, is not sufficient to increase the withdrawal force. Indeed, the configuration Dcav = 3.5 mm and Dproj = 3.0 mm generates a lower withdrawal force than the configuration Dcav = 4.0 mm and Dproj = 3.4 mm. Similarly, the configuration Dcav = 3.6 mm and Dproj = 3.2 mm generates a lower withdrawal force than the configuration Dcav = 4.1 mm and Dproj = 3.6 mm.

[0040] Moreover, for the same dimension d, it is always the configuration with the higher d / Dcav ratio which generates a higher withdrawal force.

[0041] According to the invention, the internal diameter Dcav of the second section 12b of the internal cavity 12 is between 3.5 and 4.1 mm, the internal diameter Dproj of the annular projection 16 is between 3.0 and 3.6 mm, the ratio d / Dcav is greater than or equal to 12% and the dimension d is greater than or equal to 0.50 mm, which ensures a withdrawal force of at least 5.5N, as demonstrated by the comparative tests.

[0042] Although the present invention has been described with reference to a particular embodiment, it is understood that the present invention is not limited thereby but that on the contrary a person skilled in the art can make any useful modifications thereto without departing from the scope of the present invention as defined by the appended claims.

Claims

1. A needle protection device (10) including an elastic cap (11) extending axially between an open rear end and a closed front end, said elastic cap (11) defining an inner cavity (12) delimited by a side wall (13) and by a radial end wall (14), said end wall (14) receiving in a sealing manner, in the assembled position, a tip (24) of a needle (23) of a syringe (20), said inner cavity (12) including a first segment (12a) connected to an opening (15) of said rear end of said cap (11), a second segment (12b) connected to said first segment (12a), said second segment being cylindrical and having an internal diameter (Dcav), and a third segment (12c) connected to said second segment (12b), a radial annular projection (16) being disposed between said first and second segments (12a, 12b), said annular projection (16) having an internal diameter (Dproj) and cooperating in a sealing manner with a front part (22) of the body (21) of said syringe (20) when said protection device (10) is assembled on a syringe (20), so that said annular projection (16) forms a step having a radial dimension (d) corresponding to the difference between Dcav and Dproj, characterized in that said internal diameter (Dcav) of said second segment (12b) is comprised between 3.5 mm and 4.1 mm, said internal diameter (Dproj) of said radial annular projection (16) is comprised between 3.0 mm and 3.6 mm, said radial dimension (d) is greater than or equal to 0.50 mm, and said ratio (d / Dcav) is greater than or equal to 12%, to generate a force for withdrawing said protection device (10) of at least 5.5 N.

2. The device according to claim 1, wherein said third segment (12c) is conical by narrowing towards said end wall (14).

3. The device according to claim 1 or 2, wherein a fourth segment (12d) is connected to said third segment (12c) and terminates in said end wall (14).

4. The device according to claim 3, wherein said fourth segment (12d) is cylindrical with a circular section and has a diameter substantially equal to the external diameter of a syringe needle (23).

5. The device according to any one of the preceding claims, including a rigid shell (19) wherein said elastic cap (11) is housed.

6. The device according to any one of the preceding claims, wherein said annular radial projection (16) includes at least one slot (17).

7. A dispensing assembly including a syringe (20) comprising a body (21) provided with a front part (22) supporting a needle (23) provided with a tip (24), and a needle protection device (10) according to any one of the preceding claims, removably fixed to said syringe (20).

8. The assembly according to claim 7, wherein, in the assembled state on said syringe (20), said second segment (12b) is configured to receive said front part (22) of the syringe.