FR3039071A1 - AUTOMATIC LIQUID INJECTION DEVICE COMPRISING AN END SLEEVE - Google Patents

Abstract

The automatic injection device (10) is adapted to receive an injection syringe (12) carrying an injection needle (32) covered by a protective cap (42). It comprises a syringe holder (14) configured to house the injection syringe (12) fixedly mounted throughout the operation of the device (10), an end sleeve (16) intended to be in contact with the skin of a user, slidably mounted relative to the syringe holder (14) between an injection position, wherein the syringe holder (14) and the end sleeve (16) are axially close together, and a protective position wherein the syringe holder (14) is axially remote from the end sleeve (16). The end sleeve (16) has a retaining stop (76) carried by a deformable elastic tab between a constricted position, configured to axially retain the injection syringe (12) in the distal direction in the syringe holder (14). and a remote position configured to allow distal insertion of the injection syringe (12) provided with the protective cap (42).

Description

Automatic liquid product injection device having an end sleeve

The present invention relates to the field of automatic liquid product injection devices, in particular pharmaceutical.

An automatic injection device is generally a medical device for the automatic administration of a liquid drug requiring injection. These devices allow in particular that people, for example with rheumatoid arthritis, multiple sclerosis, diabetes or undergoing anaphylactic shock in case of allergy, themselves inject their drug dose autonomously.

An example of an automatic injection device is described in US8734402. The device comprises an injection syringe which contains the liquid product to be injected and which is provided with a needle, and a syringe holder. It is usually sufficient for a short pressure exerted by pressing on the skin of the patient to trigger a penetration of the needle into the skin, followed by an injection of the liquid product, then the retraction of the needle inside the patient. device to avoid hurting a person with the needle.

More specifically, the device comprises a syringe holder configured to house the injection syringe, so that it is fixedly mounted in the syringe holder throughout the operation of the device. This syringe holder is formed by two half-shells, semi-tubular, assembled to each other once the injection syringe disposed inside, so as to form a tubular shell around the syringe. The use of two half-shells to assemble is due to the fact that the injection syringe comprises on the one hand a proximal collar, and therefore has a diameter at its proximal end wider than that of the syringe body. On the other hand, the injection syringe comprises a distal portion of a needle protection cap, for example a cap called RNS ("Rigid Needle Shield"), which often has a diameter greater than that of the body of the syringe . Thus, the injection syringe can not be easily inserted inside a tube. The invention particularly aims to provide an automatic injection device wherein the assembly of the injection syringe in the automatic injection device is simplified while limiting the risk of breakage of the syringe. For this purpose, the subject of the invention is in particular an automatic liquid product injection device intended to receive an injection syringe comprising a distal end bearing an injection needle covered by a protective cap and an opposite proximal end. the automatic injection device having an injection pin and comprising: a syringe holder configured to house the injection syringe so that the injection syringe is fixedly mounted in the syringe holder throughout operation of the automatic injection device, the syringe holder having a distal end disposed on the side of the injection needle and an opposite proximal end, an end sleeve, intended to be in contact with the skin of a user at the during the injection, attached to the distal end of the syringe holder, slidably mounted relative to the support of the syringe ingue between an injection position, in which the syringe holder and the end sleeve are axially close together, and a protective position in which the syringe holder is axially remote from the end sleeve, the end sleeve comprising a retaining stop carried by an elastic tab, the elastic tab being deformable between a constricted position, configured to retain axially in the distal direction the injection syringe in the syringe holder, and a spaced position, configured to allow insertion in the distal direction, from the proximal end of the syringe holder, the injection syringe provided with the protective cap.

Thus, thanks to the fact that the elastic tab can be removed to allow the injection syringe with the protective cap to pass through, it is possible to assemble the injection syringe in the automatic injection device from the proximal end of the injection syringe. syringe holder, and it no longer becomes necessary to have a syringe holder in the form of two half-shells to assemble. This is particularly advantageous for facilitating assembly, especially since generally the assembly of the injection syringe in the automatic injection device is carried out by a pharmaceutical laboratory and not by the manufacturer of the automatic injection device, so that any simplification of the assembly of the injection syringe in the automatic injection device avoids the need for the pharmaceutical laboratory to equip itself with complex equipment. In addition, since the resilient tab in the constricted position makes it possible to hold the injection syringe axially in the syringe holder, the positioning and the axial retention of the injection syringe in the syringe holder need not be ensured by the retention of a proximal collar of the injection syringe, so that it avoids weakening the injection syringe at such a collar. Indeed, it is known that the spring for ensuring the injection of product can be a relatively powerful spring. However, when the injection syringe is held by its collar, the latter must hold the injection syringe when the spring exerts pressure on the piston rod to perform the injection and when the movement of the piston is limited by the counterpressure liquid product to be injected contained in the injection syringe and friction between the piston and the inside of the body of the injection syringe. This pressure is even more important when the liquid product is viscous. Also, the collar is heavily stressed during injection, which may damage or break the injection syringe, especially when the latter is made of glass. As the injection syringe is retained here by its distal end and the stresses are thus reflected by a concentrated compression on the distal end of the injection syringe, the proximal end of the injection syringe, and therefore the collar, is spared. Note that materials such as glass are generally more resistant in compression than in flexion. It thus becomes possible to use particularly rigid springs, and thus to inject a product having a higher viscosity than before. In particular, it is possible to use an injection spring having a force in the compressed position of 20 Newton or even 50 Newton or 80 Newton or more. It will be understood that it is also conceivable to use an injection syringe not comprising a flange or that the injection syringe takes the form of a cartridge for receiving the liquid product.

In the present description, the injection axis corresponds to the axis of the automatic injection device, corresponding to the axis of the injection needle. The injection axis will be called X. Moreover, the distal direction designates the direction farthest from the fingers of a user, that is to say the closest to the skin of a patient at the time of an injection, and the proximal direction designates the opposite direction. In other words, it can be said that the "distal direction" is the one that goes to the "front" of the automatic injection device. In particular, the distal end of a patch corresponds to the end on the side of the injection needle, and the proximal end is the opposite end.

The automatic injection device may further comprise one or more of the following features, taken alone or in combination.

The syringe holder comprises, at its distal end, a tab for holding the elastic tab in a constricted position, this holding tab preventing the elastic tab from taking its position apart when the end sleeve is in the injection position. Thus, the retaining tab makes it possible to lock the elastic lug in the tightened position once the injection syringe is assembled in the automatic injection device and that it is no longer necessary for the elastic lug to take its position apart for pass the protective cap. This locking contributes to making the axial maintenance of the injection syringe more reliable by its distal end.

The end sleeve, when in the injection position, envelops the retaining tab, so as to prevent spacing of the retaining tab which would be due to a separation of the elastic tab. This ensures double security to prevent, once the injection syringe assembly, the elastic tab does not deviate and no longer ensures the axial retention of the injection syringe in the distal direction.

The elastic tab extends axially and has a proximal end having a surface extending in a substantially radial plane, this surface forming the axial retaining stop of the injection syringe, preventing the injection syringe from moving towards the distal end of the automatic injection device. Thus, the abutment surface being in a substantially radial plane, it ensures a frontal retention of the injection syringe during the thrust on the piston to obtain the injection, so that the stress which is exerted on the syringe of injection is a pressure against a substantially radial wall of the injection syringe, and thus differs from a stress in the form of flexion, as would be the case if the injection syringe was retained at a proximal collar, the pressure of the piston in the syringe body being then taken up by the proximal flange biased in bending, which can generate a breakage.

The automatic injection device further comprises a protective cap removal member, removably attached to the distal end of the end sleeve, comprising gripping means by a user and a hooking tab on the cap. of protection, able to drive the protective cap when the withdrawal member is removed from the automatic injection device, the hooking tab and the elastic tab being distributed angularly around the injection syringe when the withdrawal member cap is mounted on the automatic injection device. It is understood that the automatic injection device thus makes it possible to very easily remove the protective cap, in particular a cap of the RNS type, thanks to the hooking tab. The end sleeve is thus able here, very advantageously, both to allow a hooking tab to catch on the protective cap, and to maintain the elastic tab in the tightened position against the syringe. injection to retain it axially in the distal direction.

The automatic injection device is adapted to receive an injection syringe comprising a collar at its proximal end, the automatic injection device comprising an injection spring for exerting pressure on a piston rod to move the rod relative to the injection syringe and injecting liquid product, the resilient tab of the end sleeve providing axial retention of the injection syringe in the distal direction of the automatic injection device so that the pressure exerted by the injection spring on the piston rod during the injection causes pressure on the distal end of the injection syringe, thereby decreasing the possible pressure at the level of the collar of the syringe. 'injection. Thus the stresses are exerted on the distal part of the injection syringe, and not on its collar, which area is generally fragile.

The end sleeve is attached around the distal end of the syringe holder, so that the syringe holder is slidable within the end sleeve. An advantage lies in the fact that the end sleeve may in particular wrap a retaining tab formed on the syringe holder.

The syringe holder is generally tubular monobloc, distinct from two half-shells assembled to one another. Thus the injection syringe can be assembled very easily by axial insertion in the syringe holder, without requiring the radial assembly of two half-shells between them around the injection syringe. As a result, the manipulations supported by the pharmaceutical laboratory are simpler.

The syringe holder comprises, on an inner wall capable of being in contact with the injection syringe, a damping element made of elastomeric material, for example in the form of an elastomer strip extending axially. Thus, the elastomeric material makes it possible to dampen the shocks that may occur in particular at the moment of the pressure exerted by the injection spring between the syringe holder and the injection syringe, which is generally made of glass. The risks of breakage are thus further reduced. In addition, the elastomeric material contributes, by friction, to the axial retention of the syringe body. Advantageously, the syringe holder comprises a plurality of elastomeric strips angularly distributed on an inner tubular wall of the syringe holder. The damping element may also take the form of an elastomeric continuous layer, two or more elastomeric rings intended to surround the syringe body, discontinuous elastomeric bands, or a helically shaped strip. The elastomeric material is more precisely an elastomeric thermoplastic material (TPE).

The end sleeve delimits a housing for receiving a protection spring, this housing also defining a guide shape, for example recessed, complementary to a guide shape, for example in relief, provided on the syringe support to allow guiding during the relative movement of the end sleeve and the syringe holder.

The automatic injection device is configured to receive an injection syringe whose protective cap has a diameter at least equal to that of the syringe body, including a type of cap RNS. The invention will be better understood on reading the appended figures, which are provided by way of example and are in no way limitative, in which: FIG. 1 is a perspective view of an automatic injection device according to a FIG. 2 is an exploded perspective view of the automatic injection device of FIG. 1, FIGS. 3 and 4 are perspective views respectively from the proximal end and from the side of a cap removal member. of the automatic injection device of FIG. 1, FIGS. 5 and 6 are perspective views respectively from the proximal end and from the distal end of an end sleeve of the automatic injection device of FIG. FIG. 7 is an exploded perspective view of the shroud of the protective cap and the end sleeve of the automatic injection device of FIG. 1, FIGS. 8 and 9 are perspective views respectively complete and in axial section of a syringe holder of the automatic injection device of FIG. 1, FIG. 10 is an axial perspective sectional view of the FIG. end, of the syringe holder and springs of the automatic injection device of Figure 1, Figures 11, 12 and 15 are side perspective views respectively of a positioning ring, a rod of piston and a needle control member of the automatic injection device of Figure 1, Figures 13 and 14 are respectively a cross-sectional and axial sectional view of the syringe holder in which are assembled the injection syringe, the positioning ring and the piston rod of the automatic injection device of FIG. 1, FIGS. 16 to 18 and 20 are side perspective views respectively of a piston control member, a Figure 1 is a perspective sectional view from the distal end of the outer casing of FIG. 1, a positioning control member and an outer casing of the automatic injection device of FIG. 20, FIG. 21 is a partial perspective view from the proximal end of the piston control member, the piston rod and the retaining ring during injection of liquid product from the injection device. FIGS. 22 and 23 are partial axial section views of the automatic injection device of FIG. 1, showing a locking member respectively in the locked and unlocked position, FIGS. 24, 25, 27 and 28 are views in axial section of the withdrawal member, the end sleeve, the syringe holder and the injection syringe of the automatic injection device of FIG. 1, respectively at the time of insertion of the injection syringe into the syringe holder; once the injection syringe is inserted, in storage configuration; once the protective cap is removed and before insertion of the injection needle into the skin of a patient; and once the injection needle is inserted into the skin of a patient, FIG. 26 is an axial perspective sectional view of the end sleeve, the syringe holder and the injection syringe of the device. FIG. 1, showing the removal of the protective cap, FIGS. 29, 31 to 34 are perspective views, in partial axial section, of several assembled elements of the automatic injection device of FIG. in the storage position before removal of the protective cap; during the insertion of the injection needle into the skin of a patient; during the injection, the piston control member being entirely in FIG. 32 and in axial section in FIG. 33, and in the protective position, and FIG. 30 is a perspective axial sectional view of the device. automatic injection of Figure 1, shortly after a support of the distal end of the automatic injection device on the skin of a patient.

An automatic liquid product injection device 10, as shown in Figure 1, allows the automatic administration of a liquid product requiring an injection, namely a drug. It is intended to receive an injection syringe 12 (visible in particular in Figure 26) containing the liquid product. As illustrated in Figures 2 and 30, the automatic injection device 10 comprises a number of parts, more specifically in this example a syringe holder 14, two springs 15a, 15b, an end sleeve 16, a a protective cap removal member 42, a piston rod 19, a positioning ring 50, a positioning control member 20, a needle control member 21, a piston control member 22, a piston ring retainer 23, an injection spring 24, and an outer casing 25.

As can be seen for example in Figure 26 or Figure 30, the injection syringe 12 comprises a syringe body 26 of generally tubular shape about an injection axis X. The syringe body 26 comprises, at its distal end 26D, a distal shoulder 30 carrying an injection needle 32. The proximal end 26P of the syringe body 26 comprises a collar 38. A piston 40, sliding, of generally cylindrical shape about the axis of injection X, is mounted in the syringe body 26 and allows to inject a liquid product contained in the syringe body 26 by the injection needle 32. As shown in Figure 14, the piston 40 has a distal end arranged on the side of the liquid product and an opposite proximal end 40P. The injection needle 32 is covered with a protective cap 42 of the RNS ("Rigid Needle Shield") type, comprising a soft rubber inner stopper intended to receive the end of the injection needle 32 and to ensure closure, the inner cap being surrounded by a shell of rigid plastic material conferring a good mechanical strength to the inner plug. This protective cap 42 has a generally cylindrical shape around the injection axis X, and may have a diameter greater than that of the syringe body 26 and, at the end of the stroke, which bears on the distal shoulder 30. In this example, the injection syringe 12 is a pre-filled glass needle syringe with a capacity of 1 mL (milliliter). Note that the syringe body 26 defines a maximum volume of liquid reception, but that it is possible to fill only partially, advancing the piston 40 to the distal end 26D of the syringe body 26.

As shown in FIG. 8, the syringe holder 14 is generally tubular in shape around the injection axis X, it is open at both ends and is intended to receive the injection syringe 12. The support syringe 14 is thus a single piece, distinct from two half-shells assembled to one another. The syringe holder 14 is configured to house the injection syringe 12 so that it is fixedly mounted in the syringe holder 14 throughout the operation of the automatic injection device 10. The syringe holder 14 has one end. 14D distal disposed on the side of the injection needle 32 and an opposite 14P proximal end.

As can be seen in FIGS. 8 and 9, the syringe holder 14 has, at its proximal end 14P, an internal clearance 44 delimited by an internal shoulder, making it possible to receive the collar 38 of the syringe body 26 when the injection syringe 12 is inserted into the syringe holder 26. Such internal clearance 44 allows the proximal end 14P to have an inside diameter greater than the rest of the syringe holder 14, and thus to receive, on the one hand, the collar 38, on the other hand a ring 50 for positioning the piston rod 19, these two elements having a larger diameter than the syringe body 26. The proximal end 14P of the syringe holder 14 also has an external shoulder 45, complementary to the inner shoulder 44. This outer shoulder 45 forms a blocking relief of the needle control member 21. More specifically, the outer shoulder 45 makes it possible to ocher the needle control member 21 on the proximal end 14P of the syringe holder 14 at the time of assembly of a proximal assembly with a distal assembly of the automatic injection device 10 and until the end of inserting the injection needle 32 into the patient's skin. Two axial notches 48 are also arranged facing each other in the wall of the proximal end of the syringe holder 14. These axial notches 48 allow cooperation with the ring 50 for positioning the piston rod 19 shown in particular in Figures 11 and 13. The outer shoulder 45 further comprises a recess 49 forming an axial guide rail for a guide rib 108 of the needle control member 21.

Two viewing windows 47 are arranged facing each other in the wall of the syringe holder 14. Each viewing window 47 is of elongate shape and extends substantially in the direction of the injection axis X and makes it possible to make the injection syringe 12 visible when it is inserted into the syringe holder 14. This also allows the user to see that there is liquid product in the injection syringe 12. Furthermore, as shown in FIG. 9, the syringe holder 14 comprises, on an inner face of its wall that can be in contact with the injection syringe 12, a damping element 58 made of elastomeric material, presenting itself for example in the form of an elastomeric strip extending axially and also having a centering rib function. Several damping elements 58 are angularly distributed on the inner face of the syringe holder 14. They are intended firstly to center the injection syringe 12 when it is housed in the syringe holder 14, on the other hand to absorb a portion of the pressure exerted on the injection syringe 12 during the activation of the automatic injection device 10. Moreover, they contribute to the axial blocking of the injection syringe 12 in the syringe holder 14, in particular when advance the injection syringe 12 to perform the insertion and during the pressure exerted by the piston 40 on the injection syringe 12 during injection. Indeed, friction between the elastomeric material and the syringe body 26 allow the pressure received by the syringe body 26 is directly transmitted to the syringe holder 14, to avoid the breakage of the injection syringe 12, often glass . These damping elements 58 also make it possible to absorb the shocks suffered by the automatic injection device 10, for example during its transport, thus protecting the injection syringe 12 from possible risks of breakage. The elastomeric material is for example an elastomeric thermoplastic material (TPE), preferably injected or overmolded.

As can be seen in Figure 8, the syringe holder 14 has, at its distal end 14D, on either side of the viewing windows 47, retaining means of the end sleeve 16 on the syringe holder 14, having two radial projections 52 on the outer face of the syringe holder 14, substantially opposite each other. Each radial projection 52, has, on its distal face, a ramp 55 intended to cooperate with the end sleeve 16 during its assembly snap on the syringe holder 14. The distal end 14D of the syringe holder 14 also comprises retaining tabs 53, more precisely four axially extending holding tabs 53 distributed angularly along the distal contour of the syringe holder 14. Each retaining tab 53 has a bevelled surface 54 intended to cooperate with the end sleeve 16 when the latter is in the injection position. The distal end of the syringe holder 14 also comprises means for guiding the end sleeve 16 on the syringe support 14. These guide means comprise a raised guide shape, namely two guide rods 56 that are integral with each other. with the syringe holder 14, extending on either side of the outer wall of the syringe holder 16, along the axis of injection X. The guide rods 56 are intended to cooperate each with a guide shape complementary hollow, namely a slide 57 (visible in Figure 6) and provided on the end sleeve 16, comprising a passage slot to allow guiding during the relative movement of the end sleeve 16 and the syringe holder 14 Each slideway 57 has a distal portion defining a housing for receiving one of the protective springs 15a or 15b. Thus, the springs 15a, 15b, once released, can each exert a force on one of the guide rods 56 to allow the relative sliding of the end sleeve 16 and the syringe holder 14, the springs protection 15a, 15b being springs in compression. As can be seen in Figures 9 and 10, the distal end 14D of the syringe holder 14 further comprises two notches 60 for the passage of attachment tabs 66 formed on the removal member 18 of the protective cap 42 The notches 60 are axially aligned with the retaining means 52. The protective cap removal member 18, detailed in Figures 3, 4, and 7, forms the distal end of the automatic injection device 10. It is intended to be removed from the automatic injection device 10 before activation thereof. The removal member 18 has a generally frustoconical shape around the injection axis X, open at both ends, the proximal diameter greater than the distal diameter. The distal end of the withdrawal member 18 further comprises, around its distal opening 62, gripping means by a user comprising a flared base 64, further allowing the automatic injection device 10 to stand upright when it is placed on a horizontal support. The removal member 18 comprises two attachment tabs 66 of the protective cap 42. The two attachment tabs 66 are located inside the withdrawal member 18, being diametrically distributed around the syringe injection 12 when the withdrawal member 18 is mounted on the automatic injection device 10. The two attachment tabs 66 extend axially (along X) from the distal opening 62 to the proximal end of the organ 18, protruding from this proximal end. As can be seen in FIG. 4, each latching lug 66 has a proximal ramp 68 for cooperation with the external lateral wall of the protective cap 42 during the insertion of the injection syringe 12 into the syringe holder. 14, and an outer ramp 70 for cooperation with the end sleeve 16 on which the removal member 18 is mounted. Each attachment lug 66 further includes a shoulder 72 intended to cooperate with the proximal edge of the protective cap 42 of the injection syringe 12 and allowing its removal when a user pulls axially su 18. withdrawal member moreover, each external ramp 70 allows, when a user pulls axially on the withdrawal member 18, in cooperation with the end sleeve 16, to tighten the latching lug 66 against the protective cap 42. withdrawal member 18 is adapted to drive the protective cap 42 when removed from the automatic injection member 10. The withdrawal member 18 is removably attached to the distal end of the end sleeve 16, and thus itself forms a means for gripping the protective cap 42 (as illustrated in FIG. 26). The withdrawal member 18 also has, on either side of the attachment lugs 66, on the internal face of its wall, two lugs 74 for cooperation with the end sleeve 16.

As shown in Figures 1 and 2, the end sleeve 16 forms, after removal of the withdrawal member 18, the distal end of the automatic injection device 10. It is thus intended to be in contact with the skin of a patient during the injection. The end sleeve 16 is attached to the distal end 14D of the syringe holder 14. It is slidably mounted relative to the syringe holder 14 between an injection position, in which the syringe holder 14 and the 16 end are axially (along X) close together, and a protective position in which the syringe holder 14 is axially distally away from the end sleeve 16. The sliding of the end sleeve 16 relative to the support syringe 14 is made possible by the cooperation of the slides 57 formed in the inner wall of the end sleeve 16 and guide rods 56 carried by the outer wall of the syringe holder 14, forming means of cooperation between the sleeve of the syringe 14. end 16 and the syringe holder 14. The end sleeve 16 has a generally frustoconical shape around the injection axis X, open at both ends, the dia proximal meter being greater than the distal diameter.

As can be seen in FIGS. 26 and 28, the end sleeve 16 comprises two retaining stops 76, each being carried by an elastic tab 78. Each elastic tab 78 extends axially (along X) from the distal end towards the proximal end of the end sleeve 16, protruding from the inner surface of the end sleeve 16. The two elastic tabs 78 are symmetrical with respect to each other with respect to an axis of symmetry passing through. by the injection pin X. Thus, each elastic tab 78 extends axially (along X) and has a proximal end having a surface extending in a substantially radial plane, this surface forming a stop 76 of axial retention of the injection syringe 12, preventing the injection syringe 12 from moving towards the distal end of the automatic injection device 10 inadvertently. Each elastic tab 78 is deformable between a constricted position, configured to retain axially (in X) in the distal direction the injection syringe 12 in the syringe holder 14, and a spaced position, configured to allow axial insertion (according to X) in the distal direction, from the proximal end of the syringe holder 14, the injection syringe 12 provided with the protective cap 42. When the end sleeve 16 is in the injection position, visible on the fig 28, the retaining tabs 53 of the syringe holder 14 hold the elastic tabs 78 in a constricted position, the retaining tabs 53 thus preventing the resilient tabs 78 from being moved apart and thus preventing the injection syringe 12 from retreating (to the proximal end of the automatic injection device 10). In addition, when the end sleeve 16 is in the injection position, it envelopes the retaining tabs 53, so as to prevent spacing of the holding tabs 53 induced by a spacing of the elastic tabs 78.

As can be seen in FIGS. 5 and 6, the end sleeve 16 furthermore comprises, at its proximal end, means for retaining the end sleeve 16 on the syringe holder 14, comprising two proximal windows 80 intended to to serve as a guide for sliding the two radial projections 52 of the syringe holder 14, which are assembled in the proximal windows 80 by snapping. The proximal end of the end sleeve 16 further comprises, on its outer side wall, two projecting lugs 82 (see Figures 5 and 6) radially intended to cooperate with the positioning control member 20 to hold it in place.

In order to ensure that the withdrawal member 18 does not inadvertently disengage from the end sleeve 16, the end sleeve 16 further comprises, on the distal portion of its inner wall, means for retaining the the withdrawal member 18, comprising two cavities 84 intended to cooperate by clamping or latching with the two lugs 74 of the withdrawal member 18 (see Figures 6 and 7). This avoids the rotation of the protective cap 42 with respect to the end sleeve 16, rotation which could cause cutting by the cutting edge of the bevel of the injection needle 32 of a piece of the inner cap of the cap. protection 42, a phenomenon known as "coring". To allow removal of the removal member 18 on the end sleeve 16 after insertion of the injection syringe 12 into the syringe holder 14, the end sleeve 16 also has, on the distal portion of the its inner wall, on either side of the two cavities 84, means for guiding the withdrawal member 18 comprising two axial slides (along X) 86. It is understood that the end sleeve 16 is attached around the distal end of the syringe holder 14, so that the syringe holder 14 is slidable within the end sleeve 16.

The piston rod 19 makes it possible to transmit a pressure on the piston 40 in order to inject the liquid product. It comprises, as shown in Figure 12, a distal end 19D, oriented towards the piston 40 and intended to be in contact with the proximal end 40D of the piston 40, during the injection in particular. This distal end 19D of the piston rod 19 has a cross section having a polarizing contour, more precisely a non-circular contour. The piston rod 19 further has a proximal end 19P, opposite to the distal end 19D, configured to cooperate with the piston control member 22 activated by the injection spring 24. The proximal end 19P of the rod piston 19 is of generally cylindrical shape around the injection axis X and comprises four radial projections 87, angularly distributed around the injection axis X, intended to cooperate with the piston control member 22. As shown in FIG. visible in Figure 12, two sliding grooves 88 are formed in the piston support 19, substantially opposite each other and diametrically opposed. Each sliding groove 88 may, for example, be formed by an axial groove. These two sliding grooves 88 extend axially (along X) along the piston rod 19 and define the polarizing outline of the cross section. These sliding grooves 88 are intended to cooperate with an alignment cam of the positioning ring 50. The piston rod 19 furthermore comprises, on its distal end 19D, a distal abutment 90 of axial retention of the positioning ring. 50, more precisely two distal stops diametrically opposed. Preferably, the distal stop 90 is formed by a transverse groove formed in each of the sliding grooves 88.

The positioning ring 50, illustrated in FIG. 11, is intended to cooperate with the piston rod 19 to allow both a good axial and angular positioning of the piston rod 19, and to prevent the withdrawal of the piston rod. 19 from the operating ring 50, or even from the automatic injection device 10. The axial positioning makes it possible to ensure a correct position with respect to the piston 40 on the one hand and to the piston control member 22 on the other hand go. The angular positioning not only prevents the piston rod 19 from rotating on itself during the activation of the piston rod 19 but also provides a predefined angular orientation with respect to the syringe holder 14, allowing abutment axial and then an axial release of the piston rod 19 and the piston control member 22, these configurations being implemented following a rotation of the piston control member 22 relative to the rod of piston 19. The positioning ring 50 is intended to be attached to the proximal end 14P of the syringe holder 14. In order to prevent the free rotation of the positioning ring 50 relative to the syringe holder 14, the positioning ring 50 comprises angular setting means 98 of the positioning ring 50 on the proximal end 14P of the syringe holder 14. These angular setting means 98 may for example comprise external wedging lugs intended to be inserted into the axial notches 48 of the syringe holder 14, as can be seen in FIG. 13 or in FIG. 26. The means for axial positioning of the piston rod 19 formed on the positioning ring 50 comprise an axial retaining stop 94 of the piston rod 19, here carried by an elastic tab 96 extending axially from a proximal washer 50P to a distal end 50D of the positioning ring 50. More specifically, the positioning ring 50 comprises two diametrically opposed elastic tabs 96, each carrying an axial retaining stop 94, which is formed in this example by an axial retaining pin of the piston rod 19. Each axial retaining stop 94 prevents, in cooperation with a stop corresponding distal 90 of the piston rod 19, that the latter can not be withdrawn entirely (by traction in the proximal direction) of the piston ring. positioning 50 before assembly, and the injection syringe 12 after assembly. The means for axial positioning of the piston rod 19 on the positioning ring 50 are furthermore arranged so that, in the storage configuration of the automatic injection device 10, there is a clearance between the distal end 19D of the rod. 19 and the proximal end 40P of the piston 40, preferably a clearance between 0.5 and 2 mm, for example close to 1 mm, as shown in Figure 14. The positioning ring 50 further comprises means angular positioning of the piston rod 19 on the positioning ring 50, comprising a passage opening 92 of the piston rod 19 having a polarizing contour complementary to that of the distal end 19D of the piston rod 19. way, the passage opening 92 ensures a defined and controlled angular positioning of the piston rod 19 relative to the positioning ring 50 throughout the operation of the injection device. n automatic 10.

FIG. 2 shows the positioning control member 20, which comprises two parts, two half-shells intended to be snapped together around the syringe holder 14 by latching means 100 comprising various notches and lugs. The positioning control member 20 thus has a generally X-axis tubular shape. The distal end of the positioning control member 20 is provided with means for retaining the end sleeve 16, comprising a locking window. 101 intended to cooperate with the two protruding lugs 82 of the outer side wall of the end sleeve 16 (see Figure 6). This locking window 101 has a bayonet shape to allow assembly of the end sleeve 16 and the positioning control member 20 by a slight rotation. Once assembled, the end sleeve 16 and the positioning control member 20 are fixed relative to each other throughout the operation of the automatic injection device 10. As shown in FIG. 18, the positioning control member 20 also comprises first and second cam paths 102 and 104 intended to cooperate respectively with first and second positioning control cams 46, 106 respectively carried by the needle control member 21 ( Figure 15) and the piston controller 22 (Figure 16). Thus, since the needle control member 21 and the piston 22 have separate cam paths, once the automatic injection device 10 is activated, the injection needle insertion step 32 in the body of the patient and the step of injecting the liquid product contained in the injection syringe 12 are distinct and separate steps, so that they are each implemented precisely, temporally controlled and adapted to the liquid product injected. This further ensures that the injection needle 32 is inserted at the proper depth into the skin of the patient 11 before injection begins. Furthermore, as can be seen in FIG. 18, the first cam path 102 has a portion that is more inclined than the rest of the first cam path 102, namely inclined at about 45 °, which allows a progressive advance of the needle. injection 32 at the beginning, and thus limits the pain of the patient. The advancing speed of the injection needle 32 can be adjusted by varying the inclination of the first cam path 102. The needle control member 21 is generally tubular in shape, as can be seen in FIG. FIG. 15. At its proximal end 21P, it comprises temporary coupling means 112 with complementary coupling means 114 carried by the piston control member 22 (FIG. 16), so that the control member of FIG. needle 21 and piston 22 are integral in motion at the beginning of the thrust exerted by the injection spring 24. Thus, when the injection spring 24 begins to push the piston control member 22, it also pushes the a needle control member 21 which, being at this stage also coupled to the syringe holder 14, will push the syringe holder 14 in the distal direction, and thus allow insertion of the injection needle 32 into the skin of the patient 11. Pl Specifically, the temporary and complementary coupling means 112, 114 comprise two complementary parts having a mutual engagement shape, for example two axially extending inverted hooks, the first carried by the proximal end 21P of the control member. 21 and the second carried by the distal end 22D of the piston control member 22. Furthermore, the needle control member 21 comprises a guide rib 108, axial, projecting from the surface the inside of the needle control member 21, and at its distal end 21D, a locking pin 107 projecting from its inner surface and having a funnel-shaped shape, the thin portion of the funnel being oriented on the distal side. The locking pin 107 is intended to cooperate with the outer shoulder 45 of the proximal end 14P of the syringe holder 14. In fact, this outer shoulder 45 forms a locking relief of the needle control member 21 at the beginning. operation of the automatic injection device 10, during the insertion of the injection needle 32 into the skin of the patient. As mentioned above, the outer shoulder 45 thus makes it possible to hook the needle control member 21 on the proximal end 14P of the syringe holder 14 at the time of assembly of the proximal assembly with the assembly. distal of the automatic injection device 10, this assembly takes place by axial insertion of the locking pin 107 in the guide rail 49 of the syringe holder 14, then by rotation of the needle control member 21 relative to the support syringe 14 so that when the automatic injection device 10 is in the storage position, before being used, the outer shoulder 45 is stuck axially (along the injection axis X) between the blocking pin 107 on the distal side, and the distal end of the guide rib 108 on the proximal side. The needle control member 21 further comprises, on its outer surface and on its distal end 21 D, the first cam 46 intended to cooperate with the first cam path 102 formed in the positioning control member 20. The piston control member 22, visible in particular in FIG. 16, has a generally tubular shape. It is configured to apply a force on the piston 40 (via the piston rod 19), under the action of the injection spring 24. This force allows the axial displacement (along X) of the piston 40 in the distal direction of the automatic injection device 10, for injecting the liquid product into the skin of the patient. The piston control member 22 carries a stop 118 which can be retracted between an active configuration for retaining the injection spring 24 in the compressed state and a retracted configuration for releasing the injection spring 24. More specifically, the organ control 22 comprises two diametrically opposed semi-flexible semi-annular elastic tabs 116, each carrying a retractable stop 118 intended to cooperate with the member of the locking member of the outer casing 25. Each of the semi-annular elastic tabs 116 carrying the retractable stops 118 extends axially (along X) towards the proximal end of the automatic injection device 10, each semi-annular elastic tab 116 thus being deformable between a radially spaced rest configuration giving the retractable abutment 118 its configuration active and a radially retracted configuration giving the retractable stop 118 its configuration esc amotée. Each semi-annular elastic tab 116 of the piston control member 22 further having a longitudinal window 120 allowing deformation to facilitate the assembly of the injection spring 24 and the retaining ring 23 of the injection spring 24 around the two semi-annular elastic tabs 116. Thus, each retractable stop 118 is radially spaced when it is in its active configuration. This allows in particular each retractable stop 118 of the piston control member 22 to take a radially projecting position. Furthermore, each retractable stop 118 is radially retracted when it is in its retracted configuration, in particular to take a radially retracted position. The piston control member 22 has, at its distal end 22D, a generally cylindrical shape carrying the complementary coupling means 114 and the second cam 106, and delimiting a proximal shoulder 115, external, forming a seat for the spring of injection 24. This proximal shoulder 115 is also traversed by orifices, extending towards the proximal end 22P so as to form axial slots 119. The piston control member 22 is configured to be rotatable relative to the piston rod 19 between a thrust configuration, during which it abuts against the radial projection 87 and exerts a thrust on the piston rod 19, and a configuration the release of the piston rod 19, in which it is not in abutment against the radial projection 87 and releases a passage, formed by the axial slots 119, so that the piston rod 19 can retract in the prox direction imale.

The retaining ring 23 serves to retain the injection spring 24 in the compressed state. More precisely before the injection, the injection spring 24 is maintained in its compressed state by means of the retractable stop 118 carried by the control member of the piston 22, cooperating with a complementary surface carried by the retaining ring 23. In other words, the retractable stop 118 in active configuration abuts against a complementary surface carried by a retaining ring 23 of the injection spring 24. This retaining ring 23 is attached to the proximal end 20P of the positioning control member 20. For this purpose, it has two lugs 121, external and diametrically opposed, for setting the retaining ring 23 intended to cooperate with complementary notches of the positioning control member 20. The end distal of the retaining ring 23 also forms a proximal seat for the injection spring 24, and the proximal end forms a complete abutment surface for the retractable stop 118.

The injection spring 24 is the main engine of the injection. Also, it must have sufficient force to be able on the one hand to penetrate the injection needle 32 in the body of the patient, on the other hand to move the piston 40 in the syringe body 26 to inject the liquid product. Its strength is preferably greater than 20 Newton or 50 Newton or 80 Newton for a relatively viscous liquid product or for a syringe / needle section high ratio. This injection spring 24 is deformable between a compressed state before use of the automatic injection device 10 and a relaxed state after injection of the liquid product contained in the syringe body 26. As explained above, before the injection, the spring injection 24 is maintained in its compressed state by means of the retractable stop 118 carried by the control member of the piston 22, cooperating with a complementary surface carried by the retaining ring 23. This retractable stop 27 is indeed retractable between an active configuration for retaining the injection spring 24 in the compressed state, corresponding to a radially protruding position for retaining the injection spring 24 and a retracted configuration for releasing the injection spring 24 allowing it to relax.

The outer casing 25 is the part which, in this example, envelops most parts of the automatic injection device 10. It allows in particular that these parts of the automatic injection device 10 are isolated from the outside. The outer casing 25 also comprises a locking member 122 of the retractable stop 118 in its active configuration, provided in the proximal end of an outer casing 25 of the automatic injection device 10. This locking member 122 can take a position locking, in which it exerts pressure on the retractable stop 118 to prevent it from taking its retracted configuration, and an unlocking position in which the retractable stop 118 is free to take its retracted configuration. More specifically, as can be seen in FIG. 20, the proximal end 25P of the outer casing 25 comprises a radial surface, recessed (in two distinct orifices, facing each other) in the vicinity of an unlocking pin 124 so as to be traversed by the semi-annular elastic tab 116 of the piston control member 22 carrying the retractable stops 118 at least when the locking member 122 is in the locking position. The locking pin 122 comprises two axially distributed segments (along X) and of different diameters, namely a locking section 126 and an unlocking section 128. The locking section 126 has a radial dimension which is greater than a radial dimension of unlocking section 128 if we consider an axial section passing through the retractable stops 118, so that the locking section 126 exerts a radial pressure on the retractable stops 118 when the locking member 122 is in the locking position. The unlocking section 128 creates, in turn, a clearance space retractable stops 118 when the locking member 122 is in the unlocked position. The locking section 126 and the unlocking section 128 are distally offset relative to one another. The locking member 122 also carries a ramp 130 intended to cooperate by ramp effect with the semi-annular elastic tabs 116 of the piston control member 22 carrying the retractable stops 118, to move them from their active configuration to its retracted configuration. Thus, the unlocking section 128 is distally at least partially facing the ramp 130. As is explained below, the transition from the locking position to the unlocking position of the locking member 122 is triggered by a supporting the distal end of the automatic injection device 10 on the skin of a patient.

The main operating steps of the automatic injection device 10 are described below.

As can be seen in Figure 1, the automatic injection device 10 is presented to the user in the form of a tube of about ten centimeters long. Only the outer casing 25 and the removal member 18, or the end sleeve 16 if the removal member 18 is removed, are visible and accessible to the user.

A first operating step consists in holding the protective cap removal member 18 with one hand and the outer casing 25 with the other hand and pulling on the withdrawal member 18 along the injection pin X in a distal direction. The axial traction movement activates the outer ramp 70 of each latching lug 66, tightening the two latching lugs 66 against the protective cap 42, favoring the contact between the shoulder 72 of each latching lug 66 and the latch 66. Proximal rim of the protective cap 42. Thus, as illustrated in Figure 15, the withdrawal of the withdrawal member 18, allows the removal of the protective cap 42, thus denuding the injection needle 32. The needle d However, the injection 32 remains inaccessible because, as illustrated in FIG. 17, it is wrapped around the end sleeve 16. Once the withdrawal member 18 is removed from the automatic injection device 10, the end sleeve 16 shaped the distal end and the automatic injection device 10 is ready to be used. At this point, the injection needle 32 is set back in the end sleeve 16, 3 mm (millimeters), to prevent accidental puncture. In a next step, the distal end of the end sleeve 16 is placed against the skin of the patient 11, where the injection of the medical liquid contained in the injection syringe 12 is desired. This step is followed by an unlocking step, during which a slight axial pressure is applied, in the distal direction, on the outer casing 25. This support of the distal end of the automatic injection device 10 on the skin of the patient 11 triggers an axial displacement of the outer casing 25 towards the end sleeve 16. In other words, the end sleeve 16 slides slightly inside the outer casing 25 towards its proximal end, generating a sliding, to the inside of the outer casing 25 and towards the proximal end of the outer casing 25, the positioning control member 20 and the retaining stop 23. This sliding results in the unlocking of the retractable stop 118 carried by the proximal end of the piston control member 22. The automatic injection device 10 is thus in a position before injection, such that Fig. 27. The unlocking step is followed by a step of triggering the automatic injection, during which the user continues axial pressure on the outer casing 25 by pressing on the skin of the patient. , in the continuity of the axial pressure started during the unlocking step. This additional pressure generates a compression of the protective springs 15a, 15b which allows, in the first place, an axial connection (along X) of the end sleeve 16 and the syringe holder 14. Thus, the end sleeve 16 slides further within the outer housing 25 towards its proximal end, generating additional sliding, within the outer housing 25 and towards the proximal end of the outer housing 25, the positioning control member 20 and the Piston control member 22. As a result, the retractable stop 118 carried by the piston control member 22 slides toward the proximal end of the outer casing 25, which generates its retraction out of the retaining ring engagement. 23, by ramping effect between the retractable stop 118 and the proximal surface of the outer casing 25, so that the injection spring 24 is released.

The release of the injection spring 24 triggers a series of cascading reactions which result in the penetration of the injection needle 32 into the patient's body and the injection of the liquid product contained in the syringe body 26. It will be noted that that the stroke of the injection needle 32, during these operations, is 9 mm, so that the injection needle 32 exceeds about 6 mm, corresponding to the depth of injection into the skin of the patient 11. In particular, the injection spring 24 pushes distally on the piston control member 22 which is, at this point, coupled with the needle control member 21 by virtue of the entanglement of the temporary coupling means and complementary 112, 114. The displacement of the needle control member 21, being secured to the syringe holder 14 via the outer shoulder 45, generates the displacement in the distal direction of the syringe holder 14. As the injection syringe 12 is mounted integral with the syringe holder 14, the injection syringe 12 is also pushed towards the distal end of the automatic injection device 10 and the injection needle 32 springs out of the injection sleeve. end 16. This axial reconciliation of the end sleeve 16 and the syringe holder 14 is by sliding between, on the one hand, the radial projections 52 of the syringe holder 14 in the proximal windows 80 of the end sleeve 16. and, on the other hand, the guide rods 56 in the gutters 57 of the end sleeve 16. This axial approximation is illustrated in FIGS. 27 (before insertion of the injection needle 32) and 28 (after insertion of the injection needle 32). Once the injection needle 12 is inserted into the skin of the patient 11, the injection can begin. It will be noted that simultaneously with the penetration of the injection needle 32, the first cam 46 of the needle control member 21 is guided by the first corresponding cam path 102 of the positioning control member 20. more precisely by the portion inclined at 45 ° of this first cam path 102. As a result, the rate of penetration of the injection needle 32 into the skin of the patient is lower than the uninhibited speed of expansion of the spring d injection 24, so that the pain associated with the penetration of the injection needle 12 is advantageously reduced.

Simultaneously with the axial displacement of the needle control member 21, a rotation of the piston control member 22 with respect to the needle control member 21 is generated about the injection axis X, because of the second cam 106 which cooperates in the second inclined cam path 104. This rotation results in a decoupling of the needle control member 21 and the piston control member 22, as well as a coupling of the piston control member 22 and the piston rod 19, performed by an abutment of the control member of the piston 22 with the proximal end 19D of the piston rod 19, more precisely with the radial projections 87. As a result, the thrust exerted by the injection spring 24 on the piston control member 22 results in a push on the piston rod 19, thus on the piston 40 in the syringe body 26, involving an injection of the liquid product into the body of the patient.

It is understood that the relative axial advance of the needle control member 21 and the piston control member 22 is controlled by the cooperation of the first and second cams 46, 106 with the corresponding first and second cam paths. 102, 104 of the positioning control member 20. Thus, the cooperation between the first and second cams 46, 106 of the needle control 21 and piston control members 22 with the corresponding first and second cam paths 102 , 104 of the positioning control member 20 independently controls the penetration of the injection needle 32 into the skin of the patient 11 and the injection of the medical liquid contained in the syringe body 26. It will be noted that that the mechanism of successive couplings, comprising a coupling at first time of the injection needle 21 and piston 22 control members, and a coupling in a second time of the control member piston 22 and the piston rod 19, makes completely independent penetration of the injection needle 32 and injection, that is to say that it is necessary to achieve the right injection needle depth 32 before starting the injection, which avoids incorrect injection.

After the injection is complete, the syringe holder 14 rises freely in the piston control member 22, due to the rotation of the latter 22 which allowed to align the radial projections 87 of the piston rod 19 with the axial slots 119, thereby releasing a passage for the piston rod 19 to retract relative to the piston control member 22 in the proximal direction. The syringe holder 14 is thus axially remote from the end sleeve 16, and the injection needle 32 is retracted into the end sleeve 16, thus avoiding any risk of injury. The two protective springs 15a, 15b can freely relax, they are no longer subjected to the force exerted by the injection spring 24 and generate a protective position in which the syringe holder 14 is axially remote from the sleeve of end 16, resulting in the retraction of the injection needle 32 in the end sleeve 16, thus avoiding any risk of injury.

It will be noted that throughout the duration of the injection in particular, the injection syringe 12 is pressurized, it is retained within the automatic injection device 10 while the pressure exerted on the proximal end of the injection rod piston 19, so on the piston 40, can be consistent. As can be seen in FIG. 28, during the entire duration of the injection, it is the cooperation between the distal shoulder 30 of the injection syringe 12 and the two retaining stops 76 carried by the elastic tabs 78. end sleeve 16 which holds the injection syringe 12, that is to say that it is the distal end of the injection syringe 12 which receives the stress from the injection spring 24 applying the piston 40. In other words, while the injection spring 24 exerts pressure on the piston rod 19 to move the piston 40 in the syringe body 26, the elastic tab 78 of the sleeve end 16 provides the axial retention (along X) of the injection syringe 12 in the distal direction of the automatic injection device 10 so that the pressure exerted by the injection spring 24 on the piston rod 19 during injection causes pressure on the e distal end of the injection syringe 12, but does not generate pressure at the flange 38 of the injection syringe 12. The collar of an injection syringe being a fragile area, the risk of breakage of the injection syringe 12 are thus considerably reduced and the injection spring 24 can be selected from very rigid springs, allowing for example the injection of highly viscous products, up to 100 CP and / or the use of injection needles 32 of reduced diameter.

According to an alternative embodiment not shown, the flange can be supported on an elastic ring allowing the bulk of the axial pressure to be collected by the distal end of the injection syringe, thereby decreasing the pressure on the patient. body of the syringe at the level of the collar.

It will be noted moreover that during the entire duration of the injection, the end sleeve 16 envelops the four holding tongues 53 of the syringe holder 14, so as to prevent spacing of the holding tongues 53 induced by a gap of the elastic tab 78 under the effect of the pressure exerted by the distal shoulder 30 of the injection syringe 12 on the retaining stops 76. Thus, the holding tabs 53 are held in their tightened position by the proximal portion of the sleeve end 16. This prevents, by abutment effect between the bevelled surfaces 54 and the elastic tabs 78, elastic tabs 78 from moving away under the effect of the pressure exerted by the injection spring 24 and thus allows retain the distal shoulder 30 of the injection syringe 12 (see Figure 28).

It will be understood that since the elastic tabs 78 of the end sleeve 16 provide the axial retention (along X) of the injection syringe 12 in the distal direction of the automatic injection device 10, the pressure exerted by the spring of injection 24 on the piston rod 19 during injection, causes pressure on the distal end of the injection syringe 12 but does not generate pressure at the collar 38 of the injection syringe 12.

The main assembly steps of the automatic injection device 10 are now described.

Overall, the assembly of the automatic injection device 10 comprises four main steps: a step of assembling a distal subassembly comprising the syringe holder 14, a step of inserting the injection syringe in the syringe holder 14 from its proximal end 14P, - a step of inserting the positioning ring 50 preassembled with the piston rod 19 onto the proximal end 14P of the syringe holder 14, preferably being positioned therein. relative to each other axially by the axial positioning means 94, - a step of assembling a proximal subassembly, attached over the piston rod 19, with the distal subassembly.

We first assemble a first subset, called distal subset. A first step for this comprises the interlocking of the end sleeve 16 with the withdrawal member 18, by snapping the lugs 74 into the cavities 84. The attachment lugs 66 of the withdrawal member 18 slide in the slides axial 86 of the end sleeve 16 until claws 74 snap into the cavities 84. The step is followed by a detent step of the syringe holder 14 with the end sleeve 16, through the interlocking the radial projections 52 (with the ramps 55) of the syringe holder 14 in the proximal windows 80 of the end sleeve 16. The protective springs 15a, 15b are threaded onto the guide rods 56 before snapping the syringe holder 14 and the end sleeve 16 and held in place by the latching of the two parts.

Moreover, we assemble a second subset, called proximal subset. For this purpose, the positioning control member 20, the needle control member 21, the piston control member 22, the retaining ring 23, the injection spring 24 and the outer casing 25 are assembled. More specifically, the injection spring 24 is firstly assembled on the proximal end of the control member of the piston 22, by keeping it compressed by cooperation of the retaining ring 23 with the retractable stop 27 carried by the piston control member 22. Then these elements are placed in one of the two half-shells of the positioning control member 20, by additionally adding the needle control member 21 in the coupling position with the piston control member 22. The second half-shell of the positioning control member 20 is then attached to the first half-shell, and then the outer casing 25 is threaded around these elements, by finishing the assembly with a latching of the distal end of the outer casing 25 and that of the positioning control member 20, this snapping nevertheless leaving the possibility of axial sliding, allowing the positioning control member 20 to move back relative to the outer casing 25.

In addition, a third subset is assembled, called an intermediate subset. This subassembly comprises the piston rod 19 provided with the positioning ring 50.

The injection syringe 12, provided with its protective cap 42 and the piston 40, also forms another element apart.

The automatic injection device 10 assembles by inserting, into the distal subassembly, the injection syringe 12, by inserting the latter into the syringe holder 14 from its proximal end. During this insertion, as the end sleeve 16 and the syringe holder 14 are in axially distant position, the end sleeve 16 does not wrap the four holding tabs 53 of the syringe holder 14, which are thus free to move away radially when the protective cap 42 of the injection syringe 12 passes. The elastic tabs 78 of the end sleeve 16 are, in cooperation with the protective cap 42, held in their spaced apart position, thereby allowing the insertion in the distal direction, from the proximal end of the syringe holder 14, of the injection syringe 12 provided with the protective cap 42. Once the injection syringe 12 and the distal subassembly are assembled, it is reported the intermediate subassembly in the proximal end of the syringe body 26, by cooperation of the positioning ring 50 with the axial notches 48 of the syringe holder 14. Then we report the proximal subassembly over the piston rod 19, in particular inserting the locking pin 107 of the needle control member 21 within the guide rail 49 of the syringe holder 14, and the whole is locked by rotation of the withdrawal member 18 relative to the outer housing 25, in particular generating a rotation of the locking pin 107 so that the outer shoulder of the syringe holder 14 is locked between the pin of blocking 107 and the guide rib 108.

It is understood that this assembly is particularly easy to implement, without requiring complex tools. The invention is not limited to the embodiments presented and other embodiments will become apparent to those skilled in the art. Among the multiple possible variants, it will be noted that it would be possible in particular to bring the piston rod 19 to the piston 40 by screwing. In this case, the positioning ring 50 is assembled while being in the retracted position on the piston rod 19, then the piston rod 19 is screwed on and the positioning ring 50 is then slid to be wedged onto the support syringe 14 and activate the axial positioning means.

Claims (10)

An automatic fluid injection device (10) for receiving an injection syringe (12) comprising a distal end carrying an injection needle (32) covered by a protective cap (42) and an end proximal opposite, the automatic injection device (10) having an injection axis (X), characterized in that it comprises: a syringe holder (14) configured to house the injection syringe (12), whereby the injection syringe (12) is fixedly mounted in the syringe holder (14) throughout the operation of the automatic injection device (10), the syringe holder (14) having a distal end disposed on the side of the injection needle (32) and an opposite proximal end, an end sleeve (16), intended to be in contact with the skin of a user during the injection, attached to the distal end of the syringe holder (14) and slidably mounted relative to the syringe holder (14) between an injection position, wherein the syringe holder (14) and the end sleeve (16) are axially close together, and a protective position in which the holder syringe (14) is axially remote from the end sleeve (16), the end sleeve (16) having a retaining stop (76) carried by a resilient tab (78), the resilient tab (78) being deformable between a constricted position, configured to axially retain the injection syringe (12) in the distal direction in the syringe holder (14), and a spaced apart position configured to allow insertion in the distal direction from the end proximal of the syringe holder (14), the injection syringe (12) provided with the protective cap (42). 2. Automatic injection device (10) according to the preceding claim, wherein the syringe holder (14) comprises, at its distal end, a retaining tab (53) of the elastic tab (78) in the constricted position, this holding tab (53) preventing the resilient tab (78) from being moved apart when the end sleeve (16) is in the injection position. An automatic injection device (10) according to any one of the preceding claims, wherein the end sleeve (16), when in the injection position, wraps the retaining tab (53), to prevent a spacing of the retaining tab (53) which would be due to a spacing of the elastic tab (78). 4. Automatic injection device (10) according to any one of the preceding claims, wherein the elastic tab (78) extends axially and has a proximal end having a surface extending in a substantially radial plane, this surface forming the axial retaining stop (76) of the injection syringe (12), preventing the injection syringe (12) from moving towards the distal end of the automatic injection device (10). An automatic injection device (10) according to any one of the preceding claims, further comprising a removal member (18) of the protective cap (42) removably attached to the distal end of the sleeve of end (16), comprising means for gripping by a user and a hooking tab (66) on the protective cap (42), able to drive the protective cap (42) when the withdrawal member (18) is removed from the automatic injection device (10), the hooking tab (66) and the elastic tab (53) being angularly distributed around the injection syringe (12) when the cap removal member (18) ) is mounted on the automatic injection device (10). An automatic injection device (10) according to any one of the preceding claims, for receiving an injection syringe (12) comprising a collar (38) at its proximal end, the automatic injection device (10). comprising an injection spring (24) for exerting pressure on a piston rod (19) to move the piston rod (19) relative to the injection syringe (12) and provide the injection of product liquid, the elastic tab (78) of the end sleeve (16) providing axial retention of the injection syringe (12) in the distal direction of the automatic injection device (10) so that the pressure exerted by the the injection spring (24) on the piston rod (19) during the injection, generates a pressure on the distal end of the injection syringe (12) decreasing all the possible pressure at the level of the flange (38) of the injection syringe (12) . The automatic injection device (10) according to any one of the preceding claims, wherein the end sleeve (16) is attached around the distal end of the syringe holder (14), so that the carrier syringe (14) is slidable within the end sleeve (16). An automatic injection device (10) according to any one of the preceding claims, wherein the syringe holder (14) is of generally integral tubular shape, distinct from two half-shells joined to each other. The automatic injection device (10) according to any of the preceding claims, wherein the syringe holder (14) comprises, on an inner wall engageable with the injection syringe (12), a damping element (58) made of elastomeric material, for example in the form of an elastomer strip extending axially. 10. Automatic injection device (10) according to any one of the preceding claims, wherein the end sleeve (16) defines a housing for receiving a protective spring (15a, 15b), this housing also defining a recessed guide shape complementary to a relief guide shape provided on the syringe holder (14) to allow guiding during relative movement of the end sleeve (16) and the syringe holder (14).